Researchers led by Peter Gianaros at the University of Pittsburgh report that 12 months of regular aerobic exercise lowered accumulated cortisol measured in hair. The randomized trial enrolled 130 healthy adults (ages 26–58) and assigned one group to 150 minutes per week of moderate-to-vigorous aerobic activity while a control group received health education. The study was published in the Journal of Sport and Health Science.
Hair cortisol is a retrospective measure of systemic cortisol exposure across months. The exercise group attended supervised sessions, used wearable heart‑rate monitors, and progressed from moderate to more vigorous intensity after six weeks. The control group was asked not to change normal activity.
After one year the exercise group showed a statistically significant drop in hair cortisol compared with the control group. Other measured endpoints did not change in a detectable way. The investigators found no significant differences in cholesterol, blood glucose, markers of systemic inflammation, arterial stiffness, or heart‑rate variability. Brain responses to acute stress and emotion‑regulation tasks inside an MRI scanner also did not differ between groups.
Gianaros said, “The effect of exercise on long-term cortisol levels could be one of the mechanisms or benefits of exercise that protect against several diseases and some mental health conditions, but more research is needed to fully explore this possibility.”
The team warned against overinterpreting null results. Participants were screened to be unusually healthy, which reduces room for improvement on cardiovascular risk markers. The trial also ran during the early COVID‑19 pandemic, which raised dropout rates and limited collection of daily stressor questionnaires.
The study suggests sustained aerobic activity can lower a multi-month marker of stress biology in healthy midlife adults. It does not show broader changes in the cardiovascular or neural stress responses measured here. The authors call for larger trials, work in people with existing cardiometabolic or mood disorders, and studies that vary exercise dose and intensity.
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Tags: aerobic exercise, hair cortisol, stress biology, wearable heart rate monitors
Topics: Wearable neurotech, Stress, focus & mental clarity, Neuroscience & neuroplasticity