title: Caffeine, carbohydrate, and cooling use during prolonged simulated tennis.
abstract: OBJECTIVE
  To determine the effects of prolonged simulated tennis on performance and the ergogenic potential of caffeine, carbohydrates, and cooling.
  
  
  METHODS
  Twelve highly trained male tennis players (age 18.3 +/- 3.0 y, height 178.8 +/- 8.5 cm, body mass 73.95 +/- 12.30 kg, mean +/- SD) performed 4 simulated matches (2 h 40 min) against a ball machine on an indoor hard court. The counterbalanced experimental trials involved caffeine supplementation (3 mg/kg), carbohydrate supplementation (6% solution), precooling and intermittent cooling, and placebo control. Physiological markers (core temperature, heart rate, blood lactate, and blood glucose), subjective responses (ratings of perceived exertion and thermal sensation), stroke velocity and accuracy, serve kinematics, and tennis-specific perceptual skill quantified the efficacy of interventions.
  
  
  RESULTS
  Significant effects of time (P < .01) reflected increased physiological demand, reduced serve velocity and ground-stroke velocity and accuracy, and a slowing of the serve racket-arm acceleration phase. Caffeine increased serve velocity (165 +/- 15 km/h) in the final set of the match (P = .014) compared with placebo (159 +/- 15 km/h, P = .008) and carbohydrate (158 +/- 13 km/h, P = .001) conditions. Carbohydrate and cooling conditions afforded physiological advantage (increased blood glucose, P < .01, and reduced preexercise thermal sensation, P < .01) but did not affect performance relative to the placebo condition.
  
  
  CONCLUSIONS
  Prolonged simulated tennis induced significant decrements in tennis skills. Caffeine supplementation partly attenuated the effects of fatigue and increased serve velocity. In contrast, carbohydrate and cooling strategies had little ergogenic effect on tennis performance.
authors.affiliation: Dept of Physiology, Australian Institute of Sport, Canberra, Australia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hornery
authors.forename: Damian
authors.initials: D
authors.lastname: Farrow
authors.forename: Inigo
authors.initials: I
authors.lastname: Mujika
authors.forename: Warren B
authors.initials: WB
authors.lastname: Young
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D002110:Caffeine / Q000627:therapeutic use*; D003080:Cold Temperature; D004040:Dietary Carbohydrates / Q000627:therapeutic use*; D019587:Dietary Supplements; D017079:Exercise Tolerance / Q000502:physiology*; D018882:Heat Stress Disorders / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D013647:Task Performance and Analysis; D013715:Tennis / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D002110:Caffeine