DOHERTY, M., P. M. SMITH, R. C. R. DAVISON, and M. G. HUGHES. Caffeine is ergogenic after supplementation of oral creatine monohydrate. Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1785–1792, 2002.
Purpose: The purpose of this investigation was to assess the acute effects of caffeine ingestion on short-term, high-intensity exercise (ST) after a period of oral creatine supplementation and caffeine abstinence.
Methods: Fourteen trained male subjects performed treadmill running to volitional exhaustion (Tlim) at an exercise intensity equivalent to 125% V̇O2max. Three trials were performed, one before 6 d of creatine loading (0.3 g·kg−1·d−1; baseline), and two further trials after the loading period. One hour before the postloading trials, caffeine (5 mg·kg−1) or placebo was orally ingested in a cross-over, double-blind fashion. Four measurements of rating of perceived exertion were taken, one every 30 s, during the first 120 s of the exercise. Blood samples were assayed for lactate, glucose, potassium, and catecholamines, immediately before and after exercise.
Results: Body mass increased (P < 0.05) over the creatine supplementation period, and this increase was maintained for both caffeine and placebo trials. There was no increase in the maximal accumulated oxygen deficit between trials; however, total V̇O2 was significantly increased in the caffeine trial in comparison with the placebo trial (13.35 ± 3.89 L vs 11.67 ± 3.61 L). In addition, caffeine Tlim (222.1 ± 48.9 s) was significantly greater (P < 0.05) than both baseline (200.8 ± 33.4 s) and placebo (198.3 ± 45.4 s) Tlim. RPE was also lower at 90 s in the caffeine treatment (13.8 ± 1.8 RPE points) in comparison with baseline (14.6 ± 1.9 RPE points).
Conclusion: As indicated by a greater Tlim, acute caffeine ingestion was found to be ergogenic after 6-d of creatine supplementation and caffeine abstinence.
Department of Sport, Exercise and Biomedical Sciences, University of Luton, Luton, UNITED KINGDOM
Submitted for publication December 2001.
Accepted for publication May 2002.
Address for correspondence: Mike Doherty, University of Luton, Department of Sport, Exercise and Biomedical Sciences, Park Square, Luton, Beds LU1 3JU, United Kingdom; E-mail: email@example.com.
The authors express their thanks to Karl Schroder for help with data collection, Neil Willmore for his expert technical assistance, and Dr. John Wojdyla of the Luton and Dunstable Hospital, UK, for assaying of blood samples.