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Effect of Acute Mild Dehydration on Cognitive-Motor Performance in Golf
Abstract
Smith, MF, Newell, AJ, and Baker, MA. Effect of acute mild dehydration on cognitive-motor performance in golf. J Strength Cond Res 26(11): 3075-3080, 2012-Whether mild dehydration (-1 to 3% body mass change [ΔBM]) impairs neurophysiological function during sport-specific cognitive-motor performance has yet to be fully elucidated. To investigate this within a golfing context, 7 low-handicap players (age: 21 ± 1.1 years; mass: 76.1 ± 11.8 kg; stature: 1.77 ± 0.07 m; handicap: 3.0 ± 1.2) completed a golf-specific motor and cognitive performance task in a euhydrated condition (EC) and dehydrated condition (DC) (randomized counterbalanced design; 7-day interval). Dehydration was controlled using a previously effective 12-hour fluid restriction, monitored through ΔBM and urine color assessment (UCOL). Mild dehydration reduced the mean BM by 1.5 ± 0.5% (p = 0.01), with UCOL increasing from 2 (EC) to 4 (DC) (p = 0.02). Mild dehydration significantly impaired motor performance, expressed as shot distance (114.6 vs. 128.6 m; p < 0.001) and off-target accuracy (7.9 vs. 4.1 m; p = 0.001). Cognitive performance, expressed as the mean error in distance judgment to target increased from 4.1 ± 3.0 m (EC) to 8.8 ± 4.7 m (DC) (p < 0.001). The findings support those of previous research that indicates mild dehydration (-1 to 2% ΔBM) significantly impairs cognitive-motor task performance. This study is the first to show that mild dehydration can impair distance, accuracy, and distance judgment during golf performance.
... The most recent literature suggests that golf can provide a high-volume, moderate-intensity activity [~ 4.8 metabolic equivalents (METs)] with numerous physical and mental health benefits associated with playing the sport [3,4]. Poor nutrition and hydration may adversely affect golf performance, from both a physical and cognitive perspective [5,6]; however, most of the published research in golf has focussed on aspects of general health, strength and conditioning, or biomechanics [4,7,8], with limited high-quality studies on the nutritional requirements of the sport. ...
... Hydration on the golf course can be affected by several factors including participant demographics, fluid intake, exercise intensity, sweat rate, competition climate and the type of clothing worn. Dehydration is associated with poorer cognitive function, raised core body temperature, increased glycogen utilisation, and increased sensation of fatigue, which may all lead to a negative effect on golf performance [5,26]. It was therefore of no surprise that hydration and the golfer was one of the more researched areas of performance nutrition for golf. ...
... In support of this suggestion, the authors asked the golfers to complete the fluid section of a nutrition knowledge questionnaire, and it was reported that the golfers who started the round dehydrated displayed less knowledge on hydration compared with players in the euhydrated state. In a similar study using seven amateur golfers (HCP 3.0 ± 1.2), it was reported that cognitive tasks, including the golfers' overall distance and accuracy judgements were impaired when even mildly dehydrated [5]. The dehydrated athletes experienced a body weight (BW) loss of just 1.1 kg, supporting previous suggestions that even modest levels of dehydration may be associated with performance decrements [26], in particular cognitive function [29]. ...
Background
Golf is played both recreationally and professionally by approximately 66.6 million people worldwide. Despite the potential for nutrition to influence golf performance, research in this area is somewhat limited.
Objective
To identify the existing literature regarding nutrition and golf and where the current research gaps lie.
Design
Scoping review. Online databases were used to retrieve data from 2003 to the present day.
Data Sources
A three-step search strategy identified relevant primary and secondary articles as well as grey literature. Published and unpublished articles in the English language, identified by searching electronic databases (ProQuest Central, Web of Science, Scopus, SPORTDiscus and PubMed) and reference searching.
Review Methods
Relevant identified studies were screened for final inclusion. Data were extracted using a standardised tool to create a descriptive analysis and a thematic summary. In summary, studies were included if they focused on nutrition, hydration, energy requirements, supplements, or body composition in relation to golf.
Results and Discussion
Our initial search found 3616 relevant articles. Eighty-two of these articles were included for the scoping review. Nutrition has the potential to impact golf performance in areas including the maintenance of energy levels, cognitive function, and body composition. Currently, there is limited research available discussing the effects of nutrition interventions related specifically to golf performance.
Conclusion
This scoping review highlights that more work is needed to provide golfers and practitioners with golf-specific nutrition research. The key areas for future golf-specific nutrition research include nutrition on cognitive performance, body composition, energy requirements, supplementation, and the potential role of nutrition for the travelling golfer. Systematic reviews could also be used to identify future priorities for nutrition and golf research.
... Однією з важливих причин неефективної практики споживання рідини процесі тренувань є те, що спортсмени рідко мають достатнє розуміння того, що вони повинні пити, скільки або як часто [7]. Попередні дослідження показали, що коли спортсменів оцінювали на їх знання щодо питного режиму, споживання мікро-та макроелементів, лише 9% з них показали адекватні знання в цій області [12]. Дослідження також показали, що більшість спортсменів схильні покладатися на відчуття спраги, в рішенні коли їм слід пити під час тренувань і змагань. ...
... Дослідження також показали, що більшість спортсменів схильні покладатися на відчуття спраги, в рішенні коли їм слід пити під час тренувань і змагань. На жаль, коли спортсмени покладаються лише на відчуття спраги, вони не п'ють достатньо, щоб запобігти виникненню зневоднення [2,12]. Це підкріплюється даними, про те, що більшість спортсменів починають тренування або змагання в дещо зневодненому стані [3,8]. ...
... Ефективність моторного контролю учасників ми оцінювали за допомогою тесту Jebsen-Taylor [12]. Усе тестування проводилося в тихій, добре освітленій кімнаті з мінімальними сторонніми відволіканнями та складалося з семи субтестів. ...
The purpose of the study is to find out the expediency of using an individual drinking regime during the training of track and field athletes at the stage of preliminary basic training. We found out that currently there is not enough data to reasonably plan fluid consumption during the training process of track and field athletes, taking into account the individual characteristics of the intensity of sweating. And also that uncontrolled fluid consumption during training prevails in sports practice. Coaches and athletes prefer thirst as a guideline for drinking during training. We have devoted attention to the question of the effect of dehydration on the functional performance of track and field athletes-runners and the individual drinking regime as a way to increase it. In particular, we estimated the amount of fluid that student athletes lose during training, the rate of such loss, and checked how the individual drinking regimen, which takes into account the volume of fluid lost by the athlete during training, affects motor efficiency according to the Jebsen-Taylor test. And also, how this mode affects the dynamics of explosive power during training. We were able to identify a principle that, taking into account in the drinking regime, can significantly reduce the impact of fatigue on the functional performance of track and field athletes. We have formulated recommendations for establishing individual drinking regimes for track and field athletes-runners taking into account the volume of fluid lost with sweat, worked out and verified in practice the implementation of the drinking regime in the conditions of the training process.
... A decrease in cognitive functioning was observed in dehydrated state (n = 12) (Baker et al., 2007;Serwah and Marino, 2006;Lee et al., 2014;Moyen et al., 2015;Savvides et al., 2020;Donnan et al., 2021;Bandelow et al., 2010;Sun et al., 2020;Pruna et al., 2014;Fortes et al., 2018;Smith et al., 2012;Carrasco, 2008). In all the studies, athletes exercised at high intensity or stimulated competitions/protocols for more than 1 h. ...
... In the observed studies (n = 12), athletes were under heat stress (>30°C) (Baker et al., 2007;Serwah and Marino, 2006;Lee et al., 2014;Moyen et al., 2015;Savvides et al., 2020;Donnan et al., 2021;Bandelow et al., 2010). Two studies did not mention the climatic conditions (Sun et al., 2020;Pruna et al., 2014), whereas the remaining studies' (n = 3) athletes were not under heat stress (<30°C) (Fortes et al., 2018;Smith et al., 2012;Carrasco, 2008). ...
... Visual-motor skills showed no significant change with dehydration (Lee et al., 2014;MacLeod et al., 2018;Grego et al., 2004). However, motor skills were decreased in 30-ball golf play at 20.6°C in a dehydrated condition (Smith et al., 2012). No change was observed in a jockey race (Dolan et al., 2013) or 67-km cycling at 27.1°C (Herculano et al., 2019). ...
The detrimental effects of dehydration on cognitive functioning have been researched; however, definitive conclusions were not extracted. Therefore, the present review aimed to examine the role of hydration status and its influence on cognitive functioning in athletes. Research studies were identified by searching online databases such as PubMed, Google Scholar and ProQuest using the keywords ‘hypohydration’, ‘dehydration’, ‘hydration’, ‘euhydration’, ‘cognition’, ‘cognitive performance’, ‘cognitive functioning’, ‘athletes’ and ‘sportspersons’. A total of 50 original studies were identified, and 24 articles that met the inclusion criteria were examined for the review. A decrease in cognitive functioning was reported in 12 studies with dehydration. This trend was particularly observed when dehydration was coupled with increased exercise duration and/or exercising in a hot environment or high-intensity exercise. Ten studies did not find any impact of dehydration or euhydration on cognitive functioning, and two studies showed increased attention and accuracy in dehydration. Cognitive functioning seems to be unaffected due to dehydration until there is an increased exercise intensity and/or duration in hot and humid conditions. Further studies high in the hierarchy are required to provide definitive conclusions due to limited scientific evidence, heterogeneity in the methodology and non-applicability of outcomes to both genders.
... Beverages containing electrolytes and carbohydrates should be consumed to ensure adequate hydration to optimise cognitive function and remain euhydrated. [13,22,23] Supplement Use ...
... The mean number of total strokes taken to complete an 18-hole competitive round was significantly higher in players that were dehydrated before commencing competition at 79.5 ± 2.1 strokes compared to euhydrated players who used 75.7 ± 3.9 strokes [42]. Similarly, Smith and colleagues (2012) observed negative impacts on golf performance following an acute mild dehydration [23]. The results showed a significant difference in overall distance achieved using a 9-iron club (9i) in the dehydrated state (114.6 m ± 12.9 m) compared to the euhydrated state (128.6 ± 8.8 m) [23]. ...
... Similarly, Smith and colleagues (2012) observed negative impacts on golf performance following an acute mild dehydration [23]. The results showed a significant difference in overall distance achieved using a 9-iron club (9i) in the dehydrated state (114.6 m ± 12.9 m) compared to the euhydrated state (128.6 ± 8.8 m) [23]. Performance for accuracy was also negatively impacted by the dehydrated state with a significantly higher level of inaccuracy for the dehydrated players (7.9 ± 2.0 m) compared to the euhydrated players (4.1 ± 0.8 m). ...
Golf is predominantly a skill-based sport where technical aspects are regarded as a priority area for improving performance. At present, most of the existing literature has focused on improving a player’s physicality, endurance and technical attributes in an effort to enhance performance. While important, the role of nutrition in elite golf has received little attention to date. The energy demands of the sport can vary depending on the level of the individual (recreational–professional), with distances of up to 20 km being covered and the time spent on the course ranging approximately 4–8 h each day. Like other sports, a focus on pre-game, during and post-game nutrition, including hydration, is integral to ensuring that individuals are adequately fuelled, hydrated and optimally recovered. For the elite athletes who travel extensively to international tournaments, it is important to understand the additional impact of travel on the body and consider the role nutrition can play in preventing illness and ensuring minimal disruption to golf performance. Lastly, the role of dietary supplements to enhance the performance of golfers is also important to consider. This review aims to consolidate the findings of the existing research focusing on nutrition strategies for golf performance and identify areas for potential future research.
... The first study observed normal drinking habits and demonstrated that male elite collegiate golfers (n = 15) who were significantly or seriously dehydrated had a four-stroke higher average than golfers who were euhydrated or minimally dehydrated after a competitive 18-hole round [3]. The second study, a repeated measures counterbalanced study design with elite male golfers (n = 7), induced mild dehydration (change in body weight = −1.5 ± 0.5%) [4]. These golfers demonstrated an 11% loss in average iron distance, near doubling of off target iron accuracy, and over a six-fold increase in overestimation of distance from pin compared to their euhydrated condition (change in body weight = −0.3 ...
... These golfers demonstrated an 11% loss in average iron distance, near doubling of off target iron accuracy, and over a six-fold increase in overestimation of distance from pin compared to their euhydrated condition (change in body weight = −0.3 ± 0.6%) [4]. Thus, research quantifying the detriments of dehydration on performance may increase awareness among coaches and athletes. ...
... For example, euhydrated athletes have greater body fluid available to supply blood and oxygen to working muscles and to produce sweat to cool the body and prevent heat-related disorders. Some sources report that water loss beginning at 1-2% of body weight leads to an increase in heart rate and a decrease in exercise performance [1,[3][4][5]. In general, dehydration of 1-2% body weight does not appear to impact exercise performance of exercise lasting less than 90 min; however, some evidence ...
Athletes’ commitments to nutrition practices can set them apart in their field. Few studies have investigated the impact of hydration practices on golfers’ performance who compete for up to eight hours a day, and none have studied female golfers. In this pilot, randomized crossover study, female elite golfers (n = 6) completed 4 simulated golf holes in both euhydrated and dehydrated states. Euhydration was attained by following NCAA (National Collegiate Athletic Association) hydration guidelines; dehydration was attained by a 12-h overnight fluid fast. Before any fluid intervention, five out of six participants were dehydrated at baseline using urinary specific gravity (USG) classifications for euhydration (USG < 1.010) and dehydration (USG > 1.010). No significant condition by time interactions were found between hydration conditions. Although not significant, participants in a dehydrated state demonstrated lesser mean 7-iron distance (141.9 ± 10.0 vs 144.2 ± 8.0 m), lower putting accuracy (2.4 ± 1.0 vs 2.7 ± 10.0 putts made out of 4 attempts), and greater perceived effort (10.9 ± 2.1 vs 10.5 ± 1.6) as compared to their euhydrated state. The finding of one participant out of six with significant dehydration (USG = 1.021) during attempted euhydrated state may suggest the need for alternative methods to promote adequate hydration in future studies and possibly in golf practice.
... Importantly, the ad libitum water consumption of academy batters could explain the discrepancies in fluid loss between cohorts, and between previous investigations. During According to previous exercise studies, the larger reduction of body mass in schoolboy batters (0.97 kg or 1.27% BM) when compared to academy batters (0.58 kg 0.75% BM), could explain cognitive impairment (Carrasco, 2008;D'Anci et al., 2009;Ganio et al., 2011;Smith, Newell, & Baker, 2012;Hillyer et al., 2015). Exercise that induces a mean loss of ≥1% BM significantly increases cognitive impairment (Neave et al., 2004;Ganio et al., 2011). ...
... Additionally, exercise with an intensity or duration that imposes body mass reductions > 2% has even larger decrements in cognitive performance (Carrasco, 2008;D'Anci et al., 2009;Smith, Newell, & Baker, 2012;Hillyer et al., 2015). ...
... Similarly, Neave and colleagues (2004) reported significant impairment of cognitive performance when batters lost 0.8% BM during 30 min of high-intensity batting. In golf, cognitive impairment coincides with dehydration-induced body mass reduction of 1-2% (Smith et al., 2012). It is then safe to say, that dehydration of the schoolboy sample was an implicating factor that lead to cognitive impairments in executive function, vigilance and attention and working memory. ...
... Because there are many cognitive domains that contribute to cognitive function, some studies focused on specific domains. In many of the studies on athletic populations such as golfers, 10 soccer players, 15 and jockeys, 16 the testing methods were sport-specific to determine the effects of dehydration on the cognitive aspect of their specific sport. Task-specific outcomes are also seen among cognitive tests in military personnel. ...
... Another reason for the mixed results in the literature is the variety of methods employed to achieve dehydration. Common interventions include: Water deprivation, 10,19 passive heat stress, 7,11,16 exercise, 11,14,20 combined exercise and heat, 5,6,12 and comparison of dehydration methods. 7,8 Since dehydration can result from various and multiple insults, various dehydration methods must be tested and should reflect the population being studied. ...
... In contrast to our hypothesis, the main findings of the present study indicated that Stroop reaction time during the Stroop test and reaction time during the shifting attention test were enhanced by a sport-specific dehydration protocol employing both heat and exercise, and reaction time during the shifting attention test was significantly different even after the Bonferroni correction was applied. Previous studies have generally found that dehydration caused a decrement in cognitive function [5][6][7][8][9][10] or that no significant changes occurred. [13][14][15]18,19,26 However, three studies did demonstrate cognitive improvement after dehydration. ...
... The populations of the studies were all males, who were classified as healthy and active. Some of the participants were involved in specific sports including cycling, 8,12 rugby, 2 golf, 13 soccer, 14 and triathlon 7 with the remaining participants from the general population. 3,4,15 The average population size for the studies was nine participants ranging from seven to 12 participants. ...
... 3,4,7,8,12e15 Two of these anaerobic studies did however consider the effect dehydration had on the aerobic exercise that was undertaken to induce a dehydrated state. 8,12 Two studies used sport specific skills to assess performance, 13,14 two the Wingate test, 3,15 and another two a graded exercise test to exhaustion. 7,12 One study looked at distance travelled in 30 min 2 while another used a 5-km time trial to determine performance impacts. ...
... 3,7,8,12 In addition, the captured studies noted increases in relative VO 2 and heart rate with dehydration, 2 decreased gross efficiency, 7 decreased speed, 8 decreased time to exhaustion, 12 and decreased sportspecific skills. 13 Two studies identified an increase in "Ratings of Perceived Exertion" levels with dehydration 2,14 with a third study noting a 70% increase in the severity of fatigue with dehydration. 3 In contrast, one study did find only a slight, non-significant increase in fatigue severity with dehydration. ...
Purpose: The purpose of this review was to critically analyse the current evidence investigating the effect of an athlete's hydration status on physical performance.
Methods: A literature search of multiple databases was used to identify studies that met the inclusion criteria for this review. The included studies were then critically appraised using the Downs and Black protocol.
Results: Nine articles were found to meet the inclusion criteria, with an average score of 79% for methodological quality representative of a “high” standard of research.
Conclusion: The evidence suggests that dehydration has a negative impact on physical performance for activities lasting more than 30 s in duration. However dehydration was found to have no significant impact on physical performance for activities lasting less than 15 s in duration.
... Hypohydration decreases the plasma volume of blood [8], reducing cerebral [9] and muscle blood flow [10], increasing heart rate and cardiovascular strain at any given intensity [11]. Consequently, hypohydration may impair many key performance indicators which characterise elite squash performance [1], such as aerobic capacity [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], anaerobic power [32-34], muscular endurance [11,32,35,36], lower-body muscular strength [32,[37][38][39][40][41][42][43], cognitive function [44][45][46][47][48], and sport specific technical skills [34,[49][50][51][52][53]. ...
... Three players increased body mass during the session, while two players reported a body mass loss greater than 2%, the associated threshold for a decline in physical and cognitive performance [54]. Previous research has quantified the effects of hypohydration on sport-specific performance in basketball [44,51,52], cricket [50,53], field hockey [46], golf [47], horse racing [38], and soccer [49]. Future research should aim to quantify if, and at what level, hypohydration decreases squash-specific performance [1]. ...
Elite squash players are reported to train indoors at high volumes and intensities throughout a microcycle. This may increase hydration demands, with hypohydration potentially impairing many key performance indicators which characterise elite squash performance. Consequently, the main aim of this study was to quantify the sweat rates and sweat [Na+] of elite squash players throughout a training session, alongside their hydration practices. Fourteen (males = seven; females = seven) elite or world class squash player’s fluid balance, sweat [Na+] and hydration practices were calculated throughout a training session in moderate environmental conditions (20 ± 0.4 °C; 40.6 ± 1% RH). Rehydration practices were also quantified post-session until the players’ next training session, with some training the same day and some training the following day. Players had a mean fluid balance of −1.22 ± 1.22% throughout the session. Players had a mean sweat rate of 1.11 ± 0.56 L·h−1, with there being a significant difference between male and female players (p < 0.05), and a mean sweat (Na+) of 46 ± 12 mmol·L−1. Players training the following day were able to replace fluid and sodium losses, whereas players training again on the same day were not. These data suggest the variability in players hydration demands and highlight the need to individualise hydration strategies, as well as training prescription, to ensure players with high hydration demands have ample time to optimally rehydrate.
... Dehydration leads to decrease in concentration, increase in reaction time, short-term memory, anxiety, and time to exhaustion. [5][6][7][8][9][10] Regarding the above factors, novel studies focusing on understanding the deeper knowledge on water consumption and its influence on health are of great interest. In recent years, water intake and its relation with body composition and energy expenditure patterns have gained greater attention. ...
... [23,24] Loss of body mass as little as 1%-2% through sweat loss can increase the heart rate, core temperature, heat storage, muscle glycogen use, as well as a decrease in cardiac output and cognitive function that include poor concentration, increased reaction time, and short-term memory and anxiety, and time to exhaustion. [5][6][7][8] Hence, consumption of adequate fluid intake before, during, and after exercise is important for the maintenance of biological, physiological, and cognitive functions. [25] Kho-Kho sport demands speed, agility as well as endurance activity with skill included in it, which helps in building physical fitness, strength, stamina, speed, and coordination along flexibility. ...
... (increased cardiovascular strain or altered glucose kinetics) function (Hillyer et al. 2015). Although, some studies suggest hypohydration is detrimental to skilled motor performance (Baker et al. 2007;Fortes et al. 2018;Lindseth et al. 2013;Smith et al. 2012), other empirical data demonstrate this physiological state may not impact basketball shooting (Dinu et al. 2018), motor racing performance (Mollica et al. 2019), or military target shooting and trigger control (Nolte et al. 2013). Despite the equivocal findings for motor performance, no study to date has investigated whether hydration may be of importance to developing the underlying procedural knowledge required for such performances; i.e. motor learning. ...
... Similarly, impaired motor performance during practice may also result in poorer acquisition. As hypohydration has the potential to alter both neurophysiologic function (Liu et al. 2013;) and behavioural psychomotor performance (Baker et al. 2007;Smith et al. 2012), this physiological stressor may influence motor learning. The aim of this study was to investigate whether moderate hypohydration (~ 2% loss in body mass) would alter motor acquisition of a visuomotor task and determine whether this would have implications on delayed retention and learning transferability. ...
It is unknown how hypohydration influences fine motor performance training and motor learning. Here, 30 participants (aged 19–46 years) were randomly assigned to a hypohydration (HYPO) or control (CON) group (both n = 15). Moderate hypohydration (~ 2.4% loss in body mass) was produced in HYPO via active dehydration before a 46 min fluid restricted rest period was undertaken. The conclusion of rest coincided with when CON attended the facilities. Both groups undertook a discrete sequence production task consisting of 6 training blocks, and returned ~ 300 min later to complete a delayed retention and transfer test while euhydrated. Bilateral pre-frontal cortex (PFC) haemodynamics were assessed using functional near-infrared spectroscopy throughout training and delayed learning assessments. Response time improved across training ( P < 0.01) and was similar between the groups (both P = 0.22). Analysis of training PFC haemodynamics revealed a significant group by block interaction for oxygenated (O 2 Hb; P < 0.01), but not deoxygenated haemoglobin ( P = 0.77). In training block 1, bilateral O 2 Hb was higher in HYPO ( P = 0.02), while bilateral O 2 Hb increased in CON between blocks 2–3 and 5–6 (both P ≤ 0.03). During the delayed retention and transfer test, no group differences or interactions were found in response time, response error, or PFC haemodynamics (all P ≥ 0.27). Moderate hypohydration does increase PFC activation during motor skill learning, however, this appears to be transient and of little consequence to training or delayed retention or transfer performance.
... No study has compared the effect of three macronutrient feedings on outdoor golf performance (Mumford et al., 2016;Smith et al., 2012;Stevenson et al., 2009). Therefore, the objective of this study was to assess in a small group of golf players the potential performance effects of a feeding of carbohydrates, carbohydrates and protein, or a zero-calorie control during a 9-hole simulated competitive golf game. ...
... A strength of this study was that it was performed in the field-setting on a real golf course. The small sample size (n = 6) was certainly a limitation, despite being similar to previous studies (Grealy and Mathers, 2014;Higdon et al., 2012;Smith et al., 2012). Using this small sample size for a post-hoc power analysis with α = 0.05 and power 0.80, a sample of at least n = 25-29 participants will be needed to show a difference between feeding conditions for chipping accuracy. ...
Background:
No study has evaluated the effect of macronutrient feedings on golf performance.
Aim:
Determine the effect of feedings during simulated golf game using a randomized cross-over study design.
Methods:
Male participants (n = 6, USGA handicap index 8.5 ± 6.72) played three standardized nine-hole rounds, consuming 30 g of carbohydrate, 15 g + 15 g protein and carbohydrate, or a zero-calorie control. Measurements of driving, chipping, and putting distance and accuracy were taken, as well as perceived levels of fatigue and alertness.
Results:
No relevant differences (P > 0.05) were seen in golf performance or alertness, but self-reported fatigue differed between conditions (P = 0.02), with scores of 2.5 (0.8 to 3.6) for the combination of carbohydrate and protein, 3.0 (1.5 to 4.3) for carbohydrate, and 4.0 (2.9 to 6.5) for the control, with higher levels indicating more fatigue.
Conclusion:
Macronutrient feedings led to a significantly lower level of self-reported fatigue without affecting golf performance and alertness compared to a control.
... Importantly, performance is particularly affected when tasks involve alternating and/or complex motorcognitive elements, whereas more stereotypical simple tasks are less affected [61]. Furthermore, modest levels of dehydration can aggravate the influence of hyperthermia on complex motorcognitive performances [62][63][64][65][66][67][68][69][70], and also simple motor tasks are negatively affected when dehydration is superimposed on hyperthermia [66,[70][71][72]. Another important factor to consider is solar radiation, as we recently provided evidence suggesting that high levels of simulated sunlight (from ~800 to ~1000 W/m 2especially directed toward the head) have a negative impact on the performance of a complex motor-cognitive task [73]. ...
... Athletes and coaches also need to consider hydration and re-hydrations strategies. Thermoregulatory sweating is associated with loss of both water and electrolytes [29]) and as dehydration may aggravate cardiovascular stress [22,24,26,27,42] and impair motor-cognitive performance [66,68,[70][71][72]110] it is extremely important to limit these homeostatic disturbances. This is in general of importance, but particularly for athletes competing within a weight-category (i.e. for athletes that may needs to cut excess weight -due to dehydration strategies) or if multiple matches/competitions are scheduled within one day. ...
Heat strain impairs performance across a broad spectrum of sport disciplines. The impeding effects of hyperthermia and dehydration are often ascribed to compromised cardiovascular and muscular functioning, but expert performance also depends on appropriately tuned sensory, motor and cognitive processes. Considering that hyperthermia has implications for central nervous system (CNS) function and fatigue, it is highly relevant to analyze how heat stress forecasted for the upcoming Olympics may influence athletes. This paper proposes and demonstrates the use of a framework combining expected weather conditions with a heat strain and motor-cognitive model to analyze the impact of heat and associated factors on discipline- and scenario-specific performances during the Tokyo 2021 games. We pinpoint that hyperthermia-induced central fatigue may affect prolonged performances and analyze how hyperthermia may impair complex motor-cognitive performance, especially when accompanied by either moderate dehydration or exposure to severe solar radiation. Interestingly, several short explosive performances may benefit from faster cross-bridge contraction velocities at higher muscle temperatures in sport disciplines with little or no negative heat-effect on CNS fatigue or motor-cognitive performance. In the analyses of scenarios and Olympic sport disciplines, we consider thermal impacts on “motor-cognitive factors” such as decision-making, maximal and fine motor-activation as well as the influence on central fatigue and pacing. From this platform, we also provide perspectives on how athletes and coaches can identify risks for their event and potentially mitigate negative motor-cognitive effects for and optimize performance in the environmental settings projected.
... Suboptimal hydration strategies during training and competition are well known to reduce athletic performance through increased physiological stress [1][2][3][4][5][6]. Athletes who lose as little as 1-2% of their body mass through sweat loss exhibit an increase in heart rate, core temperature, muscle glycogen use, as well as a decrease in cardiac output, cognitive awareness, anaerobic power, and time to exhaustion [2][3][4][5][6]. ...
... Suboptimal hydration strategies during training and competition are well known to reduce athletic performance through increased physiological stress [1][2][3][4][5][6]. Athletes who lose as little as 1-2% of their body mass through sweat loss exhibit an increase in heart rate, core temperature, muscle glycogen use, as well as a decrease in cardiac output, cognitive awareness, anaerobic power, and time to exhaustion [2][3][4][5][6]. Additionally, inadequate replacement of sodium, the predominant electrolyte lost through sweat, is thought to exacerbate the decline of these factors [7]. ...
Background:
Athletes commonly consume insufficient fluid and electrolytes just prior to, or during training and competition. Unlike non-athletes or athletes who do not engage in frequent rigorous and prolonged training sessions, "hard trainers" may require additional sodium and better benefit from a hydration plan tailored to their individual physiology. The purpose of this randomized cross-over study was to determine whether a hydration plan based off of an athlete's sweat rate and sodium loss improves anaerobic and neurocognitive performance during a moderate to hard training session as well as heart rate recovery from this session.
Methods:
Collegiate athletes who were injury free and could exercise at ≥ 75% of their maximum heart rate for a minimum of 45 min were recruited for this randomized, cross-over study. After completing a questionnaire assessing hydration habits, participants were randomized either to a prescription hydration plan (PHP), which considered sweat rate and sodium loss or instructed to follow their normal ad libitum hydration habits (NHP) during training. Attention and awareness, as well as lower body anaerobic power (standing long jump) were assessed immediately before and after a moderate to hard training session of ≥ 45 min. Heart rate recovery was also measured. After a washout period of 7 days, the PHP group repeated the training bout with their normal hydration routine, while the NHP group were provided with a PHP plan and were assessed as previously described.
Results:
Fifteen athletes from three different sports, aged 20 ± 0.85 years, participated in this study. Most participants reported feeling somewhat or very dehydrated after a typical training session. Compared to their NHP, participants following a PHP jumped 4.53 ± 3.80 in. farther, tracked moving objects 0.36 ± 0.60 m/second faster, and exhibited a faster heart rate recovery following a moderate to hard training session of 45-120 min in duration.
Conclusion:
A tailored hydration plan, based on an athlete's fluid and sodium loss has the potential to improve anaerobic power, attention and awareness, and heart rate recovery time.
... To allow for transferring conclusions from laboratory-based research to real-life settings, the study design should simulate real life as much as possible (i.e., the external or ecologic validity of the study). One difference between many laboratory studies and real-life settings is that the majority of studies [20][21][22][23][27][28][29][30][31]33,35,[38][39][40][42][43][44][45][47][48][49][50][51][52][53][54][56][57][58]61,62,66,67,[69][70][71]73,77,82,84,86] induced dehydration before exercise, either by exercising the subject in the heat, imposing fluid restrictions of about one to two days, or administering diuretic drugs before the exercise task. This is in contrast to real life, where athletes dehydrate during exercise (exercise-induced dehydration). ...
... Pre-exercise induced dehydration of ≥2% body mass resulted in consistent reports of reduced basketball skill performance and sprint times [49,51], riding [62] or golf-specific motor and mental performance [66]. Studies about basketball-and soccer-specific exercise tasks and skills while applying during-exercise dehydration are less consistent [46,55,63,74,85], with some finding no effect on the Loughborough intermittent shuttle running test (LIST) [63,85], while others reported negative effects of drinking nothing and concomitant increased dehydration on goals shot and anaerobic or sprint performance [46,55]. ...
... Similarly, high intensity exercise has been shown to reduce tennis shot accuracy (3). furthermore, an acute mild dehydration may reduce the distance and accuracy of the shot, along with the distance judgement (22). ...
... walking during a game of golf has been shown (7) to elevate a golfers' heart rate to an average of 95 ± 12 beats per min -1 , which is in line with the average post walking heart rates observed in this study (89 ± 16 beats per min -1 ). following a round of golf a change in mood states was shown to occur in senior players with a perceived increase in the level of fatigue (15), furthermore it was suggested that such fatigue might be associated with a possible decline in ability (22). however the increased heart rate in this current study would in no way indicate a fatigued state. ...
Although walking is a fundamental part of the game of golf, the effects of walking on the golf shots outcome are largely overlooked.The purpose of the present study was to determine the effects of a hole-to-hole distance walk on the golf drive performance as well as possible physiological contributory factors were evaluated. Twenty-one volunteer golfers were recruited and divided into two groups based on their average round scores: More Competitive Golfer (McG) ≤88 (n=13) and Irregular Social Golfer (ISG) ≥89 (n=8). Drive distance was directly measured. Balance and hand-eye coordination were assessed using a modified stork test and a customised three dimensional maze. Participants hit 10 golf balls and then walked 500m
before repeating the tests. Heart rates of golfers before driving weren’t different between groups, but were elevated within the groups following walking. The MCG had longer drives following the walk (p=0.018).The change in the distance was correlated to the change in right leg balance with eyes closed (r=-0.619 p=0.003). Biomechanical changes were correlated to the change in drive distance (r=0.867 p=0.025).This study shows that an aerobic warm-up prior to a round or small amounts of walking early in a round may be beneficial to golfers of better ability.
... It remains unclear the extent to which normal self-limiting levels of hypohydration impair cognition acutely [8,58]. Even when tested without concurrent heat stress or exercise (which may exert their own complex effects; [58,59]), cognition has been found to be both reduced (at 1-3% hypohydration: [60][61][62]) and improved (at 5%: [63]). Thirst has been shown to moderate the effects of hypohydration on cognition, with impairment evident only in individuals who were thirsty [64]. ...
... Mood, particularly perceived fatigue and tiredness, has consistently been shown to be impaired during mild (1-3%) hypohydration in resting individuals [65,66,[68][69][70], but the concurrent stimulation of thirst in these fluid-deprived individuals would ordinarily act to prevent these outcomes [70]. Hypohydration has also been shown to impair skilled performance and cognition of sport-specific tasks [62,71], but interpreting these findings is again confounded by potentially important factors such as placebo effects and distraction by thirst (Table 1). It therefore remains unclear as to how much hypohydration per se (independent of heat) impacts on cognition, mood and skilled motor performance, particularly in movement situations and in the absence of thirst (which stimulates drinking, thereby reducing hypohydration). ...
Hydration pertains simplistically to body water volume. Functionally, however, hydration is one aspect of fluid regulation that is far more complex, as it involves the homeostatic regulation of total body fluid volume, composition and distribution. Deliberate or pathological alteration of these regulated factors can be disabling or fatal, whereas they are impacted by exercise and by all environmental stressors (e.g. heat, immersion, gravity) both acutely and chronically. For example, dehydration during exercising and environmental heat stress reduces water volume more than electrolyte content, causing hyperosmotic hypohydration. If exercise continues for many hours with access to food and water, composition returns to normal but extracellular volume increases well above baseline (if exercising upright and at low altitude). Repeating bouts of exercise or heat stress does likewise. Dehydration due to physical activity or environmental heat is a routine fluid-regulatory stress. How to gauge such dehydration and - more importantly-what to do about it, are contested heavily within sports medicine and nutrition. Drinking to limit changes in body mass is commonly advocated (to maintain ≤2% reduction), rather than relying on behavioural cues (mainly thirst) because the latter has been deemed too insensitive. This review, as part of the series on moving in extreme environments, critiques the validity, problems and merits of externally versus autonomously controlled fluid-regulatory behaviours, both acutely and chronically. Our contention is that externally advocated hydration policies (especially based on change in body mass with exercise in healthy individuals) have limited merit and are extrapolated and imposed too widely upon society, at the expense of autonomy. More research is warranted to examine whether ad libitum versus avid drinking is beneficial, detrimental or neither in: acute settings; adapting for obligatory dehydration (e.g. elite endurance competition in the heat), and; development of chronic diseases that are associated with an extreme lack of environmental stress.
... Conducted research has shown that dehydration may leave a mark on physical performance for up to 24 hours [17]. It was measured with handgrip strength tests, sled push time trials and medical ball throw distance, and also present worse motor-cognitive function [18]. Furthermore, athletes tend to run slower due to dehydration [19,20]. ...
Introduction and objective: Athlete’s performance depends both on training and nutrition. Although athletes analyze macronutrients intake, micronutrients are often omitted, with sodium among them. It is proven to boost performance, due to its hydrating qualities. The aim of this study is to explore positive effects of salt induced hyperhydration, its effect on muscle cramps, exercise associated hyponatremia, prevention of dehydration and possible endurance gain. Purpose of the study: The aim of this study is to look further into the positive effects of sodium loading induced hyperhydration, its effect on muscle cramps, exercise associated hyponatremia, prevention of dehydration and possible endurance gain using PubMed databases from the last 25 years. Review methods: Articles were searched by entering keywords in PubMed databases. Scientific articles written from 2016 to 2024 make up 76% of the literature. Guidelines from global societies of dietary health and sport. Studies from specialized research centers including meta-analyses and double-blind randomized trials were included. Ones conducted with methodological errors were rejected. Basic results and conclusions: We can draw a conclusion that salt-loading might indeed prove useful in endurance training preparation, and should be included in an athlete's supplements arsenal. Dehydrating nature of heat and long training make salt induced hyperhydration more efficient in such conditions. Sportsmen can improve results in both endurance performance and reduction of the occurrence of possible negative outcomes connected with metabolic and physical strain. Presented studies also advocate for the importance of sodium loading in prevention of hyponatremia and muscle cramps.
... 16,17 Therefore, the state of dehydration is likely to have an impact on the exercise performance. 18 Dehydration, occurring during both training and competition, is widely recognized to have various negative effects, including diminished stroke volume, compromised cognitive functions, and reduced anaerobic power, [19][20][21] as well as impaired motor skills. [22][23][24] Furthermore, the loss of fluids through sweat during physical exertion leads to increased heart rates (HRs) and core temperature. ...
Purpose:
Successful participation in taekwondo (TKD) requires athletes to possess quick decision-making abilities and demonstrate technical proficiency during competition. Dehydration, occurring during both training and competition, is widely recognized to have various negative effects.
Methods:
This study investigated the impact of different levels of dehydration on cognitive function, as measured by the Vienna Test System, and the specific performance of kicking techniques among TKD athletes. Using a randomized crossover design, 12 participants were involved in the study. Before and after 1 hour of training at 80% of maximal heart rate, participants were weighed and provided urine samples. All participants were randomly assigned to 3 different hydration conditions: the euhydrated (EUH) group had unrestricted access to fluid consumption, while the hypohydrated (HYP) and severely HYP (S-HYP) groups experienced reductions of 2.0% and 4.0% of their initial body weight, respectively.
Results:
The EUH group exhibited better reaction speed in reaction-time test-form S1 than the HYP and S-HYP groups. Notably, the EUH group demonstrated a significantly higher success rate in the front-side kick (EUH 98%, HYP 90%, S-HYP 88%; P < .05). However, the success rates of back roundhouse kick and free head kick were similar among the 3 statuses. Furthermore, postexercise heart rates were found to be significantly higher in the HYP and S-HYP groups compared with the EUH group.
Conclusions:
This study provides insight into the negative effects of dehydration on cognitive function and TKD-specific performance. It is recommended that TKD athletes maintain optimal hydration levels during training and competition to ensure optimal performance.
... Furthermore, gastric emptying rates have previously been reported as having an upper limit of 0.9 L/hr (Maughan & Leiper, 1999), which would indicate that the 1.5-2.1 L of mean intramatch fluid intake observed in this investigation represents the upper limit (and higher) of what can be feasibly absorbed during a match. Despite the practical limitations of rehydrating when sweat rates are high, it should also be noted that even mild dehydration (≥1% BM loss) may be detrimental to cognitive (Smith et al., 2012) and endurance (Bardis et al., 2013) performance. This is particularly relevant here given the negative effects of hypohydration are exacerbated by high heat stress (Périard et al., 2021), and >90% (13/14) of the players in this investigation experienced BM loss >1% in at least one match. ...
We examined the sweat characteristics and fluid balance of elite female field hockey players during two heat training camps. Fourteen elite female field hockey players from the Australian national squad participated in two heat training camps held ∼6 months apart, following winter- (Camp 1) and summer-based training (Camp 2). Daily waking body mass (BM) and urine specific gravity (USG) were collected, along with several markers of sweat and fluid balance across two matches per camp. There was a 19% mean reduction in estimated whole-body sweat sodium concentration from Camp 1 (45.8 ± 6.5 mmol/L) to Camp 2 (37.0 ± 5.0 mmol/L; p < .001). Waking urine specific gravity ≥ 1.020 was observed in 31% of samples, with no significant differences in mean urine specific gravity or BM between camps ( p > .05), but with substantial interindividual variation. Intramatch sweat rates were high (1.2–1.8 L/hr), with greater BM losses in Camp 1 ( p = .030), resulting in fewer players losing ≥2% BM in Camp 2 (0%–8%), as compared with Camp 1 (36%–43%; p = .017). Our field data suggest that elite female field hockey players experience substantial sweat losses during competition in the heat regardless of the season. In agreement with previous findings, we observed substantial interindividual variation in sweat and hydration indices, supporting the use of individualized athlete hydration strategies.
... Golf is reported to be a moderate-intensity sport with a physical activity level of 4.8 METs, with an extended duration of 18 holes (a round) lasting anywhere from 4 to 5 h while covering distances over 10 km [1][2][3][4][5][6]. When played competitively, golf involves high cognitive loads, critical shot-making decisions, hand-eye coordination, high-level motor and biomechanical skills, and an extended duration of play that exceeds most other sports [7,8]. This combination of critical shot-making decisions, multiple maximum effort swings, putting, and long distances of walking during a round can result in physical and mental fatigue [9], i.e., golf-specific fatigue [4], and can negatively affect golf performance. ...
This study examined the effects of continuous carbohydrate intake during a golf round on interstitial glucose, golf performance, and the cognitive performance of competitive golfers. Eleven competitive golfers participated and played 18 holes of golf in this study. Participants were randomly assigned to the group indicated to consume the test food (CHO intake) or the group required to not consume it (NOT intake). Here, gummies were used as the test food, and the amount of carbohydrates was 30 g per h. Blood glucose levels were evaluated using interstitial glucose. Golf performance was measured in five tests, including scores, 2.5 m putting test, club head speed, driving distance, and accuracy. Cognitive performance was measured in three tests, including self-perceived levels of fatigue (PLF), self-perceived levels of concentration (PLC), and self-perceived levels of relaxation (PLR). Interstitial glucose (p < 0.001) and PLF (p < 0.001) were significantly reduced in the CHO intake compared with that in the NOT intake from the sixth hole. PLC was significantly higher in the CHO intake than in the NOT intake on all 18 holes (p = 0.032). These findings suggest that continuous carbohydrate intake may be effective in reducing fatigue and maintaining the performance of competitive golfers.
... 10 In addition, poor body water balance may result in decreased cognitive functioning, such as impaired decision-making time, 11 reduced levels of alertness, 12 and reduced psychomotor performance. 13 Similar effects of hypohydration on performance and its high prevalence (i.e. 84%) have also been found in competitive combat sports athletes. ...
It has been well-documented that high-level judo athletes presented a high level of hypohydration during weight-cutting and competition periods. However, there is a lack of studies investigating the hydration status of high-level judo athletes during a weight-stable training period. Therefore, this study aimed to investigate elite judo athletes' hydration status, body mass change, and fluid intake during a weight-stable training camp. Twenty-seven judo athletes (women n = 8, men n = 19, body weight = 79.6 ± 20.9 kg) from the senior national judo team voluntarily participated in this study. Data were collected in the morning after waking up and before and after the morning and evening training sessions. On the second day, the measurements were taken again in the morning after waking up. Urine-specific gravity (USG) was classified as hydrated (USG < 1.020) and hypohydrated (USG ≥ 1.020). The athletes' USG values measured on two consecutive mornings increased (1.025 ± 0.007 to 1.029 ± 0.006) during 24 h, in which athletes performed judo training in the morning and evening. Moreover, sex and weight category did not affect the changes in USG values (p > .05). Most of the elite judo athletes presented hypohydration (92.6%). The relationship between the fluid intake of the athletes and the changes in USG and body weight values during 24 h was not significant (p > .05). The current study's findings revealed that high-level judo athletes present a high level of hypohydration even during a weight-stable training camp. Furthermore, the training sessions during the experiment period (24 h) worsened the hydration status of the senior athletes in all weight categories for both women and men.
... The −1.5% body weight was induced by fluid abstinence the night before and morning of testing. The dehydrated group's shot distance decreased from 128 to 114 m, off target accuracy increased from 4.1 to 7.9 m, and the dehydrated group significantly misjudged distance compared to the euhydrated group from 8.8 to 4.1 m [37]. ...
Nutritional guidance for competitive golfers to improve performance is limited. Recommendations and study conclusions from older research used smaller golf courses compared to today and require a reevaluation of energy expenditure. This review identifies aerobic fitness, in addition to strength, as a key determinant of success. A novel nutritional approach that incorporates carbohydrate supplementation to support aerobic fitness without sacrificing the ability to build strength is presented since longer courses require more stamina. Strategies for training, competition, and recovery are outlined based on different skill levels. American College of Sports Medicine (ACSM) guidelines for carbohydrates, protein, and hydration intake are tailored specifically for competitive golf based on this approach. Putting requires precise movement and can be affected by fatigue. Nutritional studies in golf and similar sports that require focused movements are presented, exhibiting an improvement with adequate hydration and carbohydrate status and caffeine use. Competitive golf poses unique challenges to an athlete and commonly used ergogenic supplements that can improve performance in a variety of circumstances during training, competition, and while traveling are reviewed.
... Body water loss was related to an increase in cortisol level, 27 which could induce decreases in vigilance, attention span, memory, and reasoning. 27,28 Mild dehydration significantly impaired performance in tasks that required attention 29 and distance judgment, 30 which could affect the central and assistant referees' decisions. 15 Edwards et al 31 also found a decrease in soccer performance when fluid intake was denied. ...
... On the FA + SAU day, participants were instructed to abstain from fluid intake for 15 h over the evening and night prior testing to achieve weight loss. Similar fluid restriction protocols have been previously employed by other authors [16,17,20,21]. This fluid restriction protocol has been previously used over 12 h within a pilot study to induce 1-2% body mass loss [18]. ...
Background
Lightweight rowers commonly utilize weight loss techniques over 24-h before competition to achieve the qualifying weight for racing. The objective was to investigate, using a quasi-experimental design, whether changes in weight resulting from dehydration practices are related to changes in proxies of bodily systems involved in rowing and whether these relationships depend on the dehydration technique used.
Methods
Twelve elite male rowers performed a power test, an incremental VO 2 max test, and a visuomotor battery following: weight loss via thermal exposure, weight loss via fluid abstinence and then thermal exposure, and no weight loss. The total percent body mass change (%BMC), %BMC attributable to thermal exposure, and %BMC attributable to fluid abstinence were used to predict performance variables.
Results
Fluid abstinence but not thermal exposure was related to a lower total wattage produced on a incremental VO 2 max test ( b = 4261.51 W/1%BMC, 95%CI = 1502.68–7020.34), lower wattages required to elicit 2 mmol/L ( b = 27.84 W/1%BMC, 95%CI = 14.69–40.99) and 4 mmol/L blood lactate ( b = 20.45 W/1%BMC, 95%CI = 8.91–31.99), and slower movement time on a visuomotor task ( b = -38.06 ms/1%BMC, 95%CI = -62.09–-14.03).
Conclusions
Dehydration related weight changes are associated with reductions in some proxies of bodily systems involved in rowing but depend on the dehydration technique used.
... Even mild dehydration (1-2% of body weight) impairs athletic performance (Kavouras, 2002). Furthermore, impaired body water balance can lead to decreased cognitive functioning such as decreased decision-making time (Cian et al., 2001), reduced levels of alertness (Shirreffs et al., 2004) and reduced psychomotor performance (Smith et al., 2012). Given that the percentage of weight loss is about 5-13% in weight-classified athletes (Matthews et al., 2019;Nancuvil-Suazo et al., 2020;Steen & Brownell, 1990), dehydration may negatively influence performance following dehydration-induced rapid weight loss. ...
This study aimed to investigate the effect of weigh-in time on hydration status and acute weight gain (AWG). Twenty-seven men judo athletes and 23 men wrestlers voluntarily participated in this study. Body mass and urine specific gravity (USG) of the athletes were measured just before official weigh-in and competition. Two-way analysis of variance (split-plot ANOVA) with repeated measurements (time x sport) were used to determine differences in AWG and USG between groups and measurement times. In case of significant difference between sports, t-tests were applied. There was a significant main effect of time (p<0.01, ES=0.25) on USG. A significant difference was found in USG between official weigh-in and start of the competition in wrestlers (p<0.01) but not in judo athletes. There was significant difference in AWG and AWG% between sports (p<0.01). Moreover, most of the athletes presented high level of dehydration before both official weigh-in and competition. In conclusion, judo athletes could not rehydrate as much as wrestlers despite 15h of recovery. It can be suggested that the period between official weigh-in and competition would be shortened to prevent non-optimal hydration status and rapid weight gain, with caution to allow sufficient recovery period.
... It has been proposed that ≥2% fluid loss represents the threshold for reductions in endurance performance (32). However, impaired cognition has been observed at fluid losses of <1% (40,41), which supports the assertion that the modest degree of hypohydration observed in the placebo condition (0.9% fluid loss) could have impaired cognitive function, probably as a byproduct of the aforementioned distracting symptoms, and subsequently reduced tennis skill. ...
This study examined the dose-response effects of ingesting different sodium concentrations on markers of hydration and tennis skill. Twelve British nationally-ranked tennis players (age: 21.5 ± 3.1 years; VO2peak: 45.5 ± 4.4 ml.kg.min⁻¹) completed four identical in-door tennis training sessions in a cluster randomized, single-blind, placebo-controlled, crossover design. Twenty-minutes prior to each training session, participants consumed a 250 ml sodium-containing beverage (10, 20, 50 mmol/L) or a placebo (0 mmol/L), and continued to consume 1,000 ml of the same beverage at set periods during the 1-h training session. Tennis groundstroke and serve performance, agility, urine osmolality, fluid loss, sodium sweat loss and perceptual responses (rating of perceived exertion (RPE), thirst, and gastrointestinal (GI) discomfort) were assessed. Results showed that ingesting 50 mmol/L sodium reduced urine osmolality (−119 mOsmol/kg; p = 0.037) and improved groundstroke performance (5.4; p < 0.001) compared with placebo. This was associated with a reduction in RPE (−0.42; p = 0.029), perception of thirst (−0.58; p = 0.012), and GI discomfort (−0.55; p = 0.019) during the 50 mmol/L trial compared with placebo. Linear trend analysis showed that ingesting greater concentrations of sodium proportionately reduced urine osmolality (β = −147 mOsmol/kg; p = 0.007) and improved groundstroke performance (β = 5.6; p < 0.001) in a dose response manner. Perceived thirst also decreased linearly as sodium concentration increased (β = −0.51; p = 0.044). There was no evidence for an effect of sodium consumption on fluid loss, sweat sodium loss, serve or agility performance (p > 0.05). In conclusion, consuming 50 mmol/L of sodium before and during a 1-h tennis training session reduced urine osmolality and improved groundstroke performance in nationally-ranked tennis players. There was also evidence of dose response effects, showing that ingesting greater sodium concentrations resulted in greater improvements in groundstroke performance. The enhancement in tennis skill may have resulted from an attenuation of symptomologic distracters associated with hypohydration, such as RPE, thirst and GI discomfort.
... These effects from dehydration manifest as increased glycogen utilization, core temperature, and heart rate [4,7,[9][10][11][12][13]. Furthermore, these physiological changes may hinder motor skills, alertness, mood, cognition, and flexibility [13][14][15][16][17]. ...
Background:
Similar to other combat sports, mixed martial arts (MMA) includes divisional weight classes. The purpose of our research was to further investigate the amount of weight professional MMA fighters lost prior to weighing in for competition, their methods used to cut weight, and their sources of advice on how to cut weight.
Methods:
This survey was administered to 92 male professional MMA athletes. The survey questions included duration of overall weight loss prior to competition, methods of weight-cutting, and their sources of advice regarding weight cutting.
Results:
When comparing the number of methods of weight cutting with the source of advice, those who received their advice from social media used slightly more methods of weight cutting (M = 4.86, SD = 1.27) than those who did not (M = 4.02, SD = 1.55); t(90) = - 2.53, p < .05. MMA athletes that used the help of a registered dietitian nutritionist also reported using the least amount of methods for weight-cutting than any other category (M = 3.84, SD = 1.67). Those that used teammates and did not use a registered dietitian nutritionist used slightly more methods (M = 4.46, SD = 1.41) than those who used a registered dietitian nutritionist.
Conclusions:
The findings of this study report that professional MMA athletes do undergo rapid weight loss through various methods to make weight for competition. This study adds evidence to the literature that most professional MMA athletes undergo RWL for competition without the guidance of a registered dietitian nutritionist. It is unclear what the effect of using a registered dietitian nutritionist may have on an MMA athletes' ability to reduce weight in a safe and effective manner. Future research should seek to investigate if employing a registered dietitian nutritionist may lead to a higher rate of success for MMA athletes to make weight, and help reduce adverse risks of RWL.
... Similarly, during 24 h of voluntary water deprivation in one study of 10 participants, a significant deterioration was observed in cognitive performance, such as that related to solving time in psychological tests; however, self-estimated mood did not changed significantly [38]. In a study of athletes, it was revealed that mild dehydration after 12 h of water deprivation impaired cognitive-motor task performance, such as judgment of distance to a target [39]. Few cognitive performance studies related to dehydration have been conducted using water deprivation to induce dehydration. ...
Water accounts for 75% of brain mass. Associations may exist between hydration and cognitive performance. The objective of this study was to investigate the effects of dehydration and rehydration on cognitive performance and mood. In this self-control trial, 12 men were recruited from a medical college in Cangzhou, China. After 12 h of overnight fasting, the participants took baseline tests at 8:00 AM on day 2. First morning urine and blood osmolality were analyzed to determine hydration state. Height, weight, and blood pressure were measured following standardized procedures. A visual analog scale for the subjective sensation of thirst was applied, and a profile of mood states questionnaire was applied. Tests were conducted for cognitive performance, including a test of digit span forward and backward, digit-symbol substitutions, dose-work, and stroop effects. Participants were required not to drink water for 36 h but were given three meals on day 3. On day 4, the same indexes were tested as a baseline test. At 8:30 AM, participants drank 1500 mL of purified water over 15 min. After a 1 h interval, the same measurements were performed. Compared with baseline test results, during the dehydration test, participants had lower scores of vigor (11.9 vs. 8.8, %, p = 0.007) and esteem-related affect (8.2 vs. 5.7, %, p = 0.006), lower total scores of digit span (14.3 vs. 13.3, %, p = 0.004), and higher error rates for dose-work (0.01 vs. 0.16, %, p = 0.005). Compared with the dehydration test scores, rehydration test scores showed that fatigue (4.3 vs. 2.1, %, p = 0.005) and total mood disturbance (TMD) (99.0 vs. 90.2, %, p = 0.008) improved, and scores of forward, backward, and total digit span increased (7.7 vs. 8.6, p = 0.014; 5.7 vs. 1.2, p = 0.019; 13.3 vs. 15.4, p = 0.001). Increases were also noted in correct number of digit symbol substitutions, reading speed, and mental work ability (70.8 vs. 75.4, p < 0.001; 339.3 vs. 486.4, n/min, p < 0.001; 356.1 vs. 450.2, p < 0.001), and reaction time decreased (30.2 vs. 28.7, s, p = 0.002). As a conclusion, dehydration had negative effects on vigor, esteem-related affect, short-term memory, and attention. Rehydration after water supplementation alleviated fatigue and improved TMD, short-term memory, attention, and reaction.
... It is interesting to note, however, that although several investigations on fluid balance have been conducted in a large variety of sports (4,5,12,15,21,26,(30)(31)(32)34,35,(38)(39)(40)(41)46,48), to the best of the authors' knowledge, no study has examined fluid balance in fencing. Furthermore, a possi-ble effect of ingesting a CHO-E compared with water in fencing performance has not been investigated. ...
The purpose of the study was to examine a possible effect of
a carbohydrate-electrolyte (CHO-E) solution on fluid balance
and performance in fencing at a thermoneutral environment.
Sixteen fencers performed two 120-minute training sessions
separated by 7–14 days under similar environmental conditions
(temperature: 20.38 C and humidity: 45–47%). Each session
consisted of 60-minute conditioning exercises followed by
10 bouts of 3 minutes against the same opponent with 3-
minute interval between each bout. Participants ingested at
regular intervals either a 6% CHO-E solution or an artificially
sweetened water (PL) in a counterbalanced order. No difference
was observed between conditions in the heart rate responses,
perceived exertion, changes in plasma volume, urine
specific gravity, number of bouts won or lost, or points for and
against. Considerable variability was observed in body mass
changes that revealed significant differences at the time
level (i.e., pre- vs. post-exercise) (F1,15 = 9.31, p = 0.008, h2
= 0.38), whereas no difference was found between conditions
(i.e., CHO-E vs. PL) (F1,15 = 0.43, p = 0.52, h2 = 0.03)
and conditions 3 time interaction (F1,15 = 3.57, p = 0.078,
h2 = 0.19). Fluid loss was not significantly different between
conditions (p = 0.08, d = 0.47). The blood glucose level was
higher (p , 0.01) after exercise in CHO-E, whereas the blood
lactate level was similar between conditions. In conclusion, the
CHO-E solution was as effective as the artificially sweetened
water in terms of fluid balance and fencing performance at
a thermoneutral environment. Because of large individual variability,
fencers should monitor their fluid intake and body fluid
loss in training and competition.
... Some studies have suggested motor coordination may be impaired following dehydration (Cian et al. 2000); however, a primary component of visuomotor functioning, the ability to accurately process temporal information (Buhusi and Meck 2005), has not been previously examined. Adequate visuomotor performance is essential to human-system interactions, and dysfunction (potentially from deficient visuomotor timing) might explain errant performance in tasks such as driving proficiency (Watson et al. 2015), pilot simulations (Lindseth et al. 2013), and sporting skills (Baker et al. 2007b;Smith et al. 2012) are degraded following dehydration. ...
Effects of exercise-heat stress with and without water replacement on brain structure and visuomotor performance were examined. Thirteen healthy adults (23.6 ± 4.2 years) completed counterbalanced 150 min trials of exercise-heat stress (45°C, 15% RH) with water replacement (EHS) or without (~3% body mass loss; EHS-DEH) compared to seated rest (CON). Anatomical scans and fMRI Blood-Oxygen-Level-Dependent responses during a visuomotor pacing task were evaluated. Accuracy decreased (P < 0.05) despite water replacement during EHS (-8.2 ± 6.8% vs. CON) but further degraded with EHS-DEH (-8.3 ± 6.4% vs. EHS and -16.5 ± 10.2% vs. CON). Relative to CON, EHS elicited opposing volumetric changes (P < 0.05) in brain ventricles (-5.3 ± 1.7%) and periventricular structures (cerebellum: 1.5 ± 0.8%) compared to EHS-DEH (ventricles: 6.8 ± 3.4, cerebellum: -0.7 ± 0.7; thalamus: -2.7 ± 1.3%). Changes in plasma osmolality (EHS: -3.0 ± 2.1; EHS-DEH: 9.3 ± 2.1 mOsm/kg) were related (P < 0.05) to thalamus (r = -0.45) and cerebellum volume (r = -0.61) which, in turn, were related (P < 0.05) to lateral (r = -0.41) and fourth ventricle volume (r = -0.67) changes, respectively; but, there were no associations (P > 0.50) between structural changes and visuomotor accuracy. EHS-DEH increased neural activation (P < 0.05) within motor and visual areas versus EHS and CON. Brain structural changes are related to bidirectional plasma osmolality perturbations resulting from exercise-heat stress (with and without water replacement), but do not explain visuomotor impairments. Negative impacts of exercise-heat stress on visuomotor tasks are further exacerbated by dehydration.
... Furthermore, it is also possible that due to the positive effect of exercise on cognitive function [40], the potential detriment in cognition as a result of dehydration may be masked by the facilitating effects of exercise. The fluid restriction method of inducing dehydration has shown varying results, with some showing no difference in performance [64], however the majority of studies demonstrate a decrement in cognitive performance [65][66][67]. Thus the dehydration method employed and the training status of the athletes and their experience of dehydration appear to interact to determine whether cognitive function is altered during or after exercise in the heat. ...
Background:
It has previously been suggested that heat exposure and hypohydration have negative effects on cognitive performance, which may impact upon sporting performance. The aim of the present study was to examine the independent effects of heat stress and hypohydration on cognitive performance in elite female field hockey players.
Methods:
Eight unacclimatised elite field hockey players (age: 22 ± 3 y; height: 1.68 ± 0.05 m; body mass: 63.1 ± 6.0 kg) completed a cognitive test battery before and after 50 min of field hockey specific exercise on a treadmill in four experimental trials; two in hot conditions (33.3 ± 0.1 °C), and two in moderate (16.0 ± 3.0 °C), both with and without ad libitum water intake.
Results:
On the visual search test, participants were faster overall in the heat (1941 vs. 2104 ms, p = 0.001). Response times were quicker in the heat on the Sternberg paradigm (463 vs. 473 ms, p = 0.024) and accuracy was improved (by 1.9%, p = 0.004). There was no effect of hydration status on any of the markers of cognitive function.
Conclusions:
Overall, the findings suggest that in elite field hockey players exposure to heat enhances response times and/or accuracy on a battery of cognitive function tests. However, hypohydration does not appear to affect cognitive performance in elite field hockey players.
... The food provided by commercial airlines and sporting venues is also often unsuitable for an athlete's nutritional requirements (Heaney, O'Connor, Naughton, & Gifford, 2008). Dehydration can affect performance by reducing shot distance, accuracy and distance judgement in hot and humid climates (Smith, Newell, & Baker, 2012). To deal with such challenges, players should approach nutrition proactively by planning and preparing their own food and fluid intake for the tournament (Pilgrim et al., 2018). ...
Tournament preparation in golf is used by players to increase course knowledge, develop strategy, optimise playing conditions and facilitate self-regulation. It is not known whether specific behaviours in tournament preparation should be given priority in education and practice at different stages of competition. This study aimed to achieve consensus on the importance of specific tournament preparation behaviours or “items” to players of five competitive levels. A two-round Delphi study was used, including an expert panel of 36 coaches, high-performance staff, players and academics. Participants were asked to score the relative importance of 48 items to players using a 5-point Likert-type scale. For an item to achieve consensus, 67% agreement was required in two adjacent score categories. Consensus was reached for 46 items and these were used to develop a ranked framework for each competitive level. The developed framework provides consensus-based guidelines of the behaviours that are perceived as important in tournament preparation. This framework could be used by national sport organisations to guide the development of more comprehensive learning environments for players and coaches. It could also direct future studies examining the critical behaviours for golfers across different competitive levels.
... The evidence suggests that dehydration has a negative impact on physical performance for activities lasting more than 30 minutes [13]. Dehydration can impair distance, accuracy, and distance judgment during sports performance [14][15]. Dehydration can damage physical and mental performance, as well as decrements of greater performance in hot environments and in durable exercise [12]. ...
The adequacy of body fluids is important for athletes in supporting performance. The purpose of this research was to determine the hydration status of athletes before and after training. The study was a qualitative descriptive by using random sampling. All athletes were trained for approximately 60 minutes. And they were asked to analyze their body fluid pattern routinely. Data were obtained through urine color measurement. The urinary was taken at pre and post training and was immediately assessed in the afternoon. Based on pre-training urine samples, a mean of urine color scale was 3.1 point. It meant that only 31.2% of the athletes were in dehydrated condition. However, after exercising, urine color index showed scale 4.1. And 62.5% of the athletes experienced dehydration. The results showed that there was a significant change in hydration level before and after training. It can be concluded that training for a long time increases the risk of dehydration. It is important for athletes to meet the needs of body fluids in order to avoid functional impairment in the body during sports activities.
... Experimental investigations have also demonstrated motor-skill impairments on sport-specific exercise tests (e.g. cricket [3], basketball [4,5], golf [6], field hockey [7] and surfing [8]) following fluid loss. Whilst evidence indicating a detrimental effect of dehydration on cognitive function is less consistent [9], decline in memory, perceptual discrimination and mood state has been observed in some studies [10]. ...
Background
The deleterious effects of dehydration on athletic and cognitive performance have been well documented. As such, dehydrated individuals are advised to consume fluid in volumes equivalent to 1.25 to 1.5 L kg−1 body mass (BM) lost to restore body water content. However, individuals undertaking subsequent activity may have limited time to consume fluid. Within this context, the impact of fluid intake practices is unclear. This systematic review investigated the effect of fluid consumption following a period of dehydration on subsequent athletic and cognitive performance. Methods
PubMed (MEDLINE), Web of Science (via Thomas Reuters) and Scopus databases were searched for articles reporting on athletic (categorized as: continuous, intermittent, resistance, sport-specific and balance exercise) or cognitive performance following dehydration of participants under control (no fluid) and intervention (fluid intake) conditions. Meta-analytic procedures determined intervention efficacy for continuous exercise performance. ResultsSixty-four trials (n = 643 participants) derived from 42 publications were reviewed. Dehydration decreased BM by 1.3–4.2%, and fluid intake was equivalent to 0.4–1.55 L kg−1 BM lost. Fluid intake significantly improved continuous exercise performance (22 trials), Hedges’ g = 0.46, 95% CI 0.32, 0.61. Improvement was greatest when exercise was performed in hotter environments and over longer durations. The volume or timing of fluid consumption did not influence the magnitude of this effect. Evidence indicating a benefit of fluid intake on intermittent (10 trials), resistance (9 trials), sport-specific (6 trials) and balance (2 trials) exercise and on cognitive performance (15 trials) was less apparent and requires further elucidation. Conclusions
Fluid consumption following dehydration may improve continuous exercise performance under heat stress conditions, even when the body water deficit is modest and fluid intake is inadequate for complete rehydration.
... A number of studies have looked at the relationship between dehydration and cogni tive function using a variety of approaches including case study, field, and obser vational (adults: Ackland et al. 2008;Doppelmayr et al. 2005;Lieberman et al. 2005;Suhr et al. 2004, 2010, children: Bar-David et al. 2005) and experimental (adults: Armstrong et al. 2012;Adam et al. 2008;Ainslie et al. 2002;Bandelow et al. 2010;Baker et al. 2007;Cian et al. 2000Cian et al. , 2001D'Anci et al. 2009;Ely et al. 2013;Ganio et al. 2011;Gopinathan et al. 1988;Grego et al. 2005;Irwin et al. 2013;Leibowitz et al. 1972;Lindseth et al. 2013;Neave et al. 2001;Ogino et al. 2013;Petri et al. 2006;Serwah and Marino 2006;Sharma et al. 1986;Slaven and Windle 1999;Smith et al. 2012;Szinnai et al. 2005;Shirreffs et al. 2004, children: none). Several studies have looked at the effect of fluid intake on cognitive function from a naturally occurring state of hydration (euhydration, or at least no intentional induction of dehydration) (adults: Edmonds et al. 2013;Rogers et al. 2001, chil dren: Benton and Burgess 2009;Booth et al. 2012;Edmonds 2012a;Edmonds and Burford 2009;Edmonds and Jeffes 2009;Fadda et al. 2012). ...
... Body water loss was related to an increase in cortisol level, 27 which could induce decreases in vigilance, attention span, memory, and reasoning. 27,28 Mild dehydration significantly impaired performance in tasks that required attention 29 and distance judgment, 30 which could affect the central and assistant referees' decisions. 15 Edwards et al 31 also found a decrease in soccer performance when fluid intake was denied. ...
Various continental sporting events have exposed team sports referees to different environmental conditions. Several studies have focused on strategies to prevent athlete performance impairment induced by heat or warm (or both) conditions, but few authors have investigated the effect of heat on referees' performance. In a thermoneutral environment, referees' physical activity induced mild 2.0% dehydration, which was responsible for reductions in physical, psychomotor, and cognitive performances. Therefore, the hydration status of referees should be taken into account to reduce referees' errors and misjudgments in the heat.
... Therefore, it is important to test the effects of changing hydration states in real-world settings that require a complex array of cognitive abilities. Such studies have already been carried out, testing the effects of dehydration on performance in real-life tasks such as airplane piloting and playing golf (29,31) . An attempt has been made by one study to investigate how drinking-water may be related to performance in examinations in university students: Pawson et al. (72) observed the number of people who took drinks to university examination sessions and compared the performance of these students with that of those who sat the same examination but did not take a drink. ...
Although it is well known that water is essential for human homeostasis and survival, only recently have we begun to understand its role in the maintenance of brain function. Herein, we integrate emerging evidence regarding the effects of both dehydration and additional acute water consumption on cognition and mood. Current findings in the field suggest that particular cognitive abilities and mood states are positively influenced by water consumption. The impact of dehydration on cognition and mood is particularly relevant for those with poor fluid regulation, such as the elderly and children. We critically review the most recent advances in both behavioural and neuroimaging studies of dehydration and link the findings to the known effects of water on hormonal, neurochemical and vascular functions in an attempt to suggest plausible mechanisms of action. We identify some methodological weaknesses, including inconsistent measurements in cognitive assessment and the lack of objective hydration state measurements as well as gaps in knowledge concerning mediating factors that may influence water intervention effects. Finally, we discuss how future research can best elucidate the role of water in the optimal maintenance of brain health and function.
... Regarding exercise performance issues, studies have demonstrated that relatively moderate degrees of hypohydration, i.e., -1 to -3% of BM, affect performance adversely (Maughan, 2003). In addition, a negative fluid balance can result in decreased cognitive functioning, including reduced psychomotor performance, (Smith et al., 2012) decreased decision-making time (Cian et al., 2001) and reduced levels of alertness (Shirreffs et al., 2004). Thus, if a hypohydrated state induced by rapid weight loss following official weigh-in is not reversed by proper nutritional strategies, athletes risk entering competition with suboptimal mental and physical performance capacity. ...
Weight category athletes are known for practicing rapid weight loss prior to competition weigh-in. After weigh-in, athletes strive to restore euhydration and body mass through food and fluid intake. The aim of the present study was to assess prevalence of hypohydration at competition time among elite athletes' in four different combat sports, and how water intake and timing of official weigh-in were related to hydration status. Participants were 31 taekwondo practitioners and wrestlers who performed evening weigh-in (EWI) the night before competition day and had thus time for rehydration, and 32 boxers and judokas conducting competition day morning weigh-in (MWI). In total, 32% were female. Urine specific gravity (USG) was measured by refractometry on the competition day's first morning urine sample. Hypohydration was defined as USG ≥1.020 and serious hypohydration as USG>1.030. Water intake was measured by means of dietary records. The prevalence of hypohydration was 89% in the morning of competition day. Serious hypohydration was also prevalent. This was found in over 50% of MWI athletes and was also present in 42% of the EWI group. A higher water intake, from both fluids and solid foods, in the evening before competition day was not associated with a more favourable hydration status the following morning. In conclusion, neither weigh-in close to competition nor evening weigh-in with more time for rehydration seems to prevent hypohydration prior to competition.
Objective:
Children face the risk of dehydration in varying amounts during the day due to reasons such as physical activity, sweating, eating salty foods and drinking carbonated beverages. It is assumed that dehydration can lead to impaired motor skills and cognitive performance since it affects brain function. However, inconsistencies in study results, test times and problems caused by heat stress make new research mandatory. In our research, we examined the effects of exercise-induced mild dehydration on motor skills and cognitive performance in active/sedentary boys who do/do not do regular physical activities in their daily lives.
Methods:
The study included 112 boys who do regular physical activity (n:57; 12.40 ± 0.49age) and sedentary (n:55; 12.49 ± 0.50age). The children were given a 12-h hydration program. Mild dehydration was created by giving exercises after hydration measurements. In case of hydration and mild dehydration, Bruininks-Oseretsky Motor Proficiency and d2 attention test were applied to the children. For comparison, Repeated Measures ANOVA and Bonferroni post-hoc test was performed at the second level.
Results:
According to the hydration and mild dehydration comparison results, there was no difference in total score of Fine Motor Skill Sensitivity, Fine Motor Skill Integration, Hand Dexterity and Bidirectional Coordination, Balance, Running Speed and Agility, Hand-Arm Coordination, Strength, and BOT-2 in children. There was a decrease in both groups in terms of Focused Attention, Processing Speed, Accuracy, Concentration Performance and Attention Span.
Conclusion:
As a result, mild dehydration is associated with daily physical activity in children (physical education classes, etc.) or it can easily occur due to food/beverage preferences. It may affect children's performance of school curriculum and extracurricular activities. It shows that maintaining optimal hydration is important.
Background:
A golf bag filled with a set of clubs provides a substantial load. When carried over distance this can increase the demands placed upon the golfer, leading to discomfort, fatigue and injuries. This study aimed to compare the metabolic demands of 2 methods of golf bag carriage.
Methods:
A total of 16 healthy male recreational golfers participated in the study. Participants were given an initial familiarization session in which their self-selected walking speed was determined. This was utilized as the treadmill speed for all subsequent trials. The testing protocol consisted of 3 randomized trials of treadmill walking for 5 minutes in each of three conditions: unloaded, single-strap bag and double-strap bag. Equipment consisted of a double-strap golf bag with a standard set of clubs weighing 12.5kg. For all trials oxygen consumption (L·min-1), VO2 (mL·kg·min-1) respiratory minute volume (VE) (L·min-1), and heart rate (HR) were measured.
Results:
Results showed that the double-strap bag required significantly less oxygen consumption (1.19±0.19 vs. 1.31±0.16 L·min-1, P<0.01) relative oxygen consumption (14.49±2.06 vs. 15.93±2.25 mL·kg·min-1, P<0.01), reduced respiratory minute volume (29.95±4.19 vs. 32.47±4.26 L·min-1, P<0.05), and lower heart rates (100.14±11.05 vs. 106.96±9.33 BPM, P<0.001) than the single-strap bag. Both methods of carriage showed significantly greater metabolic demands than the unloaded condition (P<0.05).
Conclusions:
The decreased metabolic cost of carrying a double-strap golf bag may facilitate a reduction in fatigue and reduced mechanical stress. Golf bag transportation must therefore be recognized as a factor in reducing the risk of injury and improving playing performance.
With the continued increase in international travel and immigration to Georgia, the Department of Public Health (DPH) continued its mission to prevent and respond to Zika virus (ZIKV) transmission.
Methods:
We analyzed surveillance data from the DPH to compare the geographical distribution of counties conducting surveillance, total number, and overall percentage of mosquito species collected in 2016 and 2017. Mosquito surveillance in 2017 was mapped by county and species using ArcMap 10.2.0.
Results:
From 2016 and 2017, mosquito surveillance increased from 60 to 159 counties (165% increase). A total of 145,346 mosquitoes were trapped and identified in 2016 compared to 152,593 in 2017 (5.43% increase). There was a difference in the type of mosquito species found by year. Some species collected in previous years were not collected in 2017, while other species found in 2017 were not previously collected during mosquito surveillance. Also, certain mosquito species were found outside of their expected geographical range.
Conclusion:
The continued collaborative response to ZIKV by the DPH allowed a continued increase in its surveillance program. Existing and new partnerships continued to develop with military and local health departments to expand and share data. This additional surveillance data allowed DPH to make sound public health decisions regarding mosquito-borne disease risks and close gaps in data related to vector distribution.
Background
The independent effects of hypohydration and hyperthermia on cognition and mood is unclear since the two stresses often confound each other. Further, it is unknown if obese individuals have the same impairments during hyperthermia and hypohydration that is often observed in non-obese individuals.
Methods
The current study was designed to assess the independent and combined effects of mild hypohydration and hyperthermia on cognition, mood, and mental task load in obese and non-obese females. Twenty-one healthy females participated in two passive heating trials, wherein they were either euhydrated or hypohydrated prior to and throughout passive heating. Cognition (ImPACT), mental task load (NASA-TLX), and mood (Brunel Mood Scale; BRUMS) were measured before and after a 1.0 °C increase in core temperature (T C ).
Results
After a 1.0 °C T C elevation, hypohydration resulted in greater ( p < 0.05) body mass loss (−1.14 ± 0.48 vs −0.58 ± 0.48 kg; hypohydrated and euhydrated, respectively) and elevation in serum osmolality (292 ± 4 vs 282 ± 3 mOsm; p < 0.05) versus euhydration. Hypohydration, independent of hyperthermia, did not affect mental task load or mood ( p > 0.05). Hyperthermia, regardless of hydration status, impaired (∼5 A.U) measures of memory-based cognition (verbal and visual memory), and increased mental task load, while worsening mood ( p < 0.05). Interestingly, obese individuals had increased mental task load while hyperthermic compared to the non-obese individuals ( p < 0.05) even while euhydrated. Hypohydration did not exacerbate any heat-related effects on cognition between obese and non-obese females ( p > 0.05).
Conclusion
These data indicate that hyperthermia independently impairs memory-based aspects of cognitive performance, mental task load, and leads to a negative mood state. Mild hypohydration did not exacerbate the effects of hyperthermia. However, obese individuals had increased mental task load during hyperthermia.
Dehydration (DEH) is believed to impair cognitive performance but which domains are affected and at what magnitude of body mass loss (BML) remains unclear.
Purpose:
To conduct systematic literature review and meta-analysis to determine the effect size (ES) of DEH on cognitive performance and influence of experimental design factors (e.g., DEH > 2% BML).
Methods:
Thirty-three studies were identified, providing 280 ES estimates from 413 subjects with DEH ranging from 1-6% BML. Outcome variables (accuracy, reaction time), cognitive domains, and methods to induce DEH varied. ES were calculated using standardized mean differences and multivariate meta-analysis.
Results:
Impairment of cognitive performance (all domains/outcomes) with DEH was small but significant (ES = -0.21; 95% CI: [-0.31, -0.11], p < 0.0001) with significant heterogeneity (Q(279) = 696.0, p < 0.0001; I = 37.6%). Tasks of executive function (ES = -0.24; [-0.37, -0.12]), attention (ES = -0.52; 95% CI: [-0.66, -0.37]), and motor coordination (ES = -0.40; [-0.63, -0.17]) were significantly impaired (p ≤ 0.01) following DEH; and, attention/motor coordination was different (p < 0.001) from reaction time specific tasks (ES = -0.10; [-0.23, 0.02]). BML was associated with the ES for cognitive impairment (p = 0.04); consequently, impairment was greater (p = 0.04) for studies reporting >2% BML (ES = -0.28, 95% CI: [-0.41, -0.16] compared to ≤ 2% (ES = -0.14, 95% CI: [-0.27, -0.00]).
Conclusions:
Despite variability among studies, DEH impairs cognitive performance, particularly for tasks involving attention, executive function, and motor coordination when water deficits exceed 2% body mass loss.
Objective
Elemental deficiencies or in excess effects growth and development. Pacific population are at a disadvantage due to food insecurity as compared to New Zealand European households. This study aims to evaluate the status and interrelationship of elements (essential, non-essential and toxic) in nine-year-old Pacific children who were part of the Pacific Island Families Study living in New Zealand.
Materials and
Methods
This observational study included 278 eligible nine-year-old children. Essential elements (including calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, selenium, zinc, molybdenum), non-essential and toxic elements (arsenic, aluminum, antimony, boron, cadmium, lead, mercury, nickel,) were determined in toenails and after acid digestion, analysed using inductively coupled plasma mass spectrometry. Principal component analysis and multivariate analysis of covariance was used to identify differences in the groups of elements and the inter-correlations between elements.
Results
The mean calcium (868 μg/g Ca), selenium (0.35 μg/g Se) and zinc (129 μg/g Zn) concentrations were lower while the mean cadmium (0.21 μg/g Cd) lead (0.86 μg/g Pb) and mercury (0.72 μg/g Hg) concentrations were higher than the optimal health requirements. Ethnic differences in relation to toenail elemental concentrations were observed for aluminium and iron. Gender differences were observed for aluminium, antimony, arsenic and lead. Selenium and molybdenum were inversely associated with mercury. Manganese, zinc and calcium were positively associated.
Conclusions
This research contributes to the understanding of the elemental concentrations for Pacific children by using tissue samples from toenails, which improves the completeness of sampling than other tissues and provides a longer exposure time frame. The study also reports several inter-correlations between essential, non-essential and toxic elements in Pacific Island population.
RESUMO O objetivo desse estudo foi avaliar o estado de hidratação e desempenho cognitivo-motor em atletas durante uma prova de fast triathlon no calor. Doze triatletas (34 ± 2,7 anos) participaram do trabalho. O estado de hidratação foi mensurado pela perda de massa corporal (MC), coloração e gravidade específica (GE) urinárias. O desempenho cognitivo-motor foi verificado pela coordenação motora (CM) e tempo de reação simples (TRS). Após a prova houve uma diminuição significativa da MC (1,8 %; P < 0,001). Um aumento significativo entre pré e pós-competição foi observado para o índice de coloração da urina (P < 0,001) e GE (P < 0,001), respectivamente. O TRS foi melhor após a prova. Porém, demonstraram dismetria, prejudicando sua CM. Conclui-se que níveis de desidratação foram observados entre os atletas após a prova. Alterações opostas foram encontradas quanto ao desempenho cognitivo-motor. Atletas demonstraram uma maior descoordenação motora, mas melhoraram seu tempo de reação. Palavras-chave: Desempenho atlético. Desidratação. Tempo de reação.
The purpose of this study was to evaluate the hydration status and cognitive-motor performance in athletes during a fast triathlon race in the heat. Twelve triathletes (34 ± 2.7 years) participated in the study. Hydration status was measured by body mass (BM) loss, urine color and urine specific gravity (SG). The cognitive-motor performance was determined by motor coordination (MC) and simple reaction time (SRT). There was a significant decrease of BM (1.8 %; P < 0.001). A significant increase from pre race to post race was observed in urine color (P < 0.001) and SG (P < 0.001), respectively. The SRT was faster after race. However, athletes demonstrated dysmetria, impairing MC. It was concluded that dehydration levels were observed among athletes after race. Adverse changes were found on the cognitive-motor performance. Athletes demonstrated greater motor incoordination, but improved the reaction time.
In almost any sport, athletes undergoing dehydration often suffer from numerous dehydration related injuries. The purpose of this study was to evaluate the validity of acoustic method to detect changes in the hydration status of athletes after undergoing acute dehydration and a 2-hour rehydration protocol. The acoustic method of assessing body hydration status is based on the experimental fact that ultrasound speed in muscle is a linear function of the tissue water content. The assessment of water imbalance was conducted by measuring speed of ultrasound in the calf muscles using through transmission method. Eighty-two male and female collegiate athletes were examined to detect changes in hydration status before and after undergoing 3% acute dehydration. Results demonstrated that the changes of ultrasound velocity are in average about 1.1 m/s per 1% of body dehydration and ultrasound velocity in muscle potentially may serve as a measure of body hydration status. However, ultrasound speed measurement using through transmission mode implemented in this study is highly dependent on the positioning of the probe: even slight variation in the acoustic path results in significant changes in the measured values, which may results in unacceptable error. A solution to this problem is proposed and discussed. [NIH2R44AG042990.]
Context:
The combination of extensive weight loss and inadequate nutritional strategies used to lose weight rapidly for competition in weight-category sports may negatively affect athletic performance and health.
Objective:
To explore the reasoning of elite combat-sport athletes about rapid weight loss and regaining of weight before competitions.
Design:
Qualitative study.
Setting:
With grounded theory as a theoretical framework, we employed a cross-examinational approach including interviews, observations, and Internet sources. Sports observations were obtained at competitions and statements by combat-sport athletes were collected on the Internet.
Patients or other participants:
Participants in the interviews were 14 Swedish national team athletes (9 men, 5 women; age range, 18 to 36 years) in 3 Olympic combat sports (wrestling, judo, and taekwondo).
Data collection and analysis:
Semistructured interviews with 14 athletes from the Swedish national teams in wrestling, judo, and taekwondo were conducted at a location of each participant's choice. The field observations were conducted at European competitions in these 3 sports. In addition, interviews and statements made by athletes in combat sports were collected on the Internet.
Results:
Positive aspects of weight regulation other than gaining physical advantage emerged from the data during the analysis: sport identity, mental diversion, and mental advantage. Together and individually, these categories point toward the positive aspects of weight regulation experienced by the athletes. Practicing weight regulation mediates a self-image of being "a real athlete." Weight regulation is also considered mentally important as a part of the precompetition preparation, serving as a coping strategy by creating a feeling of increased focus and commitment. Moreover, a mental advantage relative to one's opponents can be gained through the practice of weight regulation.
Conclusions:
Weight regulation has mentally important functions extending beyond the common notion that combat-sport athletes reduce their weight merely to gain a physical edge over their opponents.
Numerous studies have suggested that dehydration is a causal factor to fatigue across a range of sports such as soccer; however, empirical evidence is equivocal on this point. It is also possible that exercise-induced moderate dehydration is purely an outcome of significant metabolic activity during a game. The diverse yet sustained physical activities in soccer undoubtedly threaten homeostasis, but research suggests that under most environmental conditions, match-play fluid loss is minimal (∼;1–2% loss of body mass), metabolite accumulation remains fairly constant, and core temperatures do not reach levels considered sufficiently critical to require the immediate cessation of exercise. A complex (central) metabolic control system which ensures that no one (peripheral) physiological system is maximally utilized may explain the diversity of research findings concerning the impact of individual factors such as dehydration on elite soccer performance. In consideration of the existing literature, we propose a new interpretative pacing model to explain the self-regulation of elite soccer performance and, in which, players behaviourally modulate efforts according to a subconscious strategy. This strategy is based on both pre-match (intrinsic and extrinsic factors) and dynamic considerations during the game (such as skin temperature, thirst, accumulation of metabolites in the muscles, plasma osmolality and substrate availability), which enables players to avoid total failure of any single peripheral physiological system either prematurely or at the conclusion of a match. In summary, we suggest that dehydration is only an outcome of complex physiological control (operating a pacing plan) and no single metabolic factor is causal of fatigue in elite soccer.
Submitted 8 healthy, endurance trained men (mean age 27.4 yrs), unacclimated to heat, to variations in body hydration. The Ss were kept euhydrated, dehydrated by controlled passive hyperthermia or exercise on a treadmill up to a weight loss of 2.8%, or hyperhydrated using a solution containing glycerol, with a total ingested volume equal to 21.4 ml/kg of body weight. On completion of a 90-min recovery period, the Ss were assigned a pedaling exercise and psychological tests of perceptive discrimination, psycho-motor skill, memory, fatigue and mood, were administered. Both dehydration conditions impaired cognitive abilities without any relative differences between them. Following arm crank exercise, further effects of dehydration were found for tracking performance only. Moreover, long-term memory was impaired in both control and hydration situations, whereas there was no decrement in performance in the hyperhydration condition. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Cognitive and mood decrements resulting from mild dehydration and glucose consumption were studied. Men and women (total N = 54; M age = 19.8 yr., SD = 1.2) were recruited from college athletic teams. Euhydration or dehydration was achieved by athletes completing team practices with or without water replacement. Dehydration was associated with higher thirst and negative mood ratings as well as better Digit Span performance. Participants showed better Vigilance Attention with euhydration. Hydration status and athlete's sex interacted with performance on Choice Reaction Time and Vigilance Attention. In a second study, half of the athletes received glucose prior to cognitive testing. Results for negative mood and thirst ratings were similar, but for cognitive performance the results were mixed. Effects of glucose on cognition were independent of dehydration.
Numerous studies have suggested that dehydration is a causal factor to fatigue across a range of sports such as soccer; however, empirical evidence is equivocal on this point. It is also possible that exercise-induced moderate dehydration is purely an outcome of significant metabolic activity during a game. The diverse yet sustained physical activities in soccer undoubtedly threaten homeostasis, but research suggests that under most environmental conditions, match-play fluid loss is minimal ( approximately 1-2% loss of body mass), metabolite accumulation remains fairly constant, and core temperatures do not reach levels considered sufficiently critical to require the immediate cessation of exercise. A complex (central) metabolic control system which ensures that no one (peripheral) physiological system is maximally utilized may explain the diversity of research findings concerning the impact of individual factors such as dehydration on elite soccer performance. In consideration of the existing literature, we propose a new interpretative pacing model to explain the self-regulation of elite soccer performance and, in which, players behaviourally modulate efforts according to a subconscious strategy. This strategy is based on both pre-match (intrinsic and extrinsic factors) and dynamic considerations during the game (such as skin temperature, thirst, accumulation of metabolites in the muscles, plasma osmolality and substrate availability), which enables players to avoid total failure of any single peripheral physiological system either prematurely or at the conclusion of a match. In summary, we suggest that dehydration is only an outcome of complex physiological control (operating a pacing plan) and no single metabolic factor is causal of fatigue in elite soccer.
Dehydration is a reliable predictor of impaired cognitive status. Objective data, using tests of cortical function, support the deterioration of mental performance in mildly dehydrated younger adults. Dehydration frequently results in delirium as a manifestation of cognitive dysfunction. Although, the occurrence of delirium suggests transient acute global cerebral dysfunction, cognitive impairment may not be completely reversible. Animal studies have identified neuronal mitochondrial damage and glutamate hypertransmission in dehydrated rats. Additional studies have identified an increase in cerebral nicotinamide adenine dinucleotide phosphate-diaphorase activity (nitric oxide synthase, NOS) with dehydration. Available evidence also implicates NOS as a neurotransmitter in long-term potentiation, rendering this a critical enzyme in facilitating learning and memory. With ageing, a reduction of NOS activity has been identified in the cortex and striatum of rats. The reduction of NOs synthase activity that occurs with ageing may blunt the rise that occurs with dehydration, and possibly interfere with memory processing and cognitive function. Dehydration has been shown to be a reliable predictor of increasing frailty, deteriorating mental performance and poor quality of life. Intervention models directed toward improving outcomes in dehydration must incorporate strategies to enhance prompt recognition of cognitive dysfunction.
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.
OBJECTIVE: To determine the effects of functional fatigue on active multijoint position reproduction in overhead-throwing athletes. DESIGN AND SETTING: A standard, repeated-measures, randomized-ordered, counterbalanced, 2-period (crossover) design was used. During the first test session, we randomly assigned subjects to either the nonfatigue or fatigue condition. Subjects underwent pretest measurements and then either a functional fatigue protocol or rest period, followed by posttest measurements. After a recovery period, subjects crossed over to the opposing condition for the second testing session. SUBJECTS: Thirteen overhead-throwing athletes competing in National Collegiate Athletic Association Division I or club baseball, with no history of upper extremity or central nervous system disorders, volunteered for this study. MEASUREMENTS: We measured active multijoint position reproduction accuracy in 3 dimensions using an electromagnetic tracking device. We noted each subject's ability to reproduce 3 positions corresponding with distinct moments of his throwing motion. A variable error score was calculated to compare the locations of the reproduced points with reference to the target point. RESULTS: A significant difference occurred between the pretest and posttest error scores in the fatigue condition. Comparisons between positions indicated that more errors were seen in the arm-cocked position than in the follow-through position under both fatigue and nonfatigue conditions. CONCLUSIONS: Functional fatigue decreased joint position sense acuity in overhead-throwing athletes. Our findings using this novel testing measurement method are in agreement with past research, with one exception. The trend toward higher error scores in the arm-cocked position would appear to contradict findings that sensorimotor system acuity increases toward end ranges of motion.
Whether mental performance is affected by slowly progressive moderate dehydration induced by water deprivation has not been examined previously. Therefore, objective and subjective cognitive-motor function was examined in 16 volunteers (8 females, 8 males, mean age: 26 yr) twice, once after 24 h of water deprivation and once during normal water intake (randomized cross-over design; 7-day interval). Water deprivation resulted in a 2.6% decrease in body weight. Neither cognitive-motor function estimated by a paced auditory serial addition task, an adaptive 5-choice reaction time test, a manual tracking test, and a Stroop word-color conflict test nor neurophysiological function assessed by auditory event-related potentials P300 (oddball paradigm) differed (P > 0.1) between the water deprivation and the control study. However, subjective ratings of mental performance changed significantly toward increased tiredness (+1.0 points) and reduced alertness (-0.9 points on a 5-point scale; both: P < 0.05), and higher levels of perceived effort (+27 mm) and concentration (+28 mm on a 100-mm scale; both: P < 0.05) necessary for test accomplishment during dehydration. Several reaction time-based responses revealed significant interactions between gender and dehydration, with prolonged reaction time in women but shortened in men after water deprivation (Stroop word-color conflict test, reaction time in women: +26 ms, in men: -36 ms, P < 0.01; paced auditory serial addition task, reaction time in women +58 ms, in men -31 ms, P = 0.05). In conclusion, cognitive-motor function is preserved during water deprivation in young humans up to a moderate dehydration level of 2.6% of body weight. Sexual dimorphism for reaction time-based performance is present. Increased subjective task-related effort suggests that healthy volunteers exhibit cognitive compensating mechanisms for increased tiredness and reduced alertness during slowly progressive moderate dehydration.
This investigation was conducted to determine the effects of a physical conditioning program on clubhead speed, consistency, and putting distance control in 10 men and 6 women National Collegiate Athletic Association Division I golfers. Supervised strength, power, and flexibility training was performed 3 times per week for 11 weeks. Performance tests were conducted before and after the training period. Significant (p < 0.05) increases were noted for all strength, power, and flexibility tests from pre- to posttraining of between 7.3 and 19.9%. Clubhead speed increased significantly (1.6%), equating to approximately a 4.9-m increase in driving distance. Putting distance control significantly improved for the men-only group (29.6%), whereas there was no significant difference in putting distance control for the total and women-only groups. Eleven weeks of golf-specific physical conditioning increased clubhead speed without a negative effect on consistency or putting distance control in intercollegiate men and women golfers.
To present recommendations to optimize the fluid-replacement practices of athletes.
Dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes do not voluntarily drink sufficient water to prevent dehydration during physical activity. Drinking behavior can be modified by education, increasing accessibility, and optimizing palatability. However, excessive overdrinking should be avoided because it can also compromise physical performance and health. We provide practical recommendations regarding fluid replacement for athletes.
Educate athletes regarding the risks of dehydration and overhydration on health and physical performance. Work with individual athletes to develop fluid-replacement practices that optimize hydration status before, during, and after competition.
The aim of this study was to assess the effects of fatigue on decision making and goal shooting skill in water polo. Fourteen junior elite male players (age 17.2 +/- 0.5 years; mass 84.2 +/- 7.6 kg; height 1.85 +/- 0.05 m) completed four sets of eight repetitions of an approximately 18 s maximal water polo specific drill. Progressively declining rest ratios for each successive set of the drill were employed to induce increasing fatigue and reflect the demands of match-play. A video-based temporally occluded decision-making task (verbalized response to various tactical situations) or goal shooting skill test (qualitative and quantitative analysis of goal shooting) was performed after each set. Heart rate, rating of perceived exertion (RPE) and blood lactate concentration were recorded. Heart rate (159 +/- 12, 168 +/- 13, 176 +/- 12, 181 +/- 12 Deats min-1; P < 0.001) and RPE (13.1 +/- 2.2, 15.5 +/- 1.7, 17.3 +/- 1.6, 19.1 +/- 1.1; P < 0.001) increased with declining rest ratios. At very high fatigue, decision-making accuracy was 18.0 +/- 21.8% better than at low fatigue (P = 0.008). Shooting accuracy and velocity were unaffected by incremental fatigue; however, skill proficiency (technique) decreased by 43 +/- 24% between the pre-test and high-fatigue conditions (P < 0.001). In conclusion, incremental increases in fatigue differentially influenced decision making (improved) relative to the technical performance (declined), accuracy and speed of the ball (unchanged) of a water polo goal shot.
To assess if there is deterioration in mental and psychomotor performance during 24-hour voluntary fluid intake deprivation.
A battery of computer generated psychological tests (Complex Reactionmeter Drenovac-series) was applied to 10 subjects to test light signal position discrimination, short-term memory, simple visual orientation, simple arithmetics, and complex motor coordination. We measured total test solving time, minimum (best) single task solving time, total ballast time, and total number of errors. Mood self-estimate scales of depression, working energy, anxiety, and self-confidence were used to determine the emotional status of subjects. During the first day of the experiment, subjects had free access to drinks. After a 48-hour interval, subjects voluntarily abstained from fluid intake for 24 hours. During that period, the testing was performed 7 times a day, at 3-hour intervals, except during the night. Z-transformation of the results enabled the comparison of 50 dependent measurements on the same subjects.
During dehydration, there was significant deterioration in total test solving time, minimum single task solving time, and total ballast time. No significant deterioration was found by mood self-estimate scales, except on the scale of energy at 23:00 hours.
Voluntary 24-hour fluid intake deprivation led to deterioration in objective parameters of psychological processing, but not in subjective parameters. The results suggest that the duration of fluid intake deprivation can be a useful indicator of mental and psychomotor deterioration level but not of mood self-estimates.
To determine whether moderate water loss (approximately 1.5-2% of body mass (BM)) represents a significant impairment to soccer match-play and the related fitness variables.
11 moderately active male soccer players (mean (SD) age 24.4 (3) years, BM 74.03 (10.5) kg, peak oxygen consumption 50.91 (4.0) ml/kg/min) volunteered to participate. The experimental procedure comprised: (1) a 45 min pre-match period of cycle ergometry exercise (90% of individual ventilatory threshold); (2) the completion of a 45 min soccer match; and (3) the immediate post-match performance of sport-specific and mental concentration tests. The subjects completed the procedure on three occasions each in a different experimental condition (fluid intake (FL), no fluid (NF) and mouth rinse (MR)) in an individually randomised order. Core temperature (Tc), heart rates, plasma and urine osmolalities, BM, sweat rates and heat storage were all measured.
The only condition-dependent difference during the match-play element of the protocol was a significantly increased Tc in the NF condition compared with the FL condition (39.28 degrees C (0.35 degrees C) and 38.8 degrees C (0.47 degrees C), respectively; p<0.05). The immediate post-match performance of a sport-specific fitness test was significantly impaired where FL had been denied (p<0.01). The post-test evaluation of rating of perceived exertion and thirst indicated that the NF condition was perceived to be the most challenging (p<0.05).
The condition-dependent differences in match-play and post-match tests demonstrate that moderate dehydration is detrimental to soccer performance. However, it remains unclear whether this could be attributable to water loss in itself or the negative psychological associations derived from a greater perception of effort in that condition.
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.
The object of this study was to examine the effects of hydration status on exercise performance in a group of amateur athletes under conditions of hypohydration (HYPO) and euhydration (EUH) at 'neutrally stable' temperatures. Eight healthy, physically active, amateur University rugby players (age 21.0±1.4 yrs, BMI 28.3±6.1 kg/m2) underwent two 12 hr programs of hydration (fluid abstinence and consumption at ∼20 °C) in order to induce states of EUH and HYPO. The participants completed two 30 min cycle ergometer tests under each hydration state in a random order. Changes in performance were measured using heart rate (HR), rate of perceived exertion (RPE) and relative rate of oxygen uptake (VO2). Urine osmolality values (UOsm) were also measured to quantify hydration status. UOsm values were EUH 385±184 mOsm/kg and HYPO 815±110 mOsm/kg. In the EUH condition, from rest to 30 min, HR values ranged from 78±12 to 116±12 beats/min, RPE 6±0 to 11±2 units and VO2 5.7±2.1 to 16.8±3.4 mL/kg/min. In the HYPO condition, HR 85±9 to 124±13 beats/min, RPE 6±0 to 13±2 units and VO2 6.2±2.8 to 20.1±3.5 ml/kg/min (mean±SD, p≤0.05). In conclusion, HR, RPE and VO2 variables increased significantly under HYPO conditions when compared to EUH conditions at ∼20°C and therefore having a detrimental effect on performance.
The attainment of consistent high performance in golf requires effective physical conditioning that is carefully designed and monitored in accordance with the on-course demands the player will encounter. Appreciating the role that physiology plays in the attainment of consistent performance, and how a player's physicality can inhibit performance progression, supports the notion that the application of physiology is fundamental for any player wishing to excel in golf. With cardiorespiratory, metabolic, hormonal, musculoskeletal and nutritional demands acting on the golfer within and between rounds, effective physical screening of a player will ensure physiological and anatomical deficiencies that may influence performance are highlighted. The application of appropriate golf-specific assessment methods will ensure that physical attributes that have a direct effect on golf performance can be measured reliably and accurately. With the physical development of golf performance being achieved through a process of conditioning with the purpose of inducing changes in structural and metabolic functions, training must focus on foundation whole-body fitness and golf-specific functional strength and flexibility activities. For long-term player improvement to be effective, comprehensive monitoring will ensure the player reaches an optimal physical state at predetermined times in the competitive season. Through continual assessment of a player's physical attributes, training effectiveness and suitability, and the associated adaptive responses, key physical factors that may impact most on performance success can be determined.
Variation in mental performance under different levels of heat stress-induced dehydration was recorded in 11 subjects heat acclimatized to the tropicals. Dehydration was induced by a combination of water restriction and exercise in heat. The psychological functions--arithmetic ability, short-term memory, and visuomotor tracking--were assessed in a thermoneutral room after the subjects recovered fully from the effects of exercise in heat, as reflected by their oral temperature and heart rate. The results indicated significant deterioration in mental functions at 2% or more body dehydration levels.
The effect of different heat loads on vigilance and complex cognitive tasks involved in a mission of different intensities were examined. Nine healthy volunteers were randomly exposed for 2 h to three climatic conditions: comfort (21 degrees C ET), moderate heat load (30 degrees C ET) and severe heat load (35 degrees C ET). The subjects were assigned to missions of shooting at targets of three different sizes. Physiological parameters (HR, Tre, and sweat rate) and psychomotor ability were monitored. Exposure to 35 degrees C ET gave rise to elevated HR, Tre, and dehydration of 2.5%, while exposure to 21 degrees C and 30 degrees C ET caused no physiological burden. Speed of performance was significantly higher when the subjects were exposed to moderate heat load than to either comfort or severe heat load. Percentage of errors, however, rose gradually with the rise in heat load. The results indicate: a) The effect of the intensity of the task and heat load on deteriorating performance are synergistic; b) psychomotor performance deteriorates even before physiological parameters are impaired, possibly because of feelings of discomfort; c) even highly motivated subjects are effected by heat load, especially when assigned to complex missions which require a high state of vigilance, cooperation, and coordination.
The aim of this study was to investigate the effects of exercise-induced and thermal dehydration on postural balance. Eight male subjects cycled for 2 h at a power output equal to 57-63% VO2max on two different occasions: once without drinking (NF) and once with intake of 1.9 l of a carbohydrate-electrolyte solution (FR). Before and after the exercise test, the velocity of the centre of pressure (COP) excursion was measured on a force platform during 30-s bipedal standing in normal position, feet side by side, and tandem position, feet heel to toe. On another occasion, eight subjects underwent seven consecutive sauna sessions (85 degrees C, 50% rh) of 15 min duration with no fluid replacement (S) to induce thermal dehydration. Mean fluid loss was 2.7 (+/- 0.4)%, 0.5 (+/- 0.5)% and 3.0 (+/- 0.6)% of body mass after NF, FR and S, respectively. Mean velocity of COP excursion after the exercise test was significantly higher in the NF than in the FR trial (p < 0.05). Postural stability was not influenced by S. In conclusion, prolonged exercise without fluid ingestion seems to negatively affect postural stability, whereas no effect is observed after exercise with fluid replacement or after thermal dehydration.
This investigation evaluated the validity and sensitivity of urine color (Ucol), specific gravity (Usg), and osmolality (Uosm) as indices of hydration status, by comparing them to changes in body water. Nine highly trained males underwent a 42-hr protocol involving dehydration to 3.7% of body mass (Day 1, -2.64 kg), cycling to exhaustion (Day 2, -5.2% of body mass, -3.68 kg), and oral rehydration for 21 hr. The ranges of mean (across time) blood and urine values were Ucol, 1-7; Usg, 1.004-1.029; Uosm, 117-1,081 mOsm x kg-1; and plasma osmolality (Posm), 280-298 mOsm x kg-1. Urine color tracked changes in body water as effectively as (or better than) Uosm, Usg, urine volume, Posm, plasma sodium, and plasma total protein. We concluded that (a) Ucol, Uosm, and Usg are valid indices of hydration status, and (b) marked dehydration, exercise, and rehydration had little effect on the validity and sensitivity of these indices.
The aim of this study was to examine the effect of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Nine semi-professional soccer players volunteered to participate in the study. Their mean (+/- s(x)) age, body mass and maximal oxygen uptake were 20.2+/-0.4 years, 73.2+/-1.8 kg and 59.1+/-1.3 ml x kg(-1) min(-1) respectively. The players were allocated to two randomly assigned trials: ingesting or abstaining from fluid intake during a 90 min intermittent exercise protocol (Loughborough Intermittent Shuttle Test: LIST). This test was designed to simulate the minimum physical demands faced by soccer players during a game. Before and immediately after performance of the test, the players completed a soccer skill test and a mental concentration test. Performance of the soccer skill test after the 'no-fluid' trial deteriorated by 5% (P<0.05), but was maintained during the fluid trial. Mean heart rate, perceived exertion, serum aldosterone, osmolality, sodium and cortisol responses during the test were higher (P<0.05) in the 'no-fluid' trial than in the fluid trial. The results of this study suggest that soccer players should consume fluid throughout a game to help prevent a deterioration in skill performance.
The goals of this article are to suggest a basic wiring diagram for the motor neural network that controls motivated behavior, and to provide a model for the organization of cerebral hemisphere inputs to this network. Cerebral projections mediate voluntary regulation of a behavior control column in the ventromedial upper brainstem that includes (from rostral to caudal) the medial preoptic, anterior hypothalamic, descending paraventricular, ventromedial, and premammillary nuclei, the mammillary body, and finally the substantia nigra and ventral tegmental area. The rostral segment of this column is involved in controlling ingestive (eating and drinking) and social (defensive and reproductive) behaviors, whereas the caudal segment is involved in controlling general exploratory or foraging behaviors (with locomotor and orienting components) that are required for obtaining any particular goal object. Virtually all parts of the cerebral hemispheres contribute to a triple descending projection - with cortical excitatory, striatal inhibitory, and pallidal disinhibitory components - to specific parts of the behavior control column. The functional dynamics of this circuitry remain to be established.
The effects of exercise-induced hypohydration on the motor skill performance of cricket bowling was examined in seven medium-fast bowlers who performed a random order of two experimental trials. Trials consisted of a bowling test (36 deliveries; PREBOWL) in a thermoneutral (16+/-2 degrees C) environment followed by approximately 1 hr of intermittent exercise in a heated environment (28+/-2 degrees C) and a further thermoneutral bowling test (36 deliveries; POSTBOWL). During one trial fluid intake was restricted (HYPO) whereas in the other, subjects were forced to drink in an effort to maintain euhydration (EUH). During all bowling tests subjects were provided with a fixed target on a cricket pitch and the line, length, and velocity of each delivery was determined. Pre-trial hydration status was confirmed by similar body mass (BM; 89.5+/-13.7 vs. 88.9+/-13.4 kg) and haemoglobin concentration (15.0+/-0.8 vs. 14.8+/-0.8 g.100 ml(-1) for EUH and HYPO, respectively). BM loss was greater in HYPO than EUH (2.48+/-0.58 vs. 0.46+/-0.45 kg). Accordingly, the resultant hypohydration was higher after HYPO than EUH (2.78+/-0.49 vs. 0.47+/-0.41% of BM). Whereas HYPO had no effect on bowling velocity (102+/-4 vs. 105+/-8 km x h(-1)), univariate analyses revealed independent differences for both bowling line (2.9+/-0.5 vs 3.4+/-0.6, P<0.01) and length (2.9+/-0.5 vs 3.4+/-0.6, P<0.01) of delivery after HYPO. We conclude that moderate (-2.8% of BM) exercise-induced hypohydration has minimal effect on maximal bowling velocity, but there is a detrimental effect on skilled motor performance in well-trained subjects.
This study investigated the effects of heat exposure, exercise-induced dehydration and fluid ingestion on cognitive performance. Seven healthy men, unacclimatized to heat, were kept euhydrated or were dehydrated by controlled passive exposure to heat (H, two sessions) or by treadmill exercise (E, two sessions) up to a weight loss of 2.8%. On completion of a 1-h recovery period, the subjects drank a solution containing 50 g l(-1) glucose and 1.34 g l(-1) NaCl in a volume of water corresponding to 100% of his body weight loss induced by dehydration. (H1 and E1) or levels of fluid deficit were maintained (H0, E0). In the E0, H0 and control conditions, the subject drank a solution containing the same quantity of glucose diluted in 100 ml of water. Psychological tests were administered 30 min after the dehydration phase and 2 h after fluid ingestion. Both dehydration conditions impaired cognitive abilities (i.e. perceptive discrimination, short-term memory), as well as subjective estimates of fatigue, without any relevant differences between the methods. By 3.5 h after fluid deficit, dehydration (H0 and E0) no longer had any adverse effect, although the subjects felt increasingly tired. Thus, there was no beneficial effect of fluid ingestion (H1 and E1) on the cognitive variables. However, long-term memory retrieval was impaired in both control and dehydration situations, whereas there was no decrement in performance in the fluid ingestion condition (H1, E1).
The aim of this study was to examine the effect of fatigue from maximal tennis hitting on skilled tennis performance. Eighteen senior county tennis players (9 males, 9 females) volunteered to participate in the study. Their mean (+/- s(mean)) age and body mass were as follows: males 20.7 +/- 0.9 years and 60.6 +/- 2.7 kg respectively, females 21.7 +/- 0.6 years and 71.5 +/- 1.8 kg respectively. The players undertook two performance tests, both against a tennis ball serving machine, on an indoor tennis surface: (1) a pre- and post-skill test of groundstrokes and service; (2) the Loughborough Intermittent Tennis Test (4 min work plus 40 s recovery) to volitional fatigue. Body mass decreased by 1.5% (P < 0.0001). Mean heart rates differed between rest, post-warm-up and all intermittent test values (P < 0.01), between the pre- and post-skill tests (P < 0.0001) and between bouts and recoveries (P < 0.01). Peak blood glucose and lactate concentrations were 5.9 mmol l(-1) (50% into the intermittent tennis test) and 9.6 +/- 0.9 mmol x l(-1) (25% into the test) respectively. Mean time to volitional fatigue was 35.4 +/- 4.6 min. Groundstroke hitting accuracy decreased by 69% from start to volitional fatigue in the intermittent test (P < 0.01). Service accuracy to the right court declined by 30% after the intermittent tennis test. The results of this study suggest that fatigue was accompanied by a decline in some but not all tennis skills.
Postural instability can be the result of various factors, including fatigue. Although it is well known that exercise-induced fatigue may be responsible for a decrease in performance, its effects on postural control, as well as those of hydration, have been relatively little explored. This study evaluated the effects of fatigue, with and without rehydration, on postural control in 10 healthy subjects who regularly practice sports activities. All subjects were submitted to three types of ergocycle exercises: maximal oxygen uptake (Vo2max) and submaximal exercises in no-hydrated and hydrated conditions at a power corresponding to approximately 60% of the Vo2max of each subject. Static posturographic tests were performed immediately before (control) and after exercises. The postural control performance decreased from the best to the worst: control, hydration, dehydration, and Vo2max. Fast Fourier transformation of the center of foot pressure showed three patterns of amplitude spectral density, with an increase of spectral amplitude for dehydration, more important for Vo2max conditions. Spectral amplitudes for control and hydration conditions were relatively similar. This hierarchy suggests that fatigue mainly alters muscular effectors and sensory inputs, such as proprioception, resulting in poor postural regulation. Moreover, fluid ingestion could be responsible for the preservation of muscular functions and of sensory afferences accurately regulating postural control.
Chronic mild dehydration is a common condition in some population groups, including especially the elderly and those who participate in physical activity in warm environments. Hypohydration is recognised as a precipitating factor in a number of acute medical conditions in the elderly, and there may be an association, although not necessarily a causal one, between a low habitual fluid intake and some cancers, cardiovascular disease and diabetes. There is some evidence of impairments of cognitive function at moderate levels of hypohydration, but even short periods of fluid restriction, leading to a loss of body mass of 1-2%, lead to reductions in the subjective perception of alertness and ability to concentrate and to increases in self-reported tiredness and headache. In exercise lasting more than a few minutes, hypohydration clearly impairs performance capacity, but muscle strength appears to be relatively unaffected.
Water in the human body is essential for metabolism, temperature regulation, and numerous other physiological processes that are consistent with good health. Accurate, precise, and reliable methods to assess body fluid compartments are needed. This review describes the hydration assessment techniques of isotope dilution, neutron activation analysis, bioelectrical impedance, body mass change, thirst, tracer appearance, hematologic indices, and urinary markers. It also provides guidance for selecting techniques that are appropriate for use with unique individuals and situations.
Adequate fluid intake is critical for survival. While adults are at liberty to drink fluids as wanted, children and infants are dependent upon caregivers for food and fluid. Children are at greater risk for dehydration than adults due to their higher surface-to-mass ratio. Additionally, children have different thirst sensitivities and body cooling mechanisms than adults. Children differ from adults in total body water content, and boys and girls differ in body water content with maturation. Research in young adults shows that mild dehydration corresponding to only 1% to 2% of body weight loss can lead to significant impairment in cognitive function. Dehydration in infants is associated with confusion, irritability, and lethargy; in children, it may produce decrements in cognitive performance.
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.