Effect of caffeine on cycling time-trial performance in the heat.
OBJECTIVE
The purpose of this investigation was to determine whether a moderate dose of caffeine would improve a laboratory simulated cycling time-trial in the heat.


METHODS
Nine well-trained male subjects (VO2max 64.4±6.8mLmin(-1)kg(-1), peak power output 378±40W) completed one familiarisation and two experimental laboratory simulated cycling time-trials in environmental conditions of 35°C and 25% RH 90min after consuming either caffeine (3mgkg(-1) BW) or placebo, in a double blind, cross-over study.


RESULTS
Time-trial performance was faster in the caffeine trial compared with the placebo trial (mean±SD, 3806±359s versus 4079±333s, p=0.06, 90%CI 42-500s, 86% likelihood of benefit, d=-0.79). Caffeine ingestion was associated with small to moderate increases in average heart rate (p=0.178, d=0.39), VO2 (p=0.154, d=0.45), respiratory exchange ratio (p=0.292, d=0.35) and core temperature (p=0.616, d=0.22) when compared to placebo, however, these were not statistically significant. Average RPE during the caffeine supplemented time-trial was not significantly different from placebo (p=0.41, d=-0.13).


CONCLUSIONS
Caffeine supplementation at 3mgkg(-1) BW resulted in a worthwhile improvement in cycling time-trial performance in the heat.


METHODS
Double-blind cross-over study.
Sport Performance Optimisation Research Team, School of Human Life Sciences, University of Tasmania, Australia.
Nathan W
NW
Pitchford
Sport Performance Optimisation Research Team, School of Human Life Sciences, University of Tasmania, Australia.
James W
JW
Fell
School of Public Health, Griffith University, Australia; School of Human Movement Studies, The University of Queensland, Australia.
Michael D
MD
Leveritt
School of Public Health, Griffith University, Australia.
Ben
B
Desbrow
Sport Performance Optimisation Research Team, School of Human Life Sciences, University of Tasmania, Australia. Electronic address: cecilia.shing@utas.edu.au.
Cecilia M
CM
Shing
D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001831:Body Temperature / Q000187:drug effects; D002110:Caffeine / Q000097:blood / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D006339:Heart Rate / Q000187:drug effects; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D055815:Young Adult
D002110:Caffeine
1,3,7-Trimethylxanthine; Caffeine; Core temperature; Cycling; Heat