title: Voluntary fluid intake and core temperature responses in adolescent tennis players: sports beverage versus water.
abstract: OBJECTIVE
  To examine differences in ad libitum fluid intake, comparing a 6% carbohydrate/electrolyte drink (CHO-E) and water, and associated differences in core temperature and other selected physiological and perceptual responses in adolescent athletes during tennis training in the heat.
  
  
  METHODS
  Fourteen healthy, fit, young tennis players (nine male; five female; mean (SD) age 15.1 (1.4) years; weight 60.6 (8.3) kg; height 172.8 (8.6) cm) completed two 120 minute tennis specific training sessions on separate days (randomised, crossover design) in a warm environment (wet bulb globe temperature: CHO-E, 79.3 (2.6) degrees F; water, 79.9 (2.2) degrees F; p>0.05).
  
  
  RESULTS
  There were no significant differences (p>0.05) between the trials with respect to fluid intake, urine volume, fluid retention, sweat loss, perceived exertion, thirst, or gastrointestinal discomfort. However, there was a difference (p<0.05) in the percentage body weight change after training (CHO-E, -0.5 (0.7)%; water, -0.9 (0.6)%). Urine specific gravity before training (CHO-E, 1.024 (0.006); water, 1.025 (0.005)) did not correlate significantly (p>0.05) with any of these measurements or with core body temperature. In examining the main effect for trial, the CHO-E trial showed a significantly lower (p<0.001) mean body temperature (irrespective of measurement time) than the water trial. However, the mean body temperature in each trial was not associated (p>0.05) with fluid intake, fluid retention, sweat loss, or percentage body weight change.
  
  
  CONCLUSIONS
  Ad libitum consumption of a CHO-E drink may be more effective than water in minimising fluid deficits and mean core temperature responses during tennis and other similar training in adolescent athletes.
authors.affiliation: Department of Physical Therapy, Medical College of Georgia, Augusta, GA 30912-0800, USA. mbergero@mcg.edu
authors.forename: M F
authors.initials: MF
authors.lastname: Bergeron
authors.forename: J L
authors.initials: JL
authors.lastname: Waller
authors.forename: E L
authors.initials: EL
authors.lastname: Marinik
mesh_terms: D000293:Adolescent; D001831:Body Temperature / Q000502:physiology*; D018592:Cross-Over Studies; D003681:Dehydration / Q000517:prevention & control*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004326:Drinking / Q000502:physiology*; D004573:Electrolytes / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D015532:Rehydration Solutions / Q000008:administration & dosage*; D013715:Tennis / Q000502:physiology*; D013894:Thirst / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D004040:Dietary Carbohydrates; D004573:Electrolytes; D015532:Rehydration Solutions