What brain waves tell us about the link between exercise and mood

A study in Germany found that a 30-minute session of moderate-intensity physical exercise reduced rumination in depressed individuals compared to sitting. The reduction was visible in both electroencephalographic recordings and self-reports. The research was published in the Journal of Affective Disorders.

Depression is a mental health condition characterized by persistent low mood, loss of interest or pleasure, and impairments in emotional, cognitive, and physical functioning. It affects how people think, feel, and behave, interfering with daily life, work, and relationships. Common symptoms include sadness, fatigue, sleep and appetite disturbances, reduced concentration, and feelings of worthlessness or hopelessness.

One of the core cognitive symptoms of depression is rumination. Rumination is a cognitive process that involves repetitive and passive focus on one’s distress and its possible causes and consequences. However, rather than leading to problem solving, rumination tends to amplify negative mood and prolong depressive episodes without resolving the problem.

People who ruminate typically dwell on past failures, perceived flaws, or unanswered “why” questions about their suffering. This repetitive thinking can increase emotional distress and make it harder to disengage from negative thoughts. Rumination is also associated with impaired concentration and reduced motivation, further limiting adaptive coping. Research shows that higher levels of rumination predict greater severity and longer duration of depressive symptoms.

Study author Jana Welkerling and her colleagues explored the effects acute physical exercise has on ruminative thoughts. They wanted to examine the Distraction Hypothesis about rumination. This hypothesis proposes that rumination maintains or worsens depressed mood because it prevents engagement in distracting, rewarding, or problem-solving activities that could otherwise reduce negative affect. The researchers wanted to see whether exercise would shift participants from a ruminative to a distractive state and how this change develops.

The study participants were 24 individuals suffering from moderate or severe depression. Seventeen of them were women. Participants’ average age was 25 years.

Participants first underwent a diagnostic procedure (the Structured Clinical Interview for DSM-5) and completed assessments of depression symptoms (the Beck Depression Inventory II) and the tendency to ruminate (the Perseverative Thinking Questionnaire). They also completed medical examinations to confirm eligibility for physical exercise.

A week later, they completed two protocols to induce rumination and distraction in three consecutive sessions. The researchers took electroencephalography (EEG) recordings of participants’ brain activity during these sessions, allowing them to develop ways to estimate the probability that the person is engaged in rumination or distraction from EEG recordings.

In the third week, each participant completed two different experimental conditions. In both sessions, participants were first told to focus their attention on the symptoms of their depression. This was done with the aim to induce rumination. They then either completed a 30-minute moderate intensity physical exercise session (the exercise condition) or spent the 30 minutes sitting (the control condition). During these sessions, participants rated their rumination at 4.5-minute intervals and the researchers took EEG recordings of their brain activity.

Results showed that self-reported rumination decreased continuously during the physical exercise session. During the first five minutes of both the exercise and sitting sessions, self-reported rumination did not differ between the two conditions. However, from the 10th minute, rumination started decreasing significantly in the exercise condition (compared to the sitting condition).

Looking at EEG data in a subsample of participants for whom the decoding was successful, the estimated probability that the person was ruminating was lower in the exercise condition than in the sedentary condition. This happened because the estimated probability that the person is ruminating fell to a lower level already in the first minutes of the exercise session.

“This study demonstrated that a single bout of moderate-intensity physical exercise reduces self-reported and EEG-decoded rumination in individuals with moderate or severe depression, providing evidence that physical exercise reduces rumination in favor of distraction, as predicted by the Distraction-Hypothesis,” the authors concluded.

The study contributes to the scientific knowledge about the psychological effects of exercise. However, it should be noted that the study was conducted on a very small group of young people. Effects on other demographic groups might differ. It also remains unclear how long the reduction in rumination lasts.

The paper, “Single bout of exercise reduces self-reported and decoded rumination in favor of distraction in patients with major depression,” was authored by Jana Welkerling, Andreas Niess, Patrick Schneeweiss, Gorden Sudeck, Tim Rohe, and Sebastian Wolf.