The effect of progressive resistance training on the blood lipid profile in post-menopausal women
- Authors: Viljoen, Janet Erica
- Date: 2009
- Subjects: Weight training for women -- Physiological aspects , Weight training -- Physiological aspects , Exercise for women -- Physiological aspects , Physical fitness for women -- Physiological aspects , Energy metabolism , Middle aged women -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5113 , http://hdl.handle.net/10962/d1005191 , Weight training for women -- Physiological aspects , Weight training -- Physiological aspects , Exercise for women -- Physiological aspects , Physical fitness for women -- Physiological aspects , Energy metabolism , Middle aged women -- Health and hygiene
- Description: The main purpose of this study was to assess the effect of progressive resistance training on the blood lipid profile in post-menopausal women. Thirty-four female subjects aged 50 to 75 years were selected from the population of Grahamstown, South Africa. All participants were previously sedentary and possessed at least one lipid profile abnormality but were otherwise healthy. Pre-tests included a sub-maximal stress Electrocardiogram, measures of stature, mass, central and limb girths as well as an oral glucose tolerance test (OGTT) and a total blood lipid profile. Participants took part in a 24-week progressive resistance training programme, consisting of three supervised sessions per week, each lasting 45 minutes and were not permitted to lose more than 10% of initial body mass during the 24-week study. All pre-test measures, excluding the stress ECG and the OGTT, were repeated every four weeks for the duration of the study. Results were that body mass, body mass index and waist-to-hip ratio did not change. Girth measures at mid-humerus, chest, waist, hip, mid-quadricep and mid-gastrocnemius all decreased significantly (p=0.05). LDL-cholesterol increased significantly over the course of 24 weeks (3.61mmol.L-1 to 4.07mmol.L-1) as did total cholesterol (5.81mmol.L-1 to 6.24mmol.L-1). Triglyceride concentration remained unchanged and HDL-cholesterol decreased significantly between the pre-test measure (1.55mmol.L-1) and the measure after six months (1.42mmol.L-1). It can be concluded that the blood lipid profile in a sample of post-menopausal women was not positively affected by a progressive resistance training programme over a 24 week period. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2009
- Authors: Viljoen, Janet Erica
- Date: 2009
- Subjects: Weight training for women -- Physiological aspects , Weight training -- Physiological aspects , Exercise for women -- Physiological aspects , Physical fitness for women -- Physiological aspects , Energy metabolism , Middle aged women -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5113 , http://hdl.handle.net/10962/d1005191 , Weight training for women -- Physiological aspects , Weight training -- Physiological aspects , Exercise for women -- Physiological aspects , Physical fitness for women -- Physiological aspects , Energy metabolism , Middle aged women -- Health and hygiene
- Description: The main purpose of this study was to assess the effect of progressive resistance training on the blood lipid profile in post-menopausal women. Thirty-four female subjects aged 50 to 75 years were selected from the population of Grahamstown, South Africa. All participants were previously sedentary and possessed at least one lipid profile abnormality but were otherwise healthy. Pre-tests included a sub-maximal stress Electrocardiogram, measures of stature, mass, central and limb girths as well as an oral glucose tolerance test (OGTT) and a total blood lipid profile. Participants took part in a 24-week progressive resistance training programme, consisting of three supervised sessions per week, each lasting 45 minutes and were not permitted to lose more than 10% of initial body mass during the 24-week study. All pre-test measures, excluding the stress ECG and the OGTT, were repeated every four weeks for the duration of the study. Results were that body mass, body mass index and waist-to-hip ratio did not change. Girth measures at mid-humerus, chest, waist, hip, mid-quadricep and mid-gastrocnemius all decreased significantly (p=0.05). LDL-cholesterol increased significantly over the course of 24 weeks (3.61mmol.L-1 to 4.07mmol.L-1) as did total cholesterol (5.81mmol.L-1 to 6.24mmol.L-1). Triglyceride concentration remained unchanged and HDL-cholesterol decreased significantly between the pre-test measure (1.55mmol.L-1) and the measure after six months (1.42mmol.L-1). It can be concluded that the blood lipid profile in a sample of post-menopausal women was not positively affected by a progressive resistance training programme over a 24 week period. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2009
The effect of restricted environments on selected postural, physiological and perceptual responses
- Authors: Wolfe, Amy
- Date: 2008
- Subjects: Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5115 , http://hdl.handle.net/10962/d1005193 , Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
- Description: Manual lifting tasks are the predominant means of transporting materials in industry with many of these tasks being performed in confined spaces. Research has tended to focus on the biomechanical implications of working in small spaces with a decided lack of information about the physiological and perceptual responses in these environments. This holistic study therefore investigated the manner in which the human operator responded to conditions where the ceiling height was lowered and reach demands increased. Thirty-two young physically active male subjects (age: 21.55yr; stature: 1810mm) were recruited to complete a 2-way repeated measures experiment during which four lifting protocols where different combinations of ceiling height (‘normal’ or reduced to 1460mm in height) and reach demands (400mm or 800mm) were tested. A crude postural analysis was conducted while physiological responses were detailed and continuously monitored. Perceptual responses were also assessed. The tasks with a ‘normal’ ceiling height (mean compression forces: 2615N; mean shearing forces: 388N) and the greatest reach distance (mean compression forces: 3655N; mean shearing forces: 386N) placed individuals under the highest strain. Mean heart rate (HR) responses were significantly lower (p < 0.05) in the URN condition when compared to the RF condition. Furthermore, HR responses were statistically significantly affected by the height of the ceiling and the reach depth. Statistically significant differences (p< 0.05) in mean tidal volume (VT) occurred in the least (URN) and most (RF) restrictive conditions. Statistically significant differences (p < 0.05) in mean VE were evident between URN and URF, between URN and RF and between RN and RF. Ceiling height and reach demands had a statistically significant effect on all respiratory responses. There was a statistically significant difference in mean oxygen consumption (VO2) between the URN and all other conditions, and between the most restricted task (RF) and all other conditions. Both the effect of ceiling height and reach demands had a statistically statistically significant impact on VO2. Respiratory quotient (RQ) was significantly higher when loads were moved over 800mm compared to 400mm yet ceiling height did not have a statistically significant effect on RQ. Mean energy expenditure was significantly higher in the RF condition compared to the two least restrictive conditions (URN and RN). Statistically significant differences in EE were also evident between URN and RN, and between URN and URF. EE was significantly affected by reductions in ceiling height and increases in reach demands. Perceptually, the RF task (mean ‘Central’ RPE of 11) was perceived to place significantly greater cardiorespiratory demands on the operator compared to the URN (CRPE: 10) and RN (CRPE: 10) conditions. Statistically significant differences in perceived musculoskeletal strain only occurred between URN and RF. The effect of reach was perceived to have a statistically significant effect on both cardiovascular and musculoskeletal demands whereas ceiling height only had a statistically significant effect on musculoskeletal demands. The greatest discomfort was experienced in the lower back with the most intense discomfort occurring in the RN condition.
- Full Text:
- Date Issued: 2008
- Authors: Wolfe, Amy
- Date: 2008
- Subjects: Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5115 , http://hdl.handle.net/10962/d1005193 , Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
- Description: Manual lifting tasks are the predominant means of transporting materials in industry with many of these tasks being performed in confined spaces. Research has tended to focus on the biomechanical implications of working in small spaces with a decided lack of information about the physiological and perceptual responses in these environments. This holistic study therefore investigated the manner in which the human operator responded to conditions where the ceiling height was lowered and reach demands increased. Thirty-two young physically active male subjects (age: 21.55yr; stature: 1810mm) were recruited to complete a 2-way repeated measures experiment during which four lifting protocols where different combinations of ceiling height (‘normal’ or reduced to 1460mm in height) and reach demands (400mm or 800mm) were tested. A crude postural analysis was conducted while physiological responses were detailed and continuously monitored. Perceptual responses were also assessed. The tasks with a ‘normal’ ceiling height (mean compression forces: 2615N; mean shearing forces: 388N) and the greatest reach distance (mean compression forces: 3655N; mean shearing forces: 386N) placed individuals under the highest strain. Mean heart rate (HR) responses were significantly lower (p < 0.05) in the URN condition when compared to the RF condition. Furthermore, HR responses were statistically significantly affected by the height of the ceiling and the reach depth. Statistically significant differences (p< 0.05) in mean tidal volume (VT) occurred in the least (URN) and most (RF) restrictive conditions. Statistically significant differences (p < 0.05) in mean VE were evident between URN and URF, between URN and RF and between RN and RF. Ceiling height and reach demands had a statistically significant effect on all respiratory responses. There was a statistically significant difference in mean oxygen consumption (VO2) between the URN and all other conditions, and between the most restricted task (RF) and all other conditions. Both the effect of ceiling height and reach demands had a statistically statistically significant impact on VO2. Respiratory quotient (RQ) was significantly higher when loads were moved over 800mm compared to 400mm yet ceiling height did not have a statistically significant effect on RQ. Mean energy expenditure was significantly higher in the RF condition compared to the two least restrictive conditions (URN and RN). Statistically significant differences in EE were also evident between URN and RN, and between URN and URF. EE was significantly affected by reductions in ceiling height and increases in reach demands. Perceptually, the RF task (mean ‘Central’ RPE of 11) was perceived to place significantly greater cardiorespiratory demands on the operator compared to the URN (CRPE: 10) and RN (CRPE: 10) conditions. Statistically significant differences in perceived musculoskeletal strain only occurred between URN and RF. The effect of reach was perceived to have a statistically significant effect on both cardiovascular and musculoskeletal demands whereas ceiling height only had a statistically significant effect on musculoskeletal demands. The greatest discomfort was experienced in the lower back with the most intense discomfort occurring in the RN condition.
- Full Text:
- Date Issued: 2008
The effect of submersion in water and breathing modality (assisted breathing and apnea) on different stages of the information processing chain
- Authors: Goodenough, Luke Brian
- Date: 2017
- Subjects: Deep diving -- Physiological aspects , Scuba diving -- Physiological aspects , Apnea , Cognition -- Testing , Neurophysiology , Underwater breathing apparatus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7448 , vital:21261
- Description: Limited research has explored the impact of working underwater on the cognitive functioning of divers and even less has focused on the effect of breathing modality (assisted breathing and apnea) underwater. Research on the effect of submersion in water and apnea on cognitive performance is also very limited. As a result, the purpose of this study was to determine the effect of submersion in water and breathing modality on different stages of the information processing chain. This was achieved by testing participants in a laboratory setting under three conditions; on land, underwater with assisted breathing and underwater in apnea. Five different tests were used to determine which aspects of cognitive functioning were impaired in which condition. The recognition task result in the assisted breathing condition was significantly faster (p=0.04) but less accurate (p=0.01) than on land. The memory task was significantly (p=0.042) worse in terms of speed in the apnea condition compared to land, however accuracy was not affected. Performance in the visual detection task was impacted on in both underwater conditions compared to land with speed and accuracy being significantly worse (p<0.01) in the underwater conditions. These results indicate that simple tasks, (reaction time and tracking task) are not affected by condition whereas more complex tasks are. For tasks where an effect was found for only one condition, the effect was attributed to a specific aspect of that condition; either the breath hold or assisted breathing component of the condition. For tasks that were found to be affected in both underwater conditions, the effect was attributed to the actual submersion in water. The effect of the different conditions and the nature of the task they impact on should be considered for underwater work places as the general equipment used may impact on the quality of observations that are made.
- Full Text:
- Date Issued: 2017
- Authors: Goodenough, Luke Brian
- Date: 2017
- Subjects: Deep diving -- Physiological aspects , Scuba diving -- Physiological aspects , Apnea , Cognition -- Testing , Neurophysiology , Underwater breathing apparatus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7448 , vital:21261
- Description: Limited research has explored the impact of working underwater on the cognitive functioning of divers and even less has focused on the effect of breathing modality (assisted breathing and apnea) underwater. Research on the effect of submersion in water and apnea on cognitive performance is also very limited. As a result, the purpose of this study was to determine the effect of submersion in water and breathing modality on different stages of the information processing chain. This was achieved by testing participants in a laboratory setting under three conditions; on land, underwater with assisted breathing and underwater in apnea. Five different tests were used to determine which aspects of cognitive functioning were impaired in which condition. The recognition task result in the assisted breathing condition was significantly faster (p=0.04) but less accurate (p=0.01) than on land. The memory task was significantly (p=0.042) worse in terms of speed in the apnea condition compared to land, however accuracy was not affected. Performance in the visual detection task was impacted on in both underwater conditions compared to land with speed and accuracy being significantly worse (p<0.01) in the underwater conditions. These results indicate that simple tasks, (reaction time and tracking task) are not affected by condition whereas more complex tasks are. For tasks where an effect was found for only one condition, the effect was attributed to a specific aspect of that condition; either the breath hold or assisted breathing component of the condition. For tasks that were found to be affected in both underwater conditions, the effect was attributed to the actual submersion in water. The effect of the different conditions and the nature of the task they impact on should be considered for underwater work places as the general equipment used may impact on the quality of observations that are made.
- Full Text:
- Date Issued: 2017
The effect of total standing duration during sit-stand regimes on cognitive performance, rating of perceived exertion and heart rate frequency
- Authors: Berndt, Ethan
- Date: 2017
- Subjects: Standing position , Sedentary behavior , Work environment , Employee health promotion , Office furniture -- Design , Industrial hygiene , Employees -- Health risk assessment , Human engineering
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7433 , vital:21260
- Description: Although there may be numerous health benefits of sit-stand workstations, the effects of sedentary or non-sedentary work configurations on cognitive performance and executive function remain unclear (Bantoft et al., 2016). It is essential to determine any performance effects of these different work configurations; as improvements in the workplace, working posture and discomfort need to be justified in terms of improvements (or no deterioration) in work performance (Liao and Drury, 2000). The aim of the current research was to investigate the effect of two sit-stand regimes differing in total standing duration, on cognitive task performance, physiological responses and subjective ratings of perceived exertion. This laboratory based investigation incorporated a repeated measures design, where a test battery was utilized. Three experimental conditions were tested during three separate testing sessions by 30 participants. Condition 2 (15 minutes standing, followed by 45 minutes seated) and Condition 3 (15 minutes seated, followed by 15 minutes standing, followed by 15 minutes seated, followed by 15 minutes standing) were compared to each other and Condition 1 (60 minutes seated). The findings of this study show that even though the two different sit-stand regimes did not result in a significant impact on cognitive task performance, an immediate postural effect for psychomotor response time and a delayed postural effect for working memory were found. The participants perceived Condition 3 as the most physically exerting condition. Heart rate frequency was not significantly different between the conditions, but the immediate seated posture had a significantly lower heart rate frequency compared to the standing posture; indicating that being seated elicited lower energy expenditure compared to standing. Heart rate frequency while standing had a greater degree of variation compared to being seated. Taking the findings of this study into account, it is recommended that: one should be seated while performing this type of working memory task; that one should be standing while performing this type of psychomotor task; that the recommendation that implementing standing at work can be used as a blanket strategy to increase energy expenditure in all individuals needs to be explored further and that individual differences may impact energy expenditure.
- Full Text:
- Date Issued: 2017
- Authors: Berndt, Ethan
- Date: 2017
- Subjects: Standing position , Sedentary behavior , Work environment , Employee health promotion , Office furniture -- Design , Industrial hygiene , Employees -- Health risk assessment , Human engineering
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7433 , vital:21260
- Description: Although there may be numerous health benefits of sit-stand workstations, the effects of sedentary or non-sedentary work configurations on cognitive performance and executive function remain unclear (Bantoft et al., 2016). It is essential to determine any performance effects of these different work configurations; as improvements in the workplace, working posture and discomfort need to be justified in terms of improvements (or no deterioration) in work performance (Liao and Drury, 2000). The aim of the current research was to investigate the effect of two sit-stand regimes differing in total standing duration, on cognitive task performance, physiological responses and subjective ratings of perceived exertion. This laboratory based investigation incorporated a repeated measures design, where a test battery was utilized. Three experimental conditions were tested during three separate testing sessions by 30 participants. Condition 2 (15 minutes standing, followed by 45 minutes seated) and Condition 3 (15 minutes seated, followed by 15 minutes standing, followed by 15 minutes seated, followed by 15 minutes standing) were compared to each other and Condition 1 (60 minutes seated). The findings of this study show that even though the two different sit-stand regimes did not result in a significant impact on cognitive task performance, an immediate postural effect for psychomotor response time and a delayed postural effect for working memory were found. The participants perceived Condition 3 as the most physically exerting condition. Heart rate frequency was not significantly different between the conditions, but the immediate seated posture had a significantly lower heart rate frequency compared to the standing posture; indicating that being seated elicited lower energy expenditure compared to standing. Heart rate frequency while standing had a greater degree of variation compared to being seated. Taking the findings of this study into account, it is recommended that: one should be seated while performing this type of working memory task; that one should be standing while performing this type of psychomotor task; that the recommendation that implementing standing at work can be used as a blanket strategy to increase energy expenditure in all individuals needs to be explored further and that individual differences may impact energy expenditure.
- Full Text:
- Date Issued: 2017
The effects of a gradual shift rotation and a split shift nap intervention on cognitive, physiological and subjective responses under simulated night shift settings
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
The effects of age on the worker capacity and mechanisation on the task demands in a South African manufacturing industry
- Bezuidenhout, Samantha Catherine
- Authors: Bezuidenhout, Samantha Catherine
- Date: 2014
- Subjects: Age and employment -- South Africa , Labor -- Social aspects -- South Africa , Brickmaking -- South Africa -- Automation , Brickmaking -- Social aspects -- South Africa , Brick trade -- South Africa , Aging -- Social aspects -- South Africa , Aging -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5151 , http://hdl.handle.net/10962/d1013167
- Description: The focus of the study was two-fold, firstly to determine the effect of age on the capacity of manual materials handling workers and secondly to determine the effect of increasing task mechanisation on the workers’ responses to task demands. The first component of this study, namely Part I, 101 male and 12 female ‘unskilled’ manual workers – of various ages – from a brick manufacturing industry were assessed. Anthropometric, health and strength factors were measured to improve the understanding of the South African manual worker capacity and more specifically, the effect of age on this capacity. Data collection was done between 7.30am and 9.30am in a laboratory-type setting on-site. Anthropometric characteristics (including body mass index, waist to hip ratio, waist circumference and body fat percentage) provided information on the state of obesity and the impact of age in the South African context. Linked to this, the health factors (including blood pressure, resting heart rate and a self-reported questionnaire) provide an extra snapshot of the disease profile in South Africa, and could potentially influence other capacity factors. Isometric strength capacities (of eight different areas, namely: back, leg, bicep, shoulder, pinch, pinch and pull) demonstrated whether South African manual workers show the same decline in strength with aging as seen in industrially advanced countries. The second component of the study, Part II, was performed in situ and measured the workers’ responses to task demands of three brick palletising tasks, one manual (n=21) and two with increasing mechanisation (n=12 each). Spinal kinematics, joint forces and working heart rate were assessed on normal work days during a 30-lift duration and body discomfort measures were taken at the start, middle and end of the work-shift. Spinal kinematics were measured dynamically using a lumbar motion monitor, whereas the spinal forces were estimated using the three dimensional static strength prediction program. The worker capacity results showed that waist to hip ratio, waist circumference and body fat percentage increased significantly with aging, whereas body mass index was not affected by age. All body morphology values were within ‘normal’ ranges. Although diastolic blood pressure increased significantly with age, systolic was not affected significantly by age. Both groups, however, showed an increasing prevalence of hypertension with aging. There were no significant changes in resting heart rate with aging, with a range of 66 bt.min⁻¹ to 74.86 bt.min⁻¹, therefore within normal ranges. Of the strength factors, age only affected shoulder and push strength significantly: Showing a decrease in shoulder strength from 49.89 kgF to 39.91 kgF in the men aged 20-29 to the 50-59 respectively and an increase in push strength from men aged 30-39 and 40-49 to those aged 50-59. Part II results revealed highly frequent lift rates and large degrees of sagittal flexion and lateral bending in all three tasks. These postures adopted for long durations are likely to lead to the development of musculoskeletal disorders. Heart rates of workers from the three tasks were significantly different and heart rates for two tasks were above the recommended 110 bt.min⁻¹. Similarly the body discomfort ratings of the three tasks differed, although a common trend was seen in that lower back pain was the most commonly reported area of discomfort in all tasks. South African manual materials handling males did not show the same responses to aging as men from industrially advanced countries, calling for further research into these differences. Due to the high risks of the three tasks assessed, future research and interventions are required to reduce the risk of injury in the assessed tasks.
- Full Text:
- Date Issued: 2014
- Authors: Bezuidenhout, Samantha Catherine
- Date: 2014
- Subjects: Age and employment -- South Africa , Labor -- Social aspects -- South Africa , Brickmaking -- South Africa -- Automation , Brickmaking -- Social aspects -- South Africa , Brick trade -- South Africa , Aging -- Social aspects -- South Africa , Aging -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5151 , http://hdl.handle.net/10962/d1013167
- Description: The focus of the study was two-fold, firstly to determine the effect of age on the capacity of manual materials handling workers and secondly to determine the effect of increasing task mechanisation on the workers’ responses to task demands. The first component of this study, namely Part I, 101 male and 12 female ‘unskilled’ manual workers – of various ages – from a brick manufacturing industry were assessed. Anthropometric, health and strength factors were measured to improve the understanding of the South African manual worker capacity and more specifically, the effect of age on this capacity. Data collection was done between 7.30am and 9.30am in a laboratory-type setting on-site. Anthropometric characteristics (including body mass index, waist to hip ratio, waist circumference and body fat percentage) provided information on the state of obesity and the impact of age in the South African context. Linked to this, the health factors (including blood pressure, resting heart rate and a self-reported questionnaire) provide an extra snapshot of the disease profile in South Africa, and could potentially influence other capacity factors. Isometric strength capacities (of eight different areas, namely: back, leg, bicep, shoulder, pinch, pinch and pull) demonstrated whether South African manual workers show the same decline in strength with aging as seen in industrially advanced countries. The second component of the study, Part II, was performed in situ and measured the workers’ responses to task demands of three brick palletising tasks, one manual (n=21) and two with increasing mechanisation (n=12 each). Spinal kinematics, joint forces and working heart rate were assessed on normal work days during a 30-lift duration and body discomfort measures were taken at the start, middle and end of the work-shift. Spinal kinematics were measured dynamically using a lumbar motion monitor, whereas the spinal forces were estimated using the three dimensional static strength prediction program. The worker capacity results showed that waist to hip ratio, waist circumference and body fat percentage increased significantly with aging, whereas body mass index was not affected by age. All body morphology values were within ‘normal’ ranges. Although diastolic blood pressure increased significantly with age, systolic was not affected significantly by age. Both groups, however, showed an increasing prevalence of hypertension with aging. There were no significant changes in resting heart rate with aging, with a range of 66 bt.min⁻¹ to 74.86 bt.min⁻¹, therefore within normal ranges. Of the strength factors, age only affected shoulder and push strength significantly: Showing a decrease in shoulder strength from 49.89 kgF to 39.91 kgF in the men aged 20-29 to the 50-59 respectively and an increase in push strength from men aged 30-39 and 40-49 to those aged 50-59. Part II results revealed highly frequent lift rates and large degrees of sagittal flexion and lateral bending in all three tasks. These postures adopted for long durations are likely to lead to the development of musculoskeletal disorders. Heart rates of workers from the three tasks were significantly different and heart rates for two tasks were above the recommended 110 bt.min⁻¹. Similarly the body discomfort ratings of the three tasks differed, although a common trend was seen in that lower back pain was the most commonly reported area of discomfort in all tasks. South African manual materials handling males did not show the same responses to aging as men from industrially advanced countries, calling for further research into these differences. Due to the high risks of the three tasks assessed, future research and interventions are required to reduce the risk of injury in the assessed tasks.
- Full Text:
- Date Issued: 2014
The effects of booster breaks during a sedentary night shift on physiological, psychomotor, psycho-physiological, and cognitive performance over a 3 night shift habituation phase
- Authors: Lombard, Wesley Ross
- Date: 2010
- Subjects: Night work , Shift systems , Performance , Exercise , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Cognition -- Effect of exercise on , Motor ability
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5116 , http://hdl.handle.net/10962/d1005194 , Night work , Shift systems , Performance , Exercise , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Cognition -- Effect of exercise on , Motor ability
- Description: Despite extensive research into shift work, workers working under rotating shift conditions are still plagued by the effects of the desynchronisation resulting from working against their natural circadian rhythms. Additionally, modern industries are shifting towards tasks requiring greater cognitive demand with less manual labour incorporated into the tasks. Research into operator based tasks, and hence those of a sedentary cognitive base both during day and night shifts, has been focusing on the effectiveness of the standard rest/break schedule. Research indicating that the standard rest break schedule is often ineffective in eliminating operator discomfort and performance deterioration, with these affects argued to be more pronounced during a night shift schedule. Therefore current research set out to investigate alternative rest break schedules, incorporating a short bout of physical activity and stretching exercises which are proposed to enhance performance and subjective mood, while eliminating operator discomfort for sedentary based cognitive tasks. Three conditions were tested during a three day habituation shift cycle within a laboratory, incorporating two night shift groups (control and experimental) and a control day shift group. Twelve subjects made up each group, with the two night shift groups completing the shift schedule together. The control groups followed a typical 8 hour shift schedule while the experimental group performed a booster break (exercise and stretches) activity for 7.5 minutes every hour during the night shift schedule. Over the course of the shift, subjects completed a battery of six tests providing data on physiological measurements (heart rate and temperature), performance criteria (reaction time responses, memory and neurobiological) and subjective measures. Responses obtained for all the different parameters measured indicated a strong circadian influence for the majority of the variables, indicating the course of natural down regulation within physiological and performance criteria over the night shift. The booster break significantly improved reaction time performance, subjective ratings and resulted in a high sustainable activity level. Day shift comparisons indicating that within subjective measures and reaction time performance, the booster break resulted in similar responses to those of the day shift workers, while the control night shift groups reported significantly lowers results. Additionally, the booster break had positive influences during the circadian nadir, significantly improving parameters of performance and subjective ratings of sleepiness. The results of this study indicating which variables are strong predictors and indicators of the oscillations in performance and subjective ratings due to the circadian changes. The booster break interventions had positive effects on subjective ratings and reaction time performance, while also being argued to decrease the burden placed on the cardiac system as a result of increased sympathetic tone during the night shift, while additionally resulting in similar responses to those of day shift workers. Further studies are required, however, to provide conclusive evidence particularly within a working situation over a longer shift schedule.
- Full Text:
- Date Issued: 2010
- Authors: Lombard, Wesley Ross
- Date: 2010
- Subjects: Night work , Shift systems , Performance , Exercise , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Cognition -- Effect of exercise on , Motor ability
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5116 , http://hdl.handle.net/10962/d1005194 , Night work , Shift systems , Performance , Exercise , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Cognition -- Effect of exercise on , Motor ability
- Description: Despite extensive research into shift work, workers working under rotating shift conditions are still plagued by the effects of the desynchronisation resulting from working against their natural circadian rhythms. Additionally, modern industries are shifting towards tasks requiring greater cognitive demand with less manual labour incorporated into the tasks. Research into operator based tasks, and hence those of a sedentary cognitive base both during day and night shifts, has been focusing on the effectiveness of the standard rest/break schedule. Research indicating that the standard rest break schedule is often ineffective in eliminating operator discomfort and performance deterioration, with these affects argued to be more pronounced during a night shift schedule. Therefore current research set out to investigate alternative rest break schedules, incorporating a short bout of physical activity and stretching exercises which are proposed to enhance performance and subjective mood, while eliminating operator discomfort for sedentary based cognitive tasks. Three conditions were tested during a three day habituation shift cycle within a laboratory, incorporating two night shift groups (control and experimental) and a control day shift group. Twelve subjects made up each group, with the two night shift groups completing the shift schedule together. The control groups followed a typical 8 hour shift schedule while the experimental group performed a booster break (exercise and stretches) activity for 7.5 minutes every hour during the night shift schedule. Over the course of the shift, subjects completed a battery of six tests providing data on physiological measurements (heart rate and temperature), performance criteria (reaction time responses, memory and neurobiological) and subjective measures. Responses obtained for all the different parameters measured indicated a strong circadian influence for the majority of the variables, indicating the course of natural down regulation within physiological and performance criteria over the night shift. The booster break significantly improved reaction time performance, subjective ratings and resulted in a high sustainable activity level. Day shift comparisons indicating that within subjective measures and reaction time performance, the booster break resulted in similar responses to those of the day shift workers, while the control night shift groups reported significantly lowers results. Additionally, the booster break had positive influences during the circadian nadir, significantly improving parameters of performance and subjective ratings of sleepiness. The results of this study indicating which variables are strong predictors and indicators of the oscillations in performance and subjective ratings due to the circadian changes. The booster break interventions had positive effects on subjective ratings and reaction time performance, while also being argued to decrease the burden placed on the cardiac system as a result of increased sympathetic tone during the night shift, while additionally resulting in similar responses to those of day shift workers. Further studies are required, however, to provide conclusive evidence particularly within a working situation over a longer shift schedule.
- Full Text:
- Date Issued: 2010
The effects of control design and working posture on strength and work output: an isokinetic investigation
- Dirkse Van Schalkwyk, Charles Joseph
- Authors: Dirkse Van Schalkwyk, Charles Joseph
- Date: 2002
- Subjects: Posture , Human engineering
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5118 , http://hdl.handle.net/10962/d1005196 , Posture , Human engineering
- Description: he objective of the present study was to assess the isokinetic, cardiovascular and psychophysical responses of young adult males (N=30) during valve turning exercises. It aimed to evaluate the variables in relation to changes in control design and working posture. Isokinetic testing and ergonomics have not been widely linked and it was an aim of this study to show the advantages to the field of ergonomics. Furthermore, the “work-simulation” package used in the present study has not been widely exploited and it was believed that this study could thus contribute significantly to the literature. Testing was carried out using a CYBEX ® 6000 isokinetic dynamometer, a polar heart watch, an Omron M1 semi-automatic blood pressure monitor and various perceptual rating scales. Testing involved the subjects having to perform 4 maximal turning efforts in 18 different conditions. These conditions were made up by using 6 different control designs in 3 varying positions. Subjects were required to attend two sessions, each approximately one hour long, in which nine randomised conditions were tested in each session. During these sessions, isokinetic responses: peak torque (Nm), total work (J) and average power (W); cardiovascular responses: heart rate (bt.min[superscript -1]) and blood pressure (mmHg); and psychophysical responses: RPE and discomfort, were observed. The results of the tests showed that in general significant differences were encountered for isokinetic, cardiovascular and psychophysical responses in relation to changes in the control design. However, significant differences were far less evident, and in most cases non existent, in relation to changes in the spatial orientation of the control types. The essence being that operator position with respect to the control is not as crucial as the control design.
- Full Text:
- Date Issued: 2002
- Authors: Dirkse Van Schalkwyk, Charles Joseph
- Date: 2002
- Subjects: Posture , Human engineering
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5118 , http://hdl.handle.net/10962/d1005196 , Posture , Human engineering
- Description: he objective of the present study was to assess the isokinetic, cardiovascular and psychophysical responses of young adult males (N=30) during valve turning exercises. It aimed to evaluate the variables in relation to changes in control design and working posture. Isokinetic testing and ergonomics have not been widely linked and it was an aim of this study to show the advantages to the field of ergonomics. Furthermore, the “work-simulation” package used in the present study has not been widely exploited and it was believed that this study could thus contribute significantly to the literature. Testing was carried out using a CYBEX ® 6000 isokinetic dynamometer, a polar heart watch, an Omron M1 semi-automatic blood pressure monitor and various perceptual rating scales. Testing involved the subjects having to perform 4 maximal turning efforts in 18 different conditions. These conditions were made up by using 6 different control designs in 3 varying positions. Subjects were required to attend two sessions, each approximately one hour long, in which nine randomised conditions were tested in each session. During these sessions, isokinetic responses: peak torque (Nm), total work (J) and average power (W); cardiovascular responses: heart rate (bt.min[superscript -1]) and blood pressure (mmHg); and psychophysical responses: RPE and discomfort, were observed. The results of the tests showed that in general significant differences were encountered for isokinetic, cardiovascular and psychophysical responses in relation to changes in the control design. However, significant differences were far less evident, and in most cases non existent, in relation to changes in the spatial orientation of the control types. The essence being that operator position with respect to the control is not as crucial as the control design.
- Full Text:
- Date Issued: 2002
The effects of different shift patterns on nurses’ sleep-wake behaviours in selected, private healthcare facilities
- Authors: Bell, Emma Catherine
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424219 , vital:72134
- Description: Nurses are required to work shifts to provide 24-hour care, in which they complete physically and mentally demanding tasks. The length and type of shifts, particularly night shifts interfere with the natural sleep-wake behaviours, leading to extended wakefulness and overall reduced sleep, and increase the likelihood of sleepiness during subsequent shifts. This can in turn affected various cognitive processes such attention, vigilance and alertness, which are necessary during the care process. Sleepiness as a result of working shifts has also been associated with an increased risk accidents and error during the delivery of care. Given the unique demands and ways in which workplaces are structured, each context arranges its shifts in unique ways and thus, in order to determine how to manage the effects of shift work, it is important to understand how it affects self-reported fatigue and sleep, of, in this case, nurses. While there has been extensive research on this in the global north, to date, there has been limited research aimed at examining the effects of shift work on nurses’ sleep-wake behaviours and fatigue in the South African context. Therefore, the aim of this study is to characterise shift arrangements in selected private facilities and explore its effects on private healthcare nurses. This study adopted a cross-sectional, survey design using an amended version of Standard Shiftwork Index. The questionnaire included demographic and shift details and explored the impact of the shift systems on nurse sleep-wake behaviours and disturbances and fatigue and workload. It was distributed among shift working nurses registered with the South African Nursing Council across three selected, private, healthcare facilities in the Eastern Cape, over a two-month period. The responses were analysed with descriptive and inferential statistics, with open-ended questions analysed using a thematic analysis. A total of 51 nurses completed the survey. Nurses worked 12-hour shifts which included night shifts and day shifts with fixed start and end times. Over time was commonly reported and generally, nurses reported having very little control over their shift arrangements. Overall, nurses slept less than what they reported they needed on duty days, with nurses working both day and night shifts reporting to sleep less than the globally recommended required sleep. This was compensated for by longer sleep durations during days off. The data collection revealed that three different shift arrangements were in use, including permanent day shifts, permanent night shifts and rotating shift work including nights, with permanent night nurses working significantly more consecutive shifts (seven) than the other two shift types and having significantly more days off (seven) as well. While there were no significant differences in self-reported sleep across the three shift types, permanent night nurses were found to have the shortest sleep. During days off, rotating nurse reported significantly longer sleep times compared to day shift workers which may point to the need to catch up from sleep debt. Rotating nurses experienced the greater total disturbances to their sleep than permanent day and permanent night shift nurses. While not statistically significant, it may point to the fact that rotating shift workers could not obtain regularly timed sleep (due to having to change their schedules) compared to permanent day and night nurses. Workload (physical, emotional, mental and time pressure) did not differ between the shifts (day or night) or the shift types, but did reflect a heavier workload, possibly due to the data collection occurring during the 5th wave of the COVID 19 pandemic. This study highlights that nurses in private healthcare facilities are working extended hours which were associated with reduced total sleep, irrespective of the nature of the shift, with rotating shift nurses experiencing some degree of greater disturbances to their sleep. The number, duration speed and direction of the shifts of rotating nurses needs to be explored further, whilst also exploring the influence of individual factors on sleep-wake behaviours of nurses. It may be beneficial for the healthcare facilities to implement fatigue management strategies to mitigate the negative impacts of shift work, given the impact that this may impact the delivery of care. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Bell, Emma Catherine
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424219 , vital:72134
- Description: Nurses are required to work shifts to provide 24-hour care, in which they complete physically and mentally demanding tasks. The length and type of shifts, particularly night shifts interfere with the natural sleep-wake behaviours, leading to extended wakefulness and overall reduced sleep, and increase the likelihood of sleepiness during subsequent shifts. This can in turn affected various cognitive processes such attention, vigilance and alertness, which are necessary during the care process. Sleepiness as a result of working shifts has also been associated with an increased risk accidents and error during the delivery of care. Given the unique demands and ways in which workplaces are structured, each context arranges its shifts in unique ways and thus, in order to determine how to manage the effects of shift work, it is important to understand how it affects self-reported fatigue and sleep, of, in this case, nurses. While there has been extensive research on this in the global north, to date, there has been limited research aimed at examining the effects of shift work on nurses’ sleep-wake behaviours and fatigue in the South African context. Therefore, the aim of this study is to characterise shift arrangements in selected private facilities and explore its effects on private healthcare nurses. This study adopted a cross-sectional, survey design using an amended version of Standard Shiftwork Index. The questionnaire included demographic and shift details and explored the impact of the shift systems on nurse sleep-wake behaviours and disturbances and fatigue and workload. It was distributed among shift working nurses registered with the South African Nursing Council across three selected, private, healthcare facilities in the Eastern Cape, over a two-month period. The responses were analysed with descriptive and inferential statistics, with open-ended questions analysed using a thematic analysis. A total of 51 nurses completed the survey. Nurses worked 12-hour shifts which included night shifts and day shifts with fixed start and end times. Over time was commonly reported and generally, nurses reported having very little control over their shift arrangements. Overall, nurses slept less than what they reported they needed on duty days, with nurses working both day and night shifts reporting to sleep less than the globally recommended required sleep. This was compensated for by longer sleep durations during days off. The data collection revealed that three different shift arrangements were in use, including permanent day shifts, permanent night shifts and rotating shift work including nights, with permanent night nurses working significantly more consecutive shifts (seven) than the other two shift types and having significantly more days off (seven) as well. While there were no significant differences in self-reported sleep across the three shift types, permanent night nurses were found to have the shortest sleep. During days off, rotating nurse reported significantly longer sleep times compared to day shift workers which may point to the need to catch up from sleep debt. Rotating nurses experienced the greater total disturbances to their sleep than permanent day and permanent night shift nurses. While not statistically significant, it may point to the fact that rotating shift workers could not obtain regularly timed sleep (due to having to change their schedules) compared to permanent day and night nurses. Workload (physical, emotional, mental and time pressure) did not differ between the shifts (day or night) or the shift types, but did reflect a heavier workload, possibly due to the data collection occurring during the 5th wave of the COVID 19 pandemic. This study highlights that nurses in private healthcare facilities are working extended hours which were associated with reduced total sleep, irrespective of the nature of the shift, with rotating shift nurses experiencing some degree of greater disturbances to their sleep. The number, duration speed and direction of the shifts of rotating nurses needs to be explored further, whilst also exploring the influence of individual factors on sleep-wake behaviours of nurses. It may be beneficial for the healthcare facilities to implement fatigue management strategies to mitigate the negative impacts of shift work, given the impact that this may impact the delivery of care. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
The effects of glove fit on task performance and on the human operator
- Authors: Stack, Jessica Danielle
- Date: 2010
- Subjects: Hand -- Anatomy , Hand -- Wounds and injuries , Hand -- Care and hygiene , Gloves , Safety education, Industrial , Human-machine systems , Industrial safety , Industrial accidents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5119 , http://hdl.handle.net/10962/d1005197 , Hand -- Anatomy , Hand -- Wounds and injuries , Hand -- Care and hygiene , Gloves , Safety education, Industrial , Human-machine systems , Industrial safety , Industrial accidents
- Description: The hand is one of the most complex of all of the anatomical structures in the human body. It has been found that hand injuries are among the most frequent injuries that occur to the body, predominantly during industrial activities. It has therefore been concluded that more research is needed into protective factors, such as glove use. The design features of a glove emphasise either protection or performance. There is often a trade-off between increased safety and performance capability when donning gloves. It has been determined that gloves which are fitted and comfortable for the worker may provide the best compromise between protective functions and decreased performance. This investigation aimed to assess the influence of glove fit on the performance attributes of industrial tasks, as well as on the responses of the human operator. Glove fit was analysed as 35 male participants donned three different glove sizes during each test, including a best-fitting glove, a glove one size smaller than best-fitting, and a glove one size larger than best-fitting. For each glove size, gloves of two differing materials were tested, namely nitrile and neoprene. A barehanded condition was also tested, totalling seven gloved/barehanded conditions for each test. The seven conditions were assessed in a laboratory setting in a battery of tests. This consisted of components of task performance, including maximum pulling and pushing force, maximum torque, precision of force, tactility, speed and accuracy and dexterity. The performance responses were recorded, as well as participants’ perceptual responses using the Rating of Perceived Exertion scale, and muscle activity. Six muscles were selected: Flexor Digitorum Superficialis, Flexor Pollicus Longus, Extensor Carpi Ulnaris, Extensor Carpi Radialis, Flexor Carpi Ulnaris and Flexor Carpi Radialis. The results revealed that glove fit does affect certain spects of performance, and influences human operator responses for selected task components. Furthermore, discrepancies were distinguished between orking barehanded and working with an optimally fitted glove. There was also a glove material effect established. Overall, it was found that muscle activity when exerting maximum force in a pushing and pulling direction was optimal with the nitrile glove material. Maximum torque performance was enhanced with the use of a best-fitting glove, as compared with an ill-fitting glove or barehanded work. Force precision was preferable when barehanded, as opposed to the tactility task which rendered optimal results with a best-fitting glove. The same was found for speed and accuracy results, as glove fit appeared to have no effect on performance, but performance was improved when participants were barehanded. Dexterity performance was the most conclusively influenced by the conditions, resulting in barehanded performance being optimal. However, should a glove be necessary for a given task, an optimally-fitted glove which is of a thinner material would be recommended. It is necessary to distinguish the performance components of a task within industry and select the most appropriate glove for optimal performance and the least risk of overexertion.
- Full Text:
- Date Issued: 2010
- Authors: Stack, Jessica Danielle
- Date: 2010
- Subjects: Hand -- Anatomy , Hand -- Wounds and injuries , Hand -- Care and hygiene , Gloves , Safety education, Industrial , Human-machine systems , Industrial safety , Industrial accidents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5119 , http://hdl.handle.net/10962/d1005197 , Hand -- Anatomy , Hand -- Wounds and injuries , Hand -- Care and hygiene , Gloves , Safety education, Industrial , Human-machine systems , Industrial safety , Industrial accidents
- Description: The hand is one of the most complex of all of the anatomical structures in the human body. It has been found that hand injuries are among the most frequent injuries that occur to the body, predominantly during industrial activities. It has therefore been concluded that more research is needed into protective factors, such as glove use. The design features of a glove emphasise either protection or performance. There is often a trade-off between increased safety and performance capability when donning gloves. It has been determined that gloves which are fitted and comfortable for the worker may provide the best compromise between protective functions and decreased performance. This investigation aimed to assess the influence of glove fit on the performance attributes of industrial tasks, as well as on the responses of the human operator. Glove fit was analysed as 35 male participants donned three different glove sizes during each test, including a best-fitting glove, a glove one size smaller than best-fitting, and a glove one size larger than best-fitting. For each glove size, gloves of two differing materials were tested, namely nitrile and neoprene. A barehanded condition was also tested, totalling seven gloved/barehanded conditions for each test. The seven conditions were assessed in a laboratory setting in a battery of tests. This consisted of components of task performance, including maximum pulling and pushing force, maximum torque, precision of force, tactility, speed and accuracy and dexterity. The performance responses were recorded, as well as participants’ perceptual responses using the Rating of Perceived Exertion scale, and muscle activity. Six muscles were selected: Flexor Digitorum Superficialis, Flexor Pollicus Longus, Extensor Carpi Ulnaris, Extensor Carpi Radialis, Flexor Carpi Ulnaris and Flexor Carpi Radialis. The results revealed that glove fit does affect certain spects of performance, and influences human operator responses for selected task components. Furthermore, discrepancies were distinguished between orking barehanded and working with an optimally fitted glove. There was also a glove material effect established. Overall, it was found that muscle activity when exerting maximum force in a pushing and pulling direction was optimal with the nitrile glove material. Maximum torque performance was enhanced with the use of a best-fitting glove, as compared with an ill-fitting glove or barehanded work. Force precision was preferable when barehanded, as opposed to the tactility task which rendered optimal results with a best-fitting glove. The same was found for speed and accuracy results, as glove fit appeared to have no effect on performance, but performance was improved when participants were barehanded. Dexterity performance was the most conclusively influenced by the conditions, resulting in barehanded performance being optimal. However, should a glove be necessary for a given task, an optimally-fitted glove which is of a thinner material would be recommended. It is necessary to distinguish the performance components of a task within industry and select the most appropriate glove for optimal performance and the least risk of overexertion.
- Full Text:
- Date Issued: 2010
The effects of intermittent task parameters on muscle fatigue development during submaximal dynamic exertions
- Authors: King, Josephine Claire
- Date: 2018
- Subjects: Muscles -- Physiology , Muscles -- Wounds and injuries , Fatigue , Human engineering , Occupational diseases
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63855 , vital:28498
- Description: The negative effects of localised muscle fatigue on accidents, injuries and poor work performance are well known, as is the realisation that modifying task characteristics can minimise fatigue development. A large amount of literature has investigated the effects of task-dependent factors on localised muscle fatigue, most studies have focussed on prolonged or intermittent static (isometric) exertions. Few studies have investigated muscle fatigue development during more complex tasks, namely those which resemble common work activities and which tend to be intermittent and dynamic in nature. More specifically, the interactions between the main intermittent parameters - duty cycle, force level, and cycle time - during dynamic exertions are poorly understood. The purpose of this study was to investigate the effects of cycle time and combinations of duty cycles and force levels on the development of muscle fatigue during submaximal dynamic exertions while the overall mean muscle load was kept constant. A two-factorial repeated-measures experiment was developed for this study. Nine experimental conditions, each lasting 16 minutes, aimed at inducing muscle fatigue in the middle deltoid muscle via intermittent dynamic shoulder abduction and adduction motions at three cycle times (30, 60, and 120 seconds) and three combinations of duty cycles and force levels. The percentage of muscle activation during one cycle (i.e. the duty cycle) varied depending on the exertion intensity (force level) so that the overall mean muscle load remained consistent throughout all experimental conditions, namely at 20% of maximum force exertion. As a result, the three duty cycle/force level combinations were: 0.8/25% of maximum voluntary force (MVF), 0.5/40%MVF, and 0.4/50%MVF. Muscle fatigue development was inferred by changes in peak torque, total work, average power, local Ratings of Perceived Exertion (RPE), and surface electromyographical (EMG) activity (time domain and frequency domain).Two-factorial analyses of variance with Tukey post-hoc tests were used to identify significant condition effects at p<0.05. All dependent measures showed that muscle fatigue was induced by the 16-minute fatigue protocol. Peak torque, total work, average power, and EMG percentage of maximum showed that cycle time and the duty cycle/force level combination had no effect on the development of muscle fatigue, whereas the measures evaluated during the 16-minute fatigue protocol did. The cycle time of 120 seconds induced the greatest change in six of the eight variables, while the duty cycle/force level combination (0.8/25%) also resulted in the greatest effect in six of the measures. Fatigue was also found to be dependent on the interaction of cycle time and duty cycle/force level combination. The conclusion draws from this study is that shorter cycles and activities with short activation periods, and proportionally longer rest breaks result in the lowest fatigue developments.
- Full Text:
- Date Issued: 2018
- Authors: King, Josephine Claire
- Date: 2018
- Subjects: Muscles -- Physiology , Muscles -- Wounds and injuries , Fatigue , Human engineering , Occupational diseases
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63855 , vital:28498
- Description: The negative effects of localised muscle fatigue on accidents, injuries and poor work performance are well known, as is the realisation that modifying task characteristics can minimise fatigue development. A large amount of literature has investigated the effects of task-dependent factors on localised muscle fatigue, most studies have focussed on prolonged or intermittent static (isometric) exertions. Few studies have investigated muscle fatigue development during more complex tasks, namely those which resemble common work activities and which tend to be intermittent and dynamic in nature. More specifically, the interactions between the main intermittent parameters - duty cycle, force level, and cycle time - during dynamic exertions are poorly understood. The purpose of this study was to investigate the effects of cycle time and combinations of duty cycles and force levels on the development of muscle fatigue during submaximal dynamic exertions while the overall mean muscle load was kept constant. A two-factorial repeated-measures experiment was developed for this study. Nine experimental conditions, each lasting 16 minutes, aimed at inducing muscle fatigue in the middle deltoid muscle via intermittent dynamic shoulder abduction and adduction motions at three cycle times (30, 60, and 120 seconds) and three combinations of duty cycles and force levels. The percentage of muscle activation during one cycle (i.e. the duty cycle) varied depending on the exertion intensity (force level) so that the overall mean muscle load remained consistent throughout all experimental conditions, namely at 20% of maximum force exertion. As a result, the three duty cycle/force level combinations were: 0.8/25% of maximum voluntary force (MVF), 0.5/40%MVF, and 0.4/50%MVF. Muscle fatigue development was inferred by changes in peak torque, total work, average power, local Ratings of Perceived Exertion (RPE), and surface electromyographical (EMG) activity (time domain and frequency domain).Two-factorial analyses of variance with Tukey post-hoc tests were used to identify significant condition effects at p<0.05. All dependent measures showed that muscle fatigue was induced by the 16-minute fatigue protocol. Peak torque, total work, average power, and EMG percentage of maximum showed that cycle time and the duty cycle/force level combination had no effect on the development of muscle fatigue, whereas the measures evaluated during the 16-minute fatigue protocol did. The cycle time of 120 seconds induced the greatest change in six of the eight variables, while the duty cycle/force level combination (0.8/25%) also resulted in the greatest effect in six of the measures. Fatigue was also found to be dependent on the interaction of cycle time and duty cycle/force level combination. The conclusion draws from this study is that shorter cycles and activities with short activation periods, and proportionally longer rest breaks result in the lowest fatigue developments.
- Full Text:
- Date Issued: 2018
The effects of night work and task diversification on efficiency of performance
- Authors: Munton, Lynne Kerry
- Date: 1998
- Subjects: Night work -- Evaluation , Shift systems , Performance
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5175 , http://hdl.handle.net/10962/d1018253
- Description: This study investigated the effects of night work on performance efficiency. Night work is generally acknowledged to impair performance, yet much research has contradicted this assertion. The feasibility of including brief periods of physical activity to stimulate arousal within mentally demanding work shifts was also evaluated. Thirty six postgraduate volunteers were assigned to either the cognitive tasks (CT) or cognitive and motor tasks (CMT) group. All subjects performed three psycho-motor tests, using the Vienna Test System, at midday and midnight. The CMT group performed a short cycling activity before each test. Heart rate responses served as physiological measures, the Perceived Strain Scale was used to quantify individual perceptions of strain and performance efficiency was assessed in terms of speed and accuracy. Although several trends were apparent, no significant differences (p < 0.05) were revealed with respect to the three performance variables between the midday and midnight test sessions, or between the CT and CMT subjects, other than the higher heart rates recorded in the CMT group. In summary, neither time of day nor physical activity were found to affect performance within the controlled environment of this study.
- Full Text:
- Date Issued: 1998
- Authors: Munton, Lynne Kerry
- Date: 1998
- Subjects: Night work -- Evaluation , Shift systems , Performance
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5175 , http://hdl.handle.net/10962/d1018253
- Description: This study investigated the effects of night work on performance efficiency. Night work is generally acknowledged to impair performance, yet much research has contradicted this assertion. The feasibility of including brief periods of physical activity to stimulate arousal within mentally demanding work shifts was also evaluated. Thirty six postgraduate volunteers were assigned to either the cognitive tasks (CT) or cognitive and motor tasks (CMT) group. All subjects performed three psycho-motor tests, using the Vienna Test System, at midday and midnight. The CMT group performed a short cycling activity before each test. Heart rate responses served as physiological measures, the Perceived Strain Scale was used to quantify individual perceptions of strain and performance efficiency was assessed in terms of speed and accuracy. Although several trends were apparent, no significant differences (p < 0.05) were revealed with respect to the three performance variables between the midday and midnight test sessions, or between the CT and CMT subjects, other than the higher heart rates recorded in the CMT group. In summary, neither time of day nor physical activity were found to affect performance within the controlled environment of this study.
- Full Text:
- Date Issued: 1998
The effects of relative speed on selected physiological, kinematic and psychological responses at walk-to-run and run-to-walk interfaces.
- Authors: Candler, Paul David
- Date: 1987
- Subjects: Walking -- Physiological aspects , Running -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5164 , http://hdl.handle.net/10962/d1016081
- Description: [Conclusions] l) The two forms of human locomotion, walking and running, are distinctly different and in evaluating these gait patterns consideration must be given to this fact. 2) The impression created by the energy cost curves, that there is a single locomotor interface for both walking and running is a false one . There are two distinctly different locomotor interfaces, the walk-to-run interface and the run-to-walk interface. The former appears to correspond with the "metabolic intersection point" and therefore has some metabolic significance. The latter appears to be merely an "overshoot" of the walk-to-run interface and presently has no apparent metabolic significance. 3) Because the walk-to-run interface speed corresponds with the intersection point of the energy cost curves, physiological responses to walking and running at this speed do not differ significantly. However, cadence and stride length patterns for these two locomotor patterns are distinctly different at this point. 4) The identification of single physiological or kinematic factors during perceptions of exertion in any given situation is an extremely difficult if not impossible task. Perceived exertion should therefore be considered a multi-factorial concept and should be evaluated as such. 5) The use of relative speed as a technique for reducing inter-subject variability in physiological and kinematic factors is worthless unless diverse ranges in morphological linearity are a characteristic of one's subject pool
- Full Text:
- Date Issued: 1987
- Authors: Candler, Paul David
- Date: 1987
- Subjects: Walking -- Physiological aspects , Running -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5164 , http://hdl.handle.net/10962/d1016081
- Description: [Conclusions] l) The two forms of human locomotion, walking and running, are distinctly different and in evaluating these gait patterns consideration must be given to this fact. 2) The impression created by the energy cost curves, that there is a single locomotor interface for both walking and running is a false one . There are two distinctly different locomotor interfaces, the walk-to-run interface and the run-to-walk interface. The former appears to correspond with the "metabolic intersection point" and therefore has some metabolic significance. The latter appears to be merely an "overshoot" of the walk-to-run interface and presently has no apparent metabolic significance. 3) Because the walk-to-run interface speed corresponds with the intersection point of the energy cost curves, physiological responses to walking and running at this speed do not differ significantly. However, cadence and stride length patterns for these two locomotor patterns are distinctly different at this point. 4) The identification of single physiological or kinematic factors during perceptions of exertion in any given situation is an extremely difficult if not impossible task. Perceived exertion should therefore be considered a multi-factorial concept and should be evaluated as such. 5) The use of relative speed as a technique for reducing inter-subject variability in physiological and kinematic factors is worthless unless diverse ranges in morphological linearity are a characteristic of one's subject pool
- Full Text:
- Date Issued: 1987
The effects of sustained attention, workload and task-related fatigue on physiological measures and performance during a tracking task
- Authors: De Gray Birch, Casey
- Date: 2012
- Subjects: Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5120 , http://hdl.handle.net/10962/d1005198 , Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Description: Despite extensive research into the concept of mental fatigue there is as yet no “gold standard” definition or measurement technique available. Because of this a large amount of fatigue-related errors are still seen in the workplace. The complexity of the problem lies with the inability to directly measure mental processes as well as the various endogenous and exogenous factors that interact to produce the experienced fatigue. Fatigue has been divided into sleep-related and task-related fatigue; however the task-related aspect is evident both during normal waking hours as well as during periods of sleep deprivation, therefore this aspect is considered important in the understanding of fatigue in general. The concept of task-related fatigue has further been divided into active and passive fatigue states; however differentiation between the two requires careful consideration. Various physiological measures have been employed in an attempt to gain a better understanding of the mechanisms involved in the generation of fatigue, however often studies have produced dissociating results. The current study considered the task-related fatigue elicited by a tracking task requiring sustained attention, in order to evaluate the usefulness of various cardiovascular and oculomotor measures as indicators of fatigue. A secondary aim was to determine whether the behavioural and physiological parameter responses could be used to infer the type of fatigue incurred (i.e. an active versus passive fatigue state) as well as the energetical mechanisms involved during task performance. A simple driving simulator task was used as the main tracking task, requiring constant attention and concentration. This task was performed for approximately two hours. Three experimental groups (consisting of 14 subjects each) were used: a control group that performed the tracking task only, a group that performed a five minute auditory memory span task concurrently with the driving task after every 20 minutes of pure driving, and a group that performed a visual choice reaction task for five minutes following every 20 minute driving period. The secondary tasks were employed in order to evaluate the extent of resource allocation as well as arousal level. Performance measures included various driving performance parameters, as well as secondary task performance. Physiological measures included heart rate frequency (HR) and various time- and frequency-domain heart rate variability (HRV)parameters, pupil dilation, blink frequency and duration, fixations, and saccadic parameters as well as critical flicker fusion frequency (CFFF). The Borg CR-10 scale was used to evaluate subjective fatigue during the task, and the NASA-TLX was completed following the task. A decline in driving performance over time was supplemented by measures such as HR, HRV and pupil dilation 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. Longer and faster saccades were also evident over time, coupled with shorter fixations. With regards to the secondary task influence, the choice RT task did not affect any behavioural or physiological parameters, thereby contesting the active fatigue theory of resource depletion, as well as implying that the increase in demand for the same resources used by the primary task was insufficient to affect the state of the subjects. The increased load elicited by the memory span task improved driving performance and increased measures of HR, HRV, pupil dilation and blink frequency. Some of these measures produced opposite effects to what was expected; an attempt to explain the dissociation of the various physiological parameters was expressed in terms of arousal, effort and resource theories. Overall, the results indicate that the fatigue and/or reduced arousal accompanying a monotonous sustained attention task can, to some degree, be alleviated through intermittent performance of a secondary task engaging mental resources other than the ones used for the primary task. The degree to which such a task is beneficial, however, requires careful consideration as while an immediate increase in arousal and primary task performance is noted, the impact of the task on general attentional resources may be detrimental in the case of reacting should an emergency situation occur.
- Full Text:
- Date Issued: 2012
- Authors: De Gray Birch, Casey
- Date: 2012
- Subjects: Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5120 , http://hdl.handle.net/10962/d1005198 , Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Description: Despite extensive research into the concept of mental fatigue there is as yet no “gold standard” definition or measurement technique available. Because of this a large amount of fatigue-related errors are still seen in the workplace. The complexity of the problem lies with the inability to directly measure mental processes as well as the various endogenous and exogenous factors that interact to produce the experienced fatigue. Fatigue has been divided into sleep-related and task-related fatigue; however the task-related aspect is evident both during normal waking hours as well as during periods of sleep deprivation, therefore this aspect is considered important in the understanding of fatigue in general. The concept of task-related fatigue has further been divided into active and passive fatigue states; however differentiation between the two requires careful consideration. Various physiological measures have been employed in an attempt to gain a better understanding of the mechanisms involved in the generation of fatigue, however often studies have produced dissociating results. The current study considered the task-related fatigue elicited by a tracking task requiring sustained attention, in order to evaluate the usefulness of various cardiovascular and oculomotor measures as indicators of fatigue. A secondary aim was to determine whether the behavioural and physiological parameter responses could be used to infer the type of fatigue incurred (i.e. an active versus passive fatigue state) as well as the energetical mechanisms involved during task performance. A simple driving simulator task was used as the main tracking task, requiring constant attention and concentration. This task was performed for approximately two hours. Three experimental groups (consisting of 14 subjects each) were used: a control group that performed the tracking task only, a group that performed a five minute auditory memory span task concurrently with the driving task after every 20 minutes of pure driving, and a group that performed a visual choice reaction task for five minutes following every 20 minute driving period. The secondary tasks were employed in order to evaluate the extent of resource allocation as well as arousal level. Performance measures included various driving performance parameters, as well as secondary task performance. Physiological measures included heart rate frequency (HR) and various time- and frequency-domain heart rate variability (HRV)parameters, pupil dilation, blink frequency and duration, fixations, and saccadic parameters as well as critical flicker fusion frequency (CFFF). The Borg CR-10 scale was used to evaluate subjective fatigue during the task, and the NASA-TLX was completed following the task. A decline in driving performance over time was supplemented by measures such as HR, HRV and pupil dilation 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. Longer and faster saccades were also evident over time, coupled with shorter fixations. With regards to the secondary task influence, the choice RT task did not affect any behavioural or physiological parameters, thereby contesting the active fatigue theory of resource depletion, as well as implying that the increase in demand for the same resources used by the primary task was insufficient to affect the state of the subjects. The increased load elicited by the memory span task improved driving performance and increased measures of HR, HRV, pupil dilation and blink frequency. Some of these measures produced opposite effects to what was expected; an attempt to explain the dissociation of the various physiological parameters was expressed in terms of arousal, effort and resource theories. Overall, the results indicate that the fatigue and/or reduced arousal accompanying a monotonous sustained attention task can, to some degree, be alleviated through intermittent performance of a secondary task engaging mental resources other than the ones used for the primary task. The degree to which such a task is beneficial, however, requires careful consideration as while an immediate increase in arousal and primary task performance is noted, the impact of the task on general attentional resources may be detrimental in the case of reacting should an emergency situation occur.
- Full Text:
- Date Issued: 2012
The effects of the type of rest breaks on return-to-task performance in semi-automated tasks with varying complexities
- Authors: Hoyi, Zandile
- Date: 2017
- Subjects: Rest periods , Rest periods -- Physiological effect , Human-robot interaction , Aeronautics -- Human factors , Human engineering , Drowsiness
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44490 , vital:25412
- Description: Automation in the aviation industry is acknowledged as a useful tool in reducing pilot workload (Hoh, Smith & Hinton, 1987; Beringer & Harris Jr., 1999). Typically, the role of the pilot (operator) shifts from active participation in a process to a task of monitoring the system with the resumption of control should the automation ‘fail’ (Byrne & Parasuraman, 1996). Unfortunately, the skills necessary to do so would likely degrade from non-use, during this process (Landry, 2012). This project investigates the “attentional demands” for the human operator during interaction with semi-automated operations of the flight. According to Dr Abbott (1996), FAA human factors specialist, one of the problems causing disharmony between crews and their automated systems is the incorrect upset recovery, owing to the human being out-of-the-loop (OOTL) from the system. Recovery, or rather return to task, is the ability of the pilot to loop back into control, once situational awareness has been decreased due to lack of alertness and a decrease in arousal. Different types of rest tasks are commonly prescribed fatigue countermeasures in the industrial setting and have been showed to elicit beneficial effects on prolonged human performance. Understanding the effects of different rest break activity and time out-of-the-loop during semi-automated flying on return to task performance has been adequately studied, thus highlighting its importance in the context of flight safety. The present study requested participants to perform a tracking task in a laboratory where they changed from activity (30 minutes) to a break (2 vs. 30 minutes) and back to the activity (20 minutes). The task varied in the complexity of the activity (pure tracking vs. tracking plus memory plus rule-based decision making), the type of break (passive rest vs. actively supervising) and the duration of the break (2 minutes vs. 30 minutes). Performance was measured as effective response time in the tracking task and number of correct responses to secondary cognitive tasks. Physiological measures included heart rate (HR), heart rate variability (HRV- time and frequency-domain), eye blink frequency and duration. The Karolinska Sleepiness Scale was used as a subjective measure. With regards to the most appropriate rest break tasks, the study concluded that active, administrative tasks, which allowed the operator to maintain some form of situational awareness by monitoring the automated system, achieved favourable effects of being more alert than the passive rest break of being disengaged from the system. In terms of the most appropriate rest break durations, the shorter duration of being out-of-the-loop from controlling the system proved to be more advantageous than the longer out-of-the-loop duration. In looking at the workload levels of arousal, the results suggest that the higher workload level is better at maintaining the alertness of operators. This study functions as a foundational framework for future investigations around the topic of human-automation interaction, looking specifically at return-to-task performance.
- Full Text:
- Date Issued: 2017
- Authors: Hoyi, Zandile
- Date: 2017
- Subjects: Rest periods , Rest periods -- Physiological effect , Human-robot interaction , Aeronautics -- Human factors , Human engineering , Drowsiness
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44490 , vital:25412
- Description: Automation in the aviation industry is acknowledged as a useful tool in reducing pilot workload (Hoh, Smith & Hinton, 1987; Beringer & Harris Jr., 1999). Typically, the role of the pilot (operator) shifts from active participation in a process to a task of monitoring the system with the resumption of control should the automation ‘fail’ (Byrne & Parasuraman, 1996). Unfortunately, the skills necessary to do so would likely degrade from non-use, during this process (Landry, 2012). This project investigates the “attentional demands” for the human operator during interaction with semi-automated operations of the flight. According to Dr Abbott (1996), FAA human factors specialist, one of the problems causing disharmony between crews and their automated systems is the incorrect upset recovery, owing to the human being out-of-the-loop (OOTL) from the system. Recovery, or rather return to task, is the ability of the pilot to loop back into control, once situational awareness has been decreased due to lack of alertness and a decrease in arousal. Different types of rest tasks are commonly prescribed fatigue countermeasures in the industrial setting and have been showed to elicit beneficial effects on prolonged human performance. Understanding the effects of different rest break activity and time out-of-the-loop during semi-automated flying on return to task performance has been adequately studied, thus highlighting its importance in the context of flight safety. The present study requested participants to perform a tracking task in a laboratory where they changed from activity (30 minutes) to a break (2 vs. 30 minutes) and back to the activity (20 minutes). The task varied in the complexity of the activity (pure tracking vs. tracking plus memory plus rule-based decision making), the type of break (passive rest vs. actively supervising) and the duration of the break (2 minutes vs. 30 minutes). Performance was measured as effective response time in the tracking task and number of correct responses to secondary cognitive tasks. Physiological measures included heart rate (HR), heart rate variability (HRV- time and frequency-domain), eye blink frequency and duration. The Karolinska Sleepiness Scale was used as a subjective measure. With regards to the most appropriate rest break tasks, the study concluded that active, administrative tasks, which allowed the operator to maintain some form of situational awareness by monitoring the automated system, achieved favourable effects of being more alert than the passive rest break of being disengaged from the system. In terms of the most appropriate rest break durations, the shorter duration of being out-of-the-loop from controlling the system proved to be more advantageous than the longer out-of-the-loop duration. In looking at the workload levels of arousal, the results suggest that the higher workload level is better at maintaining the alertness of operators. This study functions as a foundational framework for future investigations around the topic of human-automation interaction, looking specifically at return-to-task performance.
- Full Text:
- Date Issued: 2017
The effects of whole body immersion in cold water upon subsequent terrestrial aerobic performance : a study in hypothermia
- Authors: Manley, Elizabeth
- Date: 1998 , 2013-09-04
- Subjects: Hypothermia , Cold -- Physiological effect , Temperature -- Physiological effect , Aerobic exercises , Cryobiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5143 , http://hdl.handle.net/10962/d1007458 , Hypothermia , Cold -- Physiological effect , Temperature -- Physiological effect , Aerobic exercises , Cryobiology
- Description: This study examined the extent to which physiological and psychological concomitants of aerobic terrestrial performance were affected by body cooling of varying degrees induced by cold water immersion (CWI). Thirteen male and 13 female subjects underwent three randomly assigned 30 min treadmill runs: a control run without prior manipulation of the subjects' thermal status and the same exercise after "central" (core temperature 1°C below pre-immersion) and "peripheral" cooling (skin heat loss 100kcal.m⁻².h⁻¹). During treadmill runs core temperature was measured, together with chest, leg, arm and hand temperatures, from which mean skin temperature (T [subscript]s[subscript]k) and mean body temperature (T[subscript]b) were calculated. Heart rate, oxygen consumption (VO₂,), carbon dioxide production (VCO₂), minute ventilation (V₂ (BTPS)), breathing frequency (f), cadence and ratings of perceived exertion (RPE) and thermal sensation (PTS) were also measured. Both central and peripheral cooling resulted in significantly reduced T[subscript]r[subscript]e (males : control 37.9±0. 3°C; central cooling : 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 37.9±0.4°C; central cooling: 37.2±0.5; p<0.05) during subsequent treadmill running, except following peripheral cooling for females (37.9±0.3°C) . For males and females T[subscript]s[subscript]k was lower following peripheral cooling than control values and lowest after central cooling (males: control: 30.0±1.3°C; central cooling: 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 30.5±1.2°C; central cooling: 25.9±1.8°C; peripheral cooling: 26.9±1.9°C; p<0.05). Female subjects experienced significantly higher T[subscript]r[subscript]e than males following central and peripheral cooling and a lower T[subscript]s[subscript]k following central cooling. Females experienced less of an increase in heart rate than males during exercise following central and peripheral cooling (control: l57.7±23.7b.min⁻¹; central cooling: 143.5±20.5b.min⁻¹; peripheral cooling 151.7±16.7b.min⁻¹; p<0 .05). Male responses were the same following central cooling but higher for peripheral cooling than control values (control: 139.1±7.3b.min⁻¹; central cooling 134.7±17.5b.min⁻¹; peripheral cooling: 145.0±16.4b.min⁻¹; p<0.05). These data indicate a depression in cardiovascular function for females following peripheral cooling that was not apparent for males. The VO₂ was not different between tests for males; only peripheral cooling resulted in a raised VO₂ of 28.6±3 .3ml.kg⁻¹.min⁻¹ (p<0 .05) for females compared to 27.6±2.6ml.kg⁻¹.min⁻¹ (control). A biphasic response was evident for VO₂ VCO₂ and V[subscript]B (BTPS). For both sexes overall RPE was lower for peripheral cooling (males: 9.4±1.9; females: 8.7±1.3; p<0 .05) than for control and central cooling. Central RPE was only changed for females following peripheral cooling. Changes in cadence and step length together with the effect of low skin and leg temperatures resulted in higher local RPE for females after central cooling (9.6±1.2; p<0.05) than control (9.4±1.9) and peripheral cooling (8.9±1.2 ). Males and females rated the same ambient temperature during the same exercise lower after peripheral cooling (males: 4.6±1.5; females : 5.3±1.3) than control values and lower still after central cooling (males: 3. 8±1.8; females: 2 .7±l. 5) In this study T[subscript]s[subscript]k was the primary determinant of PTS after precooling. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1998
- Authors: Manley, Elizabeth
- Date: 1998 , 2013-09-04
- Subjects: Hypothermia , Cold -- Physiological effect , Temperature -- Physiological effect , Aerobic exercises , Cryobiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5143 , http://hdl.handle.net/10962/d1007458 , Hypothermia , Cold -- Physiological effect , Temperature -- Physiological effect , Aerobic exercises , Cryobiology
- Description: This study examined the extent to which physiological and psychological concomitants of aerobic terrestrial performance were affected by body cooling of varying degrees induced by cold water immersion (CWI). Thirteen male and 13 female subjects underwent three randomly assigned 30 min treadmill runs: a control run without prior manipulation of the subjects' thermal status and the same exercise after "central" (core temperature 1°C below pre-immersion) and "peripheral" cooling (skin heat loss 100kcal.m⁻².h⁻¹). During treadmill runs core temperature was measured, together with chest, leg, arm and hand temperatures, from which mean skin temperature (T [subscript]s[subscript]k) and mean body temperature (T[subscript]b) were calculated. Heart rate, oxygen consumption (VO₂,), carbon dioxide production (VCO₂), minute ventilation (V₂ (BTPS)), breathing frequency (f), cadence and ratings of perceived exertion (RPE) and thermal sensation (PTS) were also measured. Both central and peripheral cooling resulted in significantly reduced T[subscript]r[subscript]e (males : control 37.9±0. 3°C; central cooling : 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 37.9±0.4°C; central cooling: 37.2±0.5; p<0.05) during subsequent treadmill running, except following peripheral cooling for females (37.9±0.3°C) . For males and females T[subscript]s[subscript]k was lower following peripheral cooling than control values and lowest after central cooling (males: control: 30.0±1.3°C; central cooling: 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 30.5±1.2°C; central cooling: 25.9±1.8°C; peripheral cooling: 26.9±1.9°C; p<0.05). Female subjects experienced significantly higher T[subscript]r[subscript]e than males following central and peripheral cooling and a lower T[subscript]s[subscript]k following central cooling. Females experienced less of an increase in heart rate than males during exercise following central and peripheral cooling (control: l57.7±23.7b.min⁻¹; central cooling: 143.5±20.5b.min⁻¹; peripheral cooling 151.7±16.7b.min⁻¹; p<0 .05). Male responses were the same following central cooling but higher for peripheral cooling than control values (control: 139.1±7.3b.min⁻¹; central cooling 134.7±17.5b.min⁻¹; peripheral cooling: 145.0±16.4b.min⁻¹; p<0.05). These data indicate a depression in cardiovascular function for females following peripheral cooling that was not apparent for males. The VO₂ was not different between tests for males; only peripheral cooling resulted in a raised VO₂ of 28.6±3 .3ml.kg⁻¹.min⁻¹ (p<0 .05) for females compared to 27.6±2.6ml.kg⁻¹.min⁻¹ (control). A biphasic response was evident for VO₂ VCO₂ and V[subscript]B (BTPS). For both sexes overall RPE was lower for peripheral cooling (males: 9.4±1.9; females: 8.7±1.3; p<0 .05) than for control and central cooling. Central RPE was only changed for females following peripheral cooling. Changes in cadence and step length together with the effect of low skin and leg temperatures resulted in higher local RPE for females after central cooling (9.6±1.2; p<0.05) than control (9.4±1.9) and peripheral cooling (8.9±1.2 ). Males and females rated the same ambient temperature during the same exercise lower after peripheral cooling (males: 4.6±1.5; females : 5.3±1.3) than control values and lower still after central cooling (males: 3. 8±1.8; females: 2 .7±l. 5) In this study T[subscript]s[subscript]k was the primary determinant of PTS after precooling. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1998
The efficacy of a community based eccentric hamstring strengthening program in peri-urban Black South African soccer players
- Authors: Ryan, Bennett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3573 , vital:20526
- Description: Introduction: Hamstring injury prevalence in soccer remains a major concern. Research in this context has focused on Caucasian populations with little attention given to other ethnic groups. The compatibility and applicability of such research to the South African context, particularly at an amateur level, may be minimal due to fundamental differences in physical characteristics, as well as complexities with regards to implementation. The aim of this investigation was therefore twofold. 1) Identify the lower extremity strength and performance profile of Peri-urban Amateur South African Players, and 2) Assess the efficacy of a community based intervention through the use of the Nordic Hamstring Exercise. Methods: 19 Black male Eastern Cape amateur players participated in a 12 week randomly controlled trial (9 = Control, 10 = Intervention). All participants completed regular training, while the intervention group, in addition, performed the Nordic Hamstring exercise post warm up. The incremental program design was taken from Mjolsnes et al. (2004), with a progressive increase in both sets and repetitions. Compliance was defined as completion of the required exercises for that session. Isokinetic strength evaluations (at 60°.s-1 and 180°.s-1) including assessment of peak torque and total work, as well as performance measures of countermovement and squat jump, were completed pre and post intervention, with the profile of the Peri-urban player the combined responses of both groups at baseline. Additionally, both the functional ratio (Eccentric Hamstrings/Concentric Quadriceps) and eccentric utilization ratio (Countermovement Jump/Squat Jump) were calculated. Results: Concentric quadriceps peak torque at baseline reported values of 195 (±22) Nm and 141 (±21) Nm at 60°.s-1 and 180°.s-1. Values of 162 (±21) Nm were observed for peak torque of the eccentric hamstrings at 60°.s-1, while 157 (±18) Nm was indicated at 180°.s-1. Mean functional ratio responses were observed as 0.83 (±0.11) and 1.12 (±0.16) for 60°.s-1 and 180°.s-1 respectively. Additionally, the eccentric utilization ratio responses were recorded as 1.04 (±0.08). Regarding the intervention, concentric quadriceps total work of the dominant limb significantly improved over the time course of experimentation within the intervention group. Other quadriceps variables, concentric hamstrings, squat jump capability and performance measures all reported no significant changes (p>0.05) over the course of assessment when compared to the control. Eccentric hamstrings peak torque observed significant improvements (p<0.05) of between 5.72 and 12.82 % within the intervention group, while the countermovement jump indicated a significant 15.59 % increase (p<0.05). Additionally, the functional ratio and the eccentric utilization ratio both indicated no significant changes (p>0.05), with a 2.48-7.66 % and 5.33 % improvement noted following completion of assessment. Conclusion: Isokinetic responses at baseline observed decreased quadriceps strength, and increased hamstring strength when compared to both amateur and professional populations examined in previous studies, for both isokinetic testing speeds. Additionally, performance measures indicated similar responses to other amateur populations. Regarding the intervention, significant improvements in eccentric hamstring peak torque and countermovement jump indicate the partial success of the present intervention. Additionally, while the functional ratio and eccentric utilization ratio reported no significant changes, improvements were noted within the intervention group while the control noted no change. The Nordic hamstring lower therefore resulted in strength improvements within the eccentric hamstrings, reported as a significant factor for injury risk, however, such changes were not sufficient to significantly impact the functional ratio. It can be concluded that community based programs within South Africa have the potential to be effective; however, there are many barriers to implementation, including, language, ethnic and cultural differences, while a lack of resources and infrastructure play a significant role in a lack of development. More research of this nature is required to provide scientific support for structures and guidelines for the peri-urban community based South African player, to ensure the efficacy of internationally successful interventions such as the Nordic exercise.
- Full Text:
- Date Issued: 2016
- Authors: Ryan, Bennett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3573 , vital:20526
- Description: Introduction: Hamstring injury prevalence in soccer remains a major concern. Research in this context has focused on Caucasian populations with little attention given to other ethnic groups. The compatibility and applicability of such research to the South African context, particularly at an amateur level, may be minimal due to fundamental differences in physical characteristics, as well as complexities with regards to implementation. The aim of this investigation was therefore twofold. 1) Identify the lower extremity strength and performance profile of Peri-urban Amateur South African Players, and 2) Assess the efficacy of a community based intervention through the use of the Nordic Hamstring Exercise. Methods: 19 Black male Eastern Cape amateur players participated in a 12 week randomly controlled trial (9 = Control, 10 = Intervention). All participants completed regular training, while the intervention group, in addition, performed the Nordic Hamstring exercise post warm up. The incremental program design was taken from Mjolsnes et al. (2004), with a progressive increase in both sets and repetitions. Compliance was defined as completion of the required exercises for that session. Isokinetic strength evaluations (at 60°.s-1 and 180°.s-1) including assessment of peak torque and total work, as well as performance measures of countermovement and squat jump, were completed pre and post intervention, with the profile of the Peri-urban player the combined responses of both groups at baseline. Additionally, both the functional ratio (Eccentric Hamstrings/Concentric Quadriceps) and eccentric utilization ratio (Countermovement Jump/Squat Jump) were calculated. Results: Concentric quadriceps peak torque at baseline reported values of 195 (±22) Nm and 141 (±21) Nm at 60°.s-1 and 180°.s-1. Values of 162 (±21) Nm were observed for peak torque of the eccentric hamstrings at 60°.s-1, while 157 (±18) Nm was indicated at 180°.s-1. Mean functional ratio responses were observed as 0.83 (±0.11) and 1.12 (±0.16) for 60°.s-1 and 180°.s-1 respectively. Additionally, the eccentric utilization ratio responses were recorded as 1.04 (±0.08). Regarding the intervention, concentric quadriceps total work of the dominant limb significantly improved over the time course of experimentation within the intervention group. Other quadriceps variables, concentric hamstrings, squat jump capability and performance measures all reported no significant changes (p>0.05) over the course of assessment when compared to the control. Eccentric hamstrings peak torque observed significant improvements (p<0.05) of between 5.72 and 12.82 % within the intervention group, while the countermovement jump indicated a significant 15.59 % increase (p<0.05). Additionally, the functional ratio and the eccentric utilization ratio both indicated no significant changes (p>0.05), with a 2.48-7.66 % and 5.33 % improvement noted following completion of assessment. Conclusion: Isokinetic responses at baseline observed decreased quadriceps strength, and increased hamstring strength when compared to both amateur and professional populations examined in previous studies, for both isokinetic testing speeds. Additionally, performance measures indicated similar responses to other amateur populations. Regarding the intervention, significant improvements in eccentric hamstring peak torque and countermovement jump indicate the partial success of the present intervention. Additionally, while the functional ratio and eccentric utilization ratio reported no significant changes, improvements were noted within the intervention group while the control noted no change. The Nordic hamstring lower therefore resulted in strength improvements within the eccentric hamstrings, reported as a significant factor for injury risk, however, such changes were not sufficient to significantly impact the functional ratio. It can be concluded that community based programs within South Africa have the potential to be effective; however, there are many barriers to implementation, including, language, ethnic and cultural differences, while a lack of resources and infrastructure play a significant role in a lack of development. More research of this nature is required to provide scientific support for structures and guidelines for the peri-urban community based South African player, to ensure the efficacy of internationally successful interventions such as the Nordic exercise.
- Full Text:
- Date Issued: 2016
The ergonomic assessment of two different pipette models and their effects on biomechanical, performance, and subjective outcomes
- Authors: Masoka, Bonolo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424278 , vital:72139
- Description: While laboratory workers are essential in many industries, they are also at a high risk of developing musculoskeletal disorders (MSDs). Manual pipetting has been identified as the leading cause of MSDs in laboratories because it exposes operators to high forces, repetition, static muscular loading, and awkward wrist postures for prolonged periods. The main contributors to the high risk associated with manual pipetting are the design of manual pipettes and how they are used. A laboratory-based study was conducted to assess and compare the biomechanical, subjective, and performance responses of an ergonomically designed pipette model to those of a traditional model. In a simulated laboratory workstation, 20 individuals performed 40 repetitions of pipetting tasks using each pipette model. Dependent variables consisted of muscle activity (of the Abductor Pollicis Brevis, Opponens Pollicis, Extensor pollicis longus, Abductor pollicis longus, Extensor pollicis brevis, and brachioradialis muscles), wrist postures, time to task completion, perceived muscular exertion (measured using the Borg RPE scale), perceived comfort and usability, and user preference. The results revealed that an ergonomic modification to pipette design has some effect on biomechanical and subjective outcomes. The ergonomic model significantly reduced muscular loading of the Opponens pollicis, and Abductor pollicis brevis muscles. The ergonomic model also reduced radial deviation and was associated with better subjective responses, while the time to task completion did not change. This study found that an ergonomic modification to pipette design can improve user comfort and well-being without compromising performance. Overall, the findings emphasize the importance of addressing pipette design to reduce the MSD risk associated with manual pipetting, and the necessity for a user-centred approach to tool design. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Masoka, Bonolo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424278 , vital:72139
- Description: While laboratory workers are essential in many industries, they are also at a high risk of developing musculoskeletal disorders (MSDs). Manual pipetting has been identified as the leading cause of MSDs in laboratories because it exposes operators to high forces, repetition, static muscular loading, and awkward wrist postures for prolonged periods. The main contributors to the high risk associated with manual pipetting are the design of manual pipettes and how they are used. A laboratory-based study was conducted to assess and compare the biomechanical, subjective, and performance responses of an ergonomically designed pipette model to those of a traditional model. In a simulated laboratory workstation, 20 individuals performed 40 repetitions of pipetting tasks using each pipette model. Dependent variables consisted of muscle activity (of the Abductor Pollicis Brevis, Opponens Pollicis, Extensor pollicis longus, Abductor pollicis longus, Extensor pollicis brevis, and brachioradialis muscles), wrist postures, time to task completion, perceived muscular exertion (measured using the Borg RPE scale), perceived comfort and usability, and user preference. The results revealed that an ergonomic modification to pipette design has some effect on biomechanical and subjective outcomes. The ergonomic model significantly reduced muscular loading of the Opponens pollicis, and Abductor pollicis brevis muscles. The ergonomic model also reduced radial deviation and was associated with better subjective responses, while the time to task completion did not change. This study found that an ergonomic modification to pipette design can improve user comfort and well-being without compromising performance. Overall, the findings emphasize the importance of addressing pipette design to reduce the MSD risk associated with manual pipetting, and the necessity for a user-centred approach to tool design. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
- Full Text:
- Date Issued: 2023-10-13
The factors affecting self-regulation through the analysis of physiological, psychological and behavioural measures during task-switching
- Authors: Chaplin, Caley
- Date: 2013 , 2013-07-16
- Subjects: Human multitasking -- Physiological aspects , Human multitasking -- Psychological aspects , Fatigue , Boredom , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Industrial hygiene , Employees -- Workload
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5135 , http://hdl.handle.net/10962/d1006027 , Human multitasking -- Physiological aspects , Human multitasking -- Psychological aspects , Fatigue , Boredom , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Industrial hygiene , Employees -- Workload
- Description: Individuals are required to manage multiple tasks which require strategic allocation of time and effort to ensure goals are reached efficiently. By providing the worker with autonomy over their work, performance and worker well-being have improved. This increased control allows individuals to organize work according to the needs of the body, which prevents fatigue leading to improved productivity. When given the option, humans tend to switch between tasks frequently. This behaviour can be used to determine the change in self-regulation strategies. An understanding of human task-switching behaviour is important for the design of job rotation systems. However, there is a lack of evidence explaining the factors motivating the need to switch between tasks. This study aims to use physiological, subjective and behavioural measures to explain the factors influencing selfregulation through the act of task-switching. Three primary hypotheses were developed to explain the factors underlying taskswitching behaviour. It was hypothesized that the degree of boredom experienced, the effort required to perform the task and the resource usage induced by the task are factors responsible in deciding task switching behaviour. Participants (17 males and 17 females) switched freely between five different information-processing tasks for the 45 minutes. Participants were allowed to switch back and forth between tasks and did not have to conduct all five tasks. The following measures were recorded during the experiment: subjective measures of boredom, mental effort, task frustration and perceived performance of the tasks; energy consumption and physiological measures of effort (HR, HRV and body temperature) and behavioural measures, including duration and frequency of task. Perceived boredom was found to differ among the tasks and before and after the experiment. The average boredom rating at each task transition for all tasks exceeded a score of 2.5 out of a possible 4. There were no significant changes in physiological measures between the beginning and end of the task trials. However, changes in physiological measures showed a decrease in effort investment following task transition. Heart rate variability was lower for externally-paced tasks than for self-paced tasks, despite the differences in cognitive demands. The most frequent task-switch combination occurred between tasks of high and low cognitive demand. The least frequent task-switching combination occurred between tasks of similar characteristics, which produced no differences in physiological responses. Task-switching behaviour was influenced by the degree of boredom, and therefore more time was spent on less monotonous tasks. The level of physiological effort required for the task affected task-switching behaviour. Task switches were made before any changes in effort took place in an attempt to maintain task efficiency. It appears plausible that a task switch was made to reduce effort investment and activation levels. The type of information processing resources used by different tasks affected the task-switching combinations. Individuals tended to switch between tasks of differing resources so that those in limited supply were able to replenish. Therefore the findings from this study can potentially be used to improve the design of job rotation systems. Such improvements may enhance productivity and worker well-being by inhibiting the onset of down regulation and fatigue processes. This study showed that autonomy is necessary for individuals to regulate behaviour to suit human needs. , Microsoft� Office Word 2007 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Chaplin, Caley
- Date: 2013 , 2013-07-16
- Subjects: Human multitasking -- Physiological aspects , Human multitasking -- Psychological aspects , Fatigue , Boredom , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Industrial hygiene , Employees -- Workload
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5135 , http://hdl.handle.net/10962/d1006027 , Human multitasking -- Physiological aspects , Human multitasking -- Psychological aspects , Fatigue , Boredom , Attention , Mental fatigue , Human information processing , Decision making , Labor productivity , Industrial hygiene , Employees -- Workload
- Description: Individuals are required to manage multiple tasks which require strategic allocation of time and effort to ensure goals are reached efficiently. By providing the worker with autonomy over their work, performance and worker well-being have improved. This increased control allows individuals to organize work according to the needs of the body, which prevents fatigue leading to improved productivity. When given the option, humans tend to switch between tasks frequently. This behaviour can be used to determine the change in self-regulation strategies. An understanding of human task-switching behaviour is important for the design of job rotation systems. However, there is a lack of evidence explaining the factors motivating the need to switch between tasks. This study aims to use physiological, subjective and behavioural measures to explain the factors influencing selfregulation through the act of task-switching. Three primary hypotheses were developed to explain the factors underlying taskswitching behaviour. It was hypothesized that the degree of boredom experienced, the effort required to perform the task and the resource usage induced by the task are factors responsible in deciding task switching behaviour. Participants (17 males and 17 females) switched freely between five different information-processing tasks for the 45 minutes. Participants were allowed to switch back and forth between tasks and did not have to conduct all five tasks. The following measures were recorded during the experiment: subjective measures of boredom, mental effort, task frustration and perceived performance of the tasks; energy consumption and physiological measures of effort (HR, HRV and body temperature) and behavioural measures, including duration and frequency of task. Perceived boredom was found to differ among the tasks and before and after the experiment. The average boredom rating at each task transition for all tasks exceeded a score of 2.5 out of a possible 4. There were no significant changes in physiological measures between the beginning and end of the task trials. However, changes in physiological measures showed a decrease in effort investment following task transition. Heart rate variability was lower for externally-paced tasks than for self-paced tasks, despite the differences in cognitive demands. The most frequent task-switch combination occurred between tasks of high and low cognitive demand. The least frequent task-switching combination occurred between tasks of similar characteristics, which produced no differences in physiological responses. Task-switching behaviour was influenced by the degree of boredom, and therefore more time was spent on less monotonous tasks. The level of physiological effort required for the task affected task-switching behaviour. Task switches were made before any changes in effort took place in an attempt to maintain task efficiency. It appears plausible that a task switch was made to reduce effort investment and activation levels. The type of information processing resources used by different tasks affected the task-switching combinations. Individuals tended to switch between tasks of differing resources so that those in limited supply were able to replenish. Therefore the findings from this study can potentially be used to improve the design of job rotation systems. Such improvements may enhance productivity and worker well-being by inhibiting the onset of down regulation and fatigue processes. This study showed that autonomy is necessary for individuals to regulate behaviour to suit human needs. , Microsoft� Office Word 2007 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
The impact of a one-hour self-selected nap opportunity on physiological and performance variables during a simulated night shift
- Authors: Davy, Jonathan Patrick
- Date: 2010
- Subjects: Night work , Naps (sleep) in the workplace , Naps (sleep) in the workplace -- Case studies , Shift systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5123 , http://hdl.handle.net/10962/d1005201 , Night work , Naps (sleep) in the workplace , Naps (sleep) in the workplace -- Case studies , Shift systems
- Description: Napping has been explored extensively as a means of counteracting the negative effects associated with shift work. A significant amount of this research has focused on the implementation of scheduled naps, with few studies considering flexible nap schemes. The current study therefore aimed to assess the effects of a flexible nap opportunity on the physiological, cognitive, performance, neurophysiological and subjective responses of a group of non shift workers over the course of a three-day simulated night shift regime. Additional foci were the effects of the nap condition on the extent of the circadian adaptation of the subjects to the irregular work schedule and the circadian-related influences associated with being awake during the night. 36 subjects – 18 males and 18 females – were recruited to participate in the current study. The data collection spanned twelve days, during which four, three-day long shift cycles were set up: three night shift cycles and one day shift cycle. During each night shift cycle, three separate experimental conditions were staggered, namely the nap condition, the no nap condition and a booster break condition (a collaborative study that completed the setup). The day shift served as a further comparison. Each cycle comprised of 12 subjects, which meant there were four subjects per condition during each cycle. The shifts were 8 hours in duration, with the no nap group following a standard break schedule evinced in industry. The three breaks taken during the shifts amounted to a total time of 1 hour. The nap group was afforded a 1 hour flexible nap opportunity between 00h00 and 03h00 with no other breaks. Therefore, both conditions had the same amount of work time. During the shifts, subjects performed two simple, low arousal tasks (beading and packing) and completed a test battery roughly every two hours which was comprised of physiological, performance, neurophysiological and subjective measures. It was found that the inclusion of the nap opportunity significantly improved output performance and response time during a low precision, modified Fitts tapping task over the course of three night shifts, relative to no napping. Physiologically, napping resulted in higher heart rate frequency measures by the end of the shifts, which were also accompanied by significant reductions in subjective sleepiness ratings during all iii the night shifts. The nap group’s responses in this case, did not differ significantly from those of the day shift. Both simple reaction time and memory performances improved as a result of the nap inclusion, but only during the third night shift. The majority of the measures included in the research also depicted the effects of the circadian rhythm, which was indicative of the pronounced effect that this natural biological down regulation has on performance during the night. Napping reduced the severity of these effects during beading performance and measures of subjective sleepiness. With regard to habituation, the nap opportunity also resulted in positive changes in the responses of beading performance, high precision response time, simple reaction time and both subjective sleepiness measures, relative to no napping. Sleep diary responses indicated that although sleep length and quality during the day were significantly reduced for both night-time conditions, recovery sleep (length and quality) for the nap group did not differ significantly from the no nap group. The findings of this research indicate that the inclusion of a flexible napping opportunity during the night shift had positive effects on some physiological, performance and subjective responses, and that this intervention is as beneficial as scheduled napping. Specifically, napping resulted in a significantly higher output during the beading task, relative to the no nap group despite the duration of work time being the same. As such the introduction of a flexible, self-selected nap opportunity is a practical, effective and individual-specific means of alleviating the negative effects of shift work, while improving certain performance parameters. Therefore, industries should consider its inclusion in their fatigue management programs. However, contextspecific considerations must be made, with regard work scheduling, individual differences and task demands when implementing such an intervention. This will ensure that its introduction will be well received and in time, lessen the health and work-related decrements associated with shift work.
- Full Text:
- Date Issued: 2010
- Authors: Davy, Jonathan Patrick
- Date: 2010
- Subjects: Night work , Naps (sleep) in the workplace , Naps (sleep) in the workplace -- Case studies , Shift systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5123 , http://hdl.handle.net/10962/d1005201 , Night work , Naps (sleep) in the workplace , Naps (sleep) in the workplace -- Case studies , Shift systems
- Description: Napping has been explored extensively as a means of counteracting the negative effects associated with shift work. A significant amount of this research has focused on the implementation of scheduled naps, with few studies considering flexible nap schemes. The current study therefore aimed to assess the effects of a flexible nap opportunity on the physiological, cognitive, performance, neurophysiological and subjective responses of a group of non shift workers over the course of a three-day simulated night shift regime. Additional foci were the effects of the nap condition on the extent of the circadian adaptation of the subjects to the irregular work schedule and the circadian-related influences associated with being awake during the night. 36 subjects – 18 males and 18 females – were recruited to participate in the current study. The data collection spanned twelve days, during which four, three-day long shift cycles were set up: three night shift cycles and one day shift cycle. During each night shift cycle, three separate experimental conditions were staggered, namely the nap condition, the no nap condition and a booster break condition (a collaborative study that completed the setup). The day shift served as a further comparison. Each cycle comprised of 12 subjects, which meant there were four subjects per condition during each cycle. The shifts were 8 hours in duration, with the no nap group following a standard break schedule evinced in industry. The three breaks taken during the shifts amounted to a total time of 1 hour. The nap group was afforded a 1 hour flexible nap opportunity between 00h00 and 03h00 with no other breaks. Therefore, both conditions had the same amount of work time. During the shifts, subjects performed two simple, low arousal tasks (beading and packing) and completed a test battery roughly every two hours which was comprised of physiological, performance, neurophysiological and subjective measures. It was found that the inclusion of the nap opportunity significantly improved output performance and response time during a low precision, modified Fitts tapping task over the course of three night shifts, relative to no napping. Physiologically, napping resulted in higher heart rate frequency measures by the end of the shifts, which were also accompanied by significant reductions in subjective sleepiness ratings during all iii the night shifts. The nap group’s responses in this case, did not differ significantly from those of the day shift. Both simple reaction time and memory performances improved as a result of the nap inclusion, but only during the third night shift. The majority of the measures included in the research also depicted the effects of the circadian rhythm, which was indicative of the pronounced effect that this natural biological down regulation has on performance during the night. Napping reduced the severity of these effects during beading performance and measures of subjective sleepiness. With regard to habituation, the nap opportunity also resulted in positive changes in the responses of beading performance, high precision response time, simple reaction time and both subjective sleepiness measures, relative to no napping. Sleep diary responses indicated that although sleep length and quality during the day were significantly reduced for both night-time conditions, recovery sleep (length and quality) for the nap group did not differ significantly from the no nap group. The findings of this research indicate that the inclusion of a flexible napping opportunity during the night shift had positive effects on some physiological, performance and subjective responses, and that this intervention is as beneficial as scheduled napping. Specifically, napping resulted in a significantly higher output during the beading task, relative to the no nap group despite the duration of work time being the same. As such the introduction of a flexible, self-selected nap opportunity is a practical, effective and individual-specific means of alleviating the negative effects of shift work, while improving certain performance parameters. Therefore, industries should consider its inclusion in their fatigue management programs. However, contextspecific considerations must be made, with regard work scheduling, individual differences and task demands when implementing such an intervention. This will ensure that its introduction will be well received and in time, lessen the health and work-related decrements associated with shift work.
- Full Text:
- Date Issued: 2010