Summary: A year-long randomized clinical trial has provided the first causal evidence that regular aerobic exercise reduces long-term levels of cortisol, the body’s primary stress hormone. Participants who met the recommended 150 minutes of moderate-to-vigorous exercise per week showed a sustained decline in this biological marker of stress, suggesting exercise lowers the body’s baseline stress “set point.”
By reaching the commonly recommended 150-minute weekly target, study participants effectively lowered the biological “background noise” of stress, with implications for mental and cardiovascular health.
Key Findings
- The Cortisol Drop: Participants assigned to the aerobic exercise group experienced a statistically significant reduction in long-term cortisol (measured in hair). This supports the idea that regular cardio reduces baseline physiological stress rather than only producing short-term relaxation.
- Slower Brain Aging: Previous results from this same clinical trial indicated that regular aerobic activity also slowed markers of brain aging, suggesting exercise protects both brain structure and stress-related chemistry.
- Mental Resilience: Reaching 150 minutes per week emerged as a practical threshold for promoting biological resilience. Lower cortisol may help reduce the risk or severity of depression, anxiety, and stress-related heart disease.
- Robust, Long-Term Evidence: This is the first randomized clinical trial to track these specific stress biomarkers over an entire year, providing the strongest causal data to date that aerobic exercise can be an effective medical strategy for reducing chronic stress biology.
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 completed a year-long randomized trial to investigate how aerobic exercise affects biological indices of stress and emotion over time.
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 at the AdventHealth Research Institute. Their team specifically examined how meeting the American Heart Association’s recommended physical activity target influences cortisol and related stress measures.
The randomized trial enrolled 130 healthy adults aged 26 to 58. Participants were randomly assigned to either a prescribed exercise intervention—150 minutes per week of moderate-to-vigorous aerobic activity for 12 months—or to a health-information control group that received general lifestyle advice but did not increase their activity. Over the year, investigators tracked changes in cardiorespiratory fitness, hair cortisol (a marker of long-term cortisol exposure), heart rate variability, inflammatory markers, and neural responses using advanced brain imaging paradigms.
One of the clearest outcomes was a meaningful reduction in hair cortisol among those in the exercise group. Cortisol regulates metabolism, immunity, sleep, memory, and mood; chronically elevated cortisol is associated with higher risk for cardiovascular disease, metabolic problems, and psychiatric disorders. Dr. Gianaros noted that lowering long-term cortisol could be one mechanism through which sustained exercise protects physical and mental health, though he emphasized that additional work is needed to map the full causal chain.
Unlike most prior research, which has been correlational, this randomized clinical trial establishes a cause-and-effect relationship between sustained aerobic activity and decreased long-term cortisol. The year-long duration and multi-modal assessments make this study uniquely informative about how routine exercise can shift biological stress regulation.
Earlier reports from the same trial also found evidence that consistent aerobic exercise slowed measures of brain aging, reinforcing the view that physical activity delivers both neural and endocrine benefits. Together, these results underline the health value of adhering to public guidelines—roughly 30 minutes a day, five days a week—of moderate-to-vigorous aerobic activity.
Funding information
This study was supported by 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. In this trial, adhering to 150 minutes per week of moderate-to-vigorous aerobic exercise for one year produced a measurable reduction in long-term cortisol. That dose corresponds to about 30 minutes on five days each week.
A: Cortisol is essential for acute “fight-or-flight” responses, but chronic elevation—common in ongoing work or life stress—can harm the cardiovascular system, disrupt sleep, impair memory, and affect mood. Regular exercise appears to lower accumulated cortisol, reducing these long-term risks.
A: No. Medication decisions should always be made with your healthcare provider. However, this study supports considering consistent aerobic exercise as a first-line behavioral strategy that complements therapy and medication for managing long-term stress biology.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by our 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: Image credit: 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
The trial tested whether a sustained aerobic exercise program that improves cardiorespiratory fitness also reduces (a) biomarkers of cardiovascular disease risk and (b) indicators of stress- and emotion-related neuroendocrine, autonomic, and neural activity.
Methods
In this preregistered 12-month randomized 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. Outcomes included cardiometabolic and vascular risk markers (triglycerides, total cholesterol, HDL, HbA1c, pulse-wave velocity), neuroendocrine and autonomic indicators (hair cortisol, heart rate variability), inflammatory biomarkers (interleukin-6, ICAM-1), and neural, cardiovascular, and subjective responses to 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 found a significant group-by-time interaction for hair cortisol: the exercise group showed a decrease from baseline relative to controls (between-group difference = –0.62; 95% CI: –1.14 to –0.10; p(FDR) = 0.039). This reduction was also present in per-protocol analyses. No consistent intervention effects were found across the other measured outcomes in both planned and per-protocol analyses.
Conclusion
A 12-month moderate-to-vigorous aerobic exercise program that improved cardiorespiratory fitness also reduced the stress-related biomarker hair cortisol, though it did not produce consistent changes across the remaining psychological stress and negative emotion indicators linked to cardiovascular disease risk.