Year-long study links regular exercise to lower cortisol levels

A new year-long clinical trial suggests that regular aerobic exercise may do more than improve fitness; it could also reduce the body’s long-term biological stress response.

Published in the Journal of Sport and Health Science, the study found that consistent moderate-to-vigorous physical activity was linked to measurable reductions in cortisol, the body’s primary stress hormone.

The research was led by Dr. Peter J. Gianaros of the University of Pittsburgh and Dr. Kirk I. Erickson of the AdventHealth Research Institute, who examined how structured exercise impacts stress regulation over time.

The randomized clinical trial followed 130 adults aged 26 to 58, dividing them into two groups. One group completed 150 minutes of aerobic exercise per week for one year, while the other continued usual activity with general health education.

Researchers monitored fitness levels, hormone changes, and brain activity using advanced imaging tools throughout the study.

At the end of the trial, participants in the exercise group showed a clear reduction in long-term cortisol levels compared to those who did not follow the exercise program.

Cortisol plays a key role in regulating sleep, mood, metabolism, and immune response. Long-term elevation has been associated with increased risks of cardiovascular disease, metabolic disorders, and mental health challenges.

Dr. Gianaros said the findings point to a possible biological pathway through which exercise helps protect both physical and mental health, though he noted that further research is still needed to confirm the mechanisms involved.

Unlike many earlier studies that relied on correlations, this trial’s randomized and long-duration design allowed researchers to observe direct cause-and-effect changes in stress biology.

The results also build on earlier findings from the same research project, which suggested that aerobic exercise may help slow brain aging.

Researchers say the findings reinforce public health guidelines recommending at least 150 minutes of moderate exercise per week, highlighting it as a practical and accessible way to support stress management and overall well-being.