Effect of caffeine on cycling time-trial performance in the heat.
Study Goal
The researchers aimed to determine whether a moderate dose of caffeine improves cycling time-trial performance in hot environmental conditions.
Results Summary
Caffeine supplementation (3mg/kg BW) led to a worthwhile improvement in cycling time-trial performance in the heat, with an 86% likelihood of benefit. Small to moderate increases in physiological measures (heart rate, VO2, respiratory exchange ratio, core temperature) were observed but were not statistically significant.
Population
Nine well-trained male cyclists (VO2max 64.4±6.8 mL/min/kg, peak power output 378±40W).
Effective Dosage
3 mg/kg body weight, single dose.
Duration
Single administration, 90 minutes before the time-trial.
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine (3mgkg(-1) BW) | increase | time-trial performance | nine well-trained male subjects | 3806±359s versus 4079±333s | was faster | #1 |
caffeine ingestion | increase | average heart rate | nine well-trained male subjects | d=0.39 | was associated with small to moderate increases | #2 |
caffeine ingestion | increase | VO2 | nine well-trained male subjects | d=0.45 | was associated with small to moderate increases | #3 |
caffeine ingestion | increase | respiratory exchange ratio | nine well-trained male subjects | d=0.35 | was associated with small to moderate increases | #4 |
caffeine ingestion | increase | core temperature | nine well-trained male subjects | d=0.22 | was associated with small to moderate increases | #5 |
caffeine supplementation | no change | average RPE | nine well-trained male subjects | d=-0.13 | was not significantly different | #6 |
caffeine supplementation at 3mgkg(-1) BW | increase | cycling time-trial performance in the heat | nine well-trained male subjects | - | resulted in a worthwhile improvement | #7 |
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.