Effect of time of day on exercise performance and muscle hypertrophy: a randomized controlled trial
Chtourou H, Souissi N
Evidence is still building up
Summary
An RCT examining the effects of exercise timing (morning, afternoon, evening) on strength, performance, and muscle hypertrophy. Evening exercise (16:00–20:00) showed statistically higher maximum strength, explosive power, and endurance performance compared to morning exercise (06:00–10:00), correlating with body temperature and hormonal secretion patterns. However, long-term hypertrophy differences were inconsistent.
Key findings
- 1
Evening exercise (16:00–20:00) tends to show 5–10% higher peak strength and power compared to morning (06:00–10:00)
- 2
More favorable body temperature, testosterone, and cortisol ratios in the evening are proposed mechanisms
- 3
Long-term (12+ weeks) hypertrophy differences are small and the timing effect is limited
- 4
Consistency in training time and habituation are most important; preferred timing for adherence takes priority
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