The goal of this clinical trial is to learn how different doses of caffeine taken in the evening affect rowing performance, sleep quality, and daytime alertness in trained male university rowers. The main questions it aims to answer are: Does a low, moderate, or high caffeine dose improve rowing performance? How do these doses affect sleep and recovery after evening exercise? Participants completed four rowing tests after consuming either a placebo, low (3 mg/kg), moderate (6 mg/kg), or high (9 mg/kg) dose of caffeine. Researchers measured rowing time, power, heart rate, sleep quality, and daytime sleepiness. The study found that moderate and high caffeine doses improved rowing performance the most. However, these same doses made it harder for participants to sleep well and feel alert the next day. Headaches and stomach issues were also more common with the high dose. The low dose gave smaller performance gains but caused fewer side effects. This study shows that evening caffeine can boost performance but may hurt recovery and sleep. Athletes and coaches should weigh these trade-offs when using caffeine for late-day training or competition.
Age range
20 Years – 25 Years
Sex
MALE
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Change in 2000-meter Rowing Ergometer Completion Time (seconds) Following Varying Doses of Evening Caffeine Ingestion
Timeframe: Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)
Subjective Sleep Quality Score (5-point Likert Scale)
Timeframe: Morning following each test day (approximately 10-12 hours post-dose)
Mean Power Output (Watts) During 2000-meter Rowing Ergometer Trial
Timeframe: Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)
Daytime Sleepiness Score (Epworth Sleepiness Scale)
Timeframe: Morning following each test day (approximately 10-12 hours post-dose)