Susan M Shirreffs's research while affiliated with St. Andrews University and other places

Publications (155)

Article
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Muscle cramp is a temporary but intense and painful involuntary contraction of skeletal muscle that can occur in many different situations. The causes of, and cures for, the cramps that occur during or soon after exercise remain uncertain, although there is evidence that some cases may be associated with disturbances of water and salt balance, whil...
Article
The 2019 International Amateur Athletics Federation Track-and-Field World Championships will take place in Qatar in the Middle East. The 2020 Summer Olympics will take place in Tokyo, Japan. It is quite likely that these events may set the record for hottest competitions in the recorded history of both the Track-and-Field World Championships and Ol...
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Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition program. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including the management of m...
Article
The use of dietary supplements is widespread among athletes in all sports and at all levels of competition, as it is in the general population. For the athlete training at the limits of what is sustainable, or for those seeking a shortcut to achieving their aims, supplements offer the prospect of bridging the gap between success and failure. Survey...
Article
Full-text available
Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the managemen...
Chapter
Water is the most abundant chemical constituent of the human body, typically making up approximately two thirds of body mass, but body water content is maintained within relatively narrow limits by a number of regulatory mechanisms. Both a reduction (hypohydration) and increase (hyperhydration) in body water may, if sufficiently severe, lead to adv...
Chapter
Volleyball athletes must perform numerous maximum effort jumps and quick, short sprints, interspersed by variable periods of exercise of lower intensity or brief periods of rest. The energy used during periods of high-intensity play is derived largely from anaerobic metabolism. Some standardized models of intermittent exercise have been developed r...
Article
Hypohydration, or a body water deficit, is a common occurrence in athletes and recreational exercisers following the completion of an exercise session. For those who will undertake a further exercise session that day, it is important to replace water losses to avoid beginning the next exercise session hypohydrated and the potential detrimental effe...
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Methods: Twelve males (26 ± 4 years, 80.1 ± 9.3 kg, 1.81 ± 0.05 m, V̇O2peak 60.1 ± 8.9 ml.kg(-1).min(-1)) participated in three randomised trials undertaken 7-14 days apart. Participants rested for 30 min then completed a 60 min HIIE exercise period (20 x 1 min at 100% V̇O2peak with 2 min rest) followed by 60 min of recovery, during which ad libit...
Chapter
Many different factors combine to produce a successful performance in sporting contests, with genetic endowment playing a large role. Other factors also intervene, but many of these also have a genetic basis, including the ability to adapt to a training program and probably also the psychological factors that encompass motivation, competitiveness,...
Article
This study examined the effects of sodium chloride and potassium chloride supplementation during 48-h severe energy restriction on exercise capacity in the heat. Nine males completed three 48-h trials: adequate energy intake (100 % requirement), adequate electrolyte intake (CON); restricted energy intake (33 % requirement), adequate electrolyte int...
Article
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On April 7-8, 2014, the European Hydration Institute hosted a small group of experts at Castle Combe Manor House, United Kingdom, to discuss a range of issues related to human hydration, health, and performance. The meeting included 18 recognized experts who brought a wealth of experience and knowledge to the topics under review. Eight selected top...
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Heat stress and exercise increase water loss from the body, primarily in the form of sweat. For some occupational groups, including miners, construction workers in hot climates, soldiers, and some athletes, daily water losses can reach 10-12 L. These losses must be replaced on a daily basis to maintain functional capacity. Both hyperhydration and h...
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Previous investigations have suggested that exercise at intensities greater than 70% VO2max reduces gastric emptying rate during exercise, but little is known about the effect of exercise intensity on gastric emptying in the post-exercise period. To examine this, eight healthy subjects completed three experimental trials that included 30 minutes of...
Article
This study examined the effect of electrolyte addition to drinks ingested after severe fluid and energy restriction (FER). Twelve subjects (six male, six female) completed three trials consisting of 24 h FER (energy intake: 21 kJ·kg body mass; water intake: 5 ml·kg body mass), followed by a 2 h rehydration period and a 4 h monitoring period. During...
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The aim was to examine the hydration status of adults working in different jobs at the beginning and end of a shift and their reported water intake. One hundred and fifty-six subjects (89 males, 67 females) were recruited from workplaces within the local area (students, teachers, security, office, firefighters, catering). A urine sample was obtaine...
Article
The use of alcohol is often intimately associated with sport. As well as providing a source of energy, alcohol (ethanol) has metabolic, cardiovascular, thermoregulatory, and neuromuscular actions that may affect exercise performance. Strength is minimally affected, and performance impairments depend on the dose of alcohol and subject habituation to...
Article
Exercising in cold environments results in water losses, yet examination of resultant voluntary water intake has focused on warm conditions. The purpose of the study was to assess voluntary water intake during and following exercise in a cold compared with a warm environment. Ten healthy males (22 ± 2 years, 67.8 ± 7.0 kg, 1.77 ± 0.06 m, VO2peak 60...
Article
Weight categorized athletes use a variety of techniques to induce rapid weight loss (RWL) in the days leading up to weigh in. This study examined the fluid and electrolyte balance responses to 24-hr fluid restriction (FR), energy restriction (ER) and fluid and energy restriction (F+ER) compared with a control trial (C), which are commonly used tech...
Chapter
Alcohol is both a nutrient and a drug. Being a significant source of energy, ethanol has a number of effects that have implications for athletic performance. There are reasons to believe that acute alcohol intake may impair the performance of endurance exercise because of effects on metabolic, cardiovascular, and thermoregulatory functions, and tha...
Article
Water intake occurs following a period of high-intensity intermittent exercise (HIIE) due to sensations of thirst yet this does not always appear to be caused by body water losses. Thus, the aim was to assess voluntary water intake following HIIE. Ten healthy males (22 ± 2 y, 75.6 ± 6.9 kg, V̇O2peak 57.3 ± 11.4 m·kg-1·min-1; mean± SD) completed two...
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Muscle-wasting in chronic kidney disease (CKD) arises from several factors including sedentary behaviour and metabolic acidosis. Exercise is potentially beneficial but might worsen acidosis through exercise-induced lactic acidosis. We studied the chronic effects of exercise in CKD stage 4-5 patients (brisk walking, 30 min, 5 times/week), and non-ex...
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Background: Various recommendations exist for total water intake (TWI), yet it is seldom reported in dietary surveys. Few studies have examined how real-life consumption patterns, including beverage type, variety and timing relate to TWI and energy intake (EI). Methods: We analysed weighed dietary records from the National Diet and Nutrition Sur...
Data
Time charts of beverage consumption for each day in males and females.
Article
Studies to assess water intake have been undertaken in many countries around the world. Some of these have been large-scale studies, whereas others have used a small number of subjects. These studies provide an emerging picture of water and/or fluid consumption in different populations around the world. Studies of this nature have also formed the b...
Article
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 beg...
Article
Diet can significantly influence athletic performance, but recent research developments have substantially changed our understanding of sport and exercise nutrition. Athletes adopt various nutritional strategies in training and competition in the pursuit of success. The aim of training is to promote changes in the structure and function of muscle a...
Article
The efficacy of drinks containing low concentrations of CHO (2%-6%) on physical performance in cool and warm environments was evaluated. In two separate but related studies, 24 healthy males completed a familiarization trial and four trials to volitional exhaustion (TTE) at 70% VO2max in cool conditions (10°C, n = 12) or 60% VO2max in a warm enviro...
Chapter
IntroductionDisturbances in body waterEffects of changes in hydration on exercise performanceEffects of drinking on exerciseFurther reading
Chapter
IntroductionHomeostasisAcute responses to exerciseAdaptations to exercise trainingConcluding remarksFurther reading
Article
The addition of carbohydrate to drinks designed to have a role in rehydrating the body is commonplace. The gastric emptying and fluid uptake characteristics following repeated ingestion of drinks with high and low glucose concentrations were examined in eight subjects (three male and five female). Following a 13 h fluid restriction period, the subj...
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Fluids and electrolytes (sodium) are consumed by athletes, or recommended to athletes, for a number of reasons, before, during, and after exercise. These reasons are generally to sustain total body water, as deficits (hypohydration) will increase cardiovascular and thermal strain and degrade aerobic performance. Vigorous exercise and warm/hot weath...
Article
The rate at which ingested fluid is emptied from the stomach is influenced by a number of factors. Exercise at intensities greater than 70% VO2max has been shown to reduce gastric emptying rates in healthy individuals,1 but to date, no studies have reported the effects of differing exercise intensities on gastric emptying characteristics after the...
Article
This study investigated water absorption and blood volume changes after drinking water and 3% and 6% carbohydrate drinks. Nine healthy male volunteers completed this crossover study after giving informed consent to participate. On three separate occasions they consumed 500 ml of Evian water (W), a 3% carbohydrate drink (3% CHO) or a 6% carbohydrate...
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During a football match played in warm (34.3 ± 0.6 °C), humid (64 ± 2% rh) conditions, 22 male players had their pre-match hydration status, body mass change, sweat loss and drinking behavior assessed. Pre-match urine specific gravity (1.012 ± 0.006) suggested that all but three players commenced the match euhydrated. Players lost 3.1 ± 0.6 L of sw...
Article
The high metabolic rates and body temperatures sustained by football players during training and matches causes sweating--particularly when in warm or hot environments. There is limited published data on the effects of this sweat loss on football performance. The limited information available, together with knowledge of the effects of sweat loss in...
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Dehydration and hyperthermia both, if sufficiently severe, will impair exercise performance. Dehydration can also impair performance of tasks requiring cognition and skill. Body temperature may exceed 40 °C in competitive games played in hot weather, but limited data are available. Football played in the heat, therefore, poses a challenge, and effe...
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Heat stress may contribute to decreased match performance when football is played in extreme heat. This study evaluated activity patterns and thermal responses of players during soccer matches played in different environmental conditions. Non-acclimatized soccer players (n=11, 20±2 years) played two matches in conditions of moderate heat (MH) and h...
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We investigated the cognitive effects of exercising in the heat on the field players of two football teams in a series of three matches. Different rehydration and cooling strategies were used for one of the teams during the last two games. Cognitive functions were measured before, during and immediately after each football match, as well as core te...
Article
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 hy...
Article
Dehydration, if sufficiently severe, impairs both physical and mental performance, and performance decrements are greater in hot environments and in long-lasting exercise. Athletes should begin exercise well hydrated and should drink during exercise to limit water and salt deficits. Many athletes are dehydrated to some degree when they begin exerci...
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Preamble This document focuses on recommended measures and precautions for playing football (soccer) in a hot environment with an emphasis on the prevention of heat illness in competitive male players. The prevalence of heat illness in football is unclear but incidents where footballers from various codes have died with heat-related symptoms have b...
Article
The aims of this study were to determine the effect of cold (4 °C) and thermoneutral (37 °C) beverages on thermoregulation and performance in the heat and to explore sensory factors associated with ingesting a cold stimulus. Seven males (age 32.8 ± 6.1 years, [V(.)]O(2peak) 59.4 ± 6.6 ml x kg(-1) x min(-1)) completed cold, thermoneutral, and thermo...
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Increased core temperature (T(c)), impaired cardiovascular function, and dehydration contribute to fatigue during prolonged exercise in the heat. Although many studies have examined mechanisms addressing these factors, few have investigated the effect of cold beverage temperature on thermoregulation and exercise performance in the heat. Citations f...
Article
This study investigated fluid and electrolyte balance in well-trained male and female swimmers during 2 training sessions. Participants were 17 nationally ranked swimmers measured during a period of intensive training. Sweat loss was assessed from changes in body mass after correction for fluid intake and urine collection. Sweat composition was mea...
Article
There is evidence to suggest that exercise-induced dehydration can have a negative impact on exercise performance, and restoration of fluid balance should be achieved after exercise. It is equally well known that muscle glycogen must be restored after exercise if subsequent performance is not to be negatively affected. Sports drinks are ideally pla...
Article
The effectiveness of different carbohydrate solutions in restoring fluid balance in situations of voluntary fluid intake has not been examined previously. The effect of the carbohydrate content of drinks ingested after exercise was examined in 6 males and 3 females previously dehydrated by 1.99 +/- 0.07% of body mass via intermittent exercise in th...
Article
This study investigated the effect of the osmolality and carbohydrate content of drinks on their rehydration effectiveness after exercise-induced dehydration. Six healthy male volunteers were dehydrated by 1.9+/-0.1% of body mass by intermittent cycle ergometer exercise in the heat before ingesting one of three solutions with different carbohydrate...
Article
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Exertional heat illness is one of the most important health problems of athletes who have to train and compete in hot and humid environmental conditions. To our knowledge there are no published data that reflect the effects of heat strain on soccer players under extreme heat conditions. PURPOSE: The aim of this study was to evaluate the effect of a...
Article
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Soccer teams may sometimes be obliged to play under difficult environmental conditions. Indoor laboratory measurements may underestimate the associated thermoregulatory heat stress. PURPOSE: To evaluate the heat stress responses of players during soccer matches played in different environmental temperatures and humidity. METHODS: Non-acclimatized s...
Chapter
Body water and its compositionControl of body water and its compositionBody water balance during exerciseHydration status and water turnoverPre-exercise hydration, drinking during exercise, and post-exercise rehydrationConclusions References
Article
The aim of this study was to assess water and salt balance in young football players in training during Ramadan. Measurements were made in 92 young male football players before and during the month of Ramadan. Fifty-five participants were observing Ramadan fasting, while the other 37 participants were eating and drinking without restriction. In wee...
Article
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...
Article
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...
Article
Sweat evaporation can be a key thermoregulatory mechanism and it causes a loss of water from all compartments of the body. Hypohydration can also develop with restricted fluid intake or with intake of diuretics. Hypohydration can affect physical and/or mental performance and/or have implications for dietary recommendations. A variety of different t...
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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 duri...
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Following a 2.0 +/- 0.1% body mass loss induced by intermittent exercise in the heat, seven male volunteers ingested either a carbohydrate-electrolyte solution (CE) or skimmed milk (M) in a volume equal to 150% of body mass loss. At the end of the 3 h recovery period, subjects were essentially in positive fluid balance on trial M (191 +/- 162 mL),...
Article
To investigate how differing moderate sodium chloride concentrations affect rehydration after exercise and subsequent exercise capacity, eight males lost 1.98 +/- 0.1% body mass exercising in the heat, then consumed one of four drinks in a volume equivalent to 150% of mass loss. Drinks were identical except for sodium chloride content (1 +/- 1, 31...
Article
Effect of electrolyte consumption on fluid and electrolyte balance during 24 h energy restriction - Volume 67 Issue OCE8 - Lewis J. James, Susan M. Shirreffs
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Full-text available
The effects of fluid intake during prolonged exercise have been extensively studied but at present there exists little information on the effects of milk-based drinks on the response to prolonged exercise. Thus, the purpose of this study was to investigate the effects of milk-based drinks on exercise capacity. Eight healthy males (age 24 +/- 4 y, h...
Article
Water turnover rates of a wheelchair rugby squad during an international tournament - Volume 67 Issue OCE8 - Katherine Black, Ronald Maughan, Susan Shirreffs
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In this study, we examined thermoregulatory responses to ingestion of separate aliquots of drinks at different temperatures during low-intensity exercise in conditions of moderate heat stress. Eight men cycled at 50% (s = 3) of their peak oxygen uptake (VO2peak) for 90 min (dry bulb temperature: 25.3 degrees C, s = 0.5; relative humidity: 60%, s =...
Chapter
This chapter deals with the primary factors influencing the rehydration process after exercise. These factors include the volume and composition of the fluid consumed. Studies conducted by Shirreffs and Maughan demonstrated an interaction between the drink volume consumed and its sodium content. A section on beverage composition describes the role...
Article
Fluid balance and sweat electrolyte losses were measured in the players and substitutes engaged in an English Premier League Reserve competitive football match played at an ambient temperature of 6-8 degrees C (relative humidity 50-60%). Intake of water and/or sports drink and urine output were recorded, and sweat composition was estimated from abs...
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Athletics is a popular sport among young people. To maintain health and optimize growth and athletic performance, young athletes need to consume an appropriate diet. Unfortunately, the dietary intake of many young athletes follows population trends rather than public health or sports nutrition recommendations. To optimize performance in some discip...
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The diverse nature of the athletic events, together with the varied training programmes and individuality of athletes taking part, inevitably means that fluid needs are highly variable--between athletes, perhaps between training and competition, and with differing environmental conditions and degree of training and heat acclimatization. There are l...