New study reveals how running trains the body to handle psychological stress

A study examining the effects of exercise on mental health symptom severity found that these effects are mediated by reductions in perceived stress and repetitive negative thinking. In other words, exercise reduced perceived stress and repetitive negative thinking, and these led to the reduction of other mental health symptoms. The paper was published in Psychological Medicine.

Regular physical exercise is increasingly recognized as an important tool for supporting mental health as well as physical health. Research suggests that exercise can reduce symptoms of several mental health conditions, including depression, anxiety disorders, post-traumatic stress disorder, and insomnia. Yet, researchers are still trying to understand exactly why moving the body can produce such broad psychological benefits.

One possibility is that exercise acts as a transdiagnostic treatment—meaning it influences processes that are shared across many different mental disorders rather than acting on symptoms unique to a particular diagnosis. These common processes include how strongly people perceive and experience stress, how much they become caught in repetitive negative thoughts, and how well they sleep.

Each of these factors can contribute to the development and persistence of psychological difficulties, and they can also reinforce one another over time. Exercise may help interrupt this cycle by improving the ability to cope with stress, reducing patterns of persistent negative thinking, and supporting better sleep.

Study author Anna Katharina Frei and her colleagues conducted a study in which they investigated how perceived stress, repetitive negative thinking, and sleep quality jointly mediate the effect of exercise on mental health symptom severity. They conducted a secondary analysis of the ImPuls trial data (using existing data from an already completed trial to answer this new question) that included 6- and 12-month follow-ups along with data collection at the start of the study.

The ImPuls trial was a study conducted across 10 study sites in Baden-Württemberg, Germany. Participants were randomly assigned into two parallel groups – one receiving the ImPuls exercise treatment plus treatment as usual (for the disorder participants suffered from) and one receiving only treatment as usual, which acted as a control group.

Study participants were 400 physically inactive individuals suffering from major depressive disorder, agoraphobia, panic disorder, PTSD, or insomnia. Nearly 72% of them suffered from major depressive disorder. Participants’ average age was 42 years, and about 71% of them were women.

The ImPuls treatment consisted of supervised group meetings and 30 minutes of moderate-to-vigorous aerobic exercise performed as outdoor running two to three times per week. The group meetings were focused on behavioral change techniques (e.g. goal setting, barrier management) delivered by qualified exercise therapists to increase motivation and commitment to maintaining an exercise routine.

The supervised portion of the treatment lasted for 4 weeks, after which participants were instructed to continue nonsupervised aerobic exercises for five more months, making it a 6-month intervention overall. The adherence to this regimen was monitored through phone calls with the exercise therapist. The treatment as usual condition (the control condition) included standard interventions typically provided in German outpatient settings, such as psychological treatments and medications.

Study authors assessed participants’ overall symptom severity (using the Global Severity Index, which measures combined distress from depression, anxiety, and physical symptoms), sleep quality (the German version of the Pittsburgh Sleep Quality Index), perceived stress (the Perceived Stress Scale), and repetitive negative thinking (the Perseverative Thinking Questionnaire).

Results showed that at the 6- and 12-month assessments, participants undergoing the ImPuls treatment showed significantly reduced repetitive negative thinking and perceived stress compared to the control group. However, contrary to initial expectations, the exercise intervention did not lead to improved sleep quality at either time point. The authors suggest this may be because while exercise is known to improve sleep for depression, its impact on the sleep of those with PTSD and anxiety disorders—who were also included in this mixed group—is historically less conclusive.

Study authors tested a statistical model proposing that reductions in repetitive negative thinking and perceived stress (caused by the ImPuls treatment) led to reductions in disorder symptoms. Results confirmed this relationship, showing that changes in perceived stress and repetitive negative thinking fully mediated the treatment’s effect on overall symptom severity.

“Our results suggest that changes in perceived stress and repetitive negative thinking may be key transdiagnostic mechanisms underlying the treatment effect of exercise on global symptom severity,” study authors concluded.

The researchers theorize that exercise reduces stress by safely mimicking physical stress responses (like a raised heart rate and cortisol release), effectively training the body to handle actual psychological stressors better over time. Furthermore, the physical exertion of exercise may act as a deliberate distraction, forcing the brain to shift focus away from symptoms and break the cycle of repetitive negative thinking.

The study contributes to the scientific understanding of the effects of exercise on mental health symptoms. However, the study participants were likely aware of what the study was investigating and what the expected results were, while outcome measures were based on self-reports. This could have created expectancy effects that may have affected the results.

The paper, “Changes in repetitive negative thinking and stress perception mediate treatment effects of a transdiagnostic exercise intervention,” was authored by Anna Katharina Frei, Thomas Studnitz, Britta Seiffer, Jana Welkerling, Johanna-Marie Zeibig, Eva Herzog, Mia Maria Günak, Thomas Ehring, Keisuke Takano, Tristan Nakagawa, Leonie Sundmacher, Sebastian Himmler, Stefan Peters, Anna Lena Flagmeier, Lena Zwanzleitner, Ander Ramos-Murguialday, Gorden Sudeck, and Sebastian Wolf.