Circadian rhythms in exercise performance: implications for hormonal and muscular adaptation.
Level 5 - mechanism / opinion, no new human data
Narrative review of circadian rhythms and exercise performance without systematic search methodology
What was done
This narrative review synthesized literature on circadian rhythms in human neuromuscular performance, core body temperature, and steroidal hormones (testosterone and cortisol), examining their implications for training and muscular adaptation.
What was found
The abstract provides no numerical data. Qualitatively, physical performance exhibits a circadian rhythm that typically peaks in the early evening, coinciding with peak core body temperature. While testosterone and cortisol display clear circadian profiles, the current evidence does not demonstrate a causal relationship between their daily fluctuations and neuromuscular adaptations. Time-of-day specific training enhances physical performance at the trained time point but does not alter the overall circadian profiles of testosterone and cortisol.
Why it matters
This review highlights that time-of-day performance peaks correlate primarily with core body temperature rather than fluctuations in anabolic and catabolic hormones. It indicates that while athletes can adapt to specific training times, hormonal rhythms alone do not dictate muscular training efficacy.
Limits
The abstract contains no quantitative metrics, confidence intervals, or details on the number or design of included studies. As a narrative review, it lacks systematic search criteria, risk-of-bias evaluation, and meta-analytic controls.
Cited by
- supports Data show that 3 hours after waking and 11 hours after waking are optimal times for mental and physical performance due to body temperature and cortisol rhythms.