We all know that going for a run, visiting the pool, or attending the gym makes us feel good. However, a groundbreaking new clinical trial has finally provided the hard biological proof: regular aerobic exercise leads to long-term reductions in the stress hormone cortisol. Published recently in the Journal of Sport and Health Science, this first-of-its-kind study moves past simply observing that active people seem less stressed. Instead, it proves the biological cause and effect of exercise over a full year.
The Science Behind the Activity
Led by Dr Peter J. Gianaros of the University of Pittsburgh and Dr Kirk I. Erickson of the AdventHealth Research Institute, the research team set out to see exactly what happens to our biology when we follow recommended physical activity guidelines.
To test this, the researchers designed a one-year randomised clinical trial, which is considered the gold standard for proving cause and effect. The study followed 130 adults between the ages of 26 and 58. Half of the participants committed to 150 minutes of moderate-to-vigorous aerobic activity every week. The other half acted as a control group, receiving general health information without changing their daily routines. Throughout the year, researchers meticulously monitored the participants' fitness levels, stress hormones, and emotions using state-of-the-art techniques and brain imaging.
The Cortisol Connection
The standout finding at the end of the year was a significant drop in long-term cortisol levels for the people in the exercise programme.
Cortisol is your body’s primary stress hormone. While it is essential for regulating metabolism, immunity, sleep, and mood, operating constantly with chronically high cortisol is detrimental to your health. Elevated levels are heavily linked to heart disease, metabolic disorders, and various mental health conditions.
"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," explains Dr Gianaros.
Because this study lasted a full year, it offers unique, concrete evidence that exercise can genuinely remodel our biology to mitigate the physical damage of stress.
The Takeaway
The prescription is straightforward, even if it requires a bit of effort. Aiming for 150 minutes of physical activity per week, which breaks down to just over 20 minutes a day, is a proven and highly effective strategy. Whether you lace up your trainers for a run or head out for a brisk walk, this level of activity can build mental resilience, and lower your stress hormones.
