CAFFEINE (CAF) is widely consumed by athletes to enhance performance before or during sports events due to its ergogenic effects. Studies have shown that both 3 and 6 mg/kg doses can enhance lower body endurance and peak power, with the 6 mg/kg dose observed to be more effective. However, the impact of performance benefits from CAF doses at specific times of day is underexplored, especially in female athletes.
A recent study from the High Institute of Sport and Physical Education Gafsa, Tunisia, focused on how different doses of CAF (3 mg/kg vs. 6 mg/kg) taken at certain times (morning vs. evening) affect high-intensity performance, perceived exertion, and potential side effects in female athletes.
Initially, 20 female handball players were selected, however, the final sample was reduced to 15 due to dropouts. Participants were young, well-trained, and met specific criteria, including low daily caffeine consumption and regular menstrual cycles. The study followed a double-blind, placebo-controlled, randomised design with six experimental sessions across three conditions: placebo, 3 mg/kg of CAF, and 6 mg/kg of CAF.
Tests were conducted in the morning and evening, with at least 72 hours between sessions to allow for recovery. On test days, the athletes ingested capsules (placebo, 3 mg/kg CAF, or 6 mg/kg CAF) one hour before testing, aligning with peak plasma CAF levels. The tests began 60 minutes post-ingestion with each session consisting of a standardised warm-up, a series of physical performance tests, and a CAF side effects questionnaire.
The results showed that a dose of 6 mg/kg of caffeine in the morning significantly enhanced agility and repeated sprint ability compared to a lower dose of 3 mg/kg. Both doses improved countermovement jump performance without influencing perceived exertion or oral temperature. However, in the evening, neither dose of caffeine improved performance and both were associated with an increase in side effects, such as anxiety and insomnia which were particularly pronounced in individuals with low habitual caffeine intake.
Overall, the study suggests that a 6 mg/kg dose of caffeine is recommended for morning use to enhance short-term maximal performance with minimal side effects while caution should be exercised regarding potential side effects, especially in the evening.
Katie Wright, EMJ
Reference
Bougrine H et al. Effects of different caffeine dosages on maximal physical performance and potential side effects in low-consumer female athletes: morning vs. evening administration. Nutrients. 2024;16(14):2223.
