Summary: We have long known that a run or other aerobic activity can clear the mind, and a landmark year-long randomized clinical trial now explains the long-term biological reason. This study is the first to establish a causal link between regular aerobic exercise and a sustained reduction in cortisol, the body’s primary stress hormone.
By meeting the widely recommended target of 150 minutes of moderate-to-vigorous exercise per week, participants reduced the biological “background noise” of stress.
Key Findings
- The Cortisol Drop: Participants in the exercise group experienced a clear decline in long-term cortisol levels, indicating that regular aerobic activity lowers the body’s baseline stress setting rather than only producing short-term relaxation.
- Slowing Brain Aging: Earlier results from the same trial found that regular aerobic exercise also slowed markers of brain aging, suggesting fitness protects both brain function and brain structure.
- Mental Resilience: Reducing cortisol appears to be one biological pathway by which 150 minutes per week helps build resilience against depression, anxiety, and cardiovascular disease.
- Year-Long Evidence: This is the first randomized clinical trial to monitor these specific stress biomarkers continuously for a full year, offering the strongest evidence so far that exercise is a viable medical strategy to reduce chronic stress.
Source: Journal of Sport and Health Science
In the first clinical trial of its kind, published online in the Journal of Sport and Health Science on March 17, 2026, researchers ran a one-year randomized clinical trial to study how regular aerobic exercise affects the biology of stress and emotion.
The trial was led by Dr. Peter J. Gianaros, Director of the Center for Mind-Body Science and Health at the University of Pittsburgh, and Dr. Kirk I. Erickson, Director of Translational Neuroscience and the Mardian J. Blair Endowed Chair of Neuroscience at the AdventHealth Research Institute.
The team investigated whether following the American Heart Association’s activity recommendation affects measurable biological indicators of stress and emotion, with a primary focus on cortisol. They used a combination of physiological testing, hair-based hormone assays, and advanced brain imaging to track changes over time.
The study enrolled 130 healthy adults aged 26 to 58. Participants were randomized into two groups: one group completed 150 minutes per week of moderate-to-vigorous aerobic exercise for 12 months; the control group received general health information and did not change their activity habits.
Throughout the year, researchers measured changes in cardiorespiratory fitness, hair cortisol (a marker of long-term cortisol exposure), heart rate variability, inflammatory markers, and neural responses to stress and emotion through functional MRI and other techniques.
A key result was a significant reduction in long-term cortisol among participants assigned to the exercise intervention. Cortisol influences metabolism, immune function, sleep, memory, and mood; chronic elevations are associated with cardiovascular disease, metabolic disorders, and mental health problems. Lowering sustained cortisol exposure therefore has broad implications for physical and mental well-being.
As Dr. Gianaros noted, “Reducing long-term cortisol could be one mechanism through which exercise protects against multiple diseases and certain mental health conditions. More research will help clarify how this hormonal change connects to long-term health outcomes.”
This randomized trial is particularly important because much prior work has been observational and could not demonstrate cause and effect. Tracking stress biomarkers for a full year allowed the researchers to show that regular aerobic exercise, sustained at recommended levels, can produce durable changes in stress biology.
Previous reports from this same trial documented benefits beyond hormone changes: brain imaging data indicated a slower pace of brain aging among the exercising participants, reinforcing the idea that aerobic activity supports both brain structure and function across the middle years of life.
Drs. Gianaros and Erickson hope these results will raise awareness that meeting the 150-minute-per-week guideline is a practical, evidence-based way to strengthen mental resilience and reduce long-term stress biology.
Funding information
This study received funding from the National Institutes of Health and the National Heart, Lung, and Blood Institute (grant number: P01 HL040962) awarded to the University of Pittsburgh.
Key Questions Answered:
A: Yes. That amount equals 30 minutes on five days of the week. In this trial, consistently meeting that moderate target for a year produced a measurable reduction in the body’s long-term stress hormone levels.
A: Cortisol is essential for acute “fight or flight” responses, but chronically high cortisol—common with ongoing life or work stress—can damage cardiovascular health, disrupt sleep, impair memory, and shrink certain brain regions. Regular exercise helps lower that sustained cortisol burden.
A: No. Always consult your healthcare provider before changing medications. This study supports exercise as a first-line behavioral approach that can complement therapy and medication for managing long-term effects of stress.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal article was reviewed in full.
- Additional context was added by our editorial staff.
About this exercise and stress research news
Author: Linjia Wang
Source: Journal of Sport and Health Science
Contact: Linjia Wang – Journal of Sport and Health Science
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Effects of a year-long aerobic exercise intervention on neuroendocrine, autonomic, and neural correlates of stress, emotion, and cardiovascular disease risk in midlife adults” by Peter J. Gianaros et al., Journal of Sport and Health Science
DOI:10.1016/j.jshs.2026.101135
Abstract
Effects of a year-long aerobic exercise intervention on neuroendocrine, autonomic, and neural correlates of stress, emotion, and cardiovascular disease risk in midlife adults
Purpose
To determine whether a year-long aerobic exercise program that improves cardiorespiratory fitness reduces: (a) biomarkers of cardiovascular disease risk, and (b) measures of stress- and emotion-related neuroendocrine, autonomic, and neural activity.
Methods
In this preregistered 12-month randomized clinical trial, 130 healthy adults aged 26 to 58 (mean age 41.4 years; 67.7% female) were assigned to either a 150-minute-per-week moderate-to-vigorous aerobic exercise program or to a health-information control group. The study evaluated: (a) cardiometabolic and vascular risk factors (triglycerides, total cholesterol, HDL, glycosylated hemoglobin, pulse-wave velocity); (b) neuroendocrine and autonomic indicators (hair cortisol, heart rate variability); (c) systemic and vascular inflammation markers (interleukin-6, intercellular adhesion molecule-1); and (d) neural, cardiovascular, and subjective responses during fMRI stress and emotion tasks.
Results
Follow-up assessments were completed by 41 participants in the exercise group and 40 in the control group. Intention-to-treat analyses using generalized linear mixed models showed a significant group-by-time interaction: the exercise group experienced a greater reduction in hair cortisol from baseline to follow-up compared with controls (Between-Group Difference = –0.62; 95% CI: –1.14 to –0.10; p(FDR) = 0.039). This result was also supported by per-protocol analyses. Other outcomes did not show consistent differences across planned and per-protocol analyses.
Conclusion
A 12-month moderate-to-vigorous aerobic exercise intervention that improved cardiorespiratory fitness also reduced a stress-related biomarker (hair cortisol). The intervention did not produce consistent changes in other measured indicators of psychological stress and negative emotion processes linked to cardiovascular disease risk.