Effect of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in the heat.
Study Goal
The researchers aimed to determine the effects of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in high ambient temperature.
Results Summary
Caffeine enhanced endurance performance (effect size = 0.22) compared to placebo, reduced perceived exertion in the first 60 minutes, but did not affect core/skin temperature, hormone levels, or substrate oxidation.
Population
Eight healthy, recreationally active males (mean age 22±1 years, body mass 71.1±8.5kg).
Effective Dosage
6 mg/kg
Duration
Not specified in the abstract
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
moderate caffeine dose | increase | endurance cycle performance | eight healthy, recreationally active males | 363.8±47.6kJ vs 353.0±49.0kJ | enhanced | #1 |
caffeine | no change | core temperature | eight healthy, recreationally active males | - | did not influence | #2 |
caffeine | no change | skin temperature | eight healthy, recreationally active males | - | did not influence | #3 |
caffeine | no change | circulating prolactin | eight healthy, recreationally active males | - | were similar | #4 |
caffeine | no change | cortisol | eight healthy, recreationally active males | - | were similar | #5 |
caffeine | no change | estimated rates of fat oxidation | eight healthy, recreationally active males | - | were similar | #6 |
caffeine | no change | carbohydrate oxidation | eight healthy, recreationally active males | - | were similar | #7 |
caffeine | decrease | perceived exertion | eight healthy, recreationally active males | - | attenuated | #8 |
caffeine | no change | thermal stress | eight healthy, recreationally active males | - | no difference | #9 |
OBJECTIVES: This study investigated the influence of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in high ambient temperature. DESIGN: Double-blind cross-over study. METHODS: Eight healthy, recreationally active males (mean±SD; age: 22±1 years; body mass: 71.1±8.5kg; VO RESULTS: Performance was enhanced (Cohen's d effect size=0.22) in the caffeine trial (363.8±47.6kJ) compared with placebo (353.0±49.0kJ; p=0.004). Caffeine did not influence core (p=0.188) or skin temperature (p=0.577) during exercise. Circulating prolactin (p=0.572), cortisol (p=0.842) and the estimated rates of fat (p=0.722) and carbohydrate oxidation (p=0.454) were also similar between trial conditions. Caffeine attenuated perceived exertion during the initial 60min of exercise (p=0.033), with no difference in thermal stress across trials (p=0.911). CONCLUSIONS: Supplementation with 6mgkg