A comparative study of acute responses to running in elite black and white marathon athletes
- Authors: Bosch, Andrew Norman
- Date: 1985
- Subjects: Athletics , Sports -- Physiological aspects , Running races , Marathon running , Marathon running -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5099 , http://hdl.handle.net/10962/d1001839 , Athletics , Sports -- Physiological aspects , Running races , Marathon running , Marathon running -- Physiological aspects
- Description: Experienced male marathon runners, 9 black and 10 white, with marathon times of 2 hours 45 minutes or faster, acted as subjects for the study, the purpose of which was to determine whether black runners are better suited to marathon running than whites. Body composition was determined by anthropometry. Maximal oxygen uptake (VO₂ max) and other physiological variables were measured during a continuous, speed-incremented treadmill protocol using a computer-aided data acquisition system. Subjects also ran a simulated marathon at 92.5% of the running speed at which the ventilatory threshold (VT) occurred. Physiological, gait and RPE variables were measured at 10 minute intervals during the marathon. Major findings are detailed below:- The VO₂, max averaged 60.4 ∓ 6.5 and 63.2 ∓ 2.9 mI. kg⁻¹.min⁻¹ in the black and white runners respectively and was highly correlated with best marathon race time (r = 0.86 and 0.85 respectively) and VT (r = 0.84 and 0.60 respectively) (p < 0.05). No significant differences existed between the groups in submaximal oxygen uptake (VO₂,) or % VO₂ max utilised at 16 km.hr⁻¹, but the estimated % VO₂ max utilised during a marathon race was higher in the black (89.0 ∓ 5.5%) than the white runners (81. 5 ∓ 3.1%) {p .( 0.05). The % VO₂ max utilised at 16 km.hr⁻¹ (84.8 ∓ 9.1 and 78.6 ∓ 5.8% in the black and white runners respectively) was significantly correlated with the % VO₂, max utilised while racing in the white (81.5 ∓ 3.1%) (r = 0.70) (p < 0.05), but not the black runners (89.0 ∓ 5.5%). The VT occurred at 82.7 ∓ 7.7 and 75.6 :∓ 6.2% VO₂; max in the black and white groups respectively (p < 0.05). Post-marathon blood lactic acid levels were lower in the black (1.30 ∓ 0.26 mmo1.l⁻¹) than the white runners (1.59 ∓ 0.20 mmol.l⁻¹). The respiratory exchange ratio (R) was higher in the blacks than whites when running at 16 km.hr ⁻¹ (1.03 ∓ 0.07 and 0.98 ∓ 0.03 respectively) and during the marathon (p < 0.05). There was no significant difference in pulmonary minute ventilation (Vı) between the groups, but breathing frequency (f) was higher in the black (59 ∓ 12 breaths.min⁻¹) than the white runners (45 ∓ 8 breaths. min⁻¹ ) and tidal volume (V⊤) lower in the black ( 1.33 ∓ 0.16 l.breath⁻¹) than the white runners (1.75 ∓ 0.36 I.breath⁻¹) during submaximal running at 16 km. hr⁻¹ (p < 0.05). The same trend was observed during the marathon run. During the time-course of the marathon f increased and V⊤ decreased In both groups (p < 0.05). Stroke volume decreased and heart rate increased In both groups during the time-course of the marathon (p< 0.05). Cardiac output was therefore maintained. Thermal responses were similar in the two groups. A significant increase in rectal temperature coincided with a decrease in skin temperature and may have been related to an increase in f (r = 0.86 and 0.67 in the blacks and whites respectively), H/R (r = 0.70 and 0.67 respectively) and "local" (leg) RPE (r = 0.84 and 0.82 respectively). It was concluded that black runners were able to run marathon races at a higher % VO₂ more than whites due to the blacks having lower blood lactic acid levels when running at a similar % VO₂ max. Given similar maximal oxygen uptakes, this would enable blacks to run faster. Cardiopulmonary adjustments occur during the time-course of a marathon which maintains Q and Vı
- Full Text:
- Date Issued: 1985
- Authors: Bosch, Andrew Norman
- Date: 1985
- Subjects: Athletics , Sports -- Physiological aspects , Running races , Marathon running , Marathon running -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5099 , http://hdl.handle.net/10962/d1001839 , Athletics , Sports -- Physiological aspects , Running races , Marathon running , Marathon running -- Physiological aspects
- Description: Experienced male marathon runners, 9 black and 10 white, with marathon times of 2 hours 45 minutes or faster, acted as subjects for the study, the purpose of which was to determine whether black runners are better suited to marathon running than whites. Body composition was determined by anthropometry. Maximal oxygen uptake (VO₂ max) and other physiological variables were measured during a continuous, speed-incremented treadmill protocol using a computer-aided data acquisition system. Subjects also ran a simulated marathon at 92.5% of the running speed at which the ventilatory threshold (VT) occurred. Physiological, gait and RPE variables were measured at 10 minute intervals during the marathon. Major findings are detailed below:- The VO₂, max averaged 60.4 ∓ 6.5 and 63.2 ∓ 2.9 mI. kg⁻¹.min⁻¹ in the black and white runners respectively and was highly correlated with best marathon race time (r = 0.86 and 0.85 respectively) and VT (r = 0.84 and 0.60 respectively) (p < 0.05). No significant differences existed between the groups in submaximal oxygen uptake (VO₂,) or % VO₂ max utilised at 16 km.hr⁻¹, but the estimated % VO₂ max utilised during a marathon race was higher in the black (89.0 ∓ 5.5%) than the white runners (81. 5 ∓ 3.1%) {p .( 0.05). The % VO₂ max utilised at 16 km.hr⁻¹ (84.8 ∓ 9.1 and 78.6 ∓ 5.8% in the black and white runners respectively) was significantly correlated with the % VO₂, max utilised while racing in the white (81.5 ∓ 3.1%) (r = 0.70) (p < 0.05), but not the black runners (89.0 ∓ 5.5%). The VT occurred at 82.7 ∓ 7.7 and 75.6 :∓ 6.2% VO₂; max in the black and white groups respectively (p < 0.05). Post-marathon blood lactic acid levels were lower in the black (1.30 ∓ 0.26 mmo1.l⁻¹) than the white runners (1.59 ∓ 0.20 mmol.l⁻¹). The respiratory exchange ratio (R) was higher in the blacks than whites when running at 16 km.hr ⁻¹ (1.03 ∓ 0.07 and 0.98 ∓ 0.03 respectively) and during the marathon (p < 0.05). There was no significant difference in pulmonary minute ventilation (Vı) between the groups, but breathing frequency (f) was higher in the black (59 ∓ 12 breaths.min⁻¹) than the white runners (45 ∓ 8 breaths. min⁻¹ ) and tidal volume (V⊤) lower in the black ( 1.33 ∓ 0.16 l.breath⁻¹) than the white runners (1.75 ∓ 0.36 I.breath⁻¹) during submaximal running at 16 km. hr⁻¹ (p < 0.05). The same trend was observed during the marathon run. During the time-course of the marathon f increased and V⊤ decreased In both groups (p < 0.05). Stroke volume decreased and heart rate increased In both groups during the time-course of the marathon (p< 0.05). Cardiac output was therefore maintained. Thermal responses were similar in the two groups. A significant increase in rectal temperature coincided with a decrease in skin temperature and may have been related to an increase in f (r = 0.86 and 0.67 in the blacks and whites respectively), H/R (r = 0.70 and 0.67 respectively) and "local" (leg) RPE (r = 0.84 and 0.82 respectively). It was concluded that black runners were able to run marathon races at a higher % VO₂ more than whites due to the blacks having lower blood lactic acid levels when running at a similar % VO₂ max. Given similar maximal oxygen uptakes, this would enable blacks to run faster. Cardiopulmonary adjustments occur during the time-course of a marathon which maintains Q and Vı
- Full Text:
- Date Issued: 1985
A comparison between the responsiveness of selected physiological and subjective mental workload indicators during real-world driving scenarios
- Authors: Schmidtke, Nadia-Jasmine
- Date: 2020
- Subjects: Automobile driving -- Physiological aspects , Automobile driving -- Psychological aspects , Automobile drivers -- Health and hygiene , Mental fatigue , Mental work -- Case studies
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/148115 , vital:38711
- Description: Sub-optimal levels of mental workload in automobile drivers is a risk factor for road accidents. However, mental workload as a construct cannot be directly measured. Common indicators of mental workload include heart rate frequency and variability, eye motion and subjective rating tools. Namely, the National Aeronautics and Space Administration Task Load Index (NASA-TLX), its modified, unweighted version called the Raw-TLX, and the Rating Scale of Mental Effort (RSME). Comparisons between the suitability and responsiveness of these mental workload indicators have been almost exclusively examined in driving simulators. However, real-world driving research is important as even high-fidelity simulators cannot capture the complexity of driving scenarios. Hence, this research aimed to compare the suitability and responsiveness of these mental workload indicators in response to real-world driving scenarios. Six participants drove along a set route for an hour while wearing a heart rate monitor and eye tracker. A dashcam was used to capture footage of the different driving scenarios encountered. The set route comprised of driving through the industrial, residential, provincial main road and Rhodes University campus areas. RSME scores were taken during brief stops after driving though each zone. The NASA-TLX questionnaire was administered on completion of the drive and analysed later as the modified Raw-TLX version. The data collected in response to the encountered driving scenarios were sorted into three meta-groupings. (1) Data was segmented according to the different areas that participants drove through. This was termed Area Events and were long duration scenarios of between five and thirty minutes. These driving scenarios were further segmented into two meta-groups with short duration driving scenarios (< 90 seconds). (2) The Common Events meta-group consisted of driving scenarios that were encountered by all participants. These were scenarios were anticipated by drivers. (3) The All Events meta-group was grouped according to all the driving scenarios that were encountered by participants. It consisted of both anticipated and unanticipated driving scenarios of short durations. Data were further analysed using a method of systematically selecting a threshold value for each mental workload indicator. Responses to driving scenarios which surpassed the threshold were considered indicative of an increase in mental workload. The total frequency of higher mental workload events was used as a determiner responsiveness (or ‘sensitivity’) for each mental workload indicator. Mental workload indicators were evaluated for their responsiveness and suitability for assessing mental workload. Results found blink frequency to be a responsive mental workload indicator for all categories of driving scenarios. Blink frequency and duration were the most responsive short duration mental workload indicators. Furthermore, the indicators were able to distinguish between higher and lower mental workload driving scenarios. However, blink parameters are also sensitive to driver fatigue and drowsiness. Further research on distinguishing mental workload from that of fatigue in response to real-world driving was recommended. Pupil diameter, fixation duration, saccade saccade duration and saccade amplitude were found to be responsive short duration mental workload indicators. However, these measures were not determined to be suitable for real-world driving applications. Pupil diameter was confounded by changing illumination levels. Fixation and saccade responses were confounded by the driving task itself as gaze could not be accounted for. For long duration driving scenarios heart rate frequency, heart rate variability: high-frequency power, blink frequency and RSME were found to be responsive and suitable MWL indicators. The Raw-TLX results could not be assessed for responsiveness as it was administered once. However, it was confirmed as a suitable cumulative mental workload indicator in the application of real-world driving. The moderate levels of workload reported by participants agreed with the experimental protocol that prevented inducing sub-optimal mental workload. Blink frequency shows promise as a responsive and suitable mental workload indicator for different types of driving scenarios. More research is needed regarding the assessment of mental workload during short durations using blink frequency and blink duration. For driving durations between five and thirty minutes long, further research into heart rate frequency, heart rate variability: high frequency power, and the RSME was recommended.
- Full Text:
- Date Issued: 2020
- Authors: Schmidtke, Nadia-Jasmine
- Date: 2020
- Subjects: Automobile driving -- Physiological aspects , Automobile driving -- Psychological aspects , Automobile drivers -- Health and hygiene , Mental fatigue , Mental work -- Case studies
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/148115 , vital:38711
- Description: Sub-optimal levels of mental workload in automobile drivers is a risk factor for road accidents. However, mental workload as a construct cannot be directly measured. Common indicators of mental workload include heart rate frequency and variability, eye motion and subjective rating tools. Namely, the National Aeronautics and Space Administration Task Load Index (NASA-TLX), its modified, unweighted version called the Raw-TLX, and the Rating Scale of Mental Effort (RSME). Comparisons between the suitability and responsiveness of these mental workload indicators have been almost exclusively examined in driving simulators. However, real-world driving research is important as even high-fidelity simulators cannot capture the complexity of driving scenarios. Hence, this research aimed to compare the suitability and responsiveness of these mental workload indicators in response to real-world driving scenarios. Six participants drove along a set route for an hour while wearing a heart rate monitor and eye tracker. A dashcam was used to capture footage of the different driving scenarios encountered. The set route comprised of driving through the industrial, residential, provincial main road and Rhodes University campus areas. RSME scores were taken during brief stops after driving though each zone. The NASA-TLX questionnaire was administered on completion of the drive and analysed later as the modified Raw-TLX version. The data collected in response to the encountered driving scenarios were sorted into three meta-groupings. (1) Data was segmented according to the different areas that participants drove through. This was termed Area Events and were long duration scenarios of between five and thirty minutes. These driving scenarios were further segmented into two meta-groups with short duration driving scenarios (< 90 seconds). (2) The Common Events meta-group consisted of driving scenarios that were encountered by all participants. These were scenarios were anticipated by drivers. (3) The All Events meta-group was grouped according to all the driving scenarios that were encountered by participants. It consisted of both anticipated and unanticipated driving scenarios of short durations. Data were further analysed using a method of systematically selecting a threshold value for each mental workload indicator. Responses to driving scenarios which surpassed the threshold were considered indicative of an increase in mental workload. The total frequency of higher mental workload events was used as a determiner responsiveness (or ‘sensitivity’) for each mental workload indicator. Mental workload indicators were evaluated for their responsiveness and suitability for assessing mental workload. Results found blink frequency to be a responsive mental workload indicator for all categories of driving scenarios. Blink frequency and duration were the most responsive short duration mental workload indicators. Furthermore, the indicators were able to distinguish between higher and lower mental workload driving scenarios. However, blink parameters are also sensitive to driver fatigue and drowsiness. Further research on distinguishing mental workload from that of fatigue in response to real-world driving was recommended. Pupil diameter, fixation duration, saccade saccade duration and saccade amplitude were found to be responsive short duration mental workload indicators. However, these measures were not determined to be suitable for real-world driving applications. Pupil diameter was confounded by changing illumination levels. Fixation and saccade responses were confounded by the driving task itself as gaze could not be accounted for. For long duration driving scenarios heart rate frequency, heart rate variability: high-frequency power, blink frequency and RSME were found to be responsive and suitable MWL indicators. The Raw-TLX results could not be assessed for responsiveness as it was administered once. However, it was confirmed as a suitable cumulative mental workload indicator in the application of real-world driving. The moderate levels of workload reported by participants agreed with the experimental protocol that prevented inducing sub-optimal mental workload. Blink frequency shows promise as a responsive and suitable mental workload indicator for different types of driving scenarios. More research is needed regarding the assessment of mental workload during short durations using blink frequency and blink duration. For driving durations between five and thirty minutes long, further research into heart rate frequency, heart rate variability: high frequency power, and the RSME was recommended.
- Full Text:
- Date Issued: 2020
A comparison of muscle fatigue responses between static and quasi-static exertions
- Authors: Nel, Conrad
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3475 , vital:20502
- Description: Background: This study examined localized muscle fatigue responses from sub-maximal quasi-static work protocols and additionally how it compares to purely static work. The goal was to produce research that enhances the understanding of the demands on muscles during manual work to aid in preventing injuries stemming from localized muscle fatigue. Injury rates remain a problem in manual labour sectors, particularly for the lower back and shoulder regions for the manufacturing, service and construction sectors, and for knee and elbow flexors in the sports sector. Few studies have looked at quasi-static work and what the resulting fatigue characteristics are, especially when compared to purely static or purely dynamic work. This comparison is particularly important due to the fact that risk assessment tools that are currently utilized to assess risk in the working environment are based on fatigue studies that focus on purely static or purely dynamic work. This requires attention as many working situations are neither static nor dynamic, but rather quasi-static in nature, with aspects of both dynamic and static muscle components. The scope of this study only encompasses the comparison between purely static and quasi-static work. Objectives: This study had two objectives, firstly, to determine what the fatigue characteristics of quasi-static work are and how it compares to fully static work. Secondly, to determine whether an underlying static component within an otherwise dynamic muscle force affects localized muscle fatigue compared to quasi-static work that has equal amounts of effort but with no underlying static component. Methods: Four experimental conditions were tested, each on four muscles, namely the medial deltoid, bicep brachii, bicep femoris and erector spinae muscles. To test the two objectives of this study, 16 volunteers performed a five minute fatigue protocol, that either entailed a fully static condition which involved: 1) producing a steady force at 25 percent of maximum voluntary force, 2) a quasi-static condition with fully dynamic muscle force that alternates the required force level between zero and 50 percent of maximum force, 3) a quasi-static condition with an underlying static component of five percent of maximum force, or 4) a quasi-static condition with a large underlying static component of 15 percent of maximum force. All the experimental conditions in this study had the same average workload of 25 percent of maximum voluntary force over time and thus total workload. The dependant variables of interest were ratings of perceived exertion, changes in muscle fibre recruitment (% of maximum EMG activity), maximum force and center frequency from a spectral analysis of the surface electromyography. These were measured throughout the protocols at one minute intervals to determine how muscle fatigue progressed, and how the fatigue responses differed between conditions. Results: The data from comparing fully static and quasi-static work showed that of the variables measured, the rating of perceived exertion (RPE) and maximum force data indicated that for bicep brachii and bicep femoris muscles, fully static work is more fatiguing than work that alternates between zero and 50 percent of maximum force. The results for the medial deltoid and erector spinae muscles were inconclusive. The findings regarding the comparison between quasi-static conditions with and without an underlying static component revealed that an underlying static component results in greater fatigue when compared to a quasi-static condition with no static component. The results may also suggest that a larger static component coupled with a smaller peak force results in less fatigue than a condition with a small underlying static component coupled with a higher peak force in some scenarios, provided total work is kept constant. All conditions had to have the same workload in order to be validly compared and thus the condition with a larger underlying static component had a lower peak force compared to the condition with no underlying static component or the condition with a small underlying static component. Conclusions: This study presented evidence that quasi-static work does not induce fatigue when measured by RPE and drop in maximum force in the same way as static work. Additionally, the results indicate that a larger underlying static component does not necessarily fatigue a muscle faster if the overall workload is kept constant. However, the results do suggest that any underlying static component will increase the demand on a muscle when compared to a muscle exertion with no static component. When considering the available literature on how muscles fatigue during low level static contractions, the current understanding is that the larger the force during a static contraction, the faster the onset of fatigue and decrements in performance occur. The results of this study suggest that this same relationship cannot be applied to quasi-static work where an underlying static component is part of an otherwise dynamic muscle force. Thus total workload or peak force may play a larger role than the static muscle exertion in some scenarios.
- Full Text:
- Date Issued: 2016
- Authors: Nel, Conrad
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3475 , vital:20502
- Description: Background: This study examined localized muscle fatigue responses from sub-maximal quasi-static work protocols and additionally how it compares to purely static work. The goal was to produce research that enhances the understanding of the demands on muscles during manual work to aid in preventing injuries stemming from localized muscle fatigue. Injury rates remain a problem in manual labour sectors, particularly for the lower back and shoulder regions for the manufacturing, service and construction sectors, and for knee and elbow flexors in the sports sector. Few studies have looked at quasi-static work and what the resulting fatigue characteristics are, especially when compared to purely static or purely dynamic work. This comparison is particularly important due to the fact that risk assessment tools that are currently utilized to assess risk in the working environment are based on fatigue studies that focus on purely static or purely dynamic work. This requires attention as many working situations are neither static nor dynamic, but rather quasi-static in nature, with aspects of both dynamic and static muscle components. The scope of this study only encompasses the comparison between purely static and quasi-static work. Objectives: This study had two objectives, firstly, to determine what the fatigue characteristics of quasi-static work are and how it compares to fully static work. Secondly, to determine whether an underlying static component within an otherwise dynamic muscle force affects localized muscle fatigue compared to quasi-static work that has equal amounts of effort but with no underlying static component. Methods: Four experimental conditions were tested, each on four muscles, namely the medial deltoid, bicep brachii, bicep femoris and erector spinae muscles. To test the two objectives of this study, 16 volunteers performed a five minute fatigue protocol, that either entailed a fully static condition which involved: 1) producing a steady force at 25 percent of maximum voluntary force, 2) a quasi-static condition with fully dynamic muscle force that alternates the required force level between zero and 50 percent of maximum force, 3) a quasi-static condition with an underlying static component of five percent of maximum force, or 4) a quasi-static condition with a large underlying static component of 15 percent of maximum force. All the experimental conditions in this study had the same average workload of 25 percent of maximum voluntary force over time and thus total workload. The dependant variables of interest were ratings of perceived exertion, changes in muscle fibre recruitment (% of maximum EMG activity), maximum force and center frequency from a spectral analysis of the surface electromyography. These were measured throughout the protocols at one minute intervals to determine how muscle fatigue progressed, and how the fatigue responses differed between conditions. Results: The data from comparing fully static and quasi-static work showed that of the variables measured, the rating of perceived exertion (RPE) and maximum force data indicated that for bicep brachii and bicep femoris muscles, fully static work is more fatiguing than work that alternates between zero and 50 percent of maximum force. The results for the medial deltoid and erector spinae muscles were inconclusive. The findings regarding the comparison between quasi-static conditions with and without an underlying static component revealed that an underlying static component results in greater fatigue when compared to a quasi-static condition with no static component. The results may also suggest that a larger static component coupled with a smaller peak force results in less fatigue than a condition with a small underlying static component coupled with a higher peak force in some scenarios, provided total work is kept constant. All conditions had to have the same workload in order to be validly compared and thus the condition with a larger underlying static component had a lower peak force compared to the condition with no underlying static component or the condition with a small underlying static component. Conclusions: This study presented evidence that quasi-static work does not induce fatigue when measured by RPE and drop in maximum force in the same way as static work. Additionally, the results indicate that a larger underlying static component does not necessarily fatigue a muscle faster if the overall workload is kept constant. However, the results do suggest that any underlying static component will increase the demand on a muscle when compared to a muscle exertion with no static component. When considering the available literature on how muscles fatigue during low level static contractions, the current understanding is that the larger the force during a static contraction, the faster the onset of fatigue and decrements in performance occur. The results of this study suggest that this same relationship cannot be applied to quasi-static work where an underlying static component is part of an otherwise dynamic muscle force. Thus total workload or peak force may play a larger role than the static muscle exertion in some scenarios.
- Full Text:
- Date Issued: 2016
A field investigation into the impact of task demands on worker responses in the South African forestry silviculture sector
- Authors: Parker, Rhiannon Jennifer
- Date: 2014
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Blue collar workers -- South Africa -- KwaZulu-Natal , Manual work -- South Africa -- KwaZulu-Natal , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5157 , http://hdl.handle.net/10962/d1015645
- Description: Background: In South Africa, limited research has focused on the task demands and workers responses associated with forestry silviculture work, particularly pitting and planting. The methods currently in use are manual, but despite our lack of understanding of the existing demands, advances in forestry engineering have resulted in an introduction of semi-mechanised versions of these tasks. This project aimed to compare the task demands of silviculture tasks using the current manual techniques and the more modern, semi-mechanised techniques. Methods: A holistic investigation focused on the worker characteristics of a sample of black male pitters and black female planters from the Kwa-Zulu Natal forestry industry, as well as biomechanical (spinal kinematics and L5/S1 forces), physiological (heart rate, oxygen consumption and energy expenditure) and psychophysical (ratings of perceived exertion and body discomfort) responses associated with manual and semi-mechanised pitting and planting. Results: The pitting task saw significant improvements in the spinal kinematic measures as a result of the increased mechanisation, with eight of the 16 recorded variables decreasing to a lower level of risk classification. Physiologically, the manual task was associated with a mean heart rate of 157 bt.min⁻¹ and absolute energy expenditure of 11.27 kcal.min⁻¹, which were not found to be significantly different to the values of 143 bt.min⁻¹ and 9.8 kcal.min⁻¹ recorded during the semi-mechanised technique. Psychophysical responses indicated that the workers perceived manual pitting to be more physically demanding than the semi-mechanised method. The manual and semi-mechanised planting tasks were, in general, found to be acceptable from a spinal kinematics perspective, with the majority of variables classified as low risk. However, the maximum sagittal angle was reduced by more than 20 degrees as a result of the new equipment. The physiological and psychophysical demands associated with manual planting were found to be within acceptable limits. Conclusion: In terms of pitting, it can tentatively be concluded that the semi-mechanised technique is better than the manual one, based on the biomechanical and psychophysical findings, however physiological demands require further investigation. When considering the planting techniques, the semi-mechanised method showed a slight improvement from the biomechanical perspective, but further physiological and psychophysical investigations are needed.
- Full Text:
- Date Issued: 2014
- Authors: Parker, Rhiannon Jennifer
- Date: 2014
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Blue collar workers -- South Africa -- KwaZulu-Natal , Manual work -- South Africa -- KwaZulu-Natal , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5157 , http://hdl.handle.net/10962/d1015645
- Description: Background: In South Africa, limited research has focused on the task demands and workers responses associated with forestry silviculture work, particularly pitting and planting. The methods currently in use are manual, but despite our lack of understanding of the existing demands, advances in forestry engineering have resulted in an introduction of semi-mechanised versions of these tasks. This project aimed to compare the task demands of silviculture tasks using the current manual techniques and the more modern, semi-mechanised techniques. Methods: A holistic investigation focused on the worker characteristics of a sample of black male pitters and black female planters from the Kwa-Zulu Natal forestry industry, as well as biomechanical (spinal kinematics and L5/S1 forces), physiological (heart rate, oxygen consumption and energy expenditure) and psychophysical (ratings of perceived exertion and body discomfort) responses associated with manual and semi-mechanised pitting and planting. Results: The pitting task saw significant improvements in the spinal kinematic measures as a result of the increased mechanisation, with eight of the 16 recorded variables decreasing to a lower level of risk classification. Physiologically, the manual task was associated with a mean heart rate of 157 bt.min⁻¹ and absolute energy expenditure of 11.27 kcal.min⁻¹, which were not found to be significantly different to the values of 143 bt.min⁻¹ and 9.8 kcal.min⁻¹ recorded during the semi-mechanised technique. Psychophysical responses indicated that the workers perceived manual pitting to be more physically demanding than the semi-mechanised method. The manual and semi-mechanised planting tasks were, in general, found to be acceptable from a spinal kinematics perspective, with the majority of variables classified as low risk. However, the maximum sagittal angle was reduced by more than 20 degrees as a result of the new equipment. The physiological and psychophysical demands associated with manual planting were found to be within acceptable limits. Conclusion: In terms of pitting, it can tentatively be concluded that the semi-mechanised technique is better than the manual one, based on the biomechanical and psychophysical findings, however physiological demands require further investigation. When considering the planting techniques, the semi-mechanised method showed a slight improvement from the biomechanical perspective, but further physiological and psychophysical investigations are needed.
- Full Text:
- Date Issued: 2014
A field investigation of physical workloads imposed on harvesters in South African forestry
- Authors: Christie, Candice Jo-Anne
- Date: 2006
- Subjects: Forests and forestry -- South Africa Employees -- Workload Forest products industry -- South Africa Work -- Physiological aspects Heart rate monitoring Foresters -- South Africa -- Workload Oxygen -- Physiological transport
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5122 , http://hdl.handle.net/10962/d1005200
- Description: The focus of this field investigation was an analysis of the work demands being placed on South African forestry workers, in particular Chainsaw Operators and Stackers. Working postures, physiological and perceptual responses were assessed on a sample of 58 workers (29 Chainsaw Operators and 29 Stackers) during a ‘normal’ working shift. Body mass was measured before and after work in order to determine dehydration levels. Polar heart rate monitors were fitted to six workers each day over a period of two weeks in order to record ‘working’ heart rates. Fluid and food intake was monitored and recorded during this initial data collection phase. The Rating of Perceived Exertion and Body Discomfort Scales were explained in Zulu, their native language, and workers were asked to rate their perceptions of effort at regular intervals during work, while areas and intensity of body discomfort was obtained on completion of work. After completing a work shift, a 30 minute ‘recovery’ period was given, thereafter a portable ergospirometer, the k4b², was attached to the worker who then participated in a progressive, submaximal step test for the purpose of establishing individual, and group, heart rate-oxygen uptake (HR/VO[subscript 2]) regressions for predicting oxygen uptake from ‘working’ heart rate responses. These procedures were repeated four weeks later following the introduction of a fluid and nutritional supplement during work which was delivered to the workers while they were executing their tasks. The results revealed awkward working postures with a predominance of trunk flexion during all the harvesting tasks; these postures, adopted for long periods during work, are very likely to lead to the development of musculoskeletal injuries. The mean working heart rates were 123.3 bt.min[superscript (-1)] and 117.6 bt.min[superscript (-1)] during chainsaw operations and stacking respectively. During the step test, the mean heart rate and oxygen uptake responses were 127.9 bt.min[superscript (-1)] and 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Chainsaw Operators) and 116.9 bt.min[superscript (-1)] and 24.0 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Stackers), revealing no significant difference between the ‘working’ heart rates and the heart rates recorded during the step test. Physiological responses were analyzed over the full work shift which was divided into four quarters. Heart rate and oxygen uptake were significantly higher during the last half of the Chainsaw Operators’ work shift compared to the first half. Heart rate increased from 120.7 bt.min[superscript (-1)] during the first quarter to 127.4 bt.min[superscript (-1)] during the last quarter of chainsaw operations. Likewise, oxygen uptake increased from 19.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] to 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] from the first to the last quarter of work. During stacking the heart rate (mean of 117.6 bt.min[superscript (-1)]) and oxygen uptake (mean of 24.6 ml.kg[superscript (-1)].min[superscript (-1)]) responses remained stable over the duration of the working shift. Workers lost, on average, 2.8% body mass during work while felling and cross-cutting and 3.6% during stacking. This reduced significantly to a loss of 0.4% body mass when re-tested following the introduction of water and food during the work period. Likewise, the energy deficit was significantly improved due to the introduction of a nutritional supplement. Pre-intervention the deficit was 8861.8 kJ (Chainsaw Operators) and 8804.2 kJ (Stackers) while in the post-intervention phase this deficit was reduced by approximately 50% for both groups of workers.
- Full Text:
- Date Issued: 2006
- Authors: Christie, Candice Jo-Anne
- Date: 2006
- Subjects: Forests and forestry -- South Africa Employees -- Workload Forest products industry -- South Africa Work -- Physiological aspects Heart rate monitoring Foresters -- South Africa -- Workload Oxygen -- Physiological transport
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5122 , http://hdl.handle.net/10962/d1005200
- Description: The focus of this field investigation was an analysis of the work demands being placed on South African forestry workers, in particular Chainsaw Operators and Stackers. Working postures, physiological and perceptual responses were assessed on a sample of 58 workers (29 Chainsaw Operators and 29 Stackers) during a ‘normal’ working shift. Body mass was measured before and after work in order to determine dehydration levels. Polar heart rate monitors were fitted to six workers each day over a period of two weeks in order to record ‘working’ heart rates. Fluid and food intake was monitored and recorded during this initial data collection phase. The Rating of Perceived Exertion and Body Discomfort Scales were explained in Zulu, their native language, and workers were asked to rate their perceptions of effort at regular intervals during work, while areas and intensity of body discomfort was obtained on completion of work. After completing a work shift, a 30 minute ‘recovery’ period was given, thereafter a portable ergospirometer, the k4b², was attached to the worker who then participated in a progressive, submaximal step test for the purpose of establishing individual, and group, heart rate-oxygen uptake (HR/VO[subscript 2]) regressions for predicting oxygen uptake from ‘working’ heart rate responses. These procedures were repeated four weeks later following the introduction of a fluid and nutritional supplement during work which was delivered to the workers while they were executing their tasks. The results revealed awkward working postures with a predominance of trunk flexion during all the harvesting tasks; these postures, adopted for long periods during work, are very likely to lead to the development of musculoskeletal injuries. The mean working heart rates were 123.3 bt.min[superscript (-1)] and 117.6 bt.min[superscript (-1)] during chainsaw operations and stacking respectively. During the step test, the mean heart rate and oxygen uptake responses were 127.9 bt.min[superscript (-1)] and 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Chainsaw Operators) and 116.9 bt.min[superscript (-1)] and 24.0 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] (Stackers), revealing no significant difference between the ‘working’ heart rates and the heart rates recorded during the step test. Physiological responses were analyzed over the full work shift which was divided into four quarters. Heart rate and oxygen uptake were significantly higher during the last half of the Chainsaw Operators’ work shift compared to the first half. Heart rate increased from 120.7 bt.min[superscript (-1)] during the first quarter to 127.4 bt.min[superscript (-1)] during the last quarter of chainsaw operations. Likewise, oxygen uptake increased from 19.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] to 22.9 mlO[subscript 2].kg[superscript (-1)].min[superscript (-1)] from the first to the last quarter of work. During stacking the heart rate (mean of 117.6 bt.min[superscript (-1)]) and oxygen uptake (mean of 24.6 ml.kg[superscript (-1)].min[superscript (-1)]) responses remained stable over the duration of the working shift. Workers lost, on average, 2.8% body mass during work while felling and cross-cutting and 3.6% during stacking. This reduced significantly to a loss of 0.4% body mass when re-tested following the introduction of water and food during the work period. Likewise, the energy deficit was significantly improved due to the introduction of a nutritional supplement. Pre-intervention the deficit was 8861.8 kJ (Chainsaw Operators) and 8804.2 kJ (Stackers) while in the post-intervention phase this deficit was reduced by approximately 50% for both groups of workers.
- Full Text:
- Date Issued: 2006
A holistic investigation of amateur batters performance responses to a century protocol: a focused cognitive perspective
- Authors: Goble, David
- Date: 2017
- Subjects: Cricket -- Batting -- Physiological aspects , Cricket players -- Physiology , Cricket players -- Health and hygiene , Cognition -- Testing , Neurophysiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/40725 , vital:25020
- Description: No cognitive study has implemented an exercise modality that requires both physical effort and cognitive control, therefore, the effects of such exercise are unknown. Additionally, no studies have investigated how prolonged batting impacts cognitive functioning nor how physical responses and cognitive functioning are related while batting. At intensities of 6070 percent heart rate maximum, acute and prolonged bouts of physical activity have been shown to improve cognitive functioning. At higher intensities, the beneficial effects are minimal and in some cases performance is impaired. Therefore, the aim of this investigation was to determine how prolonged intermittent batting (a task that requires high muscular and cardiovascular loads but also continuous cognitive control) affects cognitive, physiological, physical and biophysical responses in amateur batters. Further aims included to test the reliability of the method employed in assessing these responses. To answer this question, the investigation was separated into three studies: phase 1 (a large-scale pilot) and phase 2 and 3 (a repeated measures test-retest hypothesis). In each phase, batters completed the 30 over BATEX simulation, which replicated the demands of scoring a one-day international century. To establish physiological, physical and perceptual strain; heart rate, sprint times and perceived exertion data were collected each over. Changes in body mass over time were compared to determine the effects of fluid loss on cognitive performance. Before, during and after the simulation, psychomotor function, visual attention, working memory, visual learning and memory as well as executive functions were assessed (CogState brief test battery). During cognitive assessments, heart rate and heart rate variability parameters were sampled so that autonomic modulation of the heart could be determined. The methodological differences between phase 1 and phase 2 and 3, were (respectively); the frequency of cognitive assessments (five vs. three), the samples used (15 schoolboy vs. 16 academy batters), hydration protocols (250ml of Energade vs. water ad libitum) and a singular change in a physical dependent variable (batting accuracy vs. vertical jump). In schoolboy and academy batters, the prolonged batting simulation placed significant strain on the cardiovascular and muscular subsystems; increasing heart rate (p<0.01), decreasing body mass (p<0.01) and deteriorating sprint performance (p<0.01) over time. In each sample, batters’ perceived exertion increased significantly (p<0.01) and exertion was highest in the final over of the protocol. Interestingly, the changes in cardiovascular and muscular responses were larger in schoolboy batters. While the cognitive performance decrements over time were not significant in academy batters (p>0.05; d<0.2), the magnitude of impairment in psychomotor function (p>0.05; d = 0.37), visual attention (p>0.05; d = 0.56), working memory (p>0.05; d = 0.61) and executive function (p>0.05; d = 0.58) was larger in schoolboy batters. In both samples, the simulation altered the modulation of heart rate significantly. Heart rate variability decreased linearly with time spent batting (p<0.01; d>0.8). During cognitive assessments, heart rate variability increased with time-on-task, where responses were significantly higher (p<0.05) in the last task of the battery compared to the first. Importantly, the results of the retest phase were the same as in the test phase and only two condition effects were observed; (i) heart rate (retest lower: p<0.04;d = 0.39), (ii) body mass (retest lower: p<0.03;d = 0.09). A task-related condition effect in heart rate variability (PNN30) was also observed (retest higher: p<0.03; d = not calculated). Resultantly, the test-retest reliability of phase 2 and 3 was high. The results indicate that prolonged intermittent batting at an intensity of 64-77 %HRmax impaired cognitive functioning in amateur batters. However, the cardiovascular and muscular strain induced by prolonged intermittent batting and its effects on cognitive functioning are mediated by intrinsic and extrinsic factors (age, training status, playing experience and hydration). Therefore, while prolonged batting has similar effects on cognitive functioning as acute bouts of physical activity, they do not share the same relationship. The author hypothesises that the continuous cognitive component inherent in prolonged batting mitigates the beneficial effects of physical activity, as demonstrated previously. Future research is needed to elucidate this relationship. Additionally, player experience affects the way in which batters regulate performance while batting; which also affects the rate of and magnitude of impairment during batting. Finally, the methodological limitations of this study provide direction for future research into batting.
- Full Text:
- Date Issued: 2017
- Authors: Goble, David
- Date: 2017
- Subjects: Cricket -- Batting -- Physiological aspects , Cricket players -- Physiology , Cricket players -- Health and hygiene , Cognition -- Testing , Neurophysiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/40725 , vital:25020
- Description: No cognitive study has implemented an exercise modality that requires both physical effort and cognitive control, therefore, the effects of such exercise are unknown. Additionally, no studies have investigated how prolonged batting impacts cognitive functioning nor how physical responses and cognitive functioning are related while batting. At intensities of 6070 percent heart rate maximum, acute and prolonged bouts of physical activity have been shown to improve cognitive functioning. At higher intensities, the beneficial effects are minimal and in some cases performance is impaired. Therefore, the aim of this investigation was to determine how prolonged intermittent batting (a task that requires high muscular and cardiovascular loads but also continuous cognitive control) affects cognitive, physiological, physical and biophysical responses in amateur batters. Further aims included to test the reliability of the method employed in assessing these responses. To answer this question, the investigation was separated into three studies: phase 1 (a large-scale pilot) and phase 2 and 3 (a repeated measures test-retest hypothesis). In each phase, batters completed the 30 over BATEX simulation, which replicated the demands of scoring a one-day international century. To establish physiological, physical and perceptual strain; heart rate, sprint times and perceived exertion data were collected each over. Changes in body mass over time were compared to determine the effects of fluid loss on cognitive performance. Before, during and after the simulation, psychomotor function, visual attention, working memory, visual learning and memory as well as executive functions were assessed (CogState brief test battery). During cognitive assessments, heart rate and heart rate variability parameters were sampled so that autonomic modulation of the heart could be determined. The methodological differences between phase 1 and phase 2 and 3, were (respectively); the frequency of cognitive assessments (five vs. three), the samples used (15 schoolboy vs. 16 academy batters), hydration protocols (250ml of Energade vs. water ad libitum) and a singular change in a physical dependent variable (batting accuracy vs. vertical jump). In schoolboy and academy batters, the prolonged batting simulation placed significant strain on the cardiovascular and muscular subsystems; increasing heart rate (p<0.01), decreasing body mass (p<0.01) and deteriorating sprint performance (p<0.01) over time. In each sample, batters’ perceived exertion increased significantly (p<0.01) and exertion was highest in the final over of the protocol. Interestingly, the changes in cardiovascular and muscular responses were larger in schoolboy batters. While the cognitive performance decrements over time were not significant in academy batters (p>0.05; d<0.2), the magnitude of impairment in psychomotor function (p>0.05; d = 0.37), visual attention (p>0.05; d = 0.56), working memory (p>0.05; d = 0.61) and executive function (p>0.05; d = 0.58) was larger in schoolboy batters. In both samples, the simulation altered the modulation of heart rate significantly. Heart rate variability decreased linearly with time spent batting (p<0.01; d>0.8). During cognitive assessments, heart rate variability increased with time-on-task, where responses were significantly higher (p<0.05) in the last task of the battery compared to the first. Importantly, the results of the retest phase were the same as in the test phase and only two condition effects were observed; (i) heart rate (retest lower: p<0.04;d = 0.39), (ii) body mass (retest lower: p<0.03;d = 0.09). A task-related condition effect in heart rate variability (PNN30) was also observed (retest higher: p<0.03; d = not calculated). Resultantly, the test-retest reliability of phase 2 and 3 was high. The results indicate that prolonged intermittent batting at an intensity of 64-77 %HRmax impaired cognitive functioning in amateur batters. However, the cardiovascular and muscular strain induced by prolonged intermittent batting and its effects on cognitive functioning are mediated by intrinsic and extrinsic factors (age, training status, playing experience and hydration). Therefore, while prolonged batting has similar effects on cognitive functioning as acute bouts of physical activity, they do not share the same relationship. The author hypothesises that the continuous cognitive component inherent in prolonged batting mitigates the beneficial effects of physical activity, as demonstrated previously. Future research is needed to elucidate this relationship. Additionally, player experience affects the way in which batters regulate performance while batting; which also affects the rate of and magnitude of impairment during batting. Finally, the methodological limitations of this study provide direction for future research into batting.
- Full Text:
- Date Issued: 2017
A laboratory simulation investigating the impact of sunglass tint on the catching performance of cricket fielders
- Authors: Nellemann, Stacy Amanda
- Date: 2022-04-06
- Subjects: Sunglasses , Cricket Physiological aspects , Cricket players , Glare , Vision , Contrast sensitivity (Vision) , Fielders (Cricket)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291281 , vital:56839
- Description: Background: Sunglasses are popularly worn by outdoor athletes such as cricketers. They are primarily worn to preserve ocular health due to the length of time exposed to the sun’s glare on the field. More recently, sunglasses are now worn for their purported performance-enhancing benefits supposedly allowing athletes to “see clearly, react faster and perform with confidence”. Fielders typically wear sunglasses, but it is rare to see the bowler or the batter wearing sunglasses although they are exposed to the same conditions. If sunglasses provide visual clarity for better reaction time, it is assumed this would also be beneficial for both batsmen and bowlers alike. It is interesting that although fielding plays a key role in the winning of a match, it has received very little research in comparison to the areas of batting and bowling. Research concerning sunglasses in the past has been concerned with its effect on ocular parameters such as colour vision and contrast sensitivity, with minimal research on their effect on performance, specifically on how different colour tints may affect performance such as catching in fielding. Objective: The purpose of this study was to compare the catching performance of fielders when wearing three different colour tints of sunglasses. Methods: Thirty male cricketers currently playing for Rhodes University or country districts sides in Makhanda, South Africa, who were non-habitual sunglass wearers were recruited for this study. An optician administered a pre-screening test to ensure participants did not have any visual defects that would affect the results, determining who was eligible to continue with the research project. Twenty-five participants qualified with a further four withdrawing during the experimentation phase due to personal reasons. Eligible participants were required to complete four testing sessions on separate days thereafter in which they wore a different colour tint at each session (clear, blue, G30 and red). These tints were randomised among participants. Participants were required to catch 18 balls projected from a bowling machine in each session. The number of balls caught as well as the quality of catch was recorded. At the end of the fourth session, participants were presented with a questionnaire investigating their subjective experience of the protocol and preference for any particular colour of lens. Results: Statistically significant results were found between the different colour lenses for the ocular parameters of contrast sensitivity and stereopsis tested by the optician. The red lens was found to be the best for contrast sensitivity with the blue lens performing the worst on this test. With regard to stereopsis, the G30 lens was the worst, with the red lens performing the best. The performance measures resulted in no significant difference between the different colour lenses both concerning the total number of catches taken as well as the quality of catch taken. The same result was found irrespective of the colour of lens used in each session. Data gathered from the questionnaire regarding visual comfort and target visibility resulted in the red lens being rated statistically worse than the other three conditions. In terms of personal preference, the G30 lens was rated statistically as the best coloured lens. Conclusion: It can be concluded that objectively there is no difference in performance between the three coloured lenses. Although from an ocular perspective, the red lens was expected to perform the best in terms of catching performance, there was no difference. Subjectively there was a strong preference among the players for the G30 lens with players strongly disliking the red lens. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Nellemann, Stacy Amanda
- Date: 2022-04-06
- Subjects: Sunglasses , Cricket Physiological aspects , Cricket players , Glare , Vision , Contrast sensitivity (Vision) , Fielders (Cricket)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291281 , vital:56839
- Description: Background: Sunglasses are popularly worn by outdoor athletes such as cricketers. They are primarily worn to preserve ocular health due to the length of time exposed to the sun’s glare on the field. More recently, sunglasses are now worn for their purported performance-enhancing benefits supposedly allowing athletes to “see clearly, react faster and perform with confidence”. Fielders typically wear sunglasses, but it is rare to see the bowler or the batter wearing sunglasses although they are exposed to the same conditions. If sunglasses provide visual clarity for better reaction time, it is assumed this would also be beneficial for both batsmen and bowlers alike. It is interesting that although fielding plays a key role in the winning of a match, it has received very little research in comparison to the areas of batting and bowling. Research concerning sunglasses in the past has been concerned with its effect on ocular parameters such as colour vision and contrast sensitivity, with minimal research on their effect on performance, specifically on how different colour tints may affect performance such as catching in fielding. Objective: The purpose of this study was to compare the catching performance of fielders when wearing three different colour tints of sunglasses. Methods: Thirty male cricketers currently playing for Rhodes University or country districts sides in Makhanda, South Africa, who were non-habitual sunglass wearers were recruited for this study. An optician administered a pre-screening test to ensure participants did not have any visual defects that would affect the results, determining who was eligible to continue with the research project. Twenty-five participants qualified with a further four withdrawing during the experimentation phase due to personal reasons. Eligible participants were required to complete four testing sessions on separate days thereafter in which they wore a different colour tint at each session (clear, blue, G30 and red). These tints were randomised among participants. Participants were required to catch 18 balls projected from a bowling machine in each session. The number of balls caught as well as the quality of catch was recorded. At the end of the fourth session, participants were presented with a questionnaire investigating their subjective experience of the protocol and preference for any particular colour of lens. Results: Statistically significant results were found between the different colour lenses for the ocular parameters of contrast sensitivity and stereopsis tested by the optician. The red lens was found to be the best for contrast sensitivity with the blue lens performing the worst on this test. With regard to stereopsis, the G30 lens was the worst, with the red lens performing the best. The performance measures resulted in no significant difference between the different colour lenses both concerning the total number of catches taken as well as the quality of catch taken. The same result was found irrespective of the colour of lens used in each session. Data gathered from the questionnaire regarding visual comfort and target visibility resulted in the red lens being rated statistically worse than the other three conditions. In terms of personal preference, the G30 lens was rated statistically as the best coloured lens. Conclusion: It can be concluded that objectively there is no difference in performance between the three coloured lenses. Although from an ocular perspective, the red lens was expected to perform the best in terms of catching performance, there was no difference. Subjectively there was a strong preference among the players for the G30 lens with players strongly disliking the red lens. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
A study on visual inspection of citrus sorters in a packhouse in the Eastern Cape of South Africa
- Authors: Maher, Christopher Richard
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424256 , vital:72137
- Description: Background and Purpose. The South African citrus industry is a major global producer of citrus as well as the second largest exporter of citrus fruit in the world. This industry provides employment to an estimated 112 000 workers in South Africa and is vital in providing economic opportunities to communities such as those in the Sunday’s River Valley in the Eastern Cape province of South Africa due to the low employment and education levels within this province. Citrus sorting is a visual inspection task that requires workers to sustain attention and remain vigilant for the duration of a working shift. Their role in the packhouse is to ensure that no defective products are packed for export or the local market and that the fruit meets the customers’ expectations. Since the demands of sorting citrus are poorly understood, this study attempted to assess the effect that sorting citrus has on vigilance performance as well as attempt to quantify perceived workload while taking into account different contextual factors that affect perceptions of this working task. Methods. This study was conducted within a citrus packhouse in the Eastern Cape province of South Africa. The sample was comprised of individuals employed by the packhouse as citrus sorters. In addition to a recruitment and information session, testing was conducted at three intervals during a working shift on four consecutive days. Each time, indicators of vigilance, such as correct responses, sensitivity, reaction time, false alarms and misses, were collected during a 5-minute computerised version of the Mackworth Clock-test, while perceived workload was assessed with the NASA-TLX scale, and sleepiness was recording using the WITS Sleepiness Scale. Furthermore, an open-ended question was asked to further understand factors affecting the ability of participants to concentrate during their task of sorting. Results. 18 participants consented to participate in this study. 16 of these individuals identified as female with an average age of 30 years (± 7). 83% of participants were of Black African descent and were isiXhosa speakers, while 17% of participants were of Coloured descent and Afrikaans speakers. This study found that performance, as measured by the percentage of correct responses, sensitivity and reaction time on the 5-minute long Mackworth Clock Test was not significantly affected as time-on-task for sorting citrus increased during a working shift, neither did performance on the vigilance test change as days of the week proceeded. However, ‘misses’ during the vigilance test were found to significantly decrease over the course of a working shift, thus contradicting the expected outcomes of this study. Perceived workload of sorting citrus, as well as perceived sleepiness, significantly increased with time-on-task during the course of a working shift. The major contributions for this increase in perceived workload while sorting citrus were derived from the Mental Demand and Physical Demand sub-scale for the NASA-TLX. However, responses from the open-ended question indicated that participants generally enjoyed their work, although there were factors, such as the nature of fruit and social set-up of work, that negatively affected this perception. Discussion. The results from this study contradicted the researcher’s expectations. It was anticipated that measures of correct responses and sensitivity would decrease and misses, and reaction time would increase with time-on-task for sorting citrus, yet vigilance indicators from the Mackworth Clock Test generally indicated no change in vigilance, and, according to “misses” even improved with time-on-task. A likely explanation for this is that the use of a 5-minute Mackworth Clock-test was unsuitable in this context, or rather, the time of this test was not long enough to induce a ‘vigilance decrement’. Furthermore, in order to administer this vigilance test, participants were taken off the production line and led to a testing room which most likely increased their levels of arousal, thus affecting performance on the vigilance test. However, even though perceived sleepiness was found to significantly increase over the course of a working shift, these data correlated poorly with the vigilance results, thus contradicting the expected outcomes of the study. Mental demand significantly increased, possibly due to the demand of attentional informational processing required for sorting, as well as various environmental factors present within the packhouse. Physical demand, too, significantly increased as workers were required to remain standing throughout their working task as well as to make use of their upper extremities to remove defective fruit. Correlation analyses showed significantly weak correlation for Mackworth Clock Test variables and sleepiness ratings to all other variables. NASA-TLX variables, however, generally showed significantly moderate correlations with one another. Conclusion. It remains unclear how vigilance changes and sustained attention while sorting citrus, since the experiment did not show changes in performance. This is largely attributed to the methodological set-up which could have increased arousal and therefore affected vigilance. It is recommended that future studies research vigilance and sustained attention during the sorting itself, rather than attempting to infer vigilance results from a computerised vigilance test. Perceived workload of sorting, however, increased over the course of a working shift due to significant increases in perceptions of the physical and mental demands of sorting. Future studies should address concerns relating to the physical demand of sorting. Furthermore, it would be beneficial to compare responses of day and night shift sorters to further understand how the relationship between these variables may change. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Maher, Christopher Richard
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424256 , vital:72137
- Description: Background and Purpose. The South African citrus industry is a major global producer of citrus as well as the second largest exporter of citrus fruit in the world. This industry provides employment to an estimated 112 000 workers in South Africa and is vital in providing economic opportunities to communities such as those in the Sunday’s River Valley in the Eastern Cape province of South Africa due to the low employment and education levels within this province. Citrus sorting is a visual inspection task that requires workers to sustain attention and remain vigilant for the duration of a working shift. Their role in the packhouse is to ensure that no defective products are packed for export or the local market and that the fruit meets the customers’ expectations. Since the demands of sorting citrus are poorly understood, this study attempted to assess the effect that sorting citrus has on vigilance performance as well as attempt to quantify perceived workload while taking into account different contextual factors that affect perceptions of this working task. Methods. This study was conducted within a citrus packhouse in the Eastern Cape province of South Africa. The sample was comprised of individuals employed by the packhouse as citrus sorters. In addition to a recruitment and information session, testing was conducted at three intervals during a working shift on four consecutive days. Each time, indicators of vigilance, such as correct responses, sensitivity, reaction time, false alarms and misses, were collected during a 5-minute computerised version of the Mackworth Clock-test, while perceived workload was assessed with the NASA-TLX scale, and sleepiness was recording using the WITS Sleepiness Scale. Furthermore, an open-ended question was asked to further understand factors affecting the ability of participants to concentrate during their task of sorting. Results. 18 participants consented to participate in this study. 16 of these individuals identified as female with an average age of 30 years (± 7). 83% of participants were of Black African descent and were isiXhosa speakers, while 17% of participants were of Coloured descent and Afrikaans speakers. This study found that performance, as measured by the percentage of correct responses, sensitivity and reaction time on the 5-minute long Mackworth Clock Test was not significantly affected as time-on-task for sorting citrus increased during a working shift, neither did performance on the vigilance test change as days of the week proceeded. However, ‘misses’ during the vigilance test were found to significantly decrease over the course of a working shift, thus contradicting the expected outcomes of this study. Perceived workload of sorting citrus, as well as perceived sleepiness, significantly increased with time-on-task during the course of a working shift. The major contributions for this increase in perceived workload while sorting citrus were derived from the Mental Demand and Physical Demand sub-scale for the NASA-TLX. However, responses from the open-ended question indicated that participants generally enjoyed their work, although there were factors, such as the nature of fruit and social set-up of work, that negatively affected this perception. Discussion. The results from this study contradicted the researcher’s expectations. It was anticipated that measures of correct responses and sensitivity would decrease and misses, and reaction time would increase with time-on-task for sorting citrus, yet vigilance indicators from the Mackworth Clock Test generally indicated no change in vigilance, and, according to “misses” even improved with time-on-task. A likely explanation for this is that the use of a 5-minute Mackworth Clock-test was unsuitable in this context, or rather, the time of this test was not long enough to induce a ‘vigilance decrement’. Furthermore, in order to administer this vigilance test, participants were taken off the production line and led to a testing room which most likely increased their levels of arousal, thus affecting performance on the vigilance test. However, even though perceived sleepiness was found to significantly increase over the course of a working shift, these data correlated poorly with the vigilance results, thus contradicting the expected outcomes of the study. Mental demand significantly increased, possibly due to the demand of attentional informational processing required for sorting, as well as various environmental factors present within the packhouse. Physical demand, too, significantly increased as workers were required to remain standing throughout their working task as well as to make use of their upper extremities to remove defective fruit. Correlation analyses showed significantly weak correlation for Mackworth Clock Test variables and sleepiness ratings to all other variables. NASA-TLX variables, however, generally showed significantly moderate correlations with one another. Conclusion. It remains unclear how vigilance changes and sustained attention while sorting citrus, since the experiment did not show changes in performance. This is largely attributed to the methodological set-up which could have increased arousal and therefore affected vigilance. It is recommended that future studies research vigilance and sustained attention during the sorting itself, rather than attempting to infer vigilance results from a computerised vigilance test. Perceived workload of sorting, however, increased over the course of a working shift due to significant increases in perceptions of the physical and mental demands of sorting. Future studies should address concerns relating to the physical demand of sorting. Furthermore, it would be beneficial to compare responses of day and night shift sorters to further understand how the relationship between these variables may change. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
Academic or ‘zoombie’? Characterizing sleep quality, work and lifestyle behaviours among a cohort of South African academic staff during the Covid-19 pandemic
- Authors: Le Grange, Sarah-Ann
- Date: 2022-04-06
- Subjects: Sleep-wake cycle South Africa Eastern Cape , Sleep Physiological aspects , Lifestyles Health aspects South Africa Eastern Cape , COVID-19 Pandemic, 2020- Influence , Work environment Psychological aspects , Work environment Physiological aspects , College teachers Workload South Africa Eastern Cape , Pittsburgh Sleep Quality Index (PSQI)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291099 , vital:56818
- Description: Working in academe is characterized by high work demands, long and late working hours and balancing multiple roles. This often leaves academic staff (interchangeably referred to as ‘academics’ and ‘staff’) with limited time to prioritize adequate rest and sleep. While sufficient sleep is important for general well-being and work performance, it may be important for academics given the cognitive and interactive nature of their work. However, limited research has characterized sleep behaviours and sleep quality in academic staff globally and specifically in South Africa (SA). Further, research shows that academics from different academic ranks and genders differ in their work experiences but less is known about whether these factors affect their sleep and lifestyle factors. Over and above the demands of academic work, the current study was conducted during COVID-19, which saw unprecedented change in workloads for academic staff due to online teaching and learning. Additionally, the pandemic has been associated with poorer sleep quality and lifestyle behaviours in the general population, but very few studies have explored this in the context of academics. Thus, this study aimed to characterize the sleep quality, work and lifestyle factors among academics from a university in the Eastern Cape province of SA and determine the effects of gender and academic rank on these measures. Additionally, the study aimed to determine the impact of COVID-19 on sleep and work-related factors of this group. This study adopted a cross-sectional design and made use of an online questionnaire that was distributed to all academics employed at the institution via email. The data collection occurred over an 8-week testing period between August and September of 2020. The questionnaire explored sociodemographic, work and lifestyle characteristics, while the characteristics of sleep and sleep quality were explored with the Pittsburgh Sleep Quality Index (PSQI). Additionally, an open-ended section was included to determine the impact of COVID-19-related changes on sleep and work. The questionnaire responses were analyzed with descriptive and inferential statistics and the open-ended questions were analyzed with thematic analyses. A total of 84 respondents completed the questionnaire. On average, sleep quality was poor (global score of 7.09 ± 3.8), the reported sleep duration was short (6.41 ± 1.06 hrs) and the group was classified as overweight according to median BMI (26.67 [23.8-2 29.45] kg/m2). Over a third (35.71%) of academic staff reported not meeting physical activity guidelines and reported using screens one hour prior to bed every night during the week (76.19%) and the weekend (67.88%). Staff also worked long total weekly work hours (54.25 ± 11). Female academics had a poorer sleep quality (p = 0.035), spent a longer time in bed (p = 0.04), experienced more bad dreams (p = <0.01), had their last serving of alcohol earlier (p = 0.04) and worked less weekday (p = 0.04) and less total weekly (p = 0.02) hours compared to male academics. Professorship-level academics were significantly older than junior- and senior-level academics (p = <0.01) while senior-level academics had a poorer PSQI compared to professorship-level academics (p = 0.03). The thematic analysis showed that home environment, neighbourhood noise, work and mental health were the main emerging factors that disturbed sleep. The thematic analysis showed that, in relation to the impact of COVID19, sleep schedules changed and sleep duration and sleep quality improved or got worse. Respondents reported their work hours increasing, work schedules becoming less routine while working from home, dealing with the challenges of working online and experiencing worry, stress and anxiety due to the pandemic. The study highlights that, in the context of lockdown and having to work and teach online from home, academics reported poor quality sleep and short sleep duration. Further, on average, the sample reported working extensive hours and unhealthy lifestyle behaviours. The sleep health, nature of work and overall lifestyles of academic staff deserves more research attention, given the importance of their work and the impact that inadequate sleep could have on academics’ health and work performance. Sleep quality was worse for females and mid-career academics, suggesting that their sleep quality may be at greater risk than other sub-groups. However, the reasons for these differences need to be explored in future studies. The findings contribute to the narrative that academe involves numerous demands and supports previous research that has suggested that academics’ sleep is insufficient. Furthermore, COVID-19 had an impact on staff’s sleep, with staff reporting changes in their sleep quality and duration. The pandemic impacted work of academics by presenting novel demands related to online teaching, intensifying demands overall and disrupting work routines. However, future research is needed to understand academics’ sleep behaviours, work and lifestyles, especially in South Africa. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Le Grange, Sarah-Ann
- Date: 2022-04-06
- Subjects: Sleep-wake cycle South Africa Eastern Cape , Sleep Physiological aspects , Lifestyles Health aspects South Africa Eastern Cape , COVID-19 Pandemic, 2020- Influence , Work environment Psychological aspects , Work environment Physiological aspects , College teachers Workload South Africa Eastern Cape , Pittsburgh Sleep Quality Index (PSQI)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291099 , vital:56818
- Description: Working in academe is characterized by high work demands, long and late working hours and balancing multiple roles. This often leaves academic staff (interchangeably referred to as ‘academics’ and ‘staff’) with limited time to prioritize adequate rest and sleep. While sufficient sleep is important for general well-being and work performance, it may be important for academics given the cognitive and interactive nature of their work. However, limited research has characterized sleep behaviours and sleep quality in academic staff globally and specifically in South Africa (SA). Further, research shows that academics from different academic ranks and genders differ in their work experiences but less is known about whether these factors affect their sleep and lifestyle factors. Over and above the demands of academic work, the current study was conducted during COVID-19, which saw unprecedented change in workloads for academic staff due to online teaching and learning. Additionally, the pandemic has been associated with poorer sleep quality and lifestyle behaviours in the general population, but very few studies have explored this in the context of academics. Thus, this study aimed to characterize the sleep quality, work and lifestyle factors among academics from a university in the Eastern Cape province of SA and determine the effects of gender and academic rank on these measures. Additionally, the study aimed to determine the impact of COVID-19 on sleep and work-related factors of this group. This study adopted a cross-sectional design and made use of an online questionnaire that was distributed to all academics employed at the institution via email. The data collection occurred over an 8-week testing period between August and September of 2020. The questionnaire explored sociodemographic, work and lifestyle characteristics, while the characteristics of sleep and sleep quality were explored with the Pittsburgh Sleep Quality Index (PSQI). Additionally, an open-ended section was included to determine the impact of COVID-19-related changes on sleep and work. The questionnaire responses were analyzed with descriptive and inferential statistics and the open-ended questions were analyzed with thematic analyses. A total of 84 respondents completed the questionnaire. On average, sleep quality was poor (global score of 7.09 ± 3.8), the reported sleep duration was short (6.41 ± 1.06 hrs) and the group was classified as overweight according to median BMI (26.67 [23.8-2 29.45] kg/m2). Over a third (35.71%) of academic staff reported not meeting physical activity guidelines and reported using screens one hour prior to bed every night during the week (76.19%) and the weekend (67.88%). Staff also worked long total weekly work hours (54.25 ± 11). Female academics had a poorer sleep quality (p = 0.035), spent a longer time in bed (p = 0.04), experienced more bad dreams (p = <0.01), had their last serving of alcohol earlier (p = 0.04) and worked less weekday (p = 0.04) and less total weekly (p = 0.02) hours compared to male academics. Professorship-level academics were significantly older than junior- and senior-level academics (p = <0.01) while senior-level academics had a poorer PSQI compared to professorship-level academics (p = 0.03). The thematic analysis showed that home environment, neighbourhood noise, work and mental health were the main emerging factors that disturbed sleep. The thematic analysis showed that, in relation to the impact of COVID19, sleep schedules changed and sleep duration and sleep quality improved or got worse. Respondents reported their work hours increasing, work schedules becoming less routine while working from home, dealing with the challenges of working online and experiencing worry, stress and anxiety due to the pandemic. The study highlights that, in the context of lockdown and having to work and teach online from home, academics reported poor quality sleep and short sleep duration. Further, on average, the sample reported working extensive hours and unhealthy lifestyle behaviours. The sleep health, nature of work and overall lifestyles of academic staff deserves more research attention, given the importance of their work and the impact that inadequate sleep could have on academics’ health and work performance. Sleep quality was worse for females and mid-career academics, suggesting that their sleep quality may be at greater risk than other sub-groups. However, the reasons for these differences need to be explored in future studies. The findings contribute to the narrative that academe involves numerous demands and supports previous research that has suggested that academics’ sleep is insufficient. Furthermore, COVID-19 had an impact on staff’s sleep, with staff reporting changes in their sleep quality and duration. The pandemic impacted work of academics by presenting novel demands related to online teaching, intensifying demands overall and disrupting work routines. However, future research is needed to understand academics’ sleep behaviours, work and lifestyles, especially in South Africa. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
Adolescents and coaches/trainers perspectives of ergogenic sports supplement use within South African private high schools
- Authors: Butler, Nicholas John
- Date: 2022-04-06
- Subjects: Dietary supplements , Energy metabolism , Teenagers South Africa , Teenagers Physiology South Africa , Teenagers Substance use South Africa , Coaches (Athletics) South Africa , Athletic trainers South Africa , Private schools South Africa , Ergogenic aids
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232443 , vital:49992
- Description: Sports supplements, also referred to as ergogenic aids, are used because of the assertion that they can enhance physical or athletic performance and/or physical appearance. Commonly used sports supplements include creatines, proteins, amino acids, stimulants, and in some cases pro-hormones. There is a relatively high and increasing prevalence of sports supplement use by the general population globally and in South Africa, particularly among adolescents and young adults due to various factors. While some research has explored supplement use among adolescents in a school setting, no study has explored this across the private school system in South Africa. Additionally, given the important role that coaches/trainers play in adolescent development, it is critical to also understand the role that they play regarding adolescent supplement use, given that there has been limited research around this topic in South Africa. Therefore, there were two aims of this study; Firstly, this study explored the prevalence and perceptions (knowledge; attitudes; beliefs) of sports supplements among South African private high school adolescents. Secondly, this study explored the perceptions (knowledge; attitudes; application of knowledge) towards sports supplements among adolescent coaches/trainers in South African private high schools. Considering the dual aim of this study, this thesis was structured as a two-part research study. Both parts took the form of a cross-sectional design, using an online questionnaire to collect qualitative and quantitative data. In total, a cohort of n=50 adolescents and n=49 coaches/trainers participated. Adolescent participants reported a high prevalence of sports supplement use (62%) with their main reasons for using them being recovery and performance. Adolescents were primarily influenced/advised by friends and coaches/trainers to start using sports supplements. Coaches/trainers primarily relied on other coaches/trainers and internet advertising/sites as a main source of information. Less than half of the participants from both groups reported having any formal education or training related to sports nutrition or sports supplements. Both groups thought that these products are being misused by adolescents, which may account for why a portion of the adolescent participants reported experiencing adverse side-effects from using sports supplements, and a few coach/trainer participants reported witnessing this in their practice. This may be a result of the professionalisation of school sport which places pressure on athletes and their coaches/trainers to perform and may in turn be the reason why some adolescents reported that they would use, and some coaches/trainers reported they would recommend the use of sports supplements even if they were aware of risk/dangers involved. Thus, there is a need for education/training among South African high school adolescents and their coaches/trainers with respect to the use of sports supplements, so that they can make informed decisions from reliable sources of information or advice in order to use these products safely and effectively. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Butler, Nicholas John
- Date: 2022-04-06
- Subjects: Dietary supplements , Energy metabolism , Teenagers South Africa , Teenagers Physiology South Africa , Teenagers Substance use South Africa , Coaches (Athletics) South Africa , Athletic trainers South Africa , Private schools South Africa , Ergogenic aids
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232443 , vital:49992
- Description: Sports supplements, also referred to as ergogenic aids, are used because of the assertion that they can enhance physical or athletic performance and/or physical appearance. Commonly used sports supplements include creatines, proteins, amino acids, stimulants, and in some cases pro-hormones. There is a relatively high and increasing prevalence of sports supplement use by the general population globally and in South Africa, particularly among adolescents and young adults due to various factors. While some research has explored supplement use among adolescents in a school setting, no study has explored this across the private school system in South Africa. Additionally, given the important role that coaches/trainers play in adolescent development, it is critical to also understand the role that they play regarding adolescent supplement use, given that there has been limited research around this topic in South Africa. Therefore, there were two aims of this study; Firstly, this study explored the prevalence and perceptions (knowledge; attitudes; beliefs) of sports supplements among South African private high school adolescents. Secondly, this study explored the perceptions (knowledge; attitudes; application of knowledge) towards sports supplements among adolescent coaches/trainers in South African private high schools. Considering the dual aim of this study, this thesis was structured as a two-part research study. Both parts took the form of a cross-sectional design, using an online questionnaire to collect qualitative and quantitative data. In total, a cohort of n=50 adolescents and n=49 coaches/trainers participated. Adolescent participants reported a high prevalence of sports supplement use (62%) with their main reasons for using them being recovery and performance. Adolescents were primarily influenced/advised by friends and coaches/trainers to start using sports supplements. Coaches/trainers primarily relied on other coaches/trainers and internet advertising/sites as a main source of information. Less than half of the participants from both groups reported having any formal education or training related to sports nutrition or sports supplements. Both groups thought that these products are being misused by adolescents, which may account for why a portion of the adolescent participants reported experiencing adverse side-effects from using sports supplements, and a few coach/trainer participants reported witnessing this in their practice. This may be a result of the professionalisation of school sport which places pressure on athletes and their coaches/trainers to perform and may in turn be the reason why some adolescents reported that they would use, and some coaches/trainers reported they would recommend the use of sports supplements even if they were aware of risk/dangers involved. Thus, there is a need for education/training among South African high school adolescents and their coaches/trainers with respect to the use of sports supplements, so that they can make informed decisions from reliable sources of information or advice in order to use these products safely and effectively. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
An analysis of regulatory mechanisms during sustained task execution in cognitive, motor and sensory tasks
- Tau, Sethunya Harriet Hlobisa
- Authors: Tau, Sethunya Harriet Hlobisa
- Date: 2013 , 2013-10-11
- Subjects: Work -- Physiological aspects , Work -- Psychological aspects , Fatigue , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Employees -- Workload , Performance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5140 , http://hdl.handle.net/10962/d1006806 , Work -- Physiological aspects , Work -- Psychological aspects , Fatigue , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Employees -- Workload , Performance
- Description: Fatigue is a state that, although researched for many years, is still not completely understood. Alongside this lack of a general understanding of fatigue is a lack of knowledge on the processes involved in the regulation of fatigue. The existing theories relating to regulation are focussed on mental effort regulation, suggesting that performance outcomes are co-ordinated by effort regulation that functions by making alterations to physiological processes and strategic adjustments at a cognitive level in response to cognitive demands and goals. Since fatigue is a multi-dimensional construct with psychological, physiological, and behavioural effects that respond to endogenous and exogenous variables, it follows then that fatigue assessment techniques ought to include multi-dimensional measures to acquire a holistic depiction of the fatigue symptom. This study aimed to assess whether or not a mechanism that regulated fatigue during sustained task execution could be identified and whether this mechanism resulted in regulation patterns that were distinct to a specific task. An additional aim of the study was on assessing whether the manner in which performance, psychophysical and subjective variables were modified over time followed a similar regulation pattern. The research design was aimed at inducing task-related fatigue twice on two different occasions in the same participants and evaluating the resultant changes in fatigue manifestation. This was done to assess the ability of participants to cope with fatigue as a result of previous experience. The research protocol included three tasks executed for an hour aimed at targeting and taxing the sensory, cognitive, motor resources, each task performed twice. 60 participants were recruited to participate in the current study, with 20 participants – 10 males and 10 females – randomly assigned to each of the three tasks. The cognitive resource task consisted of a memory recall task relying on working memory intended to evaluate the extent of reductions in memory and attention. The sensory resource task consisted of a reading task measuring visual scanning and perception designed to evaluate the extent of reduced vigilance. The motor resource task consisted of a modified Fitts’ stimulus response task targeted at monitoring the extent of movement timing disruption. Performance measures comprised of: response delay and the number of correctly identified digits during the cognitive resource task, the amount of correctly identified errors and reading speed during the sensory resource task, response time during the motor resource task, and responses to simple auditory reaction time tests (RTT) initiated at intervals during the task and then again at the end of each task. Physiological measures included ear temperature, eye blink frequency and duration, heart rate (HR), and heart rate variability (HRV). Subjective measures included the use of the Ratings of Perceived Exertion Category Ratio 10 scale (RPE CR 10) to measure cognitive exertion and the NASA-Task Load Index (NASA-TLX) to index mental workload. Eye blink frequency and duration, HR and HRV were sensitive to the type of task executed, showing differing response patterns both over the different tasks and over the two test sessions. The subjective measures indicated increasing RPE ratings over time in all tasks while the NASA-TLX indicated that each task elicited different workloads. Differing task performance responses were measured between the 1st test session and the 2nd test session during all tasks; while performance was found to improve during the 2nd test session for the motor and sensory tasks, it declined during the cognitive task. The findings of this research indicate that there was a regulatory mechanism for fatigue that altered the manner in which performance, psychophysical and subjective variables were modified over time, initiating a unique fatigue regulation pattern for each variable and each task. This regulation mechanism is understood to be a proactive and protective mechanism that functions through reducing a person’s ability to be vigilant, attentive, to exercise discernment, and to direct their level of responsiveness, essentially impacting how the body adapts to and copes with fatigue. The noted overall findings have industry implications; industries should consider accounting for the effects of this regulatory mechanism in their fatigue management interventions, specifically when designing job rotation and work/rest schedules because each cognitive task, having elicited a unique fatigue regulation pattern, ought to also have a different management program. , Microsoft� Office Word 2007 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Tau, Sethunya Harriet Hlobisa
- Date: 2013 , 2013-10-11
- Subjects: Work -- Physiological aspects , Work -- Psychological aspects , Fatigue , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Employees -- Workload , Performance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5140 , http://hdl.handle.net/10962/d1006806 , Work -- Physiological aspects , Work -- Psychological aspects , Fatigue , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Employees -- Workload , Performance
- Description: Fatigue is a state that, although researched for many years, is still not completely understood. Alongside this lack of a general understanding of fatigue is a lack of knowledge on the processes involved in the regulation of fatigue. The existing theories relating to regulation are focussed on mental effort regulation, suggesting that performance outcomes are co-ordinated by effort regulation that functions by making alterations to physiological processes and strategic adjustments at a cognitive level in response to cognitive demands and goals. Since fatigue is a multi-dimensional construct with psychological, physiological, and behavioural effects that respond to endogenous and exogenous variables, it follows then that fatigue assessment techniques ought to include multi-dimensional measures to acquire a holistic depiction of the fatigue symptom. This study aimed to assess whether or not a mechanism that regulated fatigue during sustained task execution could be identified and whether this mechanism resulted in regulation patterns that were distinct to a specific task. An additional aim of the study was on assessing whether the manner in which performance, psychophysical and subjective variables were modified over time followed a similar regulation pattern. The research design was aimed at inducing task-related fatigue twice on two different occasions in the same participants and evaluating the resultant changes in fatigue manifestation. This was done to assess the ability of participants to cope with fatigue as a result of previous experience. The research protocol included three tasks executed for an hour aimed at targeting and taxing the sensory, cognitive, motor resources, each task performed twice. 60 participants were recruited to participate in the current study, with 20 participants – 10 males and 10 females – randomly assigned to each of the three tasks. The cognitive resource task consisted of a memory recall task relying on working memory intended to evaluate the extent of reductions in memory and attention. The sensory resource task consisted of a reading task measuring visual scanning and perception designed to evaluate the extent of reduced vigilance. The motor resource task consisted of a modified Fitts’ stimulus response task targeted at monitoring the extent of movement timing disruption. Performance measures comprised of: response delay and the number of correctly identified digits during the cognitive resource task, the amount of correctly identified errors and reading speed during the sensory resource task, response time during the motor resource task, and responses to simple auditory reaction time tests (RTT) initiated at intervals during the task and then again at the end of each task. Physiological measures included ear temperature, eye blink frequency and duration, heart rate (HR), and heart rate variability (HRV). Subjective measures included the use of the Ratings of Perceived Exertion Category Ratio 10 scale (RPE CR 10) to measure cognitive exertion and the NASA-Task Load Index (NASA-TLX) to index mental workload. Eye blink frequency and duration, HR and HRV were sensitive to the type of task executed, showing differing response patterns both over the different tasks and over the two test sessions. The subjective measures indicated increasing RPE ratings over time in all tasks while the NASA-TLX indicated that each task elicited different workloads. Differing task performance responses were measured between the 1st test session and the 2nd test session during all tasks; while performance was found to improve during the 2nd test session for the motor and sensory tasks, it declined during the cognitive task. The findings of this research indicate that there was a regulatory mechanism for fatigue that altered the manner in which performance, psychophysical and subjective variables were modified over time, initiating a unique fatigue regulation pattern for each variable and each task. This regulation mechanism is understood to be a proactive and protective mechanism that functions through reducing a person’s ability to be vigilant, attentive, to exercise discernment, and to direct their level of responsiveness, essentially impacting how the body adapts to and copes with fatigue. The noted overall findings have industry implications; industries should consider accounting for the effects of this regulatory mechanism in their fatigue management interventions, specifically when designing job rotation and work/rest schedules because each cognitive task, having elicited a unique fatigue regulation pattern, ought to also have a different management program. , Microsoft� Office Word 2007 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
An empirical investigation into task aversion
- Authors: Sunshine, Megan
- Date: 2013 , 2013-07-25
- Subjects: Work aversion , Mental fatigue , Labor productivity , Employees -- Workload , Industrial hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5138 , http://hdl.handle.net/10962/d1006085 , Work aversion , Mental fatigue , Labor productivity , Employees -- Workload , Industrial hygiene
- Description: Aversion is a complex phenomenon that arises over time through performance of cognitively demanding tasks and has been associated with the mechanisms of mental fatigue and compensatory control. However, little is known about this sensation to dissociate from the task at hand and the causation thereof. It is apparent that aversion is a negative state for the operator and could result in decreased performance and productivity. Through identification of factors that contribute to aversion when performing cognitively demanding tasks, recommendations to reduce design deficits may be employed to promote worker wellbeing and further advance performance and productivity. The current study examined possible factors that may influence aversion experienced through execution of cognitive tasks. A subsequent aim of this study was to assess a possible cause of aversion. The cause of aversion was hypothesized to be related to efficiency, namely the perception of efficiency when performing tasks and actual efficiency calculated through performance of tasks in relation to the expenditure of effort. Four investigations were undertaken with a non-repeated design between investigations and a repeated design within investigations. The first investigation was an analysis of the effect that stimulus cycling had on the aversion experienced. This consisted of a proof reading task with two conditions varying in the repetitiveness of the text, therefore, allowing an analysis as to how aversion is altered by the provision of a new stimulus to the participants. Investigation two investigated the effect that task difficulty imposed on aversion experienced. This comprised of two conditions with varied difficulty that were implemented through a driving simulator tracking task with difficulty altered by the width of the driving lane. The effect of performance feedback on the aversion experienced towards a task was the focus of the third investigation. The effect on aversion experienced was assessed through a driving simulator tracking task with a condition providing feedback of performance to participants and a condition with no knowledge of performance. The final experiment evaluated the effect of task alternations on aversion. This experiment was conducted through alternations between a driving simulator tracking task and a choice reaction task. The choice reaction tasks required participants to identify critical and non-critical stimulus. Four conditions were required for this experiment and were made up of two conditions where there was provision of alternation that varied in frequencies between the two tasks (medium alternation condition and fast alternation condition) and two conditions where no alternations were instated (driving simulator task condition and choice reaction task condition). Separations between all testing conditions were three or more days apart with sixty participants distributed between the investigations. Test duration of each condition was 30 minutes. Subjective data was recorded throughout investigations for all conditions in the form of aversion, subjectively perceived efficiency and rate of perceived exertion. Objective data was collected in the form of physiological responses and performance of tasks for the analysis of objective efficiency. For factors influencing aversion analysis, no differences in aversion experienced were found for the task difficulty and performance feedback investigations. Aversion was found to be less for the changes imposed through the task cycles and task alternation investigations. This concludes that aversion is aggravated through monotonous tasks and by a change of the stimulus or the structure of the cognitive tasks provided to operators; aversion can be alleviated. The results for the cause of aversion analysis found no difference in objective efficiency over time, with a subsequent decrease in perceived efficiency associated with the increasing aversion. Inference from these findings suggest that aversion cannot be attributed to objective inefficiency of task performance, however it can further be assumed that perception of actual efficiency is inaccurate. Perception of efficiency however had a large influence on the sensation of aversion. Aversion is seen to be more of a product of time on task, however whether this is mechanism of fatigue or compensatory control is still to be determined.
- Full Text:
- Date Issued: 2013
- Authors: Sunshine, Megan
- Date: 2013 , 2013-07-25
- Subjects: Work aversion , Mental fatigue , Labor productivity , Employees -- Workload , Industrial hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5138 , http://hdl.handle.net/10962/d1006085 , Work aversion , Mental fatigue , Labor productivity , Employees -- Workload , Industrial hygiene
- Description: Aversion is a complex phenomenon that arises over time through performance of cognitively demanding tasks and has been associated with the mechanisms of mental fatigue and compensatory control. However, little is known about this sensation to dissociate from the task at hand and the causation thereof. It is apparent that aversion is a negative state for the operator and could result in decreased performance and productivity. Through identification of factors that contribute to aversion when performing cognitively demanding tasks, recommendations to reduce design deficits may be employed to promote worker wellbeing and further advance performance and productivity. The current study examined possible factors that may influence aversion experienced through execution of cognitive tasks. A subsequent aim of this study was to assess a possible cause of aversion. The cause of aversion was hypothesized to be related to efficiency, namely the perception of efficiency when performing tasks and actual efficiency calculated through performance of tasks in relation to the expenditure of effort. Four investigations were undertaken with a non-repeated design between investigations and a repeated design within investigations. The first investigation was an analysis of the effect that stimulus cycling had on the aversion experienced. This consisted of a proof reading task with two conditions varying in the repetitiveness of the text, therefore, allowing an analysis as to how aversion is altered by the provision of a new stimulus to the participants. Investigation two investigated the effect that task difficulty imposed on aversion experienced. This comprised of two conditions with varied difficulty that were implemented through a driving simulator tracking task with difficulty altered by the width of the driving lane. The effect of performance feedback on the aversion experienced towards a task was the focus of the third investigation. The effect on aversion experienced was assessed through a driving simulator tracking task with a condition providing feedback of performance to participants and a condition with no knowledge of performance. The final experiment evaluated the effect of task alternations on aversion. This experiment was conducted through alternations between a driving simulator tracking task and a choice reaction task. The choice reaction tasks required participants to identify critical and non-critical stimulus. Four conditions were required for this experiment and were made up of two conditions where there was provision of alternation that varied in frequencies between the two tasks (medium alternation condition and fast alternation condition) and two conditions where no alternations were instated (driving simulator task condition and choice reaction task condition). Separations between all testing conditions were three or more days apart with sixty participants distributed between the investigations. Test duration of each condition was 30 minutes. Subjective data was recorded throughout investigations for all conditions in the form of aversion, subjectively perceived efficiency and rate of perceived exertion. Objective data was collected in the form of physiological responses and performance of tasks for the analysis of objective efficiency. For factors influencing aversion analysis, no differences in aversion experienced were found for the task difficulty and performance feedback investigations. Aversion was found to be less for the changes imposed through the task cycles and task alternation investigations. This concludes that aversion is aggravated through monotonous tasks and by a change of the stimulus or the structure of the cognitive tasks provided to operators; aversion can be alleviated. The results for the cause of aversion analysis found no difference in objective efficiency over time, with a subsequent decrease in perceived efficiency associated with the increasing aversion. Inference from these findings suggest that aversion cannot be attributed to objective inefficiency of task performance, however it can further be assumed that perception of actual efficiency is inaccurate. Perception of efficiency however had a large influence on the sensation of aversion. Aversion is seen to be more of a product of time on task, however whether this is mechanism of fatigue or compensatory control is still to be determined.
- Full Text:
- Date Issued: 2013
An ergonomics approach to understanding perceived barriers to the provision of high-quality healthcare: a Sarah Baartman District clinics case study
- Authors: Card, Jason
- Date: 2020
- Subjects: Medical care -- South Africa -- Eastern Cape , Public health -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/170536 , vital:41933
- Description: Background:The complex nature of healthcare systemsoftenresultsinthe emergence of context-specific barriers that limit the ability for healthcare stakeholders to ensure safe and effective care delivery. In low-to middle-income (LMIC) countries, such as South Africa (SA), limited financial, material and human resources coupled withpoor infrastructure and poor public health determinants, includingpoverty andpoor education, affectthe ability to maintain andimprove on quality care outcomes.Understanding what different stakeholders perceive as barriers, and if these barriers are understood at different levels, is therefore important when attempting to mitigate the risk for unsafe or inefficient care delivery. Human Factors and Ergonomics (HFE) adoptssystems and participatory approaches for the exploration, analysis, and design of socio-technical systems to optimize both human wellbeing and system performance.The barriers to safe and effective healthcare delivery, from an HFE perspective, are not known in the South African context, particularly in parts of the Eastern Cape Province. Elucidatingthesebarriers, even if self-reported,may guidefuture efforts aimed at mitigating risks.The purpose of this study, therefore,wasto explore and highlight the perceived systemic barriers to local and national healthcare delivery, within the Sarah Baartman District in the Eastern Cape Province of South Africa.Methods: Ashort discussion aimed at introducing HFE and components of the Work Systems Model, followed by a survey that captured participant demographics, job characteristics, the perceived national and local systemic barriers, and proposed solutions, was administered withhealthcare stakeholders from 14 primary healthcare facilities and 1 department office within the Sarah Baartman District.Participants (n=120) included management, pharmacy, administration, maintenance, community-and home-based care and nursing staff.Data from the surveys were thematically analysed and categorised according to components of the work system model (Carayon, 2009) and respective workgroup.Results: The findings revealed many overlapping,systemic barriersthat includedshortages of staff, poor management and leadership, a lack of equipmentand basic necessities, poor infrastructure, patient complexity,and high workloads. The results further indicate that the way in which the reported barriers affect worksystem interactionsand performance are unique to different workgroups. Stakeholders iiproposedthat,among others, the absorption of contract workers, the provision of training and adequate human and medical resources and the maintenance of facilities may mitigate the barriers and improve healthcare delivery.Conclusion: The findings highlight a myriad of perceived systemic barriers perceived in the Sarah Baartman district, some of which were fundamental for the effective function of any healthcare system. These barriers may have wide-spread implications for stakeholders at all levels, ultimately affecting the performance, satisfaction and safety and the quality of care. It is especially important to consider these barriers in light of the COVID-19 epidemic, which emerged throughout this study and the major threat it presents to South African healthcare systems. Future research should aim to explore how these barriers interact to contribute to processes and outcomes, as well as explore the perceptions at provincial and national levels in order to better identify areas and strategies for improvement.
- Full Text:
- Date Issued: 2020
- Authors: Card, Jason
- Date: 2020
- Subjects: Medical care -- South Africa -- Eastern Cape , Public health -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/170536 , vital:41933
- Description: Background:The complex nature of healthcare systemsoftenresultsinthe emergence of context-specific barriers that limit the ability for healthcare stakeholders to ensure safe and effective care delivery. In low-to middle-income (LMIC) countries, such as South Africa (SA), limited financial, material and human resources coupled withpoor infrastructure and poor public health determinants, includingpoverty andpoor education, affectthe ability to maintain andimprove on quality care outcomes.Understanding what different stakeholders perceive as barriers, and if these barriers are understood at different levels, is therefore important when attempting to mitigate the risk for unsafe or inefficient care delivery. Human Factors and Ergonomics (HFE) adoptssystems and participatory approaches for the exploration, analysis, and design of socio-technical systems to optimize both human wellbeing and system performance.The barriers to safe and effective healthcare delivery, from an HFE perspective, are not known in the South African context, particularly in parts of the Eastern Cape Province. Elucidatingthesebarriers, even if self-reported,may guidefuture efforts aimed at mitigating risks.The purpose of this study, therefore,wasto explore and highlight the perceived systemic barriers to local and national healthcare delivery, within the Sarah Baartman District in the Eastern Cape Province of South Africa.Methods: Ashort discussion aimed at introducing HFE and components of the Work Systems Model, followed by a survey that captured participant demographics, job characteristics, the perceived national and local systemic barriers, and proposed solutions, was administered withhealthcare stakeholders from 14 primary healthcare facilities and 1 department office within the Sarah Baartman District.Participants (n=120) included management, pharmacy, administration, maintenance, community-and home-based care and nursing staff.Data from the surveys were thematically analysed and categorised according to components of the work system model (Carayon, 2009) and respective workgroup.Results: The findings revealed many overlapping,systemic barriersthat includedshortages of staff, poor management and leadership, a lack of equipmentand basic necessities, poor infrastructure, patient complexity,and high workloads. The results further indicate that the way in which the reported barriers affect worksystem interactionsand performance are unique to different workgroups. Stakeholders iiproposedthat,among others, the absorption of contract workers, the provision of training and adequate human and medical resources and the maintenance of facilities may mitigate the barriers and improve healthcare delivery.Conclusion: The findings highlight a myriad of perceived systemic barriers perceived in the Sarah Baartman district, some of which were fundamental for the effective function of any healthcare system. These barriers may have wide-spread implications for stakeholders at all levels, ultimately affecting the performance, satisfaction and safety and the quality of care. It is especially important to consider these barriers in light of the COVID-19 epidemic, which emerged throughout this study and the major threat it presents to South African healthcare systems. Future research should aim to explore how these barriers interact to contribute to processes and outcomes, as well as explore the perceptions at provincial and national levels in order to better identify areas and strategies for improvement.
- Full Text:
- Date Issued: 2020
An ergonomics intervention study into the physiological, perceptual and productivity effects of three citrus harvesting bag designs in the Eastern Cape of South Africa : a combined laboratory and field approach
- Bassey-Duke, Elizabeth Misan
- Authors: Bassey-Duke, Elizabeth Misan
- Date: 2015
- Subjects: Citrus -- Harvesting -- South Africa -- Eastern Cape , Lifting and carrying -- South Africa -- Eastern Cape , Manual work -- South Africa -- Eastern Cape , Blue collar workers -- South Africa -- Eastern Cape , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5176 , http://hdl.handle.net/10962/d1018908
- Description: Background: Agriculture plays a vital role in the economy of any industrially developing country, including South Africa. In the Eastern Cape of South Africa citrus farming is a significant contributor to the local economy (Johnson et al., 2005). The harvesting phase of citrus farming is performed manually and exposes workers to physical risks, which can lead to the development of musculoskeletal disorders. In particular, the standard harvesting bag comprises of a single shoulder strap and promotes asymmetrical load carriage which results in shoulder and lower back pain complaints. The current study compared the physiological (EMG), perceptual (RPE), usability (PUEU) and productivity effects of two new harvesting bag designs (a hip belt and a backpack bag design) to the standard harvesting bag design. This was performed in a laboratory as well as a field setting. Methods (Laboratory phase): 36 participants (12 males and 24 females) were assigned to one worker group. The “tall ladder worker” group was comprised of only males and the “step ladder worker” and “ground worker” group of females. Each participant was required to simulate a citrus harvesting task while utilizing each of the bag designs on different days. On each day/test session, participants performed three harvesting cycles. Muscle activity was measured throughout the entire testing session and RPE were recorded at the end of each cycle. Results (Laboratory phase): The EMG and RPE results indicate that the backpack design was the most ideal design to reduce asymmetry, while the standard harvesting bag design was the worst. Although not significant, there was greater muscle asymmetry (p=0.109) and a significantly higher perceived exertion when using the standard bag (p=0.0004), in comparison to using the backpack. Methods (Field phase): 17 Xhosa-speaking citrus harvesters (6 females and 11 males) participated in this study. Each harvester worked with one of the three bag designs on a different day. Productivity of each worker was assessed every hour by recording the number of bags filled with fruit and at the end of the shift. A Perceived Usefulness & Ease of Use questionnaire was presented to each participant to obtain feedback on worker acceptance to the new bag designs. Results (Field phase): A general trend in support of the hip belt bag design over the other two bag designs were found, even within the different worker demographic groups (age, sex and worker experience). The workers perceived less exertion (7.98 ± 1.86) and were more productive (9.90 ± 2.11 bags/hour) when using the hip belt design; they also found this bag the most useful (1.02 ± 0.09) and easy to use (1.07 ± 0.25). In contrast, the backpack bag design had significantly poorer responses when compared to the other two bag designs and this was evident in all the dependent variables assessed (RPE, productivity and PUEU). Conclusion: The results from the laboratory phase supported the expectation that the backpack bag design reduces asymmetry and hence, is more suitable than the standard harvesting bag. However, results from the field show that the hip belt bag design was the most preferred and the backpack was the least preferred. Bao & Shahnavaz (1989) highlight the need for ergonomics researcher to convey laboratory findings into the field context. However, as shown by the current study, there are numerous challenges associated with field work, making it difficult for laboratory findings to be successfully conveyed to the field. Limitations and Recommendations: For the laboratory phase of the project, no biomechanical and cardiovascular responses were assessed. However, for a holistic approach, these variables should be considered in future studies. Due to high variability from one harvesting cycle to another, more than three harvesting cycles should also be performed to accurately replicate the harvesting process as done in the field over extended durations of time. For the field phase, data should be collected from more than one citrus farm and thus a larger sample size could be obtained. This would improve the validity of the study. In addition to this, data should be collected for a full working day, especially if environmental conditions are not a hindrance, as well as for a whole season, since workloads vary, depending on the time of the harvesting season. , Name on Graduation Programme: Bassey-Duke, Elizabeth Missan
- Full Text:
- Date Issued: 2015
- Authors: Bassey-Duke, Elizabeth Misan
- Date: 2015
- Subjects: Citrus -- Harvesting -- South Africa -- Eastern Cape , Lifting and carrying -- South Africa -- Eastern Cape , Manual work -- South Africa -- Eastern Cape , Blue collar workers -- South Africa -- Eastern Cape , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5176 , http://hdl.handle.net/10962/d1018908
- Description: Background: Agriculture plays a vital role in the economy of any industrially developing country, including South Africa. In the Eastern Cape of South Africa citrus farming is a significant contributor to the local economy (Johnson et al., 2005). The harvesting phase of citrus farming is performed manually and exposes workers to physical risks, which can lead to the development of musculoskeletal disorders. In particular, the standard harvesting bag comprises of a single shoulder strap and promotes asymmetrical load carriage which results in shoulder and lower back pain complaints. The current study compared the physiological (EMG), perceptual (RPE), usability (PUEU) and productivity effects of two new harvesting bag designs (a hip belt and a backpack bag design) to the standard harvesting bag design. This was performed in a laboratory as well as a field setting. Methods (Laboratory phase): 36 participants (12 males and 24 females) were assigned to one worker group. The “tall ladder worker” group was comprised of only males and the “step ladder worker” and “ground worker” group of females. Each participant was required to simulate a citrus harvesting task while utilizing each of the bag designs on different days. On each day/test session, participants performed three harvesting cycles. Muscle activity was measured throughout the entire testing session and RPE were recorded at the end of each cycle. Results (Laboratory phase): The EMG and RPE results indicate that the backpack design was the most ideal design to reduce asymmetry, while the standard harvesting bag design was the worst. Although not significant, there was greater muscle asymmetry (p=0.109) and a significantly higher perceived exertion when using the standard bag (p=0.0004), in comparison to using the backpack. Methods (Field phase): 17 Xhosa-speaking citrus harvesters (6 females and 11 males) participated in this study. Each harvester worked with one of the three bag designs on a different day. Productivity of each worker was assessed every hour by recording the number of bags filled with fruit and at the end of the shift. A Perceived Usefulness & Ease of Use questionnaire was presented to each participant to obtain feedback on worker acceptance to the new bag designs. Results (Field phase): A general trend in support of the hip belt bag design over the other two bag designs were found, even within the different worker demographic groups (age, sex and worker experience). The workers perceived less exertion (7.98 ± 1.86) and were more productive (9.90 ± 2.11 bags/hour) when using the hip belt design; they also found this bag the most useful (1.02 ± 0.09) and easy to use (1.07 ± 0.25). In contrast, the backpack bag design had significantly poorer responses when compared to the other two bag designs and this was evident in all the dependent variables assessed (RPE, productivity and PUEU). Conclusion: The results from the laboratory phase supported the expectation that the backpack bag design reduces asymmetry and hence, is more suitable than the standard harvesting bag. However, results from the field show that the hip belt bag design was the most preferred and the backpack was the least preferred. Bao & Shahnavaz (1989) highlight the need for ergonomics researcher to convey laboratory findings into the field context. However, as shown by the current study, there are numerous challenges associated with field work, making it difficult for laboratory findings to be successfully conveyed to the field. Limitations and Recommendations: For the laboratory phase of the project, no biomechanical and cardiovascular responses were assessed. However, for a holistic approach, these variables should be considered in future studies. Due to high variability from one harvesting cycle to another, more than three harvesting cycles should also be performed to accurately replicate the harvesting process as done in the field over extended durations of time. For the field phase, data should be collected from more than one citrus farm and thus a larger sample size could be obtained. This would improve the validity of the study. In addition to this, data should be collected for a full working day, especially if environmental conditions are not a hindrance, as well as for a whole season, since workloads vary, depending on the time of the harvesting season. , Name on Graduation Programme: Bassey-Duke, Elizabeth Missan
- Full Text:
- Date Issued: 2015
An ergonomics study of orthotics and prosthetics workshops in the Eastern Cape of South Africa
- Authors: Mgibantaka, Aviwe Sihle
- Date: 2021-10-29
- Subjects: Orthopedic apparatus industry South Africa Eastern Cape Administration , Prosthesis industry South Africa Eastern Cape Administration , Prosthetists Health and hygiene South Africa Eastern Cape , Prosthetists Job stress South Africa Eastern Cape , Work environment Psychological aspects , Industrial hygiene South Africa Eastern Cape , Human engineering South Africa Eastern Cape , Industrial safety South Africa Eastern Cape , Posture Health aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192108 , vital:45196
- Description: The South African healthcare system is under pressure due to inequalities inherited from the Apartheid system of the past, as well as more recent maladministration. These problems are particularly evident in the Eastern Cape province, which is considered the second poorest province in the country. Furthermore, the rehabilitation sector within healthcare is struggling for recognition in both the public and private healthcare sectors. Orthotists and prosthetists (O&Ps) form an important service in the greater rehabilitation sector since they provide an essential service for people living with disabilities, thus enabling them to function independently. Limited literature and anecdotal evidence suggest that O&Ps perform strenuous physical work under sub-optimal environmental conditions. Furthermore, it is hypothesized that the contextual influences of a struggling healthcare system such as lack or resources, poor referral systems, staff shortages and poor working environments may create a lot of challenges for O&Ps that can impact O&P’s health and well-being and work performance. Purpose: The purpose of this study was to assess the systemic challenges and enablers facing orthotists and prosthetists working in the Eastern Cape of South Africa and thus also evaluate the impact on their health and well-being as well as their job performance. Furthermore, this thesis aimed to compare the work system of O&Ps working in the public with that of O&Ps in the private sector. Methods: A quantitative research method was chosen for this study. Data were collected using a descriptive questionnaire-based approach aimed at identifying the socio-technical interactions in the work systems of O&Ps in the Eastern Cape province of South Africa. This study was approved by the Rhodes University Ethical Standards Committee. The questionnaire was created in Google forms and the link to the online form was sent to Medical O&Ps and Orthopaedic Footwear Technicians using instant messaging (WhatsApp). Two hard copies were also handed out. Data were analysed using StatSoft Statistica Software (version 13.4.0.14 by TIBCO Software Inc.). Descriptive, parametric, content and correlation analyses were conducted. Significant findings were identified at p<0.05. Results: The study received 43 respondents working in both the public and private health sectors, of which 53.5% were males and 46.5% females. The mean age of the respondents was 34.38 years with a coefficient of variation of 19.45%. Majority of respondents (68.9%) worked in the public sector, with the remainder working in the private sector, or sharing their time between both healthcare sectors. Generally, respondents were satisfied with the organizational structure of their workplaces and their work environments. Work demands were identified by respondents from both sectors as an area of concern as tasks performed by O&Ps entailed physical strength, prolonged standing, awkward postures, and repetitive movements. Furthermore, there were some concerns about lighting and noise being unfavourable in some of the workshops. For all the system components, the standard deviations had a low dispersion of less than 1.0 from the mean. The lowest dispersion was 0.63 and the highest dispersion from the mean was 0.99. The analysis using the general linear models option revealed a significant difference between the scores of the work system components (p=0.03). The subsequent Tukey post-hoc test revealed a significant difference in the mean rating scores between the “Environment” and “Work demands”, with a p-value of 0.03. There was discontentment from respondents working in both sectors with their work productivity as the public health sector respondents were 64.52% content; private sector respondents were 68.89% content, and respondents working in both sectors were only 56.67% content. When comparing the responses between O&Ps working in the different sectors, respondents working both sectors were unhappy with the provision of tools, machines, and materials, with 56.25% of the respondents working in the public health sector being less happy than the 61.11% working in the private health sector and the 63.19% working in both the private and public health sectors. Respondents had concerns regarding health and well-being with 60.60% of respondents working in both the public and private health sectors and experiencing more challenges than the 61.05% in the public and 67.24% in the private health sectors, respectively. Correlation analyses revealed very high positive correlations between the system components and the system outcomes. Conclusion: The biggest issue emerging from this study was work demands as O&Ps work is physically demanding. O&Ps had to do a lot of manual handling, heavy load lifting, endure repetitive and vibration movements, prolonged standing and bending in awkward postures to complete tasks. The results from this study indicate that the private health sector is better equipped in terms of the work environment, machines than the public healthcare sector. The finding from this study can be used to improve the factors that enable O&Ps’ job performance and come up with possible solutions to the challenges O&Ps face in their jobs. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mgibantaka, Aviwe Sihle
- Date: 2021-10-29
- Subjects: Orthopedic apparatus industry South Africa Eastern Cape Administration , Prosthesis industry South Africa Eastern Cape Administration , Prosthetists Health and hygiene South Africa Eastern Cape , Prosthetists Job stress South Africa Eastern Cape , Work environment Psychological aspects , Industrial hygiene South Africa Eastern Cape , Human engineering South Africa Eastern Cape , Industrial safety South Africa Eastern Cape , Posture Health aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192108 , vital:45196
- Description: The South African healthcare system is under pressure due to inequalities inherited from the Apartheid system of the past, as well as more recent maladministration. These problems are particularly evident in the Eastern Cape province, which is considered the second poorest province in the country. Furthermore, the rehabilitation sector within healthcare is struggling for recognition in both the public and private healthcare sectors. Orthotists and prosthetists (O&Ps) form an important service in the greater rehabilitation sector since they provide an essential service for people living with disabilities, thus enabling them to function independently. Limited literature and anecdotal evidence suggest that O&Ps perform strenuous physical work under sub-optimal environmental conditions. Furthermore, it is hypothesized that the contextual influences of a struggling healthcare system such as lack or resources, poor referral systems, staff shortages and poor working environments may create a lot of challenges for O&Ps that can impact O&P’s health and well-being and work performance. Purpose: The purpose of this study was to assess the systemic challenges and enablers facing orthotists and prosthetists working in the Eastern Cape of South Africa and thus also evaluate the impact on their health and well-being as well as their job performance. Furthermore, this thesis aimed to compare the work system of O&Ps working in the public with that of O&Ps in the private sector. Methods: A quantitative research method was chosen for this study. Data were collected using a descriptive questionnaire-based approach aimed at identifying the socio-technical interactions in the work systems of O&Ps in the Eastern Cape province of South Africa. This study was approved by the Rhodes University Ethical Standards Committee. The questionnaire was created in Google forms and the link to the online form was sent to Medical O&Ps and Orthopaedic Footwear Technicians using instant messaging (WhatsApp). Two hard copies were also handed out. Data were analysed using StatSoft Statistica Software (version 13.4.0.14 by TIBCO Software Inc.). Descriptive, parametric, content and correlation analyses were conducted. Significant findings were identified at p<0.05. Results: The study received 43 respondents working in both the public and private health sectors, of which 53.5% were males and 46.5% females. The mean age of the respondents was 34.38 years with a coefficient of variation of 19.45%. Majority of respondents (68.9%) worked in the public sector, with the remainder working in the private sector, or sharing their time between both healthcare sectors. Generally, respondents were satisfied with the organizational structure of their workplaces and their work environments. Work demands were identified by respondents from both sectors as an area of concern as tasks performed by O&Ps entailed physical strength, prolonged standing, awkward postures, and repetitive movements. Furthermore, there were some concerns about lighting and noise being unfavourable in some of the workshops. For all the system components, the standard deviations had a low dispersion of less than 1.0 from the mean. The lowest dispersion was 0.63 and the highest dispersion from the mean was 0.99. The analysis using the general linear models option revealed a significant difference between the scores of the work system components (p=0.03). The subsequent Tukey post-hoc test revealed a significant difference in the mean rating scores between the “Environment” and “Work demands”, with a p-value of 0.03. There was discontentment from respondents working in both sectors with their work productivity as the public health sector respondents were 64.52% content; private sector respondents were 68.89% content, and respondents working in both sectors were only 56.67% content. When comparing the responses between O&Ps working in the different sectors, respondents working both sectors were unhappy with the provision of tools, machines, and materials, with 56.25% of the respondents working in the public health sector being less happy than the 61.11% working in the private health sector and the 63.19% working in both the private and public health sectors. Respondents had concerns regarding health and well-being with 60.60% of respondents working in both the public and private health sectors and experiencing more challenges than the 61.05% in the public and 67.24% in the private health sectors, respectively. Correlation analyses revealed very high positive correlations between the system components and the system outcomes. Conclusion: The biggest issue emerging from this study was work demands as O&Ps work is physically demanding. O&Ps had to do a lot of manual handling, heavy load lifting, endure repetitive and vibration movements, prolonged standing and bending in awkward postures to complete tasks. The results from this study indicate that the private health sector is better equipped in terms of the work environment, machines than the public healthcare sector. The finding from this study can be used to improve the factors that enable O&Ps’ job performance and come up with possible solutions to the challenges O&Ps face in their jobs. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10-29
An explorative study of Makana local football association coaches characteristics, experiences and needs
- Authors: Callow, Gavin
- Date: 2020
- Subjects: Makana Local Football Association (South Africa) , Football -- Coaching -- South Africa , Football coaches -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138785 , vital:37672
- Description: Introduction: Sports participation has been associated with a number of benefits to young athletes, outside of purely physical health. One of the key components of a successful sports talent identification and development program is effective coaching. A foundation of effective coaching is the coach’s knowledge which can be developed through formal, non-formal and informal means of education. The majority of coach education literature has however focused on coaches from developed countries. Limited studies have looked at the educational experiences and needs of South African coaches, particularly football coaches. The purpose of the current investigation is to establish Local Football Association (LFA) coaches’ perceptions of their educational backgrounds and what knowledge they deem important to be effective coaches. Method: A mixed methods approach was used in which (n=25) Makana LFA coaches answered a questionnaire with the aim of identifying their educational histories and what their current educational needs were. A semi-structured interview was also implemented in which some of the respondents (n=4) were asked more in-depth questions around the same topics, to create a more complete coaching profile. Results: The questionnaire responses highlighted that only 8% of the coaches possess a formal coaching qualification and all of the coaches work on a volunteer basis. Previous experience as a player is the chief source of knowledge for Makana LFA coaches. Not having enough available time is the main perceived barrier for 56% of participants to seeking out further educational opportunities. Fundamentals of coaching was selected by 56% of the coaches as a key subject they want to learn more about. Findings from the interview demonstrate that participants coach multiple teams and often have to rely on senior players to take up assistant coach positions, as well as managing their time effectively to work with all their teams. Informal education is the main source of information for the coaches which includes asking for advice, reading coaching manuals or having a mentor. The coaches value all 3 forms of education, however non-formal workshops are favoured. This is due to all of the coaches already having some form of informal learning experience and formal learning opportunities being too costly to pursue. A combination of lectures, practical sessions and group discussions is desired as a delivery method of coaching knowledge. Discussion: The level of coaching qualifications in the LFA is low, this may have significant implications for talent identification and development in the Sarah Baartman region. All the coaches are volunteer coaches, who primarily rely on informal means of coaching education. ‘Time’ was indicated to be a major barrier, to coaches seeking out educational opportunities. Coaches indicated that they would benefit from a coaching program if it took into consideration their needs, such as wanting to learn more about interpersonal and intrapersonal awareness. Conclusion: If local coaching programs are to be effective, they must reflect the educational needs of their community.
- Full Text:
- Date Issued: 2020
- Authors: Callow, Gavin
- Date: 2020
- Subjects: Makana Local Football Association (South Africa) , Football -- Coaching -- South Africa , Football coaches -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138785 , vital:37672
- Description: Introduction: Sports participation has been associated with a number of benefits to young athletes, outside of purely physical health. One of the key components of a successful sports talent identification and development program is effective coaching. A foundation of effective coaching is the coach’s knowledge which can be developed through formal, non-formal and informal means of education. The majority of coach education literature has however focused on coaches from developed countries. Limited studies have looked at the educational experiences and needs of South African coaches, particularly football coaches. The purpose of the current investigation is to establish Local Football Association (LFA) coaches’ perceptions of their educational backgrounds and what knowledge they deem important to be effective coaches. Method: A mixed methods approach was used in which (n=25) Makana LFA coaches answered a questionnaire with the aim of identifying their educational histories and what their current educational needs were. A semi-structured interview was also implemented in which some of the respondents (n=4) were asked more in-depth questions around the same topics, to create a more complete coaching profile. Results: The questionnaire responses highlighted that only 8% of the coaches possess a formal coaching qualification and all of the coaches work on a volunteer basis. Previous experience as a player is the chief source of knowledge for Makana LFA coaches. Not having enough available time is the main perceived barrier for 56% of participants to seeking out further educational opportunities. Fundamentals of coaching was selected by 56% of the coaches as a key subject they want to learn more about. Findings from the interview demonstrate that participants coach multiple teams and often have to rely on senior players to take up assistant coach positions, as well as managing their time effectively to work with all their teams. Informal education is the main source of information for the coaches which includes asking for advice, reading coaching manuals or having a mentor. The coaches value all 3 forms of education, however non-formal workshops are favoured. This is due to all of the coaches already having some form of informal learning experience and formal learning opportunities being too costly to pursue. A combination of lectures, practical sessions and group discussions is desired as a delivery method of coaching knowledge. Discussion: The level of coaching qualifications in the LFA is low, this may have significant implications for talent identification and development in the Sarah Baartman region. All the coaches are volunteer coaches, who primarily rely on informal means of coaching education. ‘Time’ was indicated to be a major barrier, to coaches seeking out educational opportunities. Coaches indicated that they would benefit from a coaching program if it took into consideration their needs, such as wanting to learn more about interpersonal and intrapersonal awareness. Conclusion: If local coaching programs are to be effective, they must reflect the educational needs of their community.
- Full Text:
- Date Issued: 2020
An insight into the profile characteristics and technical batting skill of adolescent cricket players
- Authors: Clark, Matthew Edward
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2838 , vital:20331
- Description: Background: Current traditional cricket practices incorporate the use of a netted-off pitch to provide cricket players the opportunity to hone their skills with bat and ball. The lack of ecological validity of these training environments results in the absence of important task and environmental constraints which influences the manner in which the sport is played. Objectives: The purpose of the current research was two-fold: firstly, it aimed to establish a profile database of adolescent cricket players in the Eastern Cape province of South Africa; and secondly, it aimed to investigate the efficacy of a constraints-led training intervention on skill development in adolescent cricket batsmen. Methods: Study I required 90 participants (u13: n = 40; u15: n = 50) to perform measures pertaining to anthropometric, morphological, flexibility and physical performance characteristics. This included stature, mass, body composition, limb length, flexibility, agility, and power measures. Study II was a case-control study (u15: n = 24), whereby the experimental group (n = 12) was exposed to a constraints-led batting protocol during the course of the cricket season. The objective of the protocol was to encourage the manipulation of the ball around the playing field. Pre- and post-intervention measures were performed using a batting skills test, which assessed batsmen’s capability to manipulate the ball to various areas of the playing field. Results: Study I revealed significant differences (p <0.0001) in stature, mass, limb length and power variables when comparing the u15 age group with the u13 age group. No differences were recorded for agility. The u13 age group had greater linear correlations for the variables of interest compared to the u15 age group. Study II revealed no differences in technical skill between the experimental group and the control (p <0.315).. The tests also revealed that adolescent batsmen favoured hitting deliveries through the extra-cover scoring zone. The third-man and fine-leg scoring zones were least preferred to hit deliveries through. A number of limitations to the study design resulted in the inability to determine the efficacy of a constraints-led batting protocol on skill development in an adolescent batting cohort. Conclusion: The results of study I indicated that the onset of puberty played an important role in the measures and performances between the u13 and u15 age groups. The results of study II indicated that adolescent batsmen are not adept at manipulating the ball around the field. Recommendations are provided for both studies.
- Full Text:
- Date Issued: 2016
- Authors: Clark, Matthew Edward
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2838 , vital:20331
- Description: Background: Current traditional cricket practices incorporate the use of a netted-off pitch to provide cricket players the opportunity to hone their skills with bat and ball. The lack of ecological validity of these training environments results in the absence of important task and environmental constraints which influences the manner in which the sport is played. Objectives: The purpose of the current research was two-fold: firstly, it aimed to establish a profile database of adolescent cricket players in the Eastern Cape province of South Africa; and secondly, it aimed to investigate the efficacy of a constraints-led training intervention on skill development in adolescent cricket batsmen. Methods: Study I required 90 participants (u13: n = 40; u15: n = 50) to perform measures pertaining to anthropometric, morphological, flexibility and physical performance characteristics. This included stature, mass, body composition, limb length, flexibility, agility, and power measures. Study II was a case-control study (u15: n = 24), whereby the experimental group (n = 12) was exposed to a constraints-led batting protocol during the course of the cricket season. The objective of the protocol was to encourage the manipulation of the ball around the playing field. Pre- and post-intervention measures were performed using a batting skills test, which assessed batsmen’s capability to manipulate the ball to various areas of the playing field. Results: Study I revealed significant differences (p <0.0001) in stature, mass, limb length and power variables when comparing the u15 age group with the u13 age group. No differences were recorded for agility. The u13 age group had greater linear correlations for the variables of interest compared to the u15 age group. Study II revealed no differences in technical skill between the experimental group and the control (p <0.315).. The tests also revealed that adolescent batsmen favoured hitting deliveries through the extra-cover scoring zone. The third-man and fine-leg scoring zones were least preferred to hit deliveries through. A number of limitations to the study design resulted in the inability to determine the efficacy of a constraints-led batting protocol on skill development in an adolescent batting cohort. Conclusion: The results of study I indicated that the onset of puberty played an important role in the measures and performances between the u13 and u15 age groups. The results of study II indicated that adolescent batsmen are not adept at manipulating the ball around the field. Recommendations are provided for both studies.
- Full Text:
- Date Issued: 2016
An investigation into control mechanisms of driving performance : resource depletion and effort-regulation
- Authors: Louw, Tyron Linton
- Date: 2013
- Subjects: Automobile driving simulators , Automobile driving -- Psychological aspects , Automobile driving -- Physiological aspects , Traffic accidents , Traffic safety , Fatigue
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5101 , http://hdl.handle.net/10962/d1001842 , Automobile driving simulators , Automobile driving -- Psychological aspects , Automobile driving -- Physiological aspects , Traffic accidents , Traffic safety , Fatigue
- Description: Driver fatigue is a complex phenomenon that has a range of causal factors including sleeprelated and task-related factors. These manifest as different safety and performance outcomes. Extensive research has been applied to linking these factors to performance impairment. However, little research focuses on the mechanisms by which this link exists. This research project therefore focuses on the processes underlying how driving performance is controlled and maintained during the development on non-sleep-related driver fatigue. The main aim was to establish whether progressive impairment of driving control over a prolonged drive could be attributed to a depletion of attentional resources, as proposed by Resource Theory, or to a withdrawal of effort, as proposed by Effort-Regulation Theory. As a multicomponent skill, driving requires perception, cognition and motor output. The secondary aim of this research was therefore to assess whether a prolonged drive impairs stage-specific information processing. Participants (n=24) in three experimental groups performed a 90-minute simulated drive wherein they were expected to keep the bonnet of a car on a lane (tracking task). The three groups differed in terms of lane width: small, medium and large, corresponding to low, medium, and high task-demand, respectively. To assess the impacts of this task on stagespecific information processing, participants performed a set of resource specific tests before and after the prolonged drive. Each task had two difficulty variations to ensure that performance decrement was due not only to the task-characteristic, but specifically to resource depletion. The tests probing information processing were: a modified Fitts' tapping task for motor programming, a digit recall task for perception, and an object recognition reading task for cognition. Performance was measured as lateral deviation of the car. Physiological measures included heart rate frequency (HR) and various time- and frequencydomain heart rate variability (HRV) parameters, eye blink frequency and duration. The Borg CR-10 scale was used to evaluate subjective effort and fatigue during the task. Driving control declined over time and was supplemented by HR, HRV, blink frequency and duration, indicating an increase in parasympathetic activity (or a reduction in arousal). An increase in blink frequency was considered as a sign of withdrawal of attentional resources over time. Driving control declined to a greater extent in the large road width group and reflected a lower parasympathetic activity, whereas the inverse was observed for the small road width group. Resource tests reveal a non-specific impairment of information processing following the prolonged drive. However, this was accompanied by an increase in parasympathetic activity. Overall, results indicate that Effort-Regulation Theory better accounts for the impairment of driving control in prolonged driving than does Resource Theory. This suggests that the impact of fatigue is guided more by task goals and intrinsic motivation than by the manner in which the fatigue state developed. Moreover, performance impairment by effort-regulation is dependant more on time on task than on task-demand
- Full Text:
- Date Issued: 2013
- Authors: Louw, Tyron Linton
- Date: 2013
- Subjects: Automobile driving simulators , Automobile driving -- Psychological aspects , Automobile driving -- Physiological aspects , Traffic accidents , Traffic safety , Fatigue
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5101 , http://hdl.handle.net/10962/d1001842 , Automobile driving simulators , Automobile driving -- Psychological aspects , Automobile driving -- Physiological aspects , Traffic accidents , Traffic safety , Fatigue
- Description: Driver fatigue is a complex phenomenon that has a range of causal factors including sleeprelated and task-related factors. These manifest as different safety and performance outcomes. Extensive research has been applied to linking these factors to performance impairment. However, little research focuses on the mechanisms by which this link exists. This research project therefore focuses on the processes underlying how driving performance is controlled and maintained during the development on non-sleep-related driver fatigue. The main aim was to establish whether progressive impairment of driving control over a prolonged drive could be attributed to a depletion of attentional resources, as proposed by Resource Theory, or to a withdrawal of effort, as proposed by Effort-Regulation Theory. As a multicomponent skill, driving requires perception, cognition and motor output. The secondary aim of this research was therefore to assess whether a prolonged drive impairs stage-specific information processing. Participants (n=24) in three experimental groups performed a 90-minute simulated drive wherein they were expected to keep the bonnet of a car on a lane (tracking task). The three groups differed in terms of lane width: small, medium and large, corresponding to low, medium, and high task-demand, respectively. To assess the impacts of this task on stagespecific information processing, participants performed a set of resource specific tests before and after the prolonged drive. Each task had two difficulty variations to ensure that performance decrement was due not only to the task-characteristic, but specifically to resource depletion. The tests probing information processing were: a modified Fitts' tapping task for motor programming, a digit recall task for perception, and an object recognition reading task for cognition. Performance was measured as lateral deviation of the car. Physiological measures included heart rate frequency (HR) and various time- and frequencydomain heart rate variability (HRV) parameters, eye blink frequency and duration. The Borg CR-10 scale was used to evaluate subjective effort and fatigue during the task. Driving control declined over time and was supplemented by HR, HRV, blink frequency and duration, indicating an increase in parasympathetic activity (or a reduction in arousal). An increase in blink frequency was considered as a sign of withdrawal of attentional resources over time. Driving control declined to a greater extent in the large road width group and reflected a lower parasympathetic activity, whereas the inverse was observed for the small road width group. Resource tests reveal a non-specific impairment of information processing following the prolonged drive. However, this was accompanied by an increase in parasympathetic activity. Overall, results indicate that Effort-Regulation Theory better accounts for the impairment of driving control in prolonged driving than does Resource Theory. This suggests that the impact of fatigue is guided more by task goals and intrinsic motivation than by the manner in which the fatigue state developed. Moreover, performance impairment by effort-regulation is dependant more on time on task than on task-demand
- Full Text:
- Date Issued: 2013
An investigation into fatigue prevalence amongst citrus packhouse sorters in the Eastern Cape province of South Africa
- Authors: Robinson, Harry Jack
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424312 , vital:72142
- Description: Background: South Africa is the second most influential exporter of citrus fruits internationally and holds a pivotal role in economic revenue for the country. Rural areas, such as the Sundays River Valley in the Eastern Cape province of South Africa, contribute to the country’s citrus production. Many women depend on citrus packhouses for employment as citrus sorters. As humans perceive certain defects in citrus fruits more accurately than machines, these sorters must identify and manually remove any fruit that does not conform with export requirements. Citrus sorters are exposed to numerous physical and cognitive stressors during the task while faced with organizational challenges, such as shift work and long working hours. Therefore, the potential for fatigue development is anticipated. Given the multifactorial nature of fatigue and the negative consequences it may have on workers, it also has the potential to impede the accuracy of the sorting performance. Stringent disciplinary action for the entire South African citrus industry may be of consequence if nonconforming or pest-infested fruit is missed by citrus sorters and exported to foreign countries. This study aimed to investigate the prevalence of fatigue among citrus sorters in a citrus packhouse in the Sundays River Valley of the Eastern Cape throughout a citrus harvesting season and to identify factors that may contribute towards fatigue development. Methods: The research design utilized a crosssectional, two-part approach that applied mixed methods. Part one was administered once-off, incorporating demographic, work-, and non-work-related questions. Part two was a self-developed repeated measures assessment comprising close-ended contextual questions, the Modified Fatigue Impact Scale, and the Karolinska Sleepiness Scale. Environmental and work output data were also recorded. Results: Citrus sorters (n= 35) recorded a mean MFIS score of 39.35 throughout the harvest season, which was above the prescribed fatigue threshold (38). However, there was no significant difference in fatigue ratings over time (p= 0.122). Day shift workers exceeded the fatigue threshold for the entire season compared to night shift workers, who only exceeded it in the last two weeks. The physical, cognitive, and psychosocial subscales found no significant difference in fatigue scores, although physical fatigue recorded the highest scores across all weeks and displayed a significant difference over time. Overall, participants, on average, perceived to be “neither sleepy nor alert” over the season. However, eight participants (22%) recorded sleepiness scores ii exceeding the excessive sleepiness threshold of seven. Educational levels, health status, work-pace, and the number of family dependents significantly contributed to fatigue development, albeit a weak correlation. Discussion: Sorters were perceived to be fatigued from week three till the end of the study; however, there was no variation in fatigue scores over time. An accumulation of physical fatigue over time was revealed where prolonged standing, repetitive work, and irregular working postures may have contributed. Night shift workers did not receive the recommended hours of sleep (7-8 hours); hence, they registered greater sleepiness scores over the season than day shift workers. Environmental and work output recordings did not prove to have a significant influence on fatigue development, and neither did work experience or physical exercise. Conclusion: An amalgamation of numerous contributing factors within the work situation, private situation, and the individual influenced the development of fatigue, where there was no primary causal factor. Future studies should consider recording the accuracy of the sorting performance to acquire rich, objective data. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Robinson, Harry Jack
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424312 , vital:72142
- Description: Background: South Africa is the second most influential exporter of citrus fruits internationally and holds a pivotal role in economic revenue for the country. Rural areas, such as the Sundays River Valley in the Eastern Cape province of South Africa, contribute to the country’s citrus production. Many women depend on citrus packhouses for employment as citrus sorters. As humans perceive certain defects in citrus fruits more accurately than machines, these sorters must identify and manually remove any fruit that does not conform with export requirements. Citrus sorters are exposed to numerous physical and cognitive stressors during the task while faced with organizational challenges, such as shift work and long working hours. Therefore, the potential for fatigue development is anticipated. Given the multifactorial nature of fatigue and the negative consequences it may have on workers, it also has the potential to impede the accuracy of the sorting performance. Stringent disciplinary action for the entire South African citrus industry may be of consequence if nonconforming or pest-infested fruit is missed by citrus sorters and exported to foreign countries. This study aimed to investigate the prevalence of fatigue among citrus sorters in a citrus packhouse in the Sundays River Valley of the Eastern Cape throughout a citrus harvesting season and to identify factors that may contribute towards fatigue development. Methods: The research design utilized a crosssectional, two-part approach that applied mixed methods. Part one was administered once-off, incorporating demographic, work-, and non-work-related questions. Part two was a self-developed repeated measures assessment comprising close-ended contextual questions, the Modified Fatigue Impact Scale, and the Karolinska Sleepiness Scale. Environmental and work output data were also recorded. Results: Citrus sorters (n= 35) recorded a mean MFIS score of 39.35 throughout the harvest season, which was above the prescribed fatigue threshold (38). However, there was no significant difference in fatigue ratings over time (p= 0.122). Day shift workers exceeded the fatigue threshold for the entire season compared to night shift workers, who only exceeded it in the last two weeks. The physical, cognitive, and psychosocial subscales found no significant difference in fatigue scores, although physical fatigue recorded the highest scores across all weeks and displayed a significant difference over time. Overall, participants, on average, perceived to be “neither sleepy nor alert” over the season. However, eight participants (22%) recorded sleepiness scores ii exceeding the excessive sleepiness threshold of seven. Educational levels, health status, work-pace, and the number of family dependents significantly contributed to fatigue development, albeit a weak correlation. Discussion: Sorters were perceived to be fatigued from week three till the end of the study; however, there was no variation in fatigue scores over time. An accumulation of physical fatigue over time was revealed where prolonged standing, repetitive work, and irregular working postures may have contributed. Night shift workers did not receive the recommended hours of sleep (7-8 hours); hence, they registered greater sleepiness scores over the season than day shift workers. Environmental and work output recordings did not prove to have a significant influence on fatigue development, and neither did work experience or physical exercise. Conclusion: An amalgamation of numerous contributing factors within the work situation, private situation, and the individual influenced the development of fatigue, where there was no primary causal factor. Future studies should consider recording the accuracy of the sorting performance to acquire rich, objective data. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
An investigation into the force-EMG relationship for static and dynamic exertions
- Koekemoer, Wesley Agosthinho
- Authors: Koekemoer, Wesley Agosthinho
- Date: 2022-04-06
- Subjects: Electromyography , Force and energy , Muscles Physiology , Biomechanics , Muscle contraction , Isometric exercise , Isotonic exercise , Static and dynamic exertions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291076 , vital:56816
- Description: The force-EMG relationship has multiple applications in varying fields of study and practice. One such application is the development of safety guidelines and regulations. Current guidelines are based on static muscle actions even though the majority of tasks encountered in industry are dynamic in nature. This may have negative implications for the health, safety, and productivity of workers as regulations based on static muscle actions may place higher force demands on manual labourers compared to what would be expected if regulations were based on dynamic muscle actions. Regulations based on dynamic muscle actions may be more effective in worker safety as the nature of the regulation matches that of the demand. Few studies have investigated the force-EMG relationship during dynamic muscle actions and the few that do exist have reported contradictory / mixed results. Therefore, the purpose of this study was to: 1) gain an understanding of EMG responses at different load levels, and 2) show how the relationship differs between static and dynamic muscle actions. A two-factorial repeated-measures experiment was developed for this study. Eighteen experimental conditions, utilizing six load levels (0%, 20%, 40%, 60%, 80%, and 100% of maximum voluntary force) for each of the three muscle actions (isometric, concentric and eccentric). Surface EMG responses were obtained under these conditions by repeatedly dorsiflexing and plantarflexing the foot, thus activating the soleus muscle. A maximum voluntary exertion on an isokinetic dynamometer determined the maximum force level, based on which the sub-maximal loads were calculated and added to a pulley system. 31 student participants were recruited for this experiment which was conducted over two sessions – one information and habituation session, and one experimental session. The EMG data recorded were processed and checked for normality and outliers. The data was then analysed via a General Linear Model analysis to determine the effect of exertion type and of load level on the muscle activity. Significant differences were identified at p<0.05 and followed by a Tukey post-hoc test. Correlation analyses were also conducted to determine the relationship between the force and EMG at all three exertion types. All dependent measures showed that as the load level increased so did the sEMG amplitude for all muscle actions. Muscle actions differed significantly between majority of six force levels. Correlations between the load levels and sEMG amplitude for each muscle action indicated a significant correlation with a moderate strength. The conclusion draws from this study that there is a positive correlation between force and sEMG amplitude, at all load levels, with a moderate strength. However, the muscle actions differed significantly from each other. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Koekemoer, Wesley Agosthinho
- Date: 2022-04-06
- Subjects: Electromyography , Force and energy , Muscles Physiology , Biomechanics , Muscle contraction , Isometric exercise , Isotonic exercise , Static and dynamic exertions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291076 , vital:56816
- Description: The force-EMG relationship has multiple applications in varying fields of study and practice. One such application is the development of safety guidelines and regulations. Current guidelines are based on static muscle actions even though the majority of tasks encountered in industry are dynamic in nature. This may have negative implications for the health, safety, and productivity of workers as regulations based on static muscle actions may place higher force demands on manual labourers compared to what would be expected if regulations were based on dynamic muscle actions. Regulations based on dynamic muscle actions may be more effective in worker safety as the nature of the regulation matches that of the demand. Few studies have investigated the force-EMG relationship during dynamic muscle actions and the few that do exist have reported contradictory / mixed results. Therefore, the purpose of this study was to: 1) gain an understanding of EMG responses at different load levels, and 2) show how the relationship differs between static and dynamic muscle actions. A two-factorial repeated-measures experiment was developed for this study. Eighteen experimental conditions, utilizing six load levels (0%, 20%, 40%, 60%, 80%, and 100% of maximum voluntary force) for each of the three muscle actions (isometric, concentric and eccentric). Surface EMG responses were obtained under these conditions by repeatedly dorsiflexing and plantarflexing the foot, thus activating the soleus muscle. A maximum voluntary exertion on an isokinetic dynamometer determined the maximum force level, based on which the sub-maximal loads were calculated and added to a pulley system. 31 student participants were recruited for this experiment which was conducted over two sessions – one information and habituation session, and one experimental session. The EMG data recorded were processed and checked for normality and outliers. The data was then analysed via a General Linear Model analysis to determine the effect of exertion type and of load level on the muscle activity. Significant differences were identified at p<0.05 and followed by a Tukey post-hoc test. Correlation analyses were also conducted to determine the relationship between the force and EMG at all three exertion types. All dependent measures showed that as the load level increased so did the sEMG amplitude for all muscle actions. Muscle actions differed significantly between majority of six force levels. Correlations between the load levels and sEMG amplitude for each muscle action indicated a significant correlation with a moderate strength. The conclusion draws from this study that there is a positive correlation between force and sEMG amplitude, at all load levels, with a moderate strength. However, the muscle actions differed significantly from each other. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06