Effect of caffeine on cycling time-trial performance in the heat.
OBJECTIVES
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).


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


DESIGN
Double-blind cross-over study.
['Pitchford|Nathan W|NW|', 'Fell|James W|JW|', 'Leveritt|Michael D|MD|', 'Desbrow|Ben|B|', 'Shing|Cecilia M|CM|']
D000328:Adult D054874:Athletic Performance D001831:Body Temperature D002110:Caffeine D018592:Cross-Over Studies D004311:Double-Blind Method D005080:Exercise Test D006339:Heart Rate D006358:Hot Temperature D006801:Humans D008297:Male D010101:Oxygen Consumption D005082:Physical Exertion D011659:Pulmonary Gas Exchange D055815:Young Adult
Caffeine Cycling Heat Core temperature 1,3,7-Trimethylxanthine