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Sandra Fowkes Godek and Arthur R. Bartolozzi

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Alexander S.D. Gamble, Jessica L. Bigg, Tyler F. Vermeulen, Stephanie M. Boville, Greg S. Eskedjian, Sebastian Jannas-Vela, Jamie Whitfield, Matthew S. Palmer and Lawrence L. Spriet

∼2% of their body mass (BM) through sweating ( Baker et al., 2007 ; Dougherty et al., 2006 ; Edwards et al., 2007 ; Linseman et al., 2014 ; McGregor et al., 1999 ; Owen et al., 2013 ; Palmer et al., 2017 ). The equipment worn by ice hockey players becomes problematic as sweat rates increase to

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Anita M. Rivera-Brown and Roberto A. De Félix-Dávila

Adolescent judo athletes who train in tropical climates may be in a persistent state of dehydration because they frequently restrict fluids during daily training sessions to maintain or reduce their body weight and are not given enough opportunities to drink.

Purpose:

Determine the body hydration status of adolescent judo athletes before, immediately after, and 24 h after (24H) a training session and document sweat Na+ loss and symptoms of dehydration.

Methods:

Body mass and urine color and specific gravity (USG) were measured before, after, and 24 h after a training session in a high-heat-stress environment (29.5 ± 1.0°C; 77.7 ± 6.1% RH) in 24 adolescent athletes. Sweat sodium loss was also determined. A comparison was made between mid-pubertal (MP) and late pubertal (LP) subjects.

Results:

The majority of the subjects started training with a significant level of dehydration. During the training session, MP subjects lost 1.3 ± 0.8% of their pretraining body mass whereas LP subjects lost 1.9 ± 0.5% (P < .05). Sweat sodium concentration was 44.5 ± 23.3 mmol/L. Fluid intake from a water fountain was minimal. Subjects reported symptoms of dehydration during the session, which in some cases persisted throughout the night and the next day. The 24H USG was 1.028 ± 0.004 and 1.027 ± 0.005 g/mL for MP and LP, respectively.

Conclusions:

Adolescent judo athletes arrive to practice with a fluid deficit, do not drink enough during training, and experience symptoms of dehydration, which may compromise the quality of training and general well-being.

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Erin L. McCleave, Katie M. Slattery, Rob Duffield, Philo U. Saunders, Avish P. Sharma, Stephen Crowcroft and Aaron J. Coutts

acclimation reduces thermal and cardiovascular strain during exercise, predominantly by reduced core temperature, increased plasma volume (PV), increased sweat rate, and earlier sweat onset. 3 The benefits of both heat and hypoxia can last for several weeks following exposure. 5 , 6 As heat and hypoxia have

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Samuel T. Tebeck, Jonathan D. Buckley, Clint R. Bellenger and Jamie Stanley

physiological adaptations associated with the heat-acclimated phenotype (ie, plasma volume [PV] expansion, earlier onset of sweat, increased sweat rate, increased skin blood flow, etc). In these studies, the HI ranged from 28 (30°C and 24% RH 17 ) to 61 (39.5°C and 60% RH 16 ), making it difficult to elucidate

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Martin J. Barwood, Joe Kupusarevic and Stuart Goodall

and sweat rate were calculated. Performance times were not revealed until the postexperiment debrief. Statistical Analysis Mean (SD) were calculated for perceptual (TS, TC, and RPE); performance (B lac , TTE duration); thermal ( T skin , T rec , and f c ) spray variables (temperature and volume

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Elizabeth M. Broad, Louise M. Burke, Greg R. Cox, Prue Heeley and Malcolm Riley

Fluid losses (measured by body weight changes) and voluntary fluid intakes were measured in elite basketball, netball, and soccer teams during typical summer and winter exercise sessions to determine fluid requirements and the degree of fluid replacement. Each subject was weighed in minimal clothing before and immediately after training, weights, and competition sessions; fluid intake, duration of exercise, temperature and humidity, and opportunity to drink were recorded. Sweat rates were greatest during competition sessions and significantly lower during weights sessions for all sports. Seasonal variation in dehydration (%DH) was not as great as may have been expected, particularly in sports played indoors. Factors influencing fluid replacement during exercise included provision of an individual water bottle, proximity to water bottles during sessions, encouragement to drink, rules of the game, duration and number of breaks or substitutions, and awareness of personal sweat rates. Guidelines for optimizing fluid intakes in these three sports are provided.

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James M. Green, Phil A. Bishop, Ian H. Muir and Richard G. Lomax

Sweat lactate is at least partly derived from eccrine-gland metabolism. This study examined whether potential age-associated changes in sweat rate and skin blood flow influence sweat lactate. Six middle-aged (51.5 ± 3.8 years) and 6 younger (25.8 ± 1.5 years) men similar in VO2max, height, weight, percent body fat, and surface area completed constant-load (CON) cycling and interval-cycling (INT) trials. During each trial, sweat and blood were analyzed for lactate concentration at 15, 25, 35, 45, and 60 min. Sweat rates and estimated total lactate secretion were not significantly different (p > .05) between trials or groups. Blood-lactate concentrations were not significantly different between groups during CON but were significantly higher in younger men at 35 min and 45 min during INT. Sweat-lactate concentrations were not significantly different (p > .05) between groups during CON or INT. These results suggest that differences in eccrine-gland metabolism between young and middle-aged men are minimal.

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Karen Soo and Geraldine Naughton

This study investigated the hydration profile of high-performance female cricket players competing at a national tournament. The profile comprised hydration monitoring (n = 18) and a questionnaire (n = 20). Our objectives were to 1) advance the understanding of fluid losses in cricket sessions across a tournament and 2) assess the hydration knowledge and practices in female cricket players. Body mass before and after each game inning was recorded in order to estimate sweat rate, sweat loss, and percentage body-mass loss. Comparisons were made between groups categorized according to level of activity during each inning. When sweat rates were estimated according to actual activity time, results were in the range of those in other female team sports but less than results from male cricket players. A range of knowledge of hydration issues was also observed. This study supports the need for individualized hydration recommendations and provides direction for further hydration education in women’s cricket.

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Kevin Tipton, Nancy R. Green, Emily M. Haymes and Mary Waller

Zinc (Zn) loss from sweat of 9 male and 9 female athletes exercising under hot (35°C, HE) and neutral (25°C, ME) conditions was examined. Subjects exercised at 50% VO2max on a cycle ergometer for 1 hr during each trial. Cell-free sweat samples were analyzed for Zn by atomic absorption spectro-photometry. There was a significant interaction of time, gender, and temperature for whole-body sweat rates (WBSR). WBSR for males were higher during both trials and at each time. WBSR from the second half of exercise were higher than those from the first half for both sexes and temperature conditions. Sweat Zn concentration was higher in the NE than in the HE, but when the sweat rates were included, the rate of Zn loss was no different between HE and NE. Zn concentration of the sweat for the first half of exercise was over twice that of the second half. Sweat Zn concentration of the men was no different than that of the women; however, due to greater sweat rate, men had significantly higher Zn losses. Although total Zn losses are estimated to be relatively low compared to the RDA. exercise at moderate intensities may increase surface Zn losses.