No Effect of Nutritional Adenosine Receptor Antagonists on Exercise Performance in the Heat

Abstract

Nutritional adenosine receptor antagonists can enhance endurance exercise performance in temperate environments, but their efficacy during heat stress is not well understood. This double-blinded, placebo-controlled study compared the effects of an acute dose of caffeine or quercetin on endurance exercise performance during compensable heat stress (40 C, 20-30% rh). On each of three occasions, 10 healthy men each performed 30-min of cycle ergometry at 50% Vo2peak followed by a 15-min performance time trial after receiving either placebo (Group P), caffeine (Group C; 9 mg/kg), or quercetin (Group Q; 2,000 mg). Serial blood samples, physiological (heart rate, rectal, and mean skin body temperatures), perceptual (ratings of perceived exertion, pain, thermal comfort, motivation), and exercise performance measures (total work and pacing strategy) were made. Supplementation with caffeine and quercetin increased preexercise blood concentrations of caffeine (55.62 +/- 4.77 micrometers) and quercetin (4.76 +/- 2.56 micrometers) above their in vitro inhibition constants for adenosine receptors. No treatment effects were observed for any physiological or perceptual measures, with the exception of elevated rectal body temperatures (0.20 0.30 C; P < 0.05) for Group C vs. Groups Q and P. Supplementation did not affect total work performed (Groups P: 153.5 +/- 28.3, C: 157.3 +/- 28.9, and Q: 151.1 +/- 31.6 kJ; P > 0.05) or the self-selected pacing strategy employed. These findings indicate that the nutritional adenosine receptor antagonists caffeine and quercetin do not enhance endurance exercise performance during compensable heat stress.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 2008
Accession Number
ADA492987

Entities

People

  • B. B. Michniak-kohn
  • B. R. Ely
  • J. C. Rood
  • Michael N. Sawka
  • R. W. Kenefick
  • S. N. Cheuvront

Organizations

  • United States Army Research Institute of Environmental Medicine

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Biomedical Research
  • Blood
  • Body Temperature
  • Carbohydrates
  • Central Nervous System
  • Control Systems
  • Data Acquisition
  • Department Of Defense
  • Detectors
  • Dietary Supplements
  • Digestive System Processes
  • Heart Rate
  • Meals
  • Measurement
  • Steady State
  • Training
  • Vitamin C

Readers

  • Circadian Sleep-Wake Regulation and Chronobiology
  • Exercise and Sports Science.