Effect of different protocols of caffeine intake on metabolism and endurance performance

J Appl Physiol (1985). 2002 Sep;93(3):990-9. doi: 10.1152/japplphysiol.00249.2002.

Abstract

Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O(2) uptake followed by 7 kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2 g/kg) and during (6% CHO drink) exercise. In Study A, 12 subjects received either 6 mg/kg caffeine 1 h preexercise (Precaf), 6 x 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 x 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo. Improvements in TT were as follows: Precaf, 3.4% (0.2-6.5%, 95% confidence interval); Durcaf, 3.1% (-0.1-6.5%); and Coke, 3.1% (-0.2-6.2%). In Study B, eight subjects received 3 x 5 ml/kg of different cola drinks during the last 40 min of SS and TT: decaffeinated, 6% CHO (control); caffeinated, 6% CHO; decaffeinated, 11% CHO; and caffeinated, 11% CHO (Coke). Coke enhanced TT by 3.3% (0.8-5.9%), with all trials showing 2.2% TT enhancement (0.5-3.8%; P < 0.05) due to caffeine. Overall, 1) 6 mg/kg caffeine enhanced TT performance independent of timing of intake and 2) replacing sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (approximately 1.5 mg/kg).

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Beverages
  • Bicycling / physiology
  • Blood / metabolism
  • Caffeine / administration & dosage*
  • Caffeine / blood
  • Caffeine / pharmacology
  • Caffeine / urine
  • Carbohydrate Metabolism*
  • Central Nervous System Stimulants / administration & dosage*
  • Central Nervous System Stimulants / blood
  • Central Nervous System Stimulants / pharmacology
  • Central Nervous System Stimulants / urine
  • Double-Blind Method
  • Drinking
  • Humans
  • Male
  • Physical Endurance / drug effects*
  • Physical Exertion
  • Pulmonary Gas Exchange / drug effects
  • Respiration / drug effects
  • Self Concept

Substances

  • Central Nervous System Stimulants
  • Caffeine