Effect of Pre-Exercise Caffeine Intake on Endurance Performance and Core Temperature Regulation During Exercise in the Heat: A Systematic Review with Meta-Analysis.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine intake | neutral | endurance performance | adults (≥ 18 years old) | - | impact | #1 |
caffeine intake | neutral | core temperature | adults (≥ 18 years old) | - | impact | #2 |
caffeine ingestion of 6 mg/kg body mass ~ 1 h before exercise | increase | endurance performance | - | - | may provide a worthwhile improvement | #3 |
caffeine ingestion of 6 mg/kg body mass ~ 1 h before exercise | no change | endurance performance | - | - | is unlikely to be deleterious | #4 |
caffeine ingestion of 6 mg/kg body mass ~ 1 h before exercise | increase | the rate of change in core temperature | - | - | trivially increases | #5 |
BACKGROUND: Heat is associated with physiological strain and endurance performance (EP) impairments. Studies have investigated the impact of caffeine intake upon EP and core temperature (C OBJECTIVE: To use a meta-analytical approach to determine the effect of pre-exercise caffeine intake on EP and C DESIGN: Systematic review with meta-analysis. DATA SOURCES: Four databases and cross-referencing. DATA ANALYSIS: Weighted mean effect summaries using robust variance random-effects models for EP and C STUDY SELECTION: Placebo-controlled, randomized studies in adults (≥ 18 years old) with caffeine intake at least 30 min before endurance exercise ≥ 30 min, performed in ambient conditions ≥ 27 °C. RESULTS: Respectively six and 12 studies examined caffeine's impact on EP and C CONCLUSION: Caffeine ingestion of 6 mg/kg body mass ~ 1 h before exercise in the heat may provide a worthwhile improvement in EP, is unlikely to be deleterious to EP, and trivially increases the rate of change in C