The effect of acute exercise on the cortisol awakening response.
Level 2 - randomized trial
Individual randomized crossover experimental trial in humans
PubMed 36629945 · doi:10.1007/s00421-023-05132-4
What was done
Twelve healthy young participants (mean age 23 years, mean VO2max 48.9 ml/kg/min) reported to the laboratory in the evening (1800 h) on two occasions and were randomly assigned to either one hour of exercise (70–75% of maximal power output) or a rest condition. Blood and saliva samples were collected to assay cortisol, and mixed-effects quadratic growth models assessed the cortisol awakening response (CAR) the following morning.
What was found
Exercise led to an acute circulating cortisol increase of 477.3% (mean heart rate 87.04% of maximum). The following morning, the CAR was significantly lower following the exercise condition compared to rest in both serum (beta = -42.26 [95% CI -64.52 to -20.01], p < 0.001) and saliva (beta = -11.55 [95% CI -15.52 to -7.57], p < 0.001).
Why it matters
This study shows that vigorous evening exercise alters next-day neuroendocrine dynamics, suggesting the cortisol awakening response may serve as a biomarker to monitor responses and recovery from exercise.
Limits
The sample size was very small (n = 12) and limited to young individuals. The study only evaluated a single late-evening time point and intensity, without reporting objective sleep architecture or mechanistic drivers.
Cited by
- supports Late-day exercise induces a cortisol elevation that suppresses morning cortisol levels via negative feedback.