How Much Does Exercise Help With Stress? New Study Offers Answers

For years, experts have suggested that regular aerobic exercise, like brisk walking, jogging or cycling, can lower the risk of heart disease and improve how the body handles stress. But until now, much of that evidence has been based on shorter or observational studies. A 12-month clinical trial, published in the Journal of Sport and Health Science, offers a more detailed look at how exercise affects both heart health and the body’s stress systems over time.

In the study, a team of investigators followed 130 generally healthy adults between the ages of 26 and 58. Participants were divided into two groups: One group followed a structured exercise plan of about 150 minutes per week of moderate to vigorous aerobic activity, while the other group received general health information but did not take part in a guided exercise program.

The research team tracked a wide range of health markers. These included traditional cardiovascular risk factors, such as cholesterol, blood sugar and blood vessel health, as well as biological signals related to stress and emotions. These stress-related measures included cortisol (a hormone released during stress), heart rate variability (a measure of how the body responds to stress), inflammation markers and even brain activity during stress-related tasks.

One of the clearest findings was that participants in the exercise group improved their cardiorespiratory fitness, which is a key indicator of heart health. Just as importantly, they also experienced a reduction in cortisol levels, measured through hair samples. Hair cortisol reflects long-term stress exposure, so this finding suggests that regular aerobic exercise may help lower chronic stress over time.

However, the results were more nuanced when it came to other stress-related systems in the body. The study did not find consistent improvements in other biological markers, such as inflammation, heart rate variability or brain responses to stress and emotional stimuli. This suggests that while exercise clearly benefits physical fitness and may reduce certain aspects of stress, it may not have a broad or uniform effect across all of the body’s stress-related systems.

Investigators noted several important strengths that make the findings more reliable. It used a randomized controlled trial design, and participants were randomly assigned to groups, helping ensure that differences in outcomes were due to the exercise intervention. Another strength was the use of multiple health measures, including heart health markers, stress hormones, inflammation and brain responses, providing a more complete picture of how exercise affects the body.

However, there are key limitations to consider. Participants in the exercise group received more attention and support from staff, which could have influenced stress levels independently of exercise. The study also took place during the COVID-19 pandemic, a factor that may have affected stress and participation. The sample size was relatively small, which can make it harder to detect subtle effects. Additionally, strict eligibility criteria may limit how well results apply to the general population.

The results provide evidence that exercise can help reduce at least one important marker of chronic stress. But they also highlight that stress is complex and involves multiple systems in the body. Exercise alone may not fully address all aspects of emotional or physiological stress.

“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,” concluded co-lead investigator Peter J. Gianaros, Ph.D., director of the Center for Mind-Body Science and Health and faculty at the University of Pittsburgh.