Overview
- A preregistered randomized trial of 130 adults assigned 150 minutes a week of moderate‑to‑vigorous aerobic activity for 12 months cut long‑term cortisol stored in hair compared with a health‑information control.
- Hair cortisol reflects months of hormone exposure, offering a window into chronic stress biology rather than a single blood or saliva snapshot.
- The exercise group improved cardiorespiratory fitness, yet other targets tied to stress and cardiovascular risk showed no consistent change, including heart rate variability, inflammation markers, and self‑reported stress.
- Authors say the cortisol drop could help explain how regular aerobic activity protects brain and heart health, echoing earlier trial results that found a slower pace of brain aging, and they urge replication in larger and less healthy samples.
- Limitations include a moderate sample, higher dropout at follow‑up, and a very healthy cohort that left little room for change, and the study was funded by NIH and NHLBI with disclosed consulting by a senior author not involved in the study design.