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Hydration and performance during Ramadan
Journal of Sports Sciences
Abstract
In the absence of any food or fluid intake during the hours of daylight during the month of Ramadan, a progressive loss of body water will occur over the course of each day, though these losses can be completely replaced each night. Large body water deficits will impair both physical and cognitive performance. The point at which water loss will begin to affect performance is not well defined, but it may be as little as 1-2% of body mass. For resting individuals in a temperate environment, the water loss that occurs during a day without food or fluid will typically amount to about 1% of body mass by the time of sunset. This small loss of body water is unlikely to have a major adverse effect on any aspect of physical or cognitive performance. Larger body water losses will occur, however, in hot weather or if exercise is undertaken. Performance in events lasting about 1 hour or longer may be impaired in the absence of fluid intake during the event. In weight-category sports, there may be difficulties due to the impossibility of restoring body water content between the weigh-in and competition, and athletes will require alternative strategies. Where more than one competition or training session takes place in a single day and where substantial fluid losses are incurred, recovery will be impaired by the absence of fluid intake.
... The effects of the Ramadan fast on body composition and hydration can be highly variable depending on environmental factors, the subject's level of exertion, and replenishment of fluids and energy each day [21,22]. Because of the wide variation in fasting conditions, the intermittent hypohydration occurring before the fast is broken each day and the possible chronic dehydration that could occur over the month of fasting are difficult to discuss in general [21]. ...
... Athletes have been a common population for studies of hydration during Ramadan [22,[26][27][28][29]. These studies use body mass, urine concentration, and blood biomarkers to estimate changes in hydration relevant to athletic performance. ...
... It is estimated that fasting individuals experience 800 mL of net total body water loss over 12 h [22]. These losses include daily respiratory water loss, evaporation through the skin, amounts voided through urine and feces, and considers the amount produced in the body through metabolic processes. ...
Hydration is an important aspect of human health, as water is a critical nutrient used in many physiological processes. However, there is currently no clinical gold standard for non-invasively assessing hydration status. Recent work has suggested that permittivity in the microwave frequency range provides a physiologically meaningful metric for hydration monitoring. Using a simple time of flight technique for estimating permittivity, this study investigates microwave-based hydration assessment using a population of volunteers fasting during Ramadan. Volunteers are measured throughout the day while fasting during Ramadan and while not fasting after Ramadan. Comparing the estimated changes in permittivity to changes in weight and the time s fails to establish a clear relationship between permittivity and hydration. Assessing the subtle changes in hydration found in a population of sedentary, healthy adults proves difficult and more work is required to determine approaches suitable for tracking subtle changes in hydration over time with microwave-based hydration assessment techniques.
... Some competitions and events and even training programs engage the players in sessions of more than 1 h and during RIF the dehydration could lead to decrease the performance and makes the recovery slow [9]. The dehydration in players is a possible risk factor for the decreased concentration ability, increased heart rate, increased perception of fatigue and reduced alertness [10,11]. ...
... The increased participation of Muslim athletes in international sporting events has led to a growing body of research exploring how fasting impacts competitive performance. Elite-level competitions such as the Olympics and FIFA World Cup often do not adjust their schedules to accommodate religious fasting, requiring athletes to adapt their training and nutrition strategies accordingly [9]. ...
... And at least 8000 steps/day can be equated to 20 min of moderate activity [26]. The intermittent fasting schedule during Ramadan poses a challenge in performing vigorous forms of physical activity because of the lack of immediate external energy supply in a fasting state, inability to refuel, inability to hydrate while fasting [27] Individuals can utilize non-daylight hours for physical activity but the hours after sundown often involve a busy schedule in which all day-to-day activities are planned. This scenario is specifically applicable individual living in Muslim majority countries where businesses typically remain open till midnight. ...
... Lack of available time in evening after iftar or late night is a potential factor having led to this observed lower step count. During fasting state it is not recommended to peform vigorous intensity physical activity, because body energy stores are at a lowest after 13-14 h of fasting and there is no opportunity to drink water and therefore a risk of dehydration [27], especially in hot and humid locations. Naturally, duration of physical activity during daytime time will be shorter if vigorous intensity activity is invovled. ...
Background
Muslims around the world practice intermittent fasting during the month of Ramadan each year. We hypothesized that daily physical activity could be reduced among Muslims due to the inability to refuel and rehydrate in the fasting state.
Methods
A cohort study design among adults registered with national physical activity community program. Data from a pedometer-based community program was used to extract 3 months of daily step counts before, during, and after Ramadan for the past years (2013–2019). A survey was conducted among participants to determine fasting practice and other health and environmental factors.
Results
A total of 209 participants completed the survey and provided valid data on physical activity. During Ramadan, the average steps per day decreased significantly (− 385 ± SE 158) among participants who fasted (n = 151) p = 0.046 and increased (+ 731 ± SE 247) for the non- fasting participants (n = 58) p = 0.010. Fasting participants preferred before sunset (33.8%) or evening (39.7%) for physical activity. Whereas, non-fasting participants preferred early morning (34.5%).
Conclusion
Fasting during Ramadan impacts the daily physical activity behavior among Muslims. Interventions should focus on creating awareness of the importance of maintenance of adequate physical activity for adults fasting during Ramadan.
... In other words, warmer weather, which arguably causes more dehydration during Ramadan, does not lead to more accidents. This evidence is also consistent with the medical literature, which shows that the levels of dehydration observed during Ramadan fasting are not associated with major changes in physical and cognitive functions (Maughan and Shirreffs, 2012). Therefore, I conclude that hunger is the main factor behind fasting's causal effect on driving ability. ...
... For instance, it is shown that decline in caloric intake and blood glucose from deprivation from food while fasting can impair cognitive function (Waterhouse, 2010;Iraki et al., 1997). In contrast, levels of dehydration found in Ramadan fasting are "unlikely to have a major adverse effect on any aspect of physical or cognitive performance" (Maughan and Shirreffs, 2012). Therefore, one can conclude that hunger induced by fasting is causing the increase in accidents I document. ...
I study the impact of hunger on traffic accidents by exploiting the fasting that is religiously mandated during the month of Ramadan. Identification comes from working hours not being adjusted during Ra-madan in Turkey. I find that driving while fasting at rush hour is associated with a significant increase in road traffic accidents. Using existing survey evidence on fasting rates in Turkey, I conclude that hunger induced by fasting increases the probability of an accident by 25%, which is smaller than the effect of driving while intoxicated, but larger than the effect of mild sleep deprivation. JEL Classification: I18, R41, Z12.
... They could find no significant difference between children's IQ of fasting mothers and non-fasting ones. 16 Maughan et al. 17 studied hydration in athletes in Ramadan, and learnt that loss of 1- Two groups had no significant difference in short memory and inhibition. After Ramadan interference index showed a significant decline. ...
... Yet, this amount can never damage cognitive activity in an individual, unless increased water loss occurs due to extreme heat or activity. 17 In two other studies, cognitive changes were tested in different hours of a day in Ramadan. Tian et al. 18 conducted a study on 18 Muslim athletes, and examined verbal processing, verbal learning, working memory, visual memory, visual learning, visual attention, and memory speed before and after Ramadan at 9 am and 4 pm. ...
A considerable population of the Muslim community is made up of youngsters who observe fast during the month of Ramadan. There are other activities in Ramadan that the adolescents might be involved in, such as education in which one's proper cognitive activity is necessary. The current systematic review was planned to evaluate the relationship between Islamic fasting and cognitive activities. A number of studies have paid attention to the brain structure and scope of cognitive changes during fasting. Islamic fasting may affect cognitive activities such as spatial memory, visual memory and attention that play an important role in effective education. It is suggested to conduct a study with a larger sample size, using similar evaluation tools, targeting different cognitive tasks.
... Other signs of hypohydration have included a reduction in urine volume, sodium, potassium, and total solute excretion and an increase in urinary osmolality [46,47]. Other studies have shown a decrease in body mass during Ramadan [45], attributable to acute dehydration and/or decreases in fat-free mass, both being detrimental to performance [48]. ...
... The point at which water loss begins to affect performance is not well defined; but some investigators have suggested that the critical depletion may be as little as 1-2% of body mass [48]. Hypohydration limits strength, power, and high-intensity endurance and has adverse effects on neuromuscular function and short-term power [49]. ...
Judo is a weight-classified combat sport, and many athletes seek to compete at the lightest possible weight category to gain advantage from competing against shorter/smaller, and supposedly weaker opponents. To achieve a desired weight, most judokas opt for rapid weight loss techniques. Short-duration maximal efforts are not greatly affected by “making weight”, but prolonged and/or repeated exercise is significantly impaired. Negative effects on mood, ratings of perceived exertion, and cognitive function are also reported. Moreover, rapid weight loss reduces maximal cardiac output and glycogen stores, and impairs thermo-regulation. Limited empirical data suggest that Ramadan reduces judokas’ performance, and this is likely to be exacerbated by attempts at rapid weight loss. Weight reduction during Ramadan tend to be counter-productive, and judokas who aim for a lower weight category are advised to attempt any desired reduction of body mass during the weeks leading up to Ramadan, rather than during the holy month.
... However, the point at which the components of performance are affected is not well established (Maughan 2010). Although in Muslim countries some competitions and sporting events take place after sunset during Ramadan, this solution is not applicable in non-Muslim countries or in international events where timetables are dictated by television schedules, and where the majority of athletes are non-Muslim (Maughan & Shirreffs 2012). ...
... Therefore, dehydrated athletes may show impairments in both physical and cognitive performance. The point at which water loss will begin to affect performance is not well defined, but it may be as little as 1-2% of body mass (Maughan & Shirreffs 2012). In this regard, hypohydration (i.e. ...
Muslim athletes observe the Ramadan intermittent fast (RIF) while training and/or competition are often maintained during this period. In combat sports, where contestants compete in different weight categories, some athletes often undertake a prescribed acute weight loss over 4–5 days prior to competition. On the day of competition, they normally restore the body water content lost during the pre-competition period between the weigh-in and the start of the matches. However, this is not possible for those who observe the RIF. Body water and energy decrements are exacerbated when Muslim combat sport athletes have to compete in the morning and afternoon during the same day when a competition is scheduled during Ramadan. This article focuses on the several challenges faced by Muslim combat sport athletes, especially those who undergo a rapid weight loss before a major competition during Ramadan. Suggestions that could limit the difficulties encountered by these athletes during the fasting month are presented.
... This period causes significant changes in daily life management and subsequent chronobiological changes (Roky et al., 2004;Waterhouse, 2010). Although glucose homeostasis is maintained until sunset by meals taken before dawn and by liver glycogen stores, fasting during Ramadan is accompanied by dehydration and weight loss at the end of days (Alkandari et al., 2012;Maughan & Shirreffs, 2012). Despite these important changes, the fasting period of Ramadan is generally considered safe, but people with light or severe pathological state are advised not to go against medical recommendations. ...
... retinopathy, glomerulopathy, or severe muscle pain), in which altered hemorheological parameters, including high blood viscosity, are thought to play a significant role (Connes et al., 2008a(Connes et al., , 2008b(Connes et al., , 2013Eichner 2011;Hedreville et al., 2009;Loosemore et al., 2012;Tripette et al., 2007). Because the Ramadan period will occur during summers for the next couple of years in the Northern Hemisphere, which implies high temperatures and long fasting days (which can be extended until 18:00 h per day depending on location; Alkandari et al., 2012;Maughan & Shirreffs, 2012), adequate hydration should be intensively promoted in SCT carriers during the permitted hours to limit the risks for blood hyperviscosity. ...
The goal of the present study was to test whether fasting during the holy period of Ramadan may disturb blood rheology in sickle cell trait (SCT) carriers more than in a group of subjects with normal hemoglobin. Twenty African male students participated in the study: 10 SCT carriers and 10 subjects with normal hemoglobin (CONT). Biochemical parameters (plasma glucose and lipids levels), hematocrit, blood viscosity, and urine specific gravity were measured in the two groups on the 14th day of the Ramadan period (Ramadan condition) and 6 wks after the end of Ramadan (baseline condition). All the measurements were performed twice for each experimental day to measure intraday variation: 8:00 and 18:00 h. Plasma glucose level and lipid profile were not significantly different between the two groups. Although Ramadan did not affect the lipid profile, the plasma glucose concentration was lower during the Ramadan period compared with the baseline condition in the two groups. Hematocrit and urine specific gravity did not differ between the two groups and was greater in the evening than in the morning, independently of the condition. SCT carriers had higher blood viscosity than the CONT group. However, whereas blood viscosity remained unchanged through the day in the CONT group, whatever the condition, SCT carriers were characterized by a large increase of blood viscosity in the evening during the Ramadan period, indicating higher risk for microcirculatory blood flow impairments. Specific medical recommendations are needed for SCT carriers engaged in religious fasting.
... Hence, mutual understanding between players, coaches, and management is critical to prepare the team for training and competition during the fasting month. The updated knowledge needs to be supplied for this football community to nurture a better organisation participating in the competitive match [22,23]. ...
... The contradicting results might also be due to the different individual adaptations to fasting. Nonetheless, Ramadan fasting can lead to athletes starting their exercise in a state of hypohydration [51], which may worsen if exercise is conducted in the later part of the day. ...
It is well-established that appropriate hydration practices are essential in promoting health and optimizing performance and recovery. However, evidence-based hydration guidelines may not be adopted due to cultural differences across countries, such as religious beliefs, traditions, preferences, and beverage availability. Examples of hydration practices influenced by culture include beer consumption after sports in Western countries, consumption of sugarcane juice in India and Ramadan fasting among Muslims. For most cultural hydration practices, there is limited scientific evidence on their effects on rehydration, exercise performance, and recovery. Despite possible benefits of various hydration practices on exercise performance and recovery, they are inconsistent with current evidence-based hydration recommendations. More research on the impacts of cultural hydration differences on physiology, performance, and recovery is warranted to allow evidence-based guidelines and advisories.
Abbreviations: ABV: alcohol by volume, ACSM: American College of Sports Medicine, NATA: National Athletic Trainers’ Association, ROS: reactive oxygen species, TCM: Traditional Chinese Medicine
... However, the frequency of meals usually remains the same in this diet [12]. On the other hand, changes might occur in fluid intake and hydration [13]. For these reasons, changes in body weight may occur during the Ramadan period. ...
Objective:
This study was aimed at evaluating the effect of intermittent fasting of Ramadan on resting energy expenditure (REE), body composition, and nutritional status.
Methods:
The study was conducted on a total of 27 adults (16 females, 11 males) who were fasting (18 h) in the Ramadan month (May 6-June 3) of 2019. REE was measured using the indirect calorimeter. Dietary energy and nutrient intakes were evaluated by 3-day food records in baseline and post-Ramadan. Body composition and some metabolic parameters were analyzed simultaneously with REE measurements. All measurements were performed two times at baseline, and post-Ramadan.
Results:
Body weight (-2.9% vs. -1.4%), body mass index (BMI) (-3.1% vs. -2.1%), fat-free mass (-2.7% vs. -1.4%), and hydration status were decreased in both males and females after the Ramadan fasting (p < 0.05). REEs (kcal/d) of the participants were 1708.1 ± 262.50 kcal/d and 1596.5 ± 302.27 kcal/d at baseline and post-Ramadan, respectively (6.5%) (p < 0.05). This decrease in REE (kcal/d) in females was greater than that in males (-8.1% vs. -4.6%). However, no statistically significant difference was found in sleep duration (h), physical activity levels, dietary energy and nutrient intakes, and blood pressures (mm Hg) of both genders compared to baseline (p > 0.05).
Conclusion:
Intermittent circadian fasting may lead to a decreased energy expenditure and a change in fat-free mass in healthy individuals, and this effect is interpreted as gender-dependent.
... To maintain body fluids homeostasis, it was recommended to consume 1.5times the amount of water lost during training session via sweating (Coyle, 2004). Nevertheless, increasing water intake up to the values cited previously is unlikely to be effective as prompt diuresis will ensue, and the excess water will soon be expelled in the urine (Maughan & Shirreffs, 2012). In this case, void frequency will likely increase during night-time and subjects will sometimes have to wake-up at night to urinate, which may lead to greater sleep disturbance and impairment in sleep quality. ...
The purpose of this systematic review and meta‐analysis is to provide an accurate description of the effect of Ramadan observance on sleep duration, sleep quality, daily nap duration, and daytime sleepiness in athletes and physically active individuals. Five electronic databases (PubMed, Web of Science, Scopus, Wiley, and Taylor and Francis) were used to search for relevant studies conducted with athletes or physically active individuals during Ramadan, published in any language, and available before May 23, 2021. Studies that included assessments of sleep quantity and/or quality, and/or daytime sleepiness, and/or daily naps in athletes and physically active individuals were included. The methodological quality of the studies was assessed using “QualSyst”. Of the 18 papers included in this study (298 participants in total), 14 were of strong quality, two were moderate, and the remaining two were rated as weak. Individuals who continued to train during Ramadan experienced a decrease in sleep duration (number of studies, K = 17, number of participants, N = 289, g = −0.766, 95% confidence interval [CI] −1.199 to −0.333, p = 0.001). Additionally, the global score of the Pittsburgh Sleep Quality Index increased from 4.053 (K = 5, N = 65, 95% CI 3.071–5.034) pre‐Ramadan, to 5.346 (95% CI 4.362–6.333) during Ramadan, indicating a decrease in sleep quality. The duration of daytime naps increased during compared to pre‐Ramadan (K = 2, N = 31, g = 1.020, 95% CI 0.595–1.445, p = 0.000), whereas Epworth Sleepiness Scale scores remained unchanged during versus pre‐Ramadan (K = 3, N = 31, g = 0.190, 95% CI −0.139–0.519, p = 0.257). In conclusion, individuals who continued to train during Ramadan experienced a decrease in sleep duration, impairment of sleep quality, and increase in daytime nap duration, with no change in daytime sleepiness levels.
... In addition, data from the present study extended the previous findings and indicated that low energy intake was not correlated with body weight loss (Nachvak et al., 2019). In agreement with other studies (Maughan & Shirreffs, 2012;Singh et al., 2011), data revealed an increase in TBW from the second week of fasting. This is likely due to the fact that the body tends to balance the amount of water through water retention mechanism by adaptation of the kidneys. ...
This research aimed to assess the effects of Ramadan intermittent fasting (RIF) on different dimensions, namely calorie intake, fullness and hunger sensations, mental health, body weight, waist circumference (WC), quality of sleep, body composition, hydration and nutritional status among female students at the University of Bahrain. A prospective single cohort study was conducted on 20 female students. The measurements were taken before Ramadan as well as the end of each week of Ramadan. From baseline to the end of Ramadan, there was a significant decrease in body weight (−0.779 kg, CI95% −1.287, −0.271), fat mass (FM) (−1.735 kg, CI95% −2.349, −1.122) and WC (−2.158 cm, CI95% −3.902, −0.414). In addition, the Hydragram® showed an increase at week 4 (0.288% CI95% 0.72, 0.504) and nutritional status with Nutrigram® increased during the time (Ptrend <0.001). No changes were detected for anxiety status, hunger and fullness sensations and quality of sleep. The decrease in weight positively affected the loss of FM (r = 0.597), and the increase in the Pittsburgh sleep quality index affected the reduction of FM (r= −0.460). The Ptrend<0.01 for visual analogue scales and WC showed a clear effect of time on these outcomes. The findings of this study suggest potential benefits of RIF on cardiovascular and metabolic health.
... On the other hand, other research among football players suggested that RDF produces significant decrements in perceived and actual performance tests including speed, agility, dribbling speed, endurance [17], aerobic capacity and speed endurance performance [18]. Maughan & Shirreffs concluded that the dehydration associated with RDF could impair performance and recovery in competitions or events that last around one hour or more in athletes who engage in more than one event or training per day [19]. Similarly, it has been shown that dehydration in athletes increased heart rate and decreased ability to concentrate, reduced alertness and increased subjective sensations of fatigue [9]. ...
Background:
Maintaining physical performance during Ramadan Diurnal Fasting (RDF) is a challenge for professional athletes. The literature shows that sleep disturbances experienced by athletes during RDF are associated with reduced physical performance. The effect of sleep quality on physical performance, and the effect of work status on physical performance during RDF among athletes, besides engaging in trainings, have been little investigated. This study aims to evaluate the effect of RDF on the physical performance of professional athletes taking into consideration their sleep quality and work status.
Methods:
Professional medium-distance male runners (n = 32) participated in our study in the summer of 2019. Data about socio-demographics, training characteristics, sleep quality (Pittsburg Sleep Quality Index: PSQI), physical performance (Cooper Test; Harvard step test) were collected before and during Ramadan. Student's-test and Welch and Wilcoxon tests were used for data analysis.
Results:
Both quality of sleep and physical performance of athletes deteriorated during Ramadan. People with better quality of sleep had better physical fitness/performance both before and during RDF. Athletes who worked beside trainings achieved worse physical fitness test results and had worse quality of sleep.
Conclusions:
Policies aimed to improve physical performance in RDF should consider the quality of sleep and the work status of athletes.
... In contrast, fasting is reported to have negative effects on non-communicable diseases (5), sleep patterns, and cognitive function (6), in addition to other effects such as fluctuations in mood and body weight (7). Furthermore, fasting can lead to changes in some parameters such as the body mass index and hematocrit and albumin levels as well as cause dehydration (8,9). Thus, it can be presumed that hunger during the month of Ramadan may have various effects on circulation and peripheral perfusion. ...
... Fasting is practised in diverse cultures and religions. During a typical 12-hour fasting period, an estimated 1% of body mass may be lost as water by a sedentary individual in a temperate climate (Maughan & Shirreffs, 2012). This will increase with longer fasting, higher temperatures and activity. ...
https://www.who.int/publications/i/item/9789240015241
... 52,53 Dehydration during fasting should be avoided, especially when Ramadan occurs in hot seasons and in physically active people or children, by drinking an ample amount of fluids between iftar and suhoor. 50,[54][55][56] Dehydration and hyperviscosity could explain the increased incidence of cerebral venous sinus thrombosis during Ramadan fasting (1.4 times more frequent, P ¼ 0.03). 57 Although most often mild (<2%), the dehydration may raise a concern in patients with underlying kidney disease. ...
Background
The vast majority of the world population declares affiliation to a religion, predominantly Christianity and Islam. Many religions have special dietary rules, which may be more or less strictly adhered to.
Methods
Religious food rules were collected from holy books and religious websites as well as their translation into dietary practices. The literature was searched for potential associations between these rules and potential nutritional consequences.
Results
Jewish, Islamic and Indian religions support prolonged breastfeeding. Religious avoidance of alcohol is probably beneficial to health. When strictly applied, a few rules may lead to nutritional inadequacies, mainly in populations living in unfavourable socio-economic or environmental conditions. In Jewish and Muslim observants, animal slaughtering procedures may increase the risk of iron deficiency. Jews may be at risk of excess sodium intake related to home-prepared foods. A vegan diet, as observed by some believers, often by drifting from original precepts, or by some Hindus or Buddhists, may result in vitamin B12, calcium, iron, zinc, selenium and n-3 fatty acids deficiencies.
Conclusion
When implemented in accordance with the rules, most religious food precepts are not detrimental to health, as suggested by the fact that they have more or less been followed for millennia. Nevertheless, some practices may lead to nutritional inadequacies, such as iron, calcium, vitamin D and vitamin B12 deficiencies. Patients with low socio-economic status, children and women of childbearing age are of particular risk of such deficiencies. Being aware of them should help health professionals to take an individualized approach to decide whether to supplement or not.
... Ramadan is the time when Muslims who practice the prescribed fasting pattern for the duration of the month are likely to experience some dehydration during the fasting period (42). In addition, dehydration affects thermoregulatory as well as muscle function and therefore, negatively affects performance. ...
: This study aims to categorize the adaptation strategies of Muslim athletes who fast during Ramadan and proposes a self-coping strategy questionnaire as a complementary assessment tool. A total of 109 Jordanian Muslim athletes (mean age 20.0 ± 8.5 years) were surveyed by completing a self-coping questionnaire designed to classify an individual athlete’s level of adaptation. This study was conducted during the month of Ramadan 2019 and developed based on the training, nutritional, psychological, self-control, and recovery dimensions. Seventy percent of athletes found that they developed good or very good coping mechanisms. Coping strategies vary from one dimension to another, but in general, athletes often had a positive perceived coping. Athletes expressed that they are shifting the training hours with a preference for quality training rather than quantity and associated with a longer rest time. In addition, they were in favor of food hygiene associated with a strategy of sharing meals and providing water. The majority (59%) of the athletes said they were psychologically prepared for the potential effects of fasting. This research shows that athletes develop self-adjusting strategies to counter the effects of fasting. The questionnaire on the self-coping strategies provides important and precise information on the level of coping achieved by the athletes.
... Athletes are recommended to hydrate themselves well between iftar and sahur, possibly with frequent small amounts of drinks (~200 ml every 30 minutes) and eventually adding osmotically active agents such as sodium salts, in order to promote greater fluid retention and attenuate excessive urine loss. Fluids such as coffee and tea should be avoided, in that they favor fluid excretion (34). Maximal and/or optimal hydration status should be targeted by sahur time. ...
During the month of Ramadan, Muslim believers of adult-aged and healthy, restrain themselves from food consumption and liquid intake from dawn to sunset (fasting duration varying according to the geographical location and time of the year). Differently from other fasting regimens such as caloric restriction, Ramadan fasting is a unique kind of fasting, being total (i.e., absolute abstain from food as well as fluid), time-restricted, intermittent, and circadian (following the circadian rhythm and the human biological clock). As such, the fasting athletes could potentially suffer from hypohydration, altered sleep pattern and architecture, sleep disturbances, mood swings, immunological alterations, impaired psychomotor performance and overall perceived physical and perhaps, mental fatigue, among others. Hence, Muslim athletes who continue to train and compete during Ramadan faced many challenges. Research has shown that depending on the level of effort, Ramadan fasting could have diverse effects on physical performance; from no effect to marked effects. The present review aims to provide practical recommendations based on an updated, evidence-based synthesis of the existing scholarly literature and/or experts opinions on the topic and subsequently, some useful tips for athletes, coaches, medical and scientific support, and sports managers, in order to guide them on how to promote appropriate behavioral, social and psychological strategies to cope with the changes and potential constraints induced by the observance of Ramadan fasting. These recommendations should be adjusted and coped with, utilizing a holistic approach, rather than focusing on the single alterations/perturbations. Moreover, the implemented strategies should not be "one size fits it all" approach, but should rather take into account the variability among athletes and their specific needs (biological, psychological, cognitive-behavioral), and their social and living environment; as it is clearly more challenging when the individual is performing the Ramadan fasting in a predominantly non-Muslim majority country.
... Fasting pose a challenge for athletes to achieve proper rehydration and nutrients replenishment that are crucial to maintain physical performance and to allow for optimal recovery from exercise as suggested by ACSM (Thomas et al., 2016). During Ramadan, Muslims consume two meals (compared to three meals on non-fasting days), a major first meal (Iftar) immediately after sunset and another meal (sahur) before dawn (Shephard, 2013).Previous reports on Ramadan fasting have noted a reduction in energy and water consumption (Burke and King, 2012;Maughan and Shirreffs, 2012). In addition, several studies that have assessed the influence of Ramadan fasting on athletic performance, reported a decrease in physical performance during Ramadan (Chtourou et al. 2011;Chtourou et al. 2012; Aloui et al. 2015; Roy and Bandyopadhyay, 2015). ...
European Journal of Sports Science Technology (ISSN: 2409-2908), 2018, Year 9, Issue 18 (Pages 185-197). Nutrient timing has been shown to influence physical performance, but whether it benefits
exercise performance during Ramadan is unknown. This study determined the effect
of delayed interval between water and Iftar intake on running performance and energy
intake during Ramadan. Ten male runners (age 22.9 ± 1.7 years) performed two graded
exercise tests while fasting, preceded previous day by variable dietary protocols. On one trial
472 ml of water were given and immediately followed by Iftar ingestion (Control), on the
other trial the same volume of water was given 30 min prior to Iftar ingestion (Preload).
Energy and fluids intake, anthropometrics, time to exhaustion, VO2, heart rate, RPE, were
recorded and analyzed. The time to exhaustion was significantly greater after Preload as
compared to Control (1525.9 ± 63.5 seconds vs. 1460.1 ± 83.2 seconds respectively, p =
0.007, pƞ2
= 0.523). There was no difference in VO2, heart rate, RPE, and anthropometrics
between the trials (P>0.05). However, preloading was significantly higher in energy
(p=0.043) and fluid (p=0.049) intake. In conclusion, water preloading improves time to
exhaustion and energy and fluid intake in runners during Ramadan fasting.
Keywords: Ramadan, water preloading, nutrient timing, running performance
... Athletes are recommended to hydrate themselves well between iftar and sahur, possibly with frequent small amounts of drinks (~200 ml every 30 minutes) and eventually adding osmotically active agents such as sodium salts, in order to promote greater fluid retention and attenuate excessive urine loss. Fluids such as coffee and tea should be avoided, in that they favor fluid excretion (34). Maximal and/or optimal hydration status should be targeted by sahur time. ...
During the month of Ramadan, Muslim believers of adult-aged and healthy, restrain themselves from food consumption and liquid intake from dawn to sunset (fasting duration varying according to the geographical location and time of the year). Differently from other fasting regimens such as caloric restriction, Ramadan fasting is a unique kind of fasting, being total (i.e., absolute abstain from food as well as fluid), time-restricted, intermittent, and circadian (following the circadian rhythm and the human biological clock). As such, the fasting athletes could potentially suffer from hypohydration, altered sleep pattern and architecture, sleep disturbances, mood swings, immunological alterations, impaired psychomotor performance and overall perceived physical and perhaps, mental fatigue, among others. Hence, Muslim athletes who continue to train and compete during Ramadan faced many challenges. Research has shown that depending on the level of effort, Ramadan fasting could have diverse effects on physical performance; from no effect to marked effects. The present review aims to provide practical recommendations based on an updated, evidence-based synthesis of the existing scholarly literature and/or experts opinions on the topic and subsequently, some useful tips for athletes, coaches, medical and scientific support, and sports managers, in order to guide them on how to promote appropriate behavioral, social and psychological strategies to cope with the changes and potential constraints induced by the observance of Ramadan fasting. These recommendations should be adjusted and coped with, utilizing a holistic approach, rather than focusing on the single alterations/perturbations. Moreover, the implemented strategies should not be "one size fits it all" approach, but should rather take into account the variability among athletes and their specific needs (biological, psychological, cognitive-behavioral), and their social and living environment; as it is clearly more challenging when the individual is performing the Ramadan fasting in a predominantly non-Muslim majority country.
... A progressive loss of body water over the course of the day will occur which will impair both physical and cognitive performance due to the lack of food and fluid intake. The point at which water loss will begin to affect performance is still not well defined, but it may be as little as one to two percent of the body mass in which during fasting, for resting individuals in a temperate environment, the water loss typically amount to about one percent of body mass by the time of sunset (Maughan & Shirreffs, 2012). In addition, fluid and electrolyte disturbances produce significant orthostatic hypotension and fainting during fasting in field labourers, particularly when Ramadan falls during the summer in the Western countries (Born, Elmadfa, & Schmal, 1979). ...
This chapter attempts to explain fasting during the month of Ramadan and the suitable exercises for secondary school students during the Ramadan fasting month. Ramadan fasting is one of the five pillars of Islam and is compulsory for all healthy Muslims from puberty onwards except for people with medical conditions. The month consists of 30 days, which vary in length depending on the geographical location and the time of year. During this month, Muslims abstain from food, drink, smoking, and sex from dawn until sunset and Ramadan rotate around the seasons which causes the length of days to differ each year, depending on whether Ramadan falls in the winter or in the summer time. In Malaysia, the length of the time of fasting is usually around thirteen to fourteen hours. Schools with afternoon session also end early to allow more time for Muslim children to go back home earlier to break their fast. Students can freely participate in physical activity during this month but must adhere to the training schedule, proper dietary intake, modification of exercise and coping strategies in order to avoid fatigue and dehydration. From the previous studies, circuit training is a suitable exercise as part of the physical activity during this month. Low-intensity training for sedentary students are recommended during daylight hour of Ramadan. Furthermore, for active secondary school athletes and trained individuals, fasting also imposes a significant barrier to train and compete. In these situations, rather than accepting performance decrements as inevitable, athletes, coaches and sport scientists strive to plan strategies for training and competition that offset these challenges. To achieve this, more research is needed to determine the effects of fasting and the required attempt to alleviate any detrimental consequences.
... Dehydrated athletes may show impairments in both physical and cognitive performance. The point at which water loss may affect performance is not well defined, but it may be as little as 1-2% of body mass [20]. Hypo-hydration (i.e. ...
... To avoid dehydration or/overhydration, Coyle (2004) has recommended consuming 1.5 the amount of water lost during training session via sweating. It is worth noting that increasing water intake up to the values cited previously is unlikely to be effective as a prompt diuresis will ensue and the excess water will soon be lost in the urine (Maughan and Shirreffs 2012). In this case, void frequency will increase during nighttime and subjects will sometimes have to wake up at night to urinate, which may lead to greater sleep disturbance. ...
During Ramadan, dehydration and disturbed sleep patterns are common, so accurate reliable methods for the assessment of hydration and sleep of athletes are necessary to maintain performance. The purpose of this review is: (1) to identify appropriate tools/methods for monitoring hydration status and sleep in sports people; (2) to discuss which of these tools/methods can be confidently used by sport scientists and trainers during Ramadan; and (3) to discuss the possible link that may exist between sleep and hydration status. Several markers of hydration status are currently used and include body mass, plasma/serum osmolality, dilution techniques, and neutron activation analysis. Used in an appropriate context, all can be indicative of the hydration status in the laboratory. In the field, monitoring hydration status in physically active individuals and athletes may be performed using a combination of body mass with some measure of urine concentration (e.g. urine osmolality, urine-specific gravity, urine color) and sensation of thirst. During Ramadan, appropriate timing of sample collection and the use of reference methods in future studies are warranted. In the field, careful use of body mass in conjunction with urine indices may be used to monitor the hydration status of subjects practicing physical activity during Ramadan. There is a need for the use of polysomnography or actigraphy for sleep assessment during Ramadan in future laboratory-based studies of athletes. However, in the field, monitoring sleep–wake patterns may be performed using actigraphy and/or the PSQI questionnaire.
... Effects of exercise-induced dehydration have been well reported within the literature by several authors since two decades (Broad, Burke, Cox, Heeley & Riley, 1996;Maughan & Shirreffs, 2012;Mohr & Krustrup, 2012) with its detrimental effects being suggested to be more important regarding aerobic performance when compared to strength (Barr, 1999). Since the characteristics of a soccer game include repetition of high intensity actions throughout the duration of a game (Bradley, Sheldon, Wooster, Olsen, Boanas & Krustrup, 2009), dehydration may have negative effects on soccer players' physical performance. ...
The aim of the present study was to analyze the relationships between fluid ingestion, changes in body mass and physical activity amongst elite soccer players. 32 elite French soccer players were divided into six playing positions: goalkeepers (GK), central defenders (CD), full backs (FB), central midfielders (CM), wide midfielders (WM) and forwards (FW) and participated in official friendly matches within two consecutive pre-season periods. Body mass changes and fluid ingestion were recorded before, during and just after the matches. Time-motion characteristics were also analyzed. Players ingested 1.4±0.6 L of fluids during matches and lost 1.4±0.6 kg at the end of the games. WM lost more weight than GK, FB and FW (p<0.05) and CM lost more weight than GK (p<0.05). Furthermore, CD covered significantly less total distance, high (HI) and very high-intensity running distance than all other playing positions excluding GK (p<0.05); and WM covered greater distances at HI than all other playing positions. No differences were found in fluid ingestion between playing positions. The results of this study indicate that sweat loss was significantly different when comparing across various playing positions. As a result, sweat lost may be more influenced by HI activity during a game than other physical activity within game scenarios. Therefore, players with the highest amount of HI activities during a match should even more pay attention to their rehydration.
... During Ramadan, athletes should drink 600 mL/h of fluid (repeated drinking) from Iftar until bedtime and an additional 1 L at breakfast (Shephard 2013(Shephard , 2015. It should be noted that increasing water intake up to the values cited previously is unlikely to be effective as a prompt diuresis will ensue and the excess water will soon be lost in the urine (Maughan and Shirreffs 2012). To attenuate the diuretic effect water intake in excess, Evans and co-workers reported that ensuring that a substantial meal is ingested alongside the water consumed at the last meal could attenuate the diuretic effect by slowing the rate of gastric emptying and by ensuring a transient net secretion of water into the GI tract because of the high intraluminal osmotic load, thus preventing a rapid rise in blood volume and fall in plasma osmolality that would trigger diuresis. ...
Ramadan is considered to be the month of the stomach break. It has been reported that Ramadan has some health benefits. In most Muslims countries, there is a huge modification in the diet during this month. These changes could induce some gastrointestinal (GI) disorders (e.g. diarrhea, cramps, fullness, nausea). The aims of the present overview were to present some challenges that could be observed for athletes during the training sessions or competition and present some practical recommendations to avoid GI disorders during Ramadan. Based on previous studies, we could advance that the prevalence of GI disorders will be more pronounced when athletes travel for international competitions during Ramadan. Besides, GI disorders are more frequent for athletes when there is a huge modification in the training load. Dehydration observed during Ramadan is one of the factors that may induce GI disorders. The latter could be exacerbated by sweat loss during training sessions. Carbohydrate is frequently used by athletes to improve performance and is associated with some GI disorders. Therefore, during Ramadan, coaches and athletes should be advised to maintain the same diet and a good hydration as before the fasting month, and avoid air travel when preparing for competitions.
... The available literature regarding the common factors involved in detrimental effects on physical performance during Ramadan has shown alterations in circadian rhythm, 1 changes in sleep (in terms of pattern, architecture and duration), 2 3 physiological, metabolic and hormonal changes, 4 blood glucose-level reduction, 5 reduced daytime fluid intake (daytime dehydration) 6 fall in body temperature 7 alteration in psychomotor functioning 8 9 (better during the morning and deteriorating as the day progresses), 7 10 more rapid onset of fatigue and increased incidence of non-contact and overuse injury in footballers. 11 Strengths and limitations of this study ▪ The first study to assesses the knowledge, beliefs and attitudes towards Ramadan fasting among football players ▪ The participants were professional athletes participating in a high-level international competition (Olympic Games). ...
Objectives
Muslims observe fasting during the month of Ramadan by abstaining from eating and drinking from dawn to sunset. Available literature shows that although several studies have been conducted on athletes to determine the effects of Ramadan fasting in terms of physical fitness and performance, little data are available regarding the knowledge, beliefs and attitudes of athletes (particularly footballers) towards Ramadan fasting during high-level competitions. This study explored the knowledge, beliefs and attitudes towards Ramadan fasting among football players participating in the London 2012 Olympics football tournament.
Design
Cross-sectional study.
Settings
Team training facility.
Participants
54 Muslim footballers participating in the London Olympics, 2012
Outcome measures
Each participant was asked to complete a pre-validated structured questionnaire to assess knowledge, beliefs and attitudes regarding Ramadan fasting and their intention to fast during London 2012.
Results
Of the 54 participating athletes, 21(39%) reported that they intended to fast during Ramadan, but not on a match day. This attitude differed across three teams interviewed —83%, 15% and 0%—showing cross-cultural variation. Overall, there was a lack of knowledge among footballers regarding the effects of Ramadan fasting on sleep and performance; around 30% of athletes gave incorrect responses. This knowledge was independent of their decision to fast on non-competition days (p>0.05).
Conclusions
This is the first study to describe the knowledge, beliefs and attitudes towards Ramadan fasting among athletes from Muslim-majority countries participating in a high-level competition. Appropriate knowledge can ensure optimum performance for athletes during Ramadan fasting. Coaches, family members and friends also in possession of this knowledge can provide moral support to the players.
... The relevance of such conclusions to individuals who are going about their everyday life is unclear because it is unlikely that a loss of 2% of body mass will occur often. For example, during Ramadan, when no food or liquid is consumed by Muslins from sunrise to sunset, there is typically a loss of only 1% of body mass (6). Nevertheless, to our knowledge, the assumption that small changes in hydration status are readily compensated has not been systematically considered; in particular, the point at which fluid loss affects mental performance has not been established. ...
Background:
The assumption that small changes in hydration status are readily compensated by homeostatic mechanisms has been little studied. In this study, the influence of hypohydration on cognition was examined.
Objectives:
We assessed whether a loss of <1% of body mass due to hypohydration adversely influenced cognition, and examined the possible underlying mechanisms.
Design:
A total of 101 individuals were subjected to a temperature of 30°C for 4 h and randomly either did or did not consume 300 mL H2O during that period. Changes in body mass, urine osmolality, body temperature, and thirst were monitored. Episodic memory, focused attention, mood, and the perceived difficulty of tasks were measured on 3 occasions. The data were analyzed with the use of a regression-based approach whereby we looked for variables that mediated the influence of hypohydration on psychological functioning.
Results:
Drinking water improved memory and focused attention. In the short-term, thirst was associated with poorer memory. Later, a greater loss of body mass was associated with poorer memory and attention (mean loss: 0.72%). At 90 min, an increase in thirst was associated with a decline in subjective energy and increased anxiety and depression, effects that were reduced by drinking water. At 180 min, subjects found the tests easier if they had consumed water.
Conclusions:
Drinking water was shown, for the first time to our knowledge, to benefit cognitive functioning when there was a loss of <1% body mass at levels that may occur during everyday living. Establishing the variables that generate optimal fluid consumption will help to tailor individual advice, particularly in clinical situations. This trial was registered at clinicaltrials.gov as NCT02671149.
... Inevitably, there will be a progressive loss of body water that amounts typically to about 1% of body mass by sunset. 46 In one study, when individuals did not drink for 37 h, a loss of 1% of body mass was reported after 13 h, 1.7% body mass at 24 h, and 2.7% after 37 h. 31 It is, however, unlikely that many in temperate climates will experience even this degree of dehydration, because the temperature will be lower and most will drink at some stage. ...
Although it has been suggested that many in the general population are dehydrated to the extent that mood and cognition are disrupted, there has been little research investigating mild levels of dehydration. When dehydration reduces body mass by more than 2%, it has been consistently reported that mood is influenced, fatigue is greater, and alertness is lower. In contrast, the effects on cognition have been less consistent. Only a few studies have looked at females and these studies made little attempt to consider hormones that influence kidney functioning. In particular, there has been virtually no attempt to look at changes in hydration status in the range that occurs in individuals with a sedentary lifestyle in a temperate climate. There is a consequent need to study individuals who have lost up to 1% of body mass due to dehydration. While 4 intervention trials have found that the cognition of children improved in response to water consumption, the effects of water consumption on cognition in older adults, another high-risk group, have been largely ignored.
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... Furthermore, supplementation with glycerol associated with physical activity has been investigated, owing to its hyper-hydrating effects (Schott et al. 2001;Kavouras et al. 2006;Maughan and Shirreffs 2012;Patlar et al. 2012;Koehler et al. 2014). It has been suggested that the function of glycerol as a body fluid regulator is due to its osmotic properties. ...
We evaluated the effects of oral glycerol supplementation on trained rats fed a normal diet. Wistar rats were distributed among 6 groups in a completely randomized 2 × 3 factorial design. The animals were subjected to 6 weeks of aerobic training. In the last 4 weeks, the animals’ diet was supplemented with saline, glucose, or glycerol. Data were subjected to one-way analysis of variance (ANOVA) followed by a Student–Newmann–Keuls test, with values for P < 0.05 considered statistically significant. The change in body mass was lower in the trained groups, and their food and water consumption were higher. Glycerol supplementation resulted in an increase in the levels of triacylglycerol (TAG) and total cholesterol, as well as in the area and diameter of adipocytes. When associated with training, these parameters were similar to those of other trained groups. Levels of low-density lipoprotein + very-low-density lipoprotein cholesterol decreased in the trained animals that received glycerol compared with the non-trained ones. Glycerol consumption caused a reduction in food intake and increased the villous:crypt (V:C) ratio. No changes in glycemia, high density lipoproteins, or density of adipocytes were observed. Supplementation with glycerol together with aerobic physical training promoted beneficial metabolic effects. However, in non-trained rats glycerol increased the diameter and area of adipocytes, as well as the levels of TAG and total cholesterol.
... During Ramadan, dehydration develops progressively over the day [35]. Amateur soccer players thus show higher plasma sodium and potassium concentrations in the afternoon (05:00 p.m.) than in the morning (07:00 a.m.) during Ramadan [15]. ...
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Alternative and complementary medicine consists of a variety of medical
practices, therapies and treatments outside of Western medicine. Such
practices are often derived from traditional, cultural or holistic approaches
to health and healing. Examples include herbal medicine, acupuncture, dry needling,
kinesiological taping, chiropractic care, homeopathy and mind-body therapies. Alternative medicine generally emphasises the combined healing of the mind, body and
spirit to improve overall health, well-being and capacity for work. The therapies are
personalised according to the individual’s lifestyle, diet, emotional state and health
history. Most alternative medicine practices focus on preventing and maintaining
health rather than treating disease, which can improve long-term health outcomes
and reduce dependence on conventional medical interventions. Furthermore, when
alternative medicine is used in combination with conventional medicine, it can increase treatment efficacy and alleviate side effects. Alternative and complementary
therapies have been used for centuries and have a long history in various cultural
traditions. Such practices express respect for various healing modalities and cultural
heritage. Many alternative therapies may be more affordable and accessible than
conventional treatments, particularly in areas with limited access to health services.
Alternative medicine encourages patients to take an active role in their health
and healing processes, which increases a sense of empowerment and self-care in
individuals. Nevertheless, the effectiveness and safety of some alternative therapies
may be less well documented compared to conventional treatments.
Music-assisted physiotherapy is a treatment method applied by using music
in a structured way in physiotherapy processes. The therapy helps patients’
recovery processes in many areas such as improving motor skills, muscle
relaxation, pain management and psychological support. Especially thanks to the
effect of rhythm on the regulation of motor movements, it provides significant
benefits in neurological diseases (such as Parkinson’s disease, rehabilitation after
stroke). Music helps to relax muscles, reduce pain perception and increase patients’
motivation. In addition, music has a psychologically relaxing effect, making physiotherapy sessions more efficient and bearable. As an important complementary
method in the treatment of neurological and orthopedic problems, music therapy
can be applied in two different ways: active and passive. While active music therapy
involves the participation of patients in the music-making process, in passive therapy
the patient relaxes by listening to the music. Neuroplasticity plays a vital role as
music-based rehabilitation promotes recovery by engaging multiple cognitive and
motor systems (Fujioka et al., 2018). Integration of rhythmic auditory cues such as
music into rehabilitation can enhance task training, making it more enjoyable and
effective for self-management (van Wijck et al., 2012). Qualitative studies reveal
that participants in music-based rehabilitation programs report positive emotional
and social benefits and improved their overall quality of life (Pohl et al., 2018).
Research shows that music can contribute to physical, psychological and cognitive
healing.
RESUME
Les musulmans adultes en bonne santé qui pratiquent le jeûne du Ramadan (JR), suivent des règles religieuses strictes concernant leur mode de vie. Le JR a un impact sur plusieurs paramètres dont les habitudes alimentaires, le sommeil et l’hydratation, et peut potentiellement réduire les performances physiques. Il semble que le JR réduit la participation des athlètes aux entraînements et aux compétitions, et diminue la réalisation des exercices physiques par la communauté générale. En fait, les athlètes musulmans pratiquants sont dans une situation de désavantage concurrentiel durant le JR. Par conséquent, l’objectif de ce guide a été d’exposer un aperçu des recommandations pratiques, scientifiquement fondées, destinées aux athlètes en bonne santé et le personnel les encadrant sur la manière d’adopter des stratégies d‘adaptation comportementales, sociales et psychologiques appropriées et faire face aux changements et aux contraintes résultant du JR. Les recommandations développées dans ce guide ne se limitent pas à la dimension d’entraînement pendant le mois du Ramadan (c’est-à-dire l’horaire, la fréquence, l’intensité, la durée, le type d’exercice, et la charge d’entraînement), mais elles couvrent différents aspects de l’hygiène de vie tels que la nutrition, l’hydratation, et le sommeil, et traitent les aspects psychosociaux et cognitifs liés au JR. Ces recommandations sont destinées aux personnes en bonne santé. Les patients souffrant d’une maladie chronique doivent se référer à leur médecin afin d’assurer une éventuelle pratique en toute sécurité.
Les musulmans adultes en bonne santé qui pratiquent le jeûne du Ramadan (JR), suivent des règles religieuses strictes concernant leur mode de vie. Le JR a un impact sur plusieurs paramètres dont les habitudes alimentaires, le sommeil et l’hydratation, et peut potentiellement réduire les performances physiques. Il semble que le JR réduit la participation des athlètes aux entraînements et aux compétitions, et diminue la réalisation des exercices physiques par la communauté générale. En fait, les athlètes musulmans pratiquants sont dans une situation de désavantage concurrentiel durant le JR. Par conséquent, l’objectif de ce guide a été d’exposer un aperçu des recommandations pratiques, scientifiquement fondées, destinées aux athlètes en bonne santé et le personnel les encadrant sur la manière d’adopter des stratégies d‘adaptation comportementales, sociales et psychologiques appropriées et faire face aux changements et aux contraintes résultant du JR. Les recommandations développées dans ce guide ne se limitent pas à la dimension d’entraînement pendant le mois du Ramadan (c’est-à-dire l’horaire, la fréquence, l’intensité, la durée, le type d’exercice, et la charge d’entraînement), mais elles couvrent différents aspects de l’hygiène de vie tels que la nutrition, l’hydratation, et le sommeil, et traitent les aspects psychosociaux et cognitifs liés au JR. Ces recommandations sont destinées aux personnes en bonne santé. Les patients souffrant d’une maladie chronique doivent se référer à leur médecin afin d’assurer une éventuelle pratique en toute sécurité.
https://www.tawassol.ma/rmm/rmm32/rmm_n32_37.pdf
1.1 Objectives and Purpose of the Guideline
The primary aim of this guideline is to define the appropriate management of healthy, adolescent and adult athletes, who are exercising during the month of Ramadan. The objective is to enhance the prescription of appropriate exercise guidelines during the holy month of Ramadan. The second aim is to follow-up the healthy individuals from the general community. It is intended that the guideline will be used primarily by physicians, physiotherapists, nurses and health educators to provide appropriate advice to athletes, coaches and general community individuals.
1.2 Scope of the Guideline
• Population: the population covered by the guideline are healthy athletes of all categories practicing Ramadan and healthy individuals from the general public who are not exempted from fasting during Ramadan.
• Setting: athletes in Clubs and Federations and community (e.g. outpatient clinic, ward)
• Target audience: clubs and federations physicians and medical staff members, athletes, coaches and sports managers.
• Clinical issues: patients with specific pathologies are not included and should consult their physician for any exercise-related questions, including exercising during Ramadan (see section 2.4.2 of the document).
This guideline is available from: https://www.aspetar.com/ClinicalGuidelines.aspx?lang=en
Background: Muslims around the world practice intermittent fasting during the month of Ramadan once each year. We hypothesized that daily physical activity could be impacted due to the inability to refuel and rehydrate in the fasting state. Therefore, this study aimed to determine the effects of Ramadan fasting on daily physical activity in the adult community of Qatar.
Methods: A cohort study design among adults registered with national physical activity community program. Data from a pedometer-based community program was used to extract 3 months of daily step counts before, during, and after Ramadan for the past five years (2015-2019). A survey was conducted among participants to determine fasting practice and other health and environmental factors.
Results: A total of 209 participants completed the survey and provided valid data on physical activity. During Ramadan, the average steps per day decreased significantly (-385± SE 158) among participants who fasted (n=155) p=0.046 and increased (+731.4± SE 247) for the non- fasting participants (n=48) p=0.010.
Conclusion: Fasting during Ramadan impacts the daily physical activity behavior among Muslims. Interventions should focus on creating awareness of the importance of maintenance of adequate physical activity for adults fasting during Ramadan.
The use of glycerol in the diets for animals is of interest because it is a residue of biodiesel production and rich in energy. Thus, this study aimed to evaluate metabolic and physiological parameters of rats receiving supplemental pure glycerol by gavage. We used 30 Wistar rats (initial weight 202.7 ± 29.98 g) receiving 0 (control/saline), 200, 400, 800 and 1600 mg glycerol/kg of body weight (bidistilled glycerine, 99.85% glycerol) beside food and water ad libitum for 28 days. We used a completely randomised design with five treatments and six replicates. At the end of the experiment, the animals were killed, and the results showed that there was no change (p > 0.05) in the intake and excretion of water, the average daily weight gain, dry matter, ash and crude protein in the carcass or plasma triacylglycerols. There was a beneficial effect (p < 0.05) up to a dose of 800 mg/kg glycerol on feed intake, percentage of carcass fat, plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), high-density lipoprotein (HDLc) and low-/very low-density lipoprotein (LDLc + VLDLc). The levels of total cholesterol and glucose were increased with up to a dose of 800 mg/kg glycerol (but remained within the normal range); they were reduced with the dose of 1600 mg/kg. The total leucocyte count tended to be reduced, although it was within the reference values for rats. There were no renal or pancreatic lesions. In conclusion, glycerol presented as a safe supplement at the studied doses, even having some beneficial effects in a dose-dependent manner in rats.
Purpose
– Taekwondo (TKD) is a weight‐classified combat sport. Athletes are required to make weight in order to compete in their chosen weight division. However, the weight management strategies that are often employed are frequently at the expense of nutritional health and sporting performance. The purpose of this study is to investigate eating behaviours and general practices used by Taekwondo (TKD) athletes in order to make weight before competition.
Design/methodology/approach
– A total of 30 male, international and national, TKD athletes (average age: 23.4 years±4.6) were recruited from a known TKD Club in London, UK. Weight management behaviours, beliefs and attitudes were investigated with the use of a specially designed questionnaire.
Findings
– A total of 87 per cent of the TKD athletes surveyed stated that they would try to reduce body weight before competition to make weight classification and 47 per cent of the athletes reported that, in their effort to reduce weight, they would use a combination of restricting energy and fluid intake and increasing energy expenditure. A total of 80 per cent of the athletes stated that they would attempt to make weight on average six to nine times a year.
Originality/value
– Food and fluid restriction in combination with increased energy expenditure were the preferred methods of weight loss employed by TKD athletes in the sample.
Many of the socio-cultural lifestyle and dietary changes that take place during Ramadan may affect the risk of injury in athletes, but little evidence is available. The aim of the present study was to examine the effects over two consecutive years of the holy month of Ramadan on injury rates in 42 professional players of a Tunisian top-level professional soccer team. Players were retrospectively organized into fasting and non-fasting groups and monitored for 3 months: 4 weeks before Ramadan, during the month of Ramadan (4 weeks), and 4 weeks after Ramadan each year. During Ramadan, training started at 22.00 h. The circumstances (training/match) and mechanism of injury (traumatic/overuse) were recorded. No significant differences between the three periods were observed for weekly mean training load, training strain, training duration, and Hooper's Index (quality of sleep, and quantities of stress, delayed-onset muscle soreness, and fatigue). Compared with non-fasting players, fasters had a lower (P < 0.05) Hooper's Index and stress during and after Ramadan. No significant difference in injury rates was observed between fasting and non-fasting players. Nevertheless, the rates of non-contact (6.8 vs. 0.6 and 1.1) and training overuse (5.6 vs. 0.6 and 0.5) injuries were significantly higher in fasting players during the month of Ramadan than before or after Ramadan. In conclusion, Ramadan, along with the corresponding changes in nutritional habits, sleeping schedule, and socio-cultural and religious events, significantly increased overuse and non-contact injuries in fasting players despite the fact that the training load, strain, and duration were maintained.
To present athletic trainers with recommendations for safe weight loss and weight maintenance practices for athletes and active clients and to provide athletes, clients, coaches, and parents with safe guidelines that will allow athletes and clients to achieve and maintain weight and body composition goals.
Unsafe weight management practices can compromise athletic performance and negatively affect health. Athletes and clients often attempt to lose weight by not eating, limiting caloric or specific nutrients from the diet, engaging in pathogenic weight control behaviors, and restricting fluids. These people often respond to pressures of the sport or activity, coaches, peers, or parents by adopting negative body images and unsafe practices to maintain an ideal body composition for the activity. We provide athletic trainers with recommendations for safe weight loss and weight maintenance in sport and exercise. Although safe weight gain is also a concern for athletic trainers and their athletes and clients, that topic is outside the scope of this position statement.
Athletic trainers are often the source of nutrition information for athletes and clients; therefore, they must have knowledge of proper nutrition, weight management practices, and methods to change body composition. Body composition assessments should be done in the most scientifically appropriate manner possible. Reasonable and individualized weight and body composition goals should be identified by appropriately trained health care personnel (eg, athletic trainers, registered dietitians, physicians). In keeping with the American Dietetics Association (ADA) preferred nomenclature, this document uses the terms registered dietitian or dietician when referring to a food and nutrition expert who has met the academic and professional requirements specified by the ADA's Commission on Accreditation for Dietetics Education. In some cases, a registered nutritionist may have equivalent credentials and be the commonly used term. All weight management and exercise protocols used to achieve these goals should be safe and based on the most current evidence. Athletes, clients, parents, and coaches should be educated on how to determine safe weight and body composition so that athletes and clients more safely achieve competitive weights that will meet sport and activity requirements while also allowing them to meet their energy and nutritional needs for optimal health and performance.
To use the meta-analytical procedures to determine the magnitude of the effect of exercise-induced dehydration (EID) upon time-trial (TT) exercise performance.
Studies were located via database searches and cross-referencing. TT performance outcomes were converted to mean percentage changes in power output. Random-effects model meta-regressions, analogue to the ANOVA and weighted mean effect summaries were used to delineate the effect of the EID-associated body weight (BW) loss on TT performance.
Five research articles, all using cycling TTs, were included, producing 13 effect estimates and representing 39 subjects. The mean ambient temperature, relative humidity, exercise intensity and duration of the exercise trials were 26.0 ± 6.7°C, 61 ± 9%, 68 ± 14% of VO(2max) and 86 ± 34 min, respectively. The effect of EID (mean BW loss of 2.20 ± 1.0%) during self-paced exercise conditions was to produce a non-significant increase in endurance performance of 0.06 ± 2.72% (p=0.94), compared with the maintenance of euhydration (mean BW loss of 0.44 ± 0.48%). Meta-regression analyses revealed a statistically significant relationship between the percentage changes in power output and exercise intensity and duration, but not with the EID-associated percentage changes in BW loss. Drinking according to the dictate of thirst was associated with an increase in TT performance compared with a rate of drinking below (+5.2 ± 4.6%, p=0.01) or above (+2.4 ± 5.0%, p=0.40) thirst. The probability that drinking to thirst confers a real and meaningful advantage on TT performances conducted under field conditions compared with a rate of drinking below and above thirst sensation is of the order of 98% and 62%, respectively.
(1) Compared with euhydration, EID (up to 4% BW loss) does not alter cycling performances during out-of-door exercise conditions; (2) exercise intensity and duration have a much greater impact on cycling TT performances than EID and; (3) relying on thirst sensation to gauge the need for fluid replacement maximises cycling TT performances.
Hypoxia often causes body water deficits (hypohydration, HYPO); however, the effects of HYPO on aerobic exercise performance and prevalence of acute mountain sickness (AMS) at high altitude (ALT) have not been reported. We hypothesized that 1) HYPO and ALT would each degrade aerobic performance relative to sea level (SL)-euhydrated (EUH) conditions, and combining HYPO and ALT would further degrade performance more than one stressor alone; and 2) HYPO would increase the prevalence and severity of AMS symptoms. Seven lowlander men (25 ± 7 yr old; 82 ± 11 kg; mean ± SD) completed four separate experimental trials. Trials were 1) SL-EUH, 2) SL-HYPO, 3) ALT-EUH, and 4) ALT-HYPO. In HYPO, subjects were dehydrated by 4% of body mass. Subjects maintained hydration status overnight and the following morning entered a hypobaric chamber (at SL or 3,048 m, 27°C) where they completed 30 min of submaximal exercise immediately followed by a 30-min performance time trial (TT). AMS was measured with the Environmental Symptoms Questionnaire-Cerebral Score (AMS-C) and the Lake Louise Scoring System (LLS). The percent change in TT performance, relative to SL-EUH, was -19 ± 12% (334 ± 64 to 278 ± 87 kJ), -11 ± 10% (334 ± 64 to 293 ± 33 kJ), and -34 ± 22% (334 ± 64 to 227 ± 95 kJ), for SL-HYPO, ALT-EUH, and ALT-HYPO, respectively. AMS symptom prevalence was 2/7 subjects at ALT-EUH for AMS-C and LLS and 5/7 and 4/7 at ALT-HYPO for AMS-C and LLS, respectively. The AMS-C symptom severity score (AMS-C score) tended to increase from ALT-EUH to ALT-HYPO but was not significant (P = 0.07). In conclusion, hypohydration at 3,048 m 1) degrades aerobic performance in an additive manner with that induced by ALT; and 2) did not appear to increase the prevalence/severity of AMS symptoms.
Dehydration in athletes alters cardiovascular and thermoregulatory function and may inhibit endurance exercise capacity if fluid loss exceeds 2% of bodyweight (BW). If this level of dehydration cannot be prevented when starting from a state of euhydration, then athletes may create a state of hyperhydration by consuming extra fluid prior to exercise. From this hyperhydrated situation, individuals have a greater capacity to tolerate fluid loss before becoming dehydrated. Furthermore, excess pre-exercise fluid intake enhances thermoregulatory ability, as well as increasing plasma volume to maintain cardiac output. However, hyperhydrating before exercise is difficult, because a large fluid intake is typically accompanied by diuresis. Glycerol-containing beverages create an osmotic gradient in the circulation favouring fluid retention, thereby facilitating hyperhydration and protecting against dehydration. Many studies have shown that increases in body water by 1 L or more are achievable through glycerol hyperhydration. This article analyses the evidence for glycerol use in facilitating hyperhydration and rehydration, and provides guidelines for athletes wishing to use this compound. An analysis of the studies in this area indicates that endurance athletes intending to hyperhydrate with glycerol should ingest glycerol 1.2 g/kg BW in 26 mL/kg BW of fluid over a period of 60 minutes, 30 minutes prior to exercise. The effects of glycerol on total body water when used during rehydration are less well defined, due to the limited studies conducted. However, ingesting glycerol 0.125 g/kg BW in a volume equal to 5 mL/kg BW during exercise will delay dehydration, while adding glycerol 1.0 g/kg BW to each 1.5 L of fluid consumed following exercise will accelerate the restoration of plasma volume. Side effects from glycerol ingestion are rare, but include nausea, gastrointestinal discomfort and light-headedness. In summary, glycerol ingestion before, during or following exercise is likely to improve the hydration state of the endurance athlete.
To investigate the effect of drink temperature on cycling capacity in the heat.
On two separate trials, eight males cycled at 66 +/- 2% VO2peak (mean +/- SD) to exhaustion in hot (35.0 +/- 0.2 degrees C) and humid (60 +/- 1%) environments. Participants ingested three 300-mL aliquots of either a cold (4 degrees C) or a warm (37 degrees C) drink during 30 min of seated rest before exercise and 100 mL of the same drink every 10 min during exercise. Rectal and skin temperatures, heart rate, and sweat rate were recorded. Ratings of thermal sensation and perceived exertion were assessed.
Exercise time was longer (P < 0.001) with the cold drink (63.8 +/- 4.3 min) than with the warm drink (52.0 +/- 4.1 min). Rectal temperature fell by 0.5 +/- 0.1 degrees C (P < 0.001) at the end of the resting period after ingestion of the cold drinks. There was no effect of drink temperature on mean skin temperature at rest (P = 0.870), but mean skin temperature was lower from 20 min during exercise with ingestion of the cold drink than with the warm drink (P < 0.05). Heart rate was lower before exercise and for the first 35 min of exercise with ingestion of the cold drink than with the warm drink (P < 0.05). Drink temperature influenced sweat rate (1.22 +/- 0.34 and 1.40 +/- 0.41 L x h(-1) for the cold and the warm drink, respectively; P < 0.05). Ratings of thermal sensation and perceived exertion (P < 0.01) during exercise were lower when the cold drink was ingested.
Compared with a drink at 37 degrees C, the ingestion of a cold drink before and during exercise in the heat reduced physiological strain (reduced heat accumulation) during exercise, leading to an improved endurance capacity (23 +/- 6%).
Plasma volume (PV) and renal function were studied in eight subjects for 3 d prior to and 6 d after a 56 km footrace. Immediately following the race, PV, creatinine clearance, and urine flow were unchanged from pre-race values. Over the subsequent 3 d, PV increased due initially to a 17 g influx of serum albumin and an associated increase in plasma sodium content, which persisted throughout the study period. A reduction in urine sodium secretion occurred during the race day. Creatinine clearance increased after the race and remained elevated for 48 h. Increases serum enzyme activities, C-reactive protein concentration, serum uric acid content, and plasma creatinine concentration and production suggest muscle damage. We suggested the following. First, the persistent post-exercise plasma volume expansion is initiated by an influx of albumin into the intravascular space with an associated increase in plasma sodium content. A decrease in urine sodium excretion during the race day would contribute to the latter. Second, the interpretation of post-race changes in serum constituents must take account of changes in plasma volume. Third, there is an increase in creatinine clearance, indicating an increase in glomerular filtration rate, after both standard and ultramarathon running. This may be caused by the products of muscle cell damage although the physiologic mechanism for this is unclear.
A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), was recently suggested for evaluating heat stress. The purpose of this study was to evaluate the PSI for different combinations of hydration level and exercise intensity. This index was applied to two databases. The first database was obtained from eight endurance-trained men dehydrated to four different levels (1.1, 2.3, 3.4, and 4.2% of body wt) during 120 min of cycling at a power output of 62-67% maximum O2 consumption (VO2 max) in the heat [33 degrees C and 50% relative humidity (RH)]. The second database was obtained from nine men performing exercise in the heat (30 degrees C and 50% RH) for 50 min. These subjects completed a matrix of nine trials of exercise on a treadmill at three exercise intensities (25, 45, and 65% VO2 max) and three hydration levels (euhydration and hypohydration at 3 and 5% of body wt). Tre, HR, esophageal temperature (Tes), and local sweating rate were measured. PSI (obtained from either Tre or Tes) significantly (P < 0.05) differentiated among all exposures in both databases categorized by exercise intensity and hydration level, and we assessed the strain on a scale ranging from 0 to 10. Therefore, PSI applicability was extended for heat strain associated with hypohydration and continues to provide the potential to be universally accepted.
The aim of the EC Concerted Action PASSCLAIM was to develop a set of methods and procedures for assessing the scientific support for function-enhancing and health-related claims for foods and food components. This paper presents a critical review of the existing methods to evaluate the different aspects of physical performance and fitness needed to support claims on foods and food ingredients intended to enhance specific physiological functions.
Based on an inventory of labelling claims on available sport nutrition products, seven physiological functions in the field of physical performance and fitness were identified: 1) strength and power, 2) endurance, energy supply and recovery, 3) hydration/re-hydration, 4) flexibility, 5) tissue growth, 6) free radical scavenger capacity and 7) immune function. For each function the existing methodology was reviewed critically and judged on suitability to generate scientific support for physiological function claims on foods.
A database of methods including advantages and disadvantages of use has been generated for considering the scientific support of claims on foods and food ingredients relating to physical performance and fitness. It will contribute to the formulations of guidelines for assessing the scientific support of enhanced function or reduced disease risk claims on foods.
Hydration status and the effects of hypohydration have been the topic of much public and scientific debate in recent years. While many physiological responses to hypohydration have been studied extensively, the subjective responses to hypohydration have largely been ignored. The present investigation was designed to investigate the physiological responses and subjective feelings resulting from 13, 24 and 37 h of fluid restriction (FR) and to compare these with a euhydration (EU) trial of the same duration in fifteen healthy volunteers. The volunteers were nine men and six women of mean age 30 (sd 12) years and body mass 71.5 (sd 13.4) kg. Urine and blood samples were collected and subjective feelings recorded on a 100 mm verbally anchored questionnaire at intervals throughout the investigation. In the EU trial the subjects maintained their normal diet. Body mass decreased by 2.7 (sd 0.6) % at 37 h in the FR trial and did not change significantly in the EU trial. Food intake in the FR trial (n 10) provided an estimated water intake of 487 (sd 335) ml and urinary losses (n 15) amounted to 1.37 (sd 0.39) litres. This is in comparison with an estimated water intake of 3168 (sd 1167) ml and a urinary loss of 2.76 (sd 1.11) litres in the EU trial. Plasma osmolality and angiotensin II concentrations increased from 0-37 h with FR. Plasma volume decreased linearly throughout the FR trial amounting to a 6.2 (sd 5.1) % reduction by 37 h. Thirst increased from 0-13 h of FR then did not increase further (P>0.05). The subjects reported feelings of headache during the FR trial and also that their ability to concentrate and their alertness were reduced.
Sweat rate and sweat composition vary extensively between individuals, and quantification of these losses has a role to play in the individualisation of a hydration strategy to optimise training and competitive performance. Data were collected from 26 male professional football (soccer) players during one 90 min pre-season training session. This was the 2nd training session of the day, carried out between 19.30 and 21.00 h when the mean +/- SD environment was 32 +/- 3 degrees C, 20 +/- 5 %rh and WBGT 22 +/- 2 degrees C. Training consisted of interval running and 6-a-side games during which the average heart rate was 136 +/- 7 bpm with a maximum rate of 178 +/- 7 bpm (n = 19). Before and after training all players were weighed nude. During training all players had free access to sports drinks (Gatorade) and mineral water (Solan de Cabras). All drink bottles were weighed before and after training. Players were instructed to drink only from their own bottles and not to spit out any drink. No player urinated during the training session. Sweat was collected by patches from the chest, arm, back, and thigh of a subgroup of 7 players. These remained in place for the first 15 - 30 min of the training session, and sweat was analysed for sodium (Na (+)) and potassium (K (+)) concentration. Body mass loss was 1.23 +/- 0.50 kg (ranging from 0.50 to 2.55 kg), equivalent to dehydration of 1.59 +/- 0.61 % of pre-training body mass. The sweat volume lost was 2193 +/- 365 ml (1672 to 3138 ml), but only 972 +/- 335 ml (239 to 1724 ml) of fluid was consumed. 45 +/- 16 % of the sweat volume loss was replaced, but this ranged from 9 % to 73 %. The Na (+) concentration of the subgroup's sweat was 30.2 +/- 18.8 mmol/l (15.5 to 66.3 mmol/l) and Na (+) losses averaged 67 +/- 37 mmol (26 to 129 mmol). The K (+) concentration of the sweat was 3.58 +/- 0.56 mmol/l (2.96 to 4.50 mmol/l) and K (+) losses averaged 8 +/- 2 mmol (5 to 12 mmol). The drinking employed by these players meant that only 23 +/- 21 % of the sweat Na (+) losses were replaced: This ranged from replacing virtually none (when water was the only drink) to replacing 62 % when the sports drink was consumed. These elite soccer players did not drink sufficient volume to replace their sweat loss. This, however, is in accord with data in the literature from other levels of soccer players and athletes in other events. These measurements allow for an individualisation of the club's hydration strategy.
There are few data in the published literature on sweat loss and drinking behaviour in athletes training in a cool environment. Sweat loss and fluid intake were measured in 17 first-team members of an elite soccer team training for 90 min in a cool (5 degrees C, 81% relative humidity) environment. Sweat loss was assessed from the change in body mass after correction for the volume of fluid consumed. Sweat electrolyte content was measured from absorbent patches applied at four skin sites. Mean (+/- s) sweat loss during training was 1.69+/-0.45 l (range 1.06-2.65 l). Mean fluid intake during training was 423+/-215 ml (44-951 ml). There was no apparent relationship between the amount of sweat lost and the volume of fluid consumed during training (r2 = 0.013, P = 0.665). Mean sweat sodium concentration was 42.5+/-13.0 mmol l(-1) and mean sweat potassium concentration was 4.2+/-1.0 mmol x l(-1). Total salt (NaCl) loss during training was 4.3+/-1.8 g. The sweat loss data are similar to those recorded in elite players undergoing a similar training session in warm environments, but the volume of fluid ingested is less.
The maximal power that muscles can generate is reduced at low muscle temperatures. However, in prolonged heavy exercise in the heat, a high core temperature may be the factor limiting performance. Precooling has been shown to delay the attainment of hyperthermia. It is still unclear if the whole body should be cooled or if the active muscles should be excluded from cooling in order to maintain muscle power. An experiment was performed to compare thermal strain and gross efficiency following whole body or partial body cooling. Eight well-trained participants performed 40 min of 60% VO2max cycling exercise in a 30 degrees C, 70% relative humidity climatic chamber after four different precooling sessions in a water perfused suit: N (no precooling), CC (45 min whole body precooling), WC (45 min lower body precooling), and CW (45 min upper body precooling). The uncooled body part was warmed in such a way that the core temperature did not differ from that in session N. Gross efficiency was used to compare performance between the sessions since it indicates how much oxygen is needed for a certain external load. The gross efficiency did not differ significantly between the sessions. Differences in heat loss and heat storage were observed during the first 20 min of exercise. The evaporative heat loss in session WC (305 +/- 67 W) and CW (284 +/- 68 W) differed from session N (398 +/- 77 W) and CC (209 +/- 58 W). More heat was stored in session CC (442 +/- 125 W) than in sessions WC (316 +/- 39 W), CW (307 +/- 63 W), and N (221 +/- 65 W). It was confirmed that precooling reduces heat strain during exercise in the heat. No differences in heat strain and gross efficiency were observed between precooling of the body part with the exercising muscles and precooling of the tissues elsewhere in the body.
This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least several hours before the activity to enable fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited.
Significant scientific evidence documents the deleterious effects of hypohydration (reduced total body water) on endurance exercise performance; however, the influence of hypohydration on muscular strength, power and high-intensity endurance (maximal activities lasting >30 seconds but <2 minutes) is poorly understood due to the inconsistent results produced by previous investigations. Several subtle methodological choices that exacerbate or attenuate the apparent effects of hypohydration explain much of this variability. After accounting for these factors, hypohydration appears to consistently attenuate strength (by ≈2%), power (by ≈3%) and high-intensity endurance (by ∼10%), suggesting alterations in total body water affect some aspect of force generation. Unfortunately, the relationships between performance decrement and crucial variables such as mode, degree and rate of water loss remain unclear due to a lack of suitably uninfluenced data. The physiological demands of strength, power and high-intensity endurance couple with a lack of scientific support to argue against previous hypotheses that suggest alterations in cardiovascular, metabolic and/or buffering function represent the performance-reducing mechanism of hypohydration. On the other hand, hypohydration might directly affect some component of the neuromuscular system, but this possibility awaits thorough evaluation. A critical review of the available literature suggests hypohydration limits strength, power and highintensity endurance and, therefore, is an important factor to consider when attempting to maximise muscular performance in athletic, military and industrial settings.
TO OPTIMIZE PERFORMANCE IMPROVEMENTS AND TO ENHANCE SKELETAL MUSCLE RECOVERY FROM HIGH-INTENSITY TRAINING, THE ATHLETE NEEDS TO ENSURE ADEQUATE ENERGY AND PROTEIN CONSUMPTION. PROTEIN INTAKE MAY HAVE EVEN GREATER RELEVANCE DURING PERIODS OF WEIGHT LOSS OFTEN ASSOCIATED WITH THE COMBAT SPORT ATHLETE. COMBAT SPORT ATHLETES OFTEN USE WATER RESTRICTION TO ACCOMPLISH DESIRED WEIGHT LOSS. THIS HAS SEVERAL IMPORTANT PERFORMANCE AND PHYSIOLOGICAL IMPLICATIONS THAT POSE SIGNIFICANT HEALTH RISKS. THIS PAPER WILL FOCUS ON SEVERAL NUTRITIONAL AND HYDRATION STRATEGIES AND HOW THEY SPECIFICALLY RELATE TO COMBAT SPORTS WITH REGARD TO TRAINING AND COMPETITION.
Eight endurance-trained cyclists rode as far as possible in 1 h on a stationary cycle simulator in a moderate environment (20C, 60% relative humidity, 3 ms–1 wind speed) while randomly receiving either no fluid (NF) or attempting to replace their approximate 1.71 sweat loss measured in a previous 1-h familiarisation performance ride at approximately 85% of peak oxygen uptake with artificially sweetened, coloured water (F). During F, the cyclists drank mean 1.49 (SEM 0.14)1 of which mean 0.27 (SEM 0.08)1 remained in the stomach at the end of exercise and mean 0.20 (SEM 0.05) 1 was urinated after the trial. Thus, only mean 1.02 (SEM 0.12)1 of the ingested fluid was available to replace sweat losses during the 1-h performance ride. That fluid decreased the mean average heart rate from 166 (SEM 3) to 157 (SEM 5) beatsmin–1 (P < 0.0001) and reduced the final mean serum [Na–] and osmolalities from 143 (SEM 0.6) to 139 (SEM 0.6) matom1–1(P < 0.005) and from 294 (SEM 1.7) to 290 (SEM 1.9) mosmol1–1 (P = 0.05), respectively. Fluid ingestion did not significantly attenuate rises in plasma anti-diuretic hormone and angiotensin concentrations, or decrease the approximate-15% falls in estimated plasma volume in the F and NF trials. Nor did fluid ingestion significantly affect the approximate 1.71 h–1 sweat rates, the rises in rectal temperature (from 36.6 to 38.3C) or the ratings of perceived exertion in the two trials. Ingestion of approximately 1.51 of fluid produced an uncomfortable feeling of stomach fullness and reduced the mean distance covered in 1 h from 43.1 (SEM 0.7) to 42.3 (SEM 0.6) km (P < 0.05). Thus, trying to replace more than 1.01h–1 sweat losses during high-intensity, short duration exercise in a moderate environment would not appear to induce beneficial physiological effects, and may impair exercise performance.
Ramadan fasting, involving abstinence from fluid and food from sunrise to sundown, results in prolonged periods without nutrient intake and inflexibility with the timing of eating and drinking over the day. Dietary choices may also change due to special eating rituals. Although nutrition guidelines are specific to the sport, to the periodized training and competition calendar, and to the individual, many promote the consumption of carbohydrate and fluid before and during exercise, and consumption of protein, carbohydrate, and fluids soon after the session is completed. Failing to meet overall nutritional needs, or to provide specific nutritional support to a session of exercise, is likely to impair acute performance and reduce the effectiveness of training or recovery. Muslim athletes who fast during Ramadan should use overnight opportunities to consume foods and drinks that can supply the nutrients needed to promote performance, adaptation, and recovery in their sports. Because of the benefits of being able to consume at least some of these nutrients before, during or after an exercise session, the schedule of exercise should be shifted where possible to the beginning or end of the day, or during the evening when some nutritional support can be provided.
The aim of training is to achieve optimum performance on the day of competition via three processes or paradigms; training hard to create the required training stimulus, training smart to maximize adaptations to the training stimulus, and training specifically to fine- turn the behaviors or physiology needed for competition strategies. Dietary strategies for competition must target the factors that would otherwise cause fatigue during the event, promoting an enhancement of performance by reducing or delaying the onset of these factors. In some cases, the nutritional strategies needed to achieve these various paradigms are different, and even opposite to each other, so athletes need to periodize their nutrition, just as they periodize their training program. The evolution of new knowledge from sports nutrition research, such as presented in this book, usually starts with a stark concept that must be further refined; to move from individual nutrients to food, from 'one size fits all' to the individual needs and practices of different athletes, and from single issues to an integrated picture of sports nutrition. The translation from science to practice usually requires a large body of follow-up studies as well as experimentation in the field.
Prerequisites for cell survival include avoidance of excessive cell volume alterations. Cell membranes are highly permeable to water, which follows osmotic gradients. Thus, cell volume constancy requires osmotic equilibrium across cell membranes. Cells accumulate osmotically active organic substances and compensate their osmolarity by lowering cytosolic Cl(-) concentrations. Following cell shrinkage, regulatory cell volume increase is accomplished by ion uptake (activation of Na(+), K(+), 2Cl(-) cotransport, Na(+)/H(+) exchange in - parallel to Cl(-)/HCO(-)(3) exchange and Na(+) channels), by cellular accumulation of organic osmolytes (e.g. myoinositol, betaine, phosphorylcholine, taurine) as well as by proteolysis leading to generation of amino acids and glycogenolysis generating glucose phosphate. Following cell swelling, cell volume is restored by ion exit (activation of K(+) channels and/ - or anion channels, KCl cotransport, parallel activation of K(+)/H(+) exchange and Cl(-)/HCO(-)(3) exchange), release or degradation of organic osmolytes as well as stimulation of protein synthesis and of glycogen synthesis. The activity of cell volume regulatory mechanisms is modified by hormones, transmitters and drugs, which thus influence protein and glycogen metabolism. Moreover, alterations of cell volume modify generation of oxidants and the sensitivity to oxidative stress. Deranged cell volume regulation significantly contributes to the pathophysiology of several disorders such as liver insufficiency, diabetic ketoacidosis, hypercatabolism, ischemia, and fibrosing disease.
Opinion on the role of protein in promoting athletic performance is divided along the lines of how much aerobic-based versus resistance-based activity the athlete undertakes. Athletes seeking to gain muscle mass and strength are likely to consume higher amounts of dietary protein than their endurance-trained counterparts. The main belief behind the large quantities of dietary protein consumption in resistance-trained athletes is that it is needed to generate more muscle protein. Athletes may require protein for more than just alleviation of the risk for deficiency, inherent in the dietary guidelines, but also to aid in an elevated level of functioning and possibly adaptation to the exercise stimulus. It does appear, however, that there is a good rationale for recommending to athletes protein intakes that are higher than the RDA. Our consensus opinion is that leucine, and possibly the other branched-chain amino acids, occupy a position of prominence in stimulating muscle protein synthesis; that protein intakes in the range of 1.3-1.8 g · kg(-1) · day(-1) consumed as 3-4 isonitrogenous meals will maximize muscle protein synthesis. These recommendations may also be dependent on training status: experienced athletes would require less, while more protein should be consumed during periods of high frequency/intensity training. Elevated protein consumption, as high as 1.8-2.0 g · kg(-1) · day(-1) depending on the caloric deficit, may be advantageous in preventing lean mass losses during periods of energy restriction to promote fat loss.
Eighty-seven players (54 fasting players, 33 non-fasting players) who carried out their club's scheduled training and competitive matches completed the daily questionnaire before and during Ramadan. Fasting players trained on average 11 h after their last food and drink. While fasting players reported that they were slightly less ready to train during the Ramadan fast than in the period before Ramadan, there was no increase in their perceived effort during training or in training difficulty compared with their ratings before Ramadan, or with those of the non-fasting group during Ramadan. The fasting players were marginally more thirsty, hungry and tired, and slightly less able to concentrate before training during Ramadan than in the pre-Ramadan period. Before Ramadan, both groups averaged more than 9 h sleep each night. The non-fasting players recorded that they had about 105 min less sleep per night during the first week of Ramadan, before reverting back to their pre-Ramadan amount of sleep. The fasting group consistently reported having about 1 h less sleep per night throughout Ramadan, but neither group appeared to find sleep quality to have altered. In the first 2 weeks after Ramadan, the modest changes reported by the fasting players reverted back to their pre-Ramadan values.
Dehydration is typical during prolonged exercise. Because training stimulates numerous adaptations, some involving fluid regulation, it is conceivable that training involves adaptations to dehydration. This study tested the hypothesis that trained individuals have altered fluid regulatory, but not behavioural or perceptual responses to exercise when hypohydrated. Six trained (V.O2 peak: 65+/-8 mL kg(-1) min(-1)) and six untrained (V.O2 peak: 45+/-4 mL kg(-1) min(-1)) males cycled for 40 min at 70%V.O2 peak, once whilst euhydrated (EUH) and once whilst hypohydrated by ~2% body mass (HYPO), before a 40-min performance trial with euhydration (in EUH) or ad libitum drinking (in HYPO), in temperate conditions (24.3 degrees C, 50% rh). Baseline hydration was achieved by complete or partial rehydration from exercise+heat stress on the previous evening. Body mass was reduced (-1.8+/-0.1%) and plasma osmolality was increased (5+/-1 mosmol kg(-1)) similarly between fitness groups in HYPO compared to EUH (P<0.05). During exercise, plasma [AVP] rose more in HYPO than EUH; the elevation was greater in the Untrained (4.1+/-1.7 vs. 2.0+/-0.8 pmol L(-1), P<0.01) than Trained (1.4+/-0.6 vs. 1.1+/-0.5 pmol L(-1), P<0.01; P=0.02). Increases in plasma [AVP] relative to osmolality were higher in Untrained than Trained (0.47+/-0.06 vs. 0.025+/-0.05 pmol mosmol(-1), P=0.03). Fitness groups had equivalent thirst ratings during fixed exercise but Trained were thirstier than Untrained when self regulating in HYPO (4.0+/-1.5 vs. 2.7+/-1.2; P=0.05); thus Trained tended to consume more fluid (1.20+/-0.16 vs. 0.88+/-0.16 L; P=0.19), but maintained similar hypohydration consistent with their greater sweat rate during HYPO. In conclusion, aerobic fitness attenuates the neuroendocrine ([AVP]) response to hypohydrated exercise, but not perceptual (thirst) or behavioural (ad libitum drinking) responses.
Hypohydration - if sufficiently severe - adversely affects athletic performance and poses a risk to health. Strength and power events are generally less affected than endurance events, but performance in team sports that involve repeated intense efforts will be impaired. Mild hypohydration is not harmful, but many athletes begin exercise already hypohydrated. Athletes are encouraged to begin exercise well hydrated and - where opportunities exist - to consume fluid during exercise to limit water and salt deficits. In high-intensity efforts, there is no need, and may be no opportunity, to drink during competition. Most team sports players do not drink enough to match sweat losses, but some drink too much and a few may develop hyponatremia because of excessive fluid intake. Athletes should assess their hydration status and develop a personalized hydration strategy that takes account of exercise, environment and individual needs. Pre-exercise hydration status can be assessed from urine markers. Short-term changes in hydration can be estimated from the change in body mass. Sweat salt losses can be determined by collection and analysis of sweat samples. An appropriate drinking strategy will take account of pre-exercise hydration status and of fluid, electrolyte and substrate needs before, during and after exercise.
An overnight fast of 8-10 h is normal for most people. Fasting is characterised by a coordinated set of metabolic changes designed to spare carbohydrate and increase reliance on fat as a substrate for energy supply. As well as sparing the limited endogenous carbohydrate, and increased rate of gluconeogenesis from amino acids, glycerol and ketone bodies help maintain the supply of carbohydrate. Many individuals undergo periodic fasts for health, religious or cultural reasons. Ramadan fasting, involving 1 month of abstention from food and fluid intake during daylight hours, is practised by a large part of the world population. This period involves a shift in the pattern of intake from daytime to the hours of darkness. There seems to be little effect on overall daily dietary intake and only small metabolic effects, but there may be implications for both physical and cognitive function. The limited evidence suggests that effects of Ramadan-style fasting on exercise performance are generally small. This needs to be balanced, however, against the observation that small differences in performance are critical in determining the outcomes of sporting events. Studies involving challenging sporting events (prolonged sustained or intermittent high-intensity events, hot and humid environments) are needed. Increases in subjective sensations of fatigue may be the result of loss of sleep or disruption of normal sleep patterns. Modifications to the competition timetable may minimise or even eliminate any effect on performance in sport, but there may be negative effects on performance in some events.
This study investigated the effects of precooling on performance and pacing during self-paced endurance cycling in the heat and, further, the effects of cooling on contractile function as a mechanism for performance changes.
After familiarization, eight male cyclists performed two randomized 40-min time trials on a cycle ergometer in 33 degrees C. Before the time trials, participants underwent either a 20-min lower-body cold-water immersion procedure or no cooling intervention. Before and after the intervention and the time trial, voluntary force (maximal voluntary contraction (MVC)), superimposed force (SIF), evoked twitch force (peak twitch force (Pf)), muscle temperature, and blood metabolites were measured. Further, measures of core and skin temperature and HR were recorded before, during, and after cooling and time trial.
Results indicated that cycling performance was improved with precooling (198 +/- 25 vs 178 +/- 26 W for precooling and control, respectively; P = 0.05). Although core, muscle, skin, and mean body temperatures were lower in the cooling condition until the 20th minute (P < 0.05), performance did not differ until the last 10 min of the time trial, by which time no differences in physiological measures were present. Further, while MVC and SIF were reduced postexercise in both conditions, MVC, SIF, and Pf were not different between conditions preexercise or postexercise.
In conclusion, a precooling intervention improved self-paced endurance exercise; however, the improvement in performance became evident after measured physiological differences induced by precooling had dissipated. Further, the lack of difference between conditions in MVC, SIF, or Pf indicates that improvements in performance did not result from an improvement in contractile function, suggesting that improvements may result from other mechanisms such as muscle recruitment.
To identify the prevalence, magnitude, and methods of rapid weight loss among judo competitors.
Athletes (607 males and 215 females; age = 19.3 T 5.3 yr, weight = 70 T 7.5 kg, height = 170.6 T 9.8 cm) completed a previously validated questionnaire developed to evaluate rapid weight loss in judo athletes, which provides a score. The higher the score obtained, the more aggressive the weight loss behaviors. Data were analyzed using descriptive statistics and frequency analyses. Mean scores obtained in the questionnaire were used to compare specific groups of athletes using, when appropriate, Mann-Whitney U-test or general linear model one-way ANOVA followed by Tamhane post hoc test.
Eighty-six percent of athletes reported that have already lost weight to compete. When heavy weights are excluded, this percentage rises to 89%.Most athletes reported reductions of up to 5% of body weight (mean T SD: 2.5 T 2.3%). The most weight ever lost was 2%-5%,whereas a great part of athletes reported reductions of 5%-10% (mean T SD: 6 T 4%). The number of reductions underwent in a season was 3 T 5. The reductions usually occurred within 7 T 7 d. Athletes began cutting weight at 12.6 T 6.1 yr. No significant differences were found in the score obtained by male versus female athletes as well as by athletes from different weight classes. Elite athletes scored significantly higher in the questionnaire than non elite. Athletes who began cutting weight earlier also scored higher than those who began later.
Rapid weight loss is highly prevalent in judo competitors. The level of aggressiveness in weight management behaviors seems to not be influenced by the gender or by the weight class, but it seems to be influenced by competitive level and by the age at which athletes began cutting weight.
Hypohydration exacerbates cardiovascular and thermal strain and can impair exercise capacity in temperate and warm conditions. Yet, athletes often dehydrate in exercise, are hypervolaemic and have less cardiovascular sensitivity to acute hypervolaemia. We tested the hypothesis that trained individuals have less cardiovascular, thermoregulatory and performance affect of hypohydration during exercise.
After familiarization, six trained [VO(2 peak) = 64 (SD 8) mL kg(-1) min(-1)] and six untrained [O(2 peak) = 45 (4) mL kg(-1) min(-1)] males cycled 40 min at 70%O(2 peak) while euhydrated or hypohydrated by 1.5-2.0% body mass (crossover design), before a 40-min work trial with euhydration or ad libitum drinking (in Hypohydration trial), in temperate conditions (24.3 degrees C, RH 50%, v(a) = 4.5 m s(-1)). Baseline hydration was by complete or partial rehydration from exercise+heat stress the previous evening.
During constant workload, heart rate and its drift were increased in Hypohydration compared with Euhydration for Untrained [drift: 33 (11) vs. 24 beats min(-1) h(-1) (10), 95% CI 5-11] but not Trained [14 (3) vs. 13 beats min(-1) h(-1) (3), CI -2 to 3; P = 0.01 vs. Untrained]. Similarly, rectal temperature drift was faster in Hypohydration for Untrained only [by 0.57 degrees C h(-1) (0.25); P = 0.03 vs. Trained], concomitant with their reduced sweat rate (P = 0.05) and its relation to plasma osmolality (P = 0.03). Performance power tended to be reduced for Untrained (-13%, CI -35 to 2) and Trained (-7%, CI: -16 to 1), without an effect of fitness (P = 0.38).
Mild hypohydration exacerbated cardiovascular and thermoregulatory strain and tended to impair endurance performance, but aerobic fitness attenuated the physiological effects.
Athletes are encouraged to begin exercise well hydrated and to consume sufficient amounts of appropriate fluids during exercise to limit water and salt deficits. Available evidence suggests that many athletes begin exercise already dehydrated to some degree, and although most fail to drink enough to match sweat losses, some drink too much and a few develop hyponatremia. Some simple advice can help athletes assess their hydration status and develop a personalized hydration strategy that takes account of exercise, environment, and individual needs. Preexercise hydration status can be assessed from urine frequency and volume, with additional information from urine color, specific gravity, or osmolality. Change in hydration during exercise can be estimated from the change in body mass that occurs during a bout of exercise. Sweat rate can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses can be determined by collection and analysis of sweat samples, but athletes losing large amounts of salt are likely to be aware of the taste of salt in sweat and the development of salt crusts on skin and clothing where sweat has evaporated. An appropriate drinking strategy will take account of preexercise hydration status and of fluid, electrolyte, and substrate needs before, during, and after a period of exercise. Strategies will vary greatly between individuals and will also be influenced by environmental conditions, competition regulations, and other factors.
The change in blood and plasma volume following ingestion of glucose solutions of varying concentrations was estimated in twelve healthy male volunteers. Subjects consumed, within a 5 min period, 600 ml of a solution containing 0, 2, 5 or 10 % glucose with osmolalities of 0 (sd 0), 111 (sd 1), 266 (sd 7) and 565 (sd 5) mOsm/kg, respectively. Blood samples were collected over the course of 1 h after ingestion at intervals of 10 min. After ingestion of the 2 % glucose solution, plasma volume increased from baseline levels at 20 min. Plasma volume decreased from baseline levels at 10 and 60 min after ingestion of the 10 % glucose solution. Heart rate was elevated at 10 and 60 min after ingestion of the 10 % glucose solution and decreased at 30 and 40 min after ingestion of the 2 % glucose solution relative to the average heart rate recorded before drinking. It is concluded that ingestion of hypertonic, energy-dense glucose solutions results in a decrease in plasma and extracellular fluid volume, most likely due to the net secretion of water into the intestinal lumen.
These studies demonstrate the body's capacity to minimize electrolyte losses during acute and repeated bouts of exercise and dehydration. Although there are marked shifts in water and selected ions in the exercising muscle, only during prolonged exertion is the ratio of intramuscular to extramuscular K+ significantly altered, suggesting that some modifications of the muscle cell membrane may occur. Muscle tissue not engaged in the exercise seems unaffected by the sweat lost during prolonged activity but relinquishes intracellular water shortly after work is terminated. Blood, muscle, sweat, and urine measurements before and following varied levels of dehydration demonstrate that body water lost during exercise in the heat is accomplished at the expense of larger water losses from extracellular than from intracellular compartments. Moreover, the loss of ions in sweat and urine had little effect on the K+ content of either plasma or muscle. With repeated days of dehydration and heavy exercise, plasma volume increased in proportion to an increase in body Na+ storage. At this point some mention should be made concerning the effect of this increased plasma water on the concentration of blood constiutents. Since red blood cells and hemoglobin are confined to the vascular space, both may decrease significantly as a function of the hemodilution induced by repeated days of exercise and dehydration. This may in part explain the apparent anemia reported by sports physicians among athletes undergoing intensive training. It is also possible that such hemodilution may produce low concentrations of plasma K+, which might be falsely interpreted as suggestive of a hypokalemic state. In any event, some caution should be used in the clinical interpretation of plasma concentrations of various constituents among the endurance trained athletes. In general, it seems that the large sweat losses incurred during training and marathon competition are adequately tolerated by the runner, with concomitant adjustments in the water and electrolyte distribution of the runner's body fluid compartments. Despite the sizeable excretion of ions in sweat, the runner's large caloric intake and renal conservation of Na+ minimize the threat of chronic dehydration and/or electrolyte deficiencies.
Humans may lose large amounts of water and electrolytes from sweat during prolonged exercise in a hot climate. Gender and maturational differences for the total sweat electrolyte losses have not been reported. The purpose of this study was to compare sweat electrolyte losses of prepubescent (PP), pubescent (P) and young adult (YA) males and females, under the same environmental conditions and relative exercise intensities. Twenty-five females (8 PP, 9 P, 8 YA) and 26 males (10 PP, 8 P, 8 YA) cycled for two 20-min bouts at 50% of their peak VO2 in a climatic chamber (42 degrees C, 18% relative humidity). Sweat was collected from a plastic bag attached to the lower back. Total body sweat loss was calculated from the differences in nude body weight corrected for fluid intake, urine, and respiratory water loss. Sweat [Na+] and [Cl-] tended to increase with maturation while sweat [K+] was lower in YA compared with that of PP. Children had a lower sweating rate than YA, even when corrected for body surface area. As a result, total Na+ and Cl- losses per kg body weight from sweat (mEq.kg-1.h-1) were higher in YA compared with those of PP and P; however, no maturational difference was found in K+ losses. Within the same maturational group, there were no gender differences in any of the electrolyte losses. These results may be useful in recommending "optimal" fluid-electrolyte drinks for children exercising in the heat.
Exercise-induced muscle cramp has been considered to result from disturbances of fluid and electrolyte balance resulting from excessive sweat loss. Serum biochemical and haematological measurements were made on 82 male marathon runners before and after a 42.2-km race. Fifteen (18%) of the runners reported an attack of muscle cramp which occurred after 35 +/- 6 km (mean +/- S.D.) had been covered. These subjects were not different from the others in terms of racing performance or training status. Serum electrolyte concentrations, including sodium and potassium, were not different between those suffering from cramp and those not so affected either before or after the race, although a significant (P less than 0.001) increase in serum sodium concentrations occurred in both groups. Serum bicarbonate concentrations fell to the same extent (from 28 to 24 mmol l-1) in both groups. Significant decreases in plasma volume, calculated from the changes in circulating haemoglobin and haematocrit, occurred in both groups of subjects, but there was no difference in the extent of the haemoconcentration. The results suggest that exercise-induced muscle cramp may not be associated with gross disturbances of fluid and electrolyte balance.
The 1982 Aberdeen marathon race was held on a cool (12 degrees C) day on a flat, fast course. Fifty-nine of the 750 runners volunteered to take part in this study: rectal temperature of these competitors was measured within 5 min of completing the race. Venous blood samples were obtained before and immediately after the race; body weight of these subjects was also recorded before and after the race. During the race, 200 ml of fluid, either water or a glucose/electrolyte drink, was consumed at each of the seven feeding stations. The mean finishing time of the subjects was 221 +/- 37 min (mean +/- SD, range = 144-307 min). Post-race rectal temperature was 38.3 +/- 0.9 degrees C with a range of values from 35.6 degrees to 39.8 degrees C. The net weight loss was 2.02 +/- 0.72 kg equivalent to 2.9% +/- 0.8% of body weight. The correlation between post-race rectal temperature and finishing time (r = -0.234) was not statistically significant; post-race rectal temperature was significantly correlated with the time taken to complete the second half of the race (r = -0.348, P less than 0.01). No cases of heat illness were seen among the competitors. The results suggest that hypothermia rather than hyperthermia may be a problem for marathon runners competing under these conditions.
A diuretic drug (40 mg of furosemide) was utilized to study the effects of dehydration (D) on competitive running performance, without prior thermal or exercise stress. Eight men competed in randomized races of 1,500, 5,000, and 10,000 m, while normally hydrated (H) and with mean plasma volume reductions of 9.9, 12.3, and 9.9%, respectively. As a result of the reduced body water (change in body weight = -1.9, -1.6, and -2.1%), mean outdoor performance times on a running track increased 0.16 min, 1.31 min (P less than 0.05), and 2.62 min (P less than 0.05) in the 1,500-m, 5,000-m, and 10,000-m trials. Running performance decrements due to dehydration were more strongly correlated with changes in body weight (r = -0.79, -0.65, and -0.40) than with urine volume or plasma volume differences. In addition, subjects were studied during submaximal and maximal treadmill exercise while H and D (mean change in plasma volume = -7.1%). Neither submaximal nor maximal oxygen uptake was significantly altered (P greater than 0.05) as a consequence of D. Mean treadmill run time to volitional exhaustion was reduced by 41.4 s (P less than 0.05) during the D treadmill trial. Therefore, it appears that competitive performance in trials of long duration (5,000 and 10,000 m) was affected to a greater extent by D than the shorter 1,500-m event, even though submaximal and maximal oxygen uptake was not altered.
Evaporative water loss from the respiratory tract was determined over a wide range of exercise. The absolute humidity of the expired air was the same at all levels of exercise and equal to that measured at rest. The rate of respiratory water loss during exercise was found to be 0.019 of the oxygen uptake times (44 minus water vapor pressure). The rate of weight loss during exercise due to CO2-O2 exchange was calculated. For exercise at oxygen consumption rates exceeding 1.5 L/min in a dry environment with a water vapor pressure of 10 mm Hg, the total rate of weight loss via the respiratory tract is on the order of 2-5 g/min.
Thirty male and twenty-six female Caucasians were tested at work levels of 1.0 liters O 2 consumption in 90 F wet-bulb temperature, 93 F dry-bulb temperature, and 80 ft/min air velocity for comparative heat reactions in the unacclimatized state. The females had more severe physiological and psychological reactions. Rectal temperatures of 104 F and heart rates of 180 beat/min were reached more rapidly than in the male. The females sweated less and their oxygen consumptions were lower than those of the males. Ten males and four females were then acclimatized to the same extent at the same work rate in 93 F wet-bulb temperature. At the end of the period their reactions were closely similar, although the females responded slower to the acclimatization procedure. Both groups ended with heart rates of 140 beat/min and rectal temperatures of 102 F. The females, however, continued to sweat less. In a retest at 90 F wet-bulb temperature, both groups had heart rates of 130–140 beat/min and rectal temperatures of 101 F. Females still sweated less. The results demonstrate the fact that females react more severely on exposure to severe heat and work conditions. Once acclimatized, however, the temperature and circulatory reactions of both sexes are closely similar, but the females sweat less than males.
acclimatization of Caucasians to heat; Caucasians—acclimatization to heat; sex differences—heat reactions; physiological reactions to heat
Submitted on September 14, 1964
The physiology of marathon running has been extensively studied both in the laboratory and in the field, but these investigations have been confined to elite competitors. In the present study 28 competitors who took part in a marathon race (42.2 km) have been studied; 18 male subjects recorded times from 2 h 19 min 58 s to 4 h 53 min 23 s; 10 female subjects recorded times between 2 h 53 min 4 s and 5 h 16 min 1 s. Subjects visited the laboratory 2-3 weeks after the race and ran on a motor driven treadmill at a series of speeds and inclines; oxygen uptake (VO2) was measured during running at average marathon racing pace. Maximum oxygen uptake (VO2 max) was measured during uphill running. For both males (r = 0.88) and females (r = 0.63), linear relationships were found to exist between marathon performance and aerobic capacity. Similarly, the fraction of VO2 max which was sustained throughout the race was significantly correlated with performance for both male (r = 0.74) and female (r = 0.73) runners. The fastest runners were running at a speed requiring approximately 75% of VO2 max; for the slowest runners, the work load corresponded to approximately 60% of VO2 max. Correction of these estimates for the additional effort involved in overcoming air resistance, and in running on uneven terrain will substantially increase the oxygen requirement for the faster runners, while having a much smaller effect on the work rate of the slowest competitors. Five minutes of treadmill running at average racing pace at zero gradient did not result in marked elevation of the blood lactate concentration in any of the subjects.
This study determined the effects of fluid and carbohydrate ingestion on performance, core temperature, and cardiovascular responses during intense exercise lasting 1 h. On four occasions, eight men cycled at 80 +/- 1% (+/- SEM) of VO2max for 50 min followed by a performance test. During exercise, they consumed either a large volume (1330 +/- 60 ml) of a 6% carbohydrate (79 +/- 4 g) solution or water or a small volume (200 +/- 10 ml) of a 40% maltodextrin (79 +/- 4 g) solution or water. These trials were pooled so the effects of fluid replacement (Large FR vs Small FR) and carbohydrate ingestion (CHO vs NO CHO) could be determined. Performance times were 6.5% faster during Large FR than Small FR and 6.3% faster during CHO than NO CHO (P < 0.05). At 50 min, heart rate was 4 +/- 1 b.min-1 lower and esophageal temperature was 0.33 +/- 0.04 degrees C lower during Large FR than Small FR (P < 0.05) but no differences occurred between CHO and NO CHO. In summary, Large FR slightly attenuates the increase in heart rate and core temperature which occurs during Small FR. Both fluid and carbohydrate ingestion equally improve cycling performance and their effects are additive.
Formulation of oral rehydration solutions (ORS) is reviewed in the context of methods for measuring absorption of water and component substrates, transport mechanisms of substrates and water, requirements of the athlete, and effects of exercise on absorption. The triple lumen tube intubation perfusion method is the optimal technique for obtaining absorption data from the human small intestine during rest and exercise. Factors that must be considered when interpreting absorption data obtained by this technique include the role of the mixing segment in altering composition of the infused solution, defining optimal segment length, effects of ORS osmolality, and absorption of "nonabsorbed" indicators. Absorption data are applicable only to the test segment and may lack relevance to ORS transport proximal and distal to the test segment. Absorption rate of an ORS measured by perfusion may not correlate with absorption rate following ingestion. Transport of water, electrolytes, carbohydrates, and other solutes including glutamine and amino acids is considered in relation to ORS formulation. Factors affecting absorption of an ORS including the unstirred layer, motility, intestinal blood flow, and maximal absorptive capacity of the alimentary tract are considered. Exercise per se at 30-70% VO2max for 60-90 min probably has minimal effects in limiting absorption of an ORS. Consideration relevant to supplying needs of the athlete during prolonged exercise in relation for ORS formulation are discussed.
Sodium and water loss during, and replacement after, exercise-induced volume depletion was investigated in six volunteers volume depleted by 1.89 +/- 0.17% (SD) of body mass by intermittent exercise in a warm, humid environment. Subjects exercised in a large, open plastic bag, allowing collection of all sweat secreted during exercise. For over 60 min beginning 40 min after the end of exercise, subjects ingested drinks containing 0, 25, 50, or 100 mmol/l sodium (trials 0, 25, 50, and 100) in a volume (ml) equivalent to 150% of the mass lost (g) by volume depletion. Body mass loss and sweat electrolyte (Na+, K+, and Cl-) loss were the same on each trial. The measured sweat sodium concentration was 49.2 +/- 18.5 mmol/l, and the total loss (63.9 +/- 38.7 mmol) was greater than that ingested on trials 0 and 25. Urine production over the 6-h recovery period was inversely related to the amount of sodium ingested. Subjects were in whole body negative sodium balance on trials 0 (-104 +/- 48 mmol) and 25 (-65 +/- 30 mmol) and essentially in balance on trial 50 (-13 +/- 29 mmol) but were in positive sodium balance on trial 100 (75 +/- 40 mmol). Only on trial 100 were subjects in positive fluid balance at the end of the study. There was a large urinary loss of potassium over the recovery period on trial 100, despite a negligible intake during volume repletion. These results confirm the importance of replacement of sodium as well as water for volume repletion after sweat loss. The sodium intake on trial 100 was appropriate for acute fluid balance restoration, but its consequences for potassium levels must be considered to be undesirable in terms of whole body electrolyte homeostasis for anything other than the short term.
During endurance exercise, about 75% of the energy produced from metabolism is in the form of heat, which cannot accumulate. The remaining 25% of energy available can be used for movement. As running pace increases, the rate of heat production increases. Also, the larger one's body mass, the greater the heat production at a particular pace. Sweat evaporation provides the primary cooling mechanism for the body, and for this reason athletes are encouraged to drink fluids to ensure continued fluid availability for evaporation and circulatory flow to the tissues. Elite level runners could be in danger of heat illness if they race too quickly in hot/humid conditions and may collapse at the end of their event. Most marathon races are scheduled at cooler times of the year or day, however, so that heat loss to the environment is adequate. Typically, this postrace collapse is due simply to postural hypotension from decreased skeletal muscle massage of the venous return circulation to the heart on stopping. Elite athletes manage adequate hydration by ingesting about 200-800 mL/hour, and such collapse is rare. Athletes "back in the pack" are moving at a much slower pace, however, with heat accumulation unlikely and drinking much easier to manage. They are often urged to drink "as much as tolerable," ostensibly to prevent dehydration from their hours out on the race course. Excessive drinking among these participants can lead to hyponatremia severe enough to cause fatalities. A more reasonable approach is to urge these participants not to drink as much as possible but to drink ad libitum (according to the dictates of thirst) no more than 400-800 mL/hour.
To investigate the possible role of carbohydrate (CHO) receptors in the mouth in influencing exercise performance, seven male and two female endurance cyclists (VO(2max) 63.2 +/- 2.7 (mean +/- SE) mL.kg*(-1).min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (914 +/- 40 kJ). On one occasion a 6.4% maltodextrin solution (CHO) was rinsed around the mouth for every 12.5% of the trial completed. On the other occasion, water (PLA) was rinsed. Subjects were not allowed to swallow either the CHO solution or water, and each mouthful was spat out after a 5-s rinse.
Performance time was significantly improved with CHO compared with PLA (59.57 +/- 1.50 min vs 61.37 +/- 1.56 min, respectively, P = 0.011). This improvement resulted in a significantly higher average power output during the CHO compared with the PLA trial (259 +/- 16 W and 252 +/- 16 W, respectively, P = 0.003). There were no differences in heart rate or rating of perceived exertion (RPE) between the two trials (P > 0.05).
The results demonstrate that carbohydrate mouth rinse has a positive effect on 1-h time trial performance. The mechanism responsible for the improvement in high-intensity exercise performance with exogenous carbohydrate appears to involve an increase in central drive or motivation rather than having any metabolic cause. The nature and role of putative CHO receptors in the mouth warrants further investigation.
Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance.