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Ramadan fasting and exercise performance
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Type
Thesis
Author
Abdul Rashid Aziz
Supervisor
Chia, Michael
Abstract
The observance of Ramadan fasting is a compulsory religious act of faith that all healthy adult individuals of the Islamic faith must go through annually. During Ramadan fast, the Muslim individual refrains from consuming food and fluid throughout the daylight hours, on a daily basis for between 29 to 30 days. Muslim athletes, except those who are sick or frail, are not exempted from this religious obligation, and they may need to train and compete during this period. Physical exertion during Ramadan is obviously challenging for these athletes. The literature on the impact of Ramadan fasting on exercise performance is unclear and requires further clarification. This is because many studies were fraught with methodological problems because of the inability to control for several factors such as dietary intake, sleep hours and training load.
This dissertation consists of eight chapters where the primary aim is to add to the body of literature examining the influence of Ramadan fasting on various aspects of exercise performance under ecologically valid conditions whilst concurrently controlling for the confounding factors of pre-exercise food and fluid intake, sleep hours and training load; factors that were not well accounted for in previous Ramadan research.
Chapter 1 provides the general background of Ramadan fasting, its importance, purpose and the cultural, social and sporting behaviours and/or patterns associated with the observance of the Ramadan fast.
Chapter 2 is a tabulated and narrative summary of the current literature on the effects of Ramadan fasting on various aspects of exercise and sporting performances. The limitations of previous studies and the postulated factors that have contributed to the adverse impact of Ramadan fasting on exercise performances were also discussed. The chapter conveys that the effects of Ramadan fasting on the ATP-PCr fuelled exercise performances and strength capabilities measures remain unsubstantiated. The effects of Ramadan fasting on cognitive functions and motor skills are unequivocal. The negative effects of Ramadan fasting on anaerobic glycolytic and aerobic exercise performance are however well-documented.
Few Ramadan studies have included sports-specific activities, in particular in team-sports events. This is because the “start-and-stop” nature of the intermittent game and the fluctuating intensity of the match as a result of team tactics or the players delibrate pacing may perhaps, makes it difficult to detect the influence of Ramadan fasting on physical performance. Chapter 3 describes the first study of the thesis (i.e., Study 1) which examined the effect of Ramadan fasting on physical performance during a 90-minute competitive football match using the global positioning system technology, in trained Muslim footballers. Players’ pre-exercise meal was standardized, sleep hours were self-reported and training load was recorded. Total distance covered was significantly lower in the Ramadan fasted compared to playing in the non-fasted state. Similarly, other match performances such as distance ran in the high-intensity zone and high-velocity accelerations were markedly lowered in the fasted state, and interestingly, these were already noticeable during the first-half of the match. A notable finding in Study 1 was that players’ work-rate was significantly reduced in the Ramadan compared to the Control match, which was observed as early as during the first 15-minute of match play. Limitations of Study 1 such as lower training load were also foregrounded.
Chapter 4 describes Study 2, which developed from the findings of Study 1. Compared to Study 1, players were provided with pre-prepared food and fluid sufficient for the 24-hour period prior to all experimental trials. Players’ sleep hours were objectively measured with a motion-detector sleep watch and training was controlled by the coach to ensure consistency throughout the period of investigation. Study 2 describes the effect of Ramadan fasting on sprint performance throughout a 60-minute modified Loughborough Intermittent Shuttle Test (mLIST). The mLIST is an intermittent exercise protocol which resembles a football match play movement of running, jogging and striding at various specific velocities, except for the 15-metre sprints where the players exerted themselves maximally. In addition, three maximal muscular exertion tests of isometric single-leg knee extension, countermovement jump (exercised muscles) and hand-grip (non-exercise muscle) were undertaken at 15-minute intervals to provide an indication of the player’s central or peripheral associated pathways of fatigue during the 60-minute exercise. The results indicated that sprinting performance, as a marker of intermittent performance ability, was reduced throughout exercise in Ramadan compared to the sprinting performance in the non-Ramadan state. As in Study 1, the players’ sprint performance decrements were also observed during the initial 15 minutes the exercise in Study 2. This observation of early decrement in physical performance or “early onset of fatigue” was reasoned not to be due to limitations attributed to peripheral (i.e., metabolic and substrate) factors. This view was supported by the lack of significant differences between the Ramadan and non-Ramadan trials for the single-leg knee extension and countermovement jump tests taken throughout the 60-minute exercise. Also, central fatigue pathways did not appear be a major contributing factor to the poorer sprint performances in Ramadan since the hand-grip test indicated no decrement throughout exercise in Ramadan.
No study has apparently examined the effects of Ramadan on motor skills performance during a match play. Chapter 5 describes Study 3, which determined the impact of Ramadan fasting on the accuracy and power performance of the low-serve and smash during a 40-minute simulated badminton singles match, among well-trained male Muslim players from the National men’s squad. The aim was to determine if Ramadan fasting has an effect on sport-specific skills when performed after experiencing a degree of physical fatigue in an ecologically valid sporting situation. Performance accuracy during the low-serve and smash were not affected, but during the smash, the velocity of the shuttlecock was significantly lower during the Ramadan trial compared to the non-Ramadan trial. It was concluded that in Ramadan, fasted athletes compromise their power-generating capabilities for accuracy when executing a complex motor skill, although it is not known whether this was a deliberate or unconscious action on the part of the fasted athletes.
Chapter 6 describes the last study of the thesis, i.e., Study 4, which involved well-trained National senior athletes from the sport of pencak-silat, to examine the impact of Ramadan fasting on maximal strength and dynamic power. Relative to previous research, the strength and power measures in Study 4 were performed using multi-joint exercises (isometric mid-thigh pull and loaded squat jump exercises for the lower body and isometric bench push and loaded bench throw exercises for the upper body) that resemble dynamic sporting movements, and the tests were conducted on a force plate and with a linear force transducer. This provided a more sensitive assessment of force characteristics (such as peak force, average force, maximum rate of force development, and height jumped or bar travelled). Findings from Study 4 showed that Ramadan fasting has no impact on maximal strength and dynamic power measures in well-trained athletes.
Chapter 7 describes the summative findings of all four studies. Seminal findings are that Ramadan fasting had an adverse impact on i) physical performance during a 90-minute football match play (Study 1), ii) sprint performance during a 60-minute of intermittent endurance exercise (Study 2), and iii) power-generating capabilities during the execution of the badminton smash (Study 3). Ramadan however, had no effect on strength and power attributes in trained athletes (Study 4). Despite controlling for all the three confounding factors of dietary intake, sleep and training load, Studies 1 to 3 provided compelling evidence on the adverse influence of Ramadan fasting on physical performance and skill execution of fasted athletes, in particular during sustained maximal efforts within an endurance-based exercise challenge. Results show that Ramadan fasting does not affect isolated, and single maximal exertion of muscles (as evidenced from the three muscular tests in Study 3 and from the maximal strength and high-powered tests in Study 4). Given that blood markers such as blood lactate and blood glucose concentration levels were not affected during exercise (which indirectly indicate sufficient availability of endogenous substrates) and that physical performance was affected as early as within the first 15-min of exercise (Studies 1 and 2) where exercise-induced fatigue due to metabolic- and central-associated pathways were likely non-limiting, it appears that there is a placebo (or aptly nocebo) effect of Ramadan fasting on exercise performance. The minimal impact of Ramadan fasting in Studies 3 and 4 relative to Studies 1 and 2 also suggest that relatively well-trained athletes were less affected by the perturbations of Ramadan fasting. However, the hot and humid conditions (in Studies 1 and 2) could also play a part in exacerbating the impact of Ramadan fast on exercise performance.
The last chapter of this thesis (Chapter 8), describes the key challenges when conducting the four studies such as the lack of a non-fasting control group, controlling for various confounding factors, and the applicability of the findings of the four studies. Practical implications and/or recommendations are also discussed. Future research, employing the use of non-invasive technology to investigate exercise performance during Ramadan was proposed. It is hoped that this thesis will provide an impetus for future Ramadan studies seeking to explain the mechanisms that underpin the adverse effects of Ramadan fasting on exercise performance and find ways to circumvent or attenuate the impact of Ramadan fasting during exercise.
This dissertation consists of eight chapters where the primary aim is to add to the body of literature examining the influence of Ramadan fasting on various aspects of exercise performance under ecologically valid conditions whilst concurrently controlling for the confounding factors of pre-exercise food and fluid intake, sleep hours and training load; factors that were not well accounted for in previous Ramadan research.
Chapter 1 provides the general background of Ramadan fasting, its importance, purpose and the cultural, social and sporting behaviours and/or patterns associated with the observance of the Ramadan fast.
Chapter 2 is a tabulated and narrative summary of the current literature on the effects of Ramadan fasting on various aspects of exercise and sporting performances. The limitations of previous studies and the postulated factors that have contributed to the adverse impact of Ramadan fasting on exercise performances were also discussed. The chapter conveys that the effects of Ramadan fasting on the ATP-PCr fuelled exercise performances and strength capabilities measures remain unsubstantiated. The effects of Ramadan fasting on cognitive functions and motor skills are unequivocal. The negative effects of Ramadan fasting on anaerobic glycolytic and aerobic exercise performance are however well-documented.
Few Ramadan studies have included sports-specific activities, in particular in team-sports events. This is because the “start-and-stop” nature of the intermittent game and the fluctuating intensity of the match as a result of team tactics or the players delibrate pacing may perhaps, makes it difficult to detect the influence of Ramadan fasting on physical performance. Chapter 3 describes the first study of the thesis (i.e., Study 1) which examined the effect of Ramadan fasting on physical performance during a 90-minute competitive football match using the global positioning system technology, in trained Muslim footballers. Players’ pre-exercise meal was standardized, sleep hours were self-reported and training load was recorded. Total distance covered was significantly lower in the Ramadan fasted compared to playing in the non-fasted state. Similarly, other match performances such as distance ran in the high-intensity zone and high-velocity accelerations were markedly lowered in the fasted state, and interestingly, these were already noticeable during the first-half of the match. A notable finding in Study 1 was that players’ work-rate was significantly reduced in the Ramadan compared to the Control match, which was observed as early as during the first 15-minute of match play. Limitations of Study 1 such as lower training load were also foregrounded.
Chapter 4 describes Study 2, which developed from the findings of Study 1. Compared to Study 1, players were provided with pre-prepared food and fluid sufficient for the 24-hour period prior to all experimental trials. Players’ sleep hours were objectively measured with a motion-detector sleep watch and training was controlled by the coach to ensure consistency throughout the period of investigation. Study 2 describes the effect of Ramadan fasting on sprint performance throughout a 60-minute modified Loughborough Intermittent Shuttle Test (mLIST). The mLIST is an intermittent exercise protocol which resembles a football match play movement of running, jogging and striding at various specific velocities, except for the 15-metre sprints where the players exerted themselves maximally. In addition, three maximal muscular exertion tests of isometric single-leg knee extension, countermovement jump (exercised muscles) and hand-grip (non-exercise muscle) were undertaken at 15-minute intervals to provide an indication of the player’s central or peripheral associated pathways of fatigue during the 60-minute exercise. The results indicated that sprinting performance, as a marker of intermittent performance ability, was reduced throughout exercise in Ramadan compared to the sprinting performance in the non-Ramadan state. As in Study 1, the players’ sprint performance decrements were also observed during the initial 15 minutes the exercise in Study 2. This observation of early decrement in physical performance or “early onset of fatigue” was reasoned not to be due to limitations attributed to peripheral (i.e., metabolic and substrate) factors. This view was supported by the lack of significant differences between the Ramadan and non-Ramadan trials for the single-leg knee extension and countermovement jump tests taken throughout the 60-minute exercise. Also, central fatigue pathways did not appear be a major contributing factor to the poorer sprint performances in Ramadan since the hand-grip test indicated no decrement throughout exercise in Ramadan.
No study has apparently examined the effects of Ramadan on motor skills performance during a match play. Chapter 5 describes Study 3, which determined the impact of Ramadan fasting on the accuracy and power performance of the low-serve and smash during a 40-minute simulated badminton singles match, among well-trained male Muslim players from the National men’s squad. The aim was to determine if Ramadan fasting has an effect on sport-specific skills when performed after experiencing a degree of physical fatigue in an ecologically valid sporting situation. Performance accuracy during the low-serve and smash were not affected, but during the smash, the velocity of the shuttlecock was significantly lower during the Ramadan trial compared to the non-Ramadan trial. It was concluded that in Ramadan, fasted athletes compromise their power-generating capabilities for accuracy when executing a complex motor skill, although it is not known whether this was a deliberate or unconscious action on the part of the fasted athletes.
Chapter 6 describes the last study of the thesis, i.e., Study 4, which involved well-trained National senior athletes from the sport of pencak-silat, to examine the impact of Ramadan fasting on maximal strength and dynamic power. Relative to previous research, the strength and power measures in Study 4 were performed using multi-joint exercises (isometric mid-thigh pull and loaded squat jump exercises for the lower body and isometric bench push and loaded bench throw exercises for the upper body) that resemble dynamic sporting movements, and the tests were conducted on a force plate and with a linear force transducer. This provided a more sensitive assessment of force characteristics (such as peak force, average force, maximum rate of force development, and height jumped or bar travelled). Findings from Study 4 showed that Ramadan fasting has no impact on maximal strength and dynamic power measures in well-trained athletes.
Chapter 7 describes the summative findings of all four studies. Seminal findings are that Ramadan fasting had an adverse impact on i) physical performance during a 90-minute football match play (Study 1), ii) sprint performance during a 60-minute of intermittent endurance exercise (Study 2), and iii) power-generating capabilities during the execution of the badminton smash (Study 3). Ramadan however, had no effect on strength and power attributes in trained athletes (Study 4). Despite controlling for all the three confounding factors of dietary intake, sleep and training load, Studies 1 to 3 provided compelling evidence on the adverse influence of Ramadan fasting on physical performance and skill execution of fasted athletes, in particular during sustained maximal efforts within an endurance-based exercise challenge. Results show that Ramadan fasting does not affect isolated, and single maximal exertion of muscles (as evidenced from the three muscular tests in Study 3 and from the maximal strength and high-powered tests in Study 4). Given that blood markers such as blood lactate and blood glucose concentration levels were not affected during exercise (which indirectly indicate sufficient availability of endogenous substrates) and that physical performance was affected as early as within the first 15-min of exercise (Studies 1 and 2) where exercise-induced fatigue due to metabolic- and central-associated pathways were likely non-limiting, it appears that there is a placebo (or aptly nocebo) effect of Ramadan fasting on exercise performance. The minimal impact of Ramadan fasting in Studies 3 and 4 relative to Studies 1 and 2 also suggest that relatively well-trained athletes were less affected by the perturbations of Ramadan fasting. However, the hot and humid conditions (in Studies 1 and 2) could also play a part in exacerbating the impact of Ramadan fast on exercise performance.
The last chapter of this thesis (Chapter 8), describes the key challenges when conducting the four studies such as the lack of a non-fasting control group, controlling for various confounding factors, and the applicability of the findings of the four studies. Practical implications and/or recommendations are also discussed. Future research, employing the use of non-invasive technology to investigate exercise performance during Ramadan was proposed. It is hoped that this thesis will provide an impetus for future Ramadan studies seeking to explain the mechanisms that underpin the adverse effects of Ramadan fasting on exercise performance and find ways to circumvent or attenuate the impact of Ramadan fasting during exercise.
Date Issued
2016
Call Number
GV706.42 Abd
Date Submitted
2016