A laboratory simulation investigating the impact of sunglass tint on the catching performance of cricket fielders
- Authors: Nellemann, Stacy Amanda
- Date: 2022-04-06
- Subjects: Sunglasses , Cricket Physiological aspects , Cricket players , Glare , Vision , Contrast sensitivity (Vision) , Fielders (Cricket)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291281 , vital:56839
- Description: Background: Sunglasses are popularly worn by outdoor athletes such as cricketers. They are primarily worn to preserve ocular health due to the length of time exposed to the sun’s glare on the field. More recently, sunglasses are now worn for their purported performance-enhancing benefits supposedly allowing athletes to “see clearly, react faster and perform with confidence”. Fielders typically wear sunglasses, but it is rare to see the bowler or the batter wearing sunglasses although they are exposed to the same conditions. If sunglasses provide visual clarity for better reaction time, it is assumed this would also be beneficial for both batsmen and bowlers alike. It is interesting that although fielding plays a key role in the winning of a match, it has received very little research in comparison to the areas of batting and bowling. Research concerning sunglasses in the past has been concerned with its effect on ocular parameters such as colour vision and contrast sensitivity, with minimal research on their effect on performance, specifically on how different colour tints may affect performance such as catching in fielding. Objective: The purpose of this study was to compare the catching performance of fielders when wearing three different colour tints of sunglasses. Methods: Thirty male cricketers currently playing for Rhodes University or country districts sides in Makhanda, South Africa, who were non-habitual sunglass wearers were recruited for this study. An optician administered a pre-screening test to ensure participants did not have any visual defects that would affect the results, determining who was eligible to continue with the research project. Twenty-five participants qualified with a further four withdrawing during the experimentation phase due to personal reasons. Eligible participants were required to complete four testing sessions on separate days thereafter in which they wore a different colour tint at each session (clear, blue, G30 and red). These tints were randomised among participants. Participants were required to catch 18 balls projected from a bowling machine in each session. The number of balls caught as well as the quality of catch was recorded. At the end of the fourth session, participants were presented with a questionnaire investigating their subjective experience of the protocol and preference for any particular colour of lens. Results: Statistically significant results were found between the different colour lenses for the ocular parameters of contrast sensitivity and stereopsis tested by the optician. The red lens was found to be the best for contrast sensitivity with the blue lens performing the worst on this test. With regard to stereopsis, the G30 lens was the worst, with the red lens performing the best. The performance measures resulted in no significant difference between the different colour lenses both concerning the total number of catches taken as well as the quality of catch taken. The same result was found irrespective of the colour of lens used in each session. Data gathered from the questionnaire regarding visual comfort and target visibility resulted in the red lens being rated statistically worse than the other three conditions. In terms of personal preference, the G30 lens was rated statistically as the best coloured lens. Conclusion: It can be concluded that objectively there is no difference in performance between the three coloured lenses. Although from an ocular perspective, the red lens was expected to perform the best in terms of catching performance, there was no difference. Subjectively there was a strong preference among the players for the G30 lens with players strongly disliking the red lens. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Nellemann, Stacy Amanda
- Date: 2022-04-06
- Subjects: Sunglasses , Cricket Physiological aspects , Cricket players , Glare , Vision , Contrast sensitivity (Vision) , Fielders (Cricket)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291281 , vital:56839
- Description: Background: Sunglasses are popularly worn by outdoor athletes such as cricketers. They are primarily worn to preserve ocular health due to the length of time exposed to the sun’s glare on the field. More recently, sunglasses are now worn for their purported performance-enhancing benefits supposedly allowing athletes to “see clearly, react faster and perform with confidence”. Fielders typically wear sunglasses, but it is rare to see the bowler or the batter wearing sunglasses although they are exposed to the same conditions. If sunglasses provide visual clarity for better reaction time, it is assumed this would also be beneficial for both batsmen and bowlers alike. It is interesting that although fielding plays a key role in the winning of a match, it has received very little research in comparison to the areas of batting and bowling. Research concerning sunglasses in the past has been concerned with its effect on ocular parameters such as colour vision and contrast sensitivity, with minimal research on their effect on performance, specifically on how different colour tints may affect performance such as catching in fielding. Objective: The purpose of this study was to compare the catching performance of fielders when wearing three different colour tints of sunglasses. Methods: Thirty male cricketers currently playing for Rhodes University or country districts sides in Makhanda, South Africa, who were non-habitual sunglass wearers were recruited for this study. An optician administered a pre-screening test to ensure participants did not have any visual defects that would affect the results, determining who was eligible to continue with the research project. Twenty-five participants qualified with a further four withdrawing during the experimentation phase due to personal reasons. Eligible participants were required to complete four testing sessions on separate days thereafter in which they wore a different colour tint at each session (clear, blue, G30 and red). These tints were randomised among participants. Participants were required to catch 18 balls projected from a bowling machine in each session. The number of balls caught as well as the quality of catch was recorded. At the end of the fourth session, participants were presented with a questionnaire investigating their subjective experience of the protocol and preference for any particular colour of lens. Results: Statistically significant results were found between the different colour lenses for the ocular parameters of contrast sensitivity and stereopsis tested by the optician. The red lens was found to be the best for contrast sensitivity with the blue lens performing the worst on this test. With regard to stereopsis, the G30 lens was the worst, with the red lens performing the best. The performance measures resulted in no significant difference between the different colour lenses both concerning the total number of catches taken as well as the quality of catch taken. The same result was found irrespective of the colour of lens used in each session. Data gathered from the questionnaire regarding visual comfort and target visibility resulted in the red lens being rated statistically worse than the other three conditions. In terms of personal preference, the G30 lens was rated statistically as the best coloured lens. Conclusion: It can be concluded that objectively there is no difference in performance between the three coloured lenses. Although from an ocular perspective, the red lens was expected to perform the best in terms of catching performance, there was no difference. Subjectively there was a strong preference among the players for the G30 lens with players strongly disliking the red lens. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
Academic or ‘zoombie’? Characterizing sleep quality, work and lifestyle behaviours among a cohort of South African academic staff during the Covid-19 pandemic
- Authors: Le Grange, Sarah-Ann
- Date: 2022-04-06
- Subjects: Sleep-wake cycle South Africa Eastern Cape , Sleep Physiological aspects , Lifestyles Health aspects South Africa Eastern Cape , COVID-19 Pandemic, 2020- Influence , Work environment Psychological aspects , Work environment Physiological aspects , College teachers Workload South Africa Eastern Cape , Pittsburgh Sleep Quality Index (PSQI)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291099 , vital:56818
- Description: Working in academe is characterized by high work demands, long and late working hours and balancing multiple roles. This often leaves academic staff (interchangeably referred to as ‘academics’ and ‘staff’) with limited time to prioritize adequate rest and sleep. While sufficient sleep is important for general well-being and work performance, it may be important for academics given the cognitive and interactive nature of their work. However, limited research has characterized sleep behaviours and sleep quality in academic staff globally and specifically in South Africa (SA). Further, research shows that academics from different academic ranks and genders differ in their work experiences but less is known about whether these factors affect their sleep and lifestyle factors. Over and above the demands of academic work, the current study was conducted during COVID-19, which saw unprecedented change in workloads for academic staff due to online teaching and learning. Additionally, the pandemic has been associated with poorer sleep quality and lifestyle behaviours in the general population, but very few studies have explored this in the context of academics. Thus, this study aimed to characterize the sleep quality, work and lifestyle factors among academics from a university in the Eastern Cape province of SA and determine the effects of gender and academic rank on these measures. Additionally, the study aimed to determine the impact of COVID-19 on sleep and work-related factors of this group. This study adopted a cross-sectional design and made use of an online questionnaire that was distributed to all academics employed at the institution via email. The data collection occurred over an 8-week testing period between August and September of 2020. The questionnaire explored sociodemographic, work and lifestyle characteristics, while the characteristics of sleep and sleep quality were explored with the Pittsburgh Sleep Quality Index (PSQI). Additionally, an open-ended section was included to determine the impact of COVID-19-related changes on sleep and work. The questionnaire responses were analyzed with descriptive and inferential statistics and the open-ended questions were analyzed with thematic analyses. A total of 84 respondents completed the questionnaire. On average, sleep quality was poor (global score of 7.09 ± 3.8), the reported sleep duration was short (6.41 ± 1.06 hrs) and the group was classified as overweight according to median BMI (26.67 [23.8-2 29.45] kg/m2). Over a third (35.71%) of academic staff reported not meeting physical activity guidelines and reported using screens one hour prior to bed every night during the week (76.19%) and the weekend (67.88%). Staff also worked long total weekly work hours (54.25 ± 11). Female academics had a poorer sleep quality (p = 0.035), spent a longer time in bed (p = 0.04), experienced more bad dreams (p = <0.01), had their last serving of alcohol earlier (p = 0.04) and worked less weekday (p = 0.04) and less total weekly (p = 0.02) hours compared to male academics. Professorship-level academics were significantly older than junior- and senior-level academics (p = <0.01) while senior-level academics had a poorer PSQI compared to professorship-level academics (p = 0.03). The thematic analysis showed that home environment, neighbourhood noise, work and mental health were the main emerging factors that disturbed sleep. The thematic analysis showed that, in relation to the impact of COVID19, sleep schedules changed and sleep duration and sleep quality improved or got worse. Respondents reported their work hours increasing, work schedules becoming less routine while working from home, dealing with the challenges of working online and experiencing worry, stress and anxiety due to the pandemic. The study highlights that, in the context of lockdown and having to work and teach online from home, academics reported poor quality sleep and short sleep duration. Further, on average, the sample reported working extensive hours and unhealthy lifestyle behaviours. The sleep health, nature of work and overall lifestyles of academic staff deserves more research attention, given the importance of their work and the impact that inadequate sleep could have on academics’ health and work performance. Sleep quality was worse for females and mid-career academics, suggesting that their sleep quality may be at greater risk than other sub-groups. However, the reasons for these differences need to be explored in future studies. The findings contribute to the narrative that academe involves numerous demands and supports previous research that has suggested that academics’ sleep is insufficient. Furthermore, COVID-19 had an impact on staff’s sleep, with staff reporting changes in their sleep quality and duration. The pandemic impacted work of academics by presenting novel demands related to online teaching, intensifying demands overall and disrupting work routines. However, future research is needed to understand academics’ sleep behaviours, work and lifestyles, especially in South Africa. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Le Grange, Sarah-Ann
- Date: 2022-04-06
- Subjects: Sleep-wake cycle South Africa Eastern Cape , Sleep Physiological aspects , Lifestyles Health aspects South Africa Eastern Cape , COVID-19 Pandemic, 2020- Influence , Work environment Psychological aspects , Work environment Physiological aspects , College teachers Workload South Africa Eastern Cape , Pittsburgh Sleep Quality Index (PSQI)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291099 , vital:56818
- Description: Working in academe is characterized by high work demands, long and late working hours and balancing multiple roles. This often leaves academic staff (interchangeably referred to as ‘academics’ and ‘staff’) with limited time to prioritize adequate rest and sleep. While sufficient sleep is important for general well-being and work performance, it may be important for academics given the cognitive and interactive nature of their work. However, limited research has characterized sleep behaviours and sleep quality in academic staff globally and specifically in South Africa (SA). Further, research shows that academics from different academic ranks and genders differ in their work experiences but less is known about whether these factors affect their sleep and lifestyle factors. Over and above the demands of academic work, the current study was conducted during COVID-19, which saw unprecedented change in workloads for academic staff due to online teaching and learning. Additionally, the pandemic has been associated with poorer sleep quality and lifestyle behaviours in the general population, but very few studies have explored this in the context of academics. Thus, this study aimed to characterize the sleep quality, work and lifestyle factors among academics from a university in the Eastern Cape province of SA and determine the effects of gender and academic rank on these measures. Additionally, the study aimed to determine the impact of COVID-19 on sleep and work-related factors of this group. This study adopted a cross-sectional design and made use of an online questionnaire that was distributed to all academics employed at the institution via email. The data collection occurred over an 8-week testing period between August and September of 2020. The questionnaire explored sociodemographic, work and lifestyle characteristics, while the characteristics of sleep and sleep quality were explored with the Pittsburgh Sleep Quality Index (PSQI). Additionally, an open-ended section was included to determine the impact of COVID-19-related changes on sleep and work. The questionnaire responses were analyzed with descriptive and inferential statistics and the open-ended questions were analyzed with thematic analyses. A total of 84 respondents completed the questionnaire. On average, sleep quality was poor (global score of 7.09 ± 3.8), the reported sleep duration was short (6.41 ± 1.06 hrs) and the group was classified as overweight according to median BMI (26.67 [23.8-2 29.45] kg/m2). Over a third (35.71%) of academic staff reported not meeting physical activity guidelines and reported using screens one hour prior to bed every night during the week (76.19%) and the weekend (67.88%). Staff also worked long total weekly work hours (54.25 ± 11). Female academics had a poorer sleep quality (p = 0.035), spent a longer time in bed (p = 0.04), experienced more bad dreams (p = <0.01), had their last serving of alcohol earlier (p = 0.04) and worked less weekday (p = 0.04) and less total weekly (p = 0.02) hours compared to male academics. Professorship-level academics were significantly older than junior- and senior-level academics (p = <0.01) while senior-level academics had a poorer PSQI compared to professorship-level academics (p = 0.03). The thematic analysis showed that home environment, neighbourhood noise, work and mental health were the main emerging factors that disturbed sleep. The thematic analysis showed that, in relation to the impact of COVID19, sleep schedules changed and sleep duration and sleep quality improved or got worse. Respondents reported their work hours increasing, work schedules becoming less routine while working from home, dealing with the challenges of working online and experiencing worry, stress and anxiety due to the pandemic. The study highlights that, in the context of lockdown and having to work and teach online from home, academics reported poor quality sleep and short sleep duration. Further, on average, the sample reported working extensive hours and unhealthy lifestyle behaviours. The sleep health, nature of work and overall lifestyles of academic staff deserves more research attention, given the importance of their work and the impact that inadequate sleep could have on academics’ health and work performance. Sleep quality was worse for females and mid-career academics, suggesting that their sleep quality may be at greater risk than other sub-groups. However, the reasons for these differences need to be explored in future studies. The findings contribute to the narrative that academe involves numerous demands and supports previous research that has suggested that academics’ sleep is insufficient. Furthermore, COVID-19 had an impact on staff’s sleep, with staff reporting changes in their sleep quality and duration. The pandemic impacted work of academics by presenting novel demands related to online teaching, intensifying demands overall and disrupting work routines. However, future research is needed to understand academics’ sleep behaviours, work and lifestyles, especially in South Africa. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
Adolescents and coaches/trainers perspectives of ergogenic sports supplement use within South African private high schools
- Authors: Butler, Nicholas John
- Date: 2022-04-06
- Subjects: Dietary supplements , Energy metabolism , Teenagers South Africa , Teenagers Physiology South Africa , Teenagers Substance use South Africa , Coaches (Athletics) South Africa , Athletic trainers South Africa , Private schools South Africa , Ergogenic aids
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232443 , vital:49992
- Description: Sports supplements, also referred to as ergogenic aids, are used because of the assertion that they can enhance physical or athletic performance and/or physical appearance. Commonly used sports supplements include creatines, proteins, amino acids, stimulants, and in some cases pro-hormones. There is a relatively high and increasing prevalence of sports supplement use by the general population globally and in South Africa, particularly among adolescents and young adults due to various factors. While some research has explored supplement use among adolescents in a school setting, no study has explored this across the private school system in South Africa. Additionally, given the important role that coaches/trainers play in adolescent development, it is critical to also understand the role that they play regarding adolescent supplement use, given that there has been limited research around this topic in South Africa. Therefore, there were two aims of this study; Firstly, this study explored the prevalence and perceptions (knowledge; attitudes; beliefs) of sports supplements among South African private high school adolescents. Secondly, this study explored the perceptions (knowledge; attitudes; application of knowledge) towards sports supplements among adolescent coaches/trainers in South African private high schools. Considering the dual aim of this study, this thesis was structured as a two-part research study. Both parts took the form of a cross-sectional design, using an online questionnaire to collect qualitative and quantitative data. In total, a cohort of n=50 adolescents and n=49 coaches/trainers participated. Adolescent participants reported a high prevalence of sports supplement use (62%) with their main reasons for using them being recovery and performance. Adolescents were primarily influenced/advised by friends and coaches/trainers to start using sports supplements. Coaches/trainers primarily relied on other coaches/trainers and internet advertising/sites as a main source of information. Less than half of the participants from both groups reported having any formal education or training related to sports nutrition or sports supplements. Both groups thought that these products are being misused by adolescents, which may account for why a portion of the adolescent participants reported experiencing adverse side-effects from using sports supplements, and a few coach/trainer participants reported witnessing this in their practice. This may be a result of the professionalisation of school sport which places pressure on athletes and their coaches/trainers to perform and may in turn be the reason why some adolescents reported that they would use, and some coaches/trainers reported they would recommend the use of sports supplements even if they were aware of risk/dangers involved. Thus, there is a need for education/training among South African high school adolescents and their coaches/trainers with respect to the use of sports supplements, so that they can make informed decisions from reliable sources of information or advice in order to use these products safely and effectively. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Butler, Nicholas John
- Date: 2022-04-06
- Subjects: Dietary supplements , Energy metabolism , Teenagers South Africa , Teenagers Physiology South Africa , Teenagers Substance use South Africa , Coaches (Athletics) South Africa , Athletic trainers South Africa , Private schools South Africa , Ergogenic aids
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232443 , vital:49992
- Description: Sports supplements, also referred to as ergogenic aids, are used because of the assertion that they can enhance physical or athletic performance and/or physical appearance. Commonly used sports supplements include creatines, proteins, amino acids, stimulants, and in some cases pro-hormones. There is a relatively high and increasing prevalence of sports supplement use by the general population globally and in South Africa, particularly among adolescents and young adults due to various factors. While some research has explored supplement use among adolescents in a school setting, no study has explored this across the private school system in South Africa. Additionally, given the important role that coaches/trainers play in adolescent development, it is critical to also understand the role that they play regarding adolescent supplement use, given that there has been limited research around this topic in South Africa. Therefore, there were two aims of this study; Firstly, this study explored the prevalence and perceptions (knowledge; attitudes; beliefs) of sports supplements among South African private high school adolescents. Secondly, this study explored the perceptions (knowledge; attitudes; application of knowledge) towards sports supplements among adolescent coaches/trainers in South African private high schools. Considering the dual aim of this study, this thesis was structured as a two-part research study. Both parts took the form of a cross-sectional design, using an online questionnaire to collect qualitative and quantitative data. In total, a cohort of n=50 adolescents and n=49 coaches/trainers participated. Adolescent participants reported a high prevalence of sports supplement use (62%) with their main reasons for using them being recovery and performance. Adolescents were primarily influenced/advised by friends and coaches/trainers to start using sports supplements. Coaches/trainers primarily relied on other coaches/trainers and internet advertising/sites as a main source of information. Less than half of the participants from both groups reported having any formal education or training related to sports nutrition or sports supplements. Both groups thought that these products are being misused by adolescents, which may account for why a portion of the adolescent participants reported experiencing adverse side-effects from using sports supplements, and a few coach/trainer participants reported witnessing this in their practice. This may be a result of the professionalisation of school sport which places pressure on athletes and their coaches/trainers to perform and may in turn be the reason why some adolescents reported that they would use, and some coaches/trainers reported they would recommend the use of sports supplements even if they were aware of risk/dangers involved. Thus, there is a need for education/training among South African high school adolescents and their coaches/trainers with respect to the use of sports supplements, so that they can make informed decisions from reliable sources of information or advice in order to use these products safely and effectively. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
An investigation into the force-EMG relationship for static and dynamic exertions
- Koekemoer, Wesley Agosthinho
- Authors: Koekemoer, Wesley Agosthinho
- Date: 2022-04-06
- Subjects: Electromyography , Force and energy , Muscles Physiology , Biomechanics , Muscle contraction , Isometric exercise , Isotonic exercise , Static and dynamic exertions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291076 , vital:56816
- Description: The force-EMG relationship has multiple applications in varying fields of study and practice. One such application is the development of safety guidelines and regulations. Current guidelines are based on static muscle actions even though the majority of tasks encountered in industry are dynamic in nature. This may have negative implications for the health, safety, and productivity of workers as regulations based on static muscle actions may place higher force demands on manual labourers compared to what would be expected if regulations were based on dynamic muscle actions. Regulations based on dynamic muscle actions may be more effective in worker safety as the nature of the regulation matches that of the demand. Few studies have investigated the force-EMG relationship during dynamic muscle actions and the few that do exist have reported contradictory / mixed results. Therefore, the purpose of this study was to: 1) gain an understanding of EMG responses at different load levels, and 2) show how the relationship differs between static and dynamic muscle actions. A two-factorial repeated-measures experiment was developed for this study. Eighteen experimental conditions, utilizing six load levels (0%, 20%, 40%, 60%, 80%, and 100% of maximum voluntary force) for each of the three muscle actions (isometric, concentric and eccentric). Surface EMG responses were obtained under these conditions by repeatedly dorsiflexing and plantarflexing the foot, thus activating the soleus muscle. A maximum voluntary exertion on an isokinetic dynamometer determined the maximum force level, based on which the sub-maximal loads were calculated and added to a pulley system. 31 student participants were recruited for this experiment which was conducted over two sessions – one information and habituation session, and one experimental session. The EMG data recorded were processed and checked for normality and outliers. The data was then analysed via a General Linear Model analysis to determine the effect of exertion type and of load level on the muscle activity. Significant differences were identified at p<0.05 and followed by a Tukey post-hoc test. Correlation analyses were also conducted to determine the relationship between the force and EMG at all three exertion types. All dependent measures showed that as the load level increased so did the sEMG amplitude for all muscle actions. Muscle actions differed significantly between majority of six force levels. Correlations between the load levels and sEMG amplitude for each muscle action indicated a significant correlation with a moderate strength. The conclusion draws from this study that there is a positive correlation between force and sEMG amplitude, at all load levels, with a moderate strength. However, the muscle actions differed significantly from each other. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Koekemoer, Wesley Agosthinho
- Date: 2022-04-06
- Subjects: Electromyography , Force and energy , Muscles Physiology , Biomechanics , Muscle contraction , Isometric exercise , Isotonic exercise , Static and dynamic exertions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291076 , vital:56816
- Description: The force-EMG relationship has multiple applications in varying fields of study and practice. One such application is the development of safety guidelines and regulations. Current guidelines are based on static muscle actions even though the majority of tasks encountered in industry are dynamic in nature. This may have negative implications for the health, safety, and productivity of workers as regulations based on static muscle actions may place higher force demands on manual labourers compared to what would be expected if regulations were based on dynamic muscle actions. Regulations based on dynamic muscle actions may be more effective in worker safety as the nature of the regulation matches that of the demand. Few studies have investigated the force-EMG relationship during dynamic muscle actions and the few that do exist have reported contradictory / mixed results. Therefore, the purpose of this study was to: 1) gain an understanding of EMG responses at different load levels, and 2) show how the relationship differs between static and dynamic muscle actions. A two-factorial repeated-measures experiment was developed for this study. Eighteen experimental conditions, utilizing six load levels (0%, 20%, 40%, 60%, 80%, and 100% of maximum voluntary force) for each of the three muscle actions (isometric, concentric and eccentric). Surface EMG responses were obtained under these conditions by repeatedly dorsiflexing and plantarflexing the foot, thus activating the soleus muscle. A maximum voluntary exertion on an isokinetic dynamometer determined the maximum force level, based on which the sub-maximal loads were calculated and added to a pulley system. 31 student participants were recruited for this experiment which was conducted over two sessions – one information and habituation session, and one experimental session. The EMG data recorded were processed and checked for normality and outliers. The data was then analysed via a General Linear Model analysis to determine the effect of exertion type and of load level on the muscle activity. Significant differences were identified at p<0.05 and followed by a Tukey post-hoc test. Correlation analyses were also conducted to determine the relationship between the force and EMG at all three exertion types. All dependent measures showed that as the load level increased so did the sEMG amplitude for all muscle actions. Muscle actions differed significantly between majority of six force levels. Correlations between the load levels and sEMG amplitude for each muscle action indicated a significant correlation with a moderate strength. The conclusion draws from this study that there is a positive correlation between force and sEMG amplitude, at all load levels, with a moderate strength. However, the muscle actions differed significantly from each other. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
Potential running related injury contributors in South African long-distance runners
- Authors: Jäger, Chloë Rose Laubscher
- Date: 2022-04-06
- Subjects: Running injuries South Africa , Long-distance running South Africa , Running Physiological aspects , Running shoes , Biomechanics , Chi-square test , Fisher exact test
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290943 , vital:56801
- Description: Running related injuries (RRIs) are a common problem among long-distance runners, with injury rates ranging from 19.4% to 79.3%. Many studies have been done, investigating possible contributors to RRIs however, very few studies have investigated RRIs in South African long-distance runners, a population which may differ from previously studied populations. The current study aimed to build a descriptive profile of South African long-distance runners, as well as to determine associated factors that may contribute to RRIs. In order to do this, a cross-sectional, retrospective study design was employed using a questionnaire which was mostly electronically distributed. The sample consisted of 378 long-distance runners from each province in South Africa (SA). Using the Chi-square analysis and Fisher exact tests, significant associations were established (p<0.05). The current study found that certain RRI variables were associated with specific aspects of the participants’ personal characteristics and demographics, training characteristics, running experience, footwear, and cross training activities. Footwear and training characteristics produced the largest number of significant RRI associations. The findings of the current study could assist future research on RRIs in South African long-distance runners, by informing researchers of potential areas where more in-depth research is needed. In the long term, researchers may be able to narrow down the main contributors to RRI, possibly decreasing RRI rates in the unique population of South African long-distance runners. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Jäger, Chloë Rose Laubscher
- Date: 2022-04-06
- Subjects: Running injuries South Africa , Long-distance running South Africa , Running Physiological aspects , Running shoes , Biomechanics , Chi-square test , Fisher exact test
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290943 , vital:56801
- Description: Running related injuries (RRIs) are a common problem among long-distance runners, with injury rates ranging from 19.4% to 79.3%. Many studies have been done, investigating possible contributors to RRIs however, very few studies have investigated RRIs in South African long-distance runners, a population which may differ from previously studied populations. The current study aimed to build a descriptive profile of South African long-distance runners, as well as to determine associated factors that may contribute to RRIs. In order to do this, a cross-sectional, retrospective study design was employed using a questionnaire which was mostly electronically distributed. The sample consisted of 378 long-distance runners from each province in South Africa (SA). Using the Chi-square analysis and Fisher exact tests, significant associations were established (p<0.05). The current study found that certain RRI variables were associated with specific aspects of the participants’ personal characteristics and demographics, training characteristics, running experience, footwear, and cross training activities. Footwear and training characteristics produced the largest number of significant RRI associations. The findings of the current study could assist future research on RRIs in South African long-distance runners, by informing researchers of potential areas where more in-depth research is needed. In the long term, researchers may be able to narrow down the main contributors to RRI, possibly decreasing RRI rates in the unique population of South African long-distance runners. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
- Full Text:
- Date Issued: 2022-04-06
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