Physical activity can offset the negative effects of social isolation, study finds

A new study published in Nature Mental Health provides evidence that engaging in physical activity can mitigate the adverse impacts of social isolation on mental well-being, particularly among individuals who are psychologically and neurobiologically vulnerable. This finding holds profound implications for public health, especially in a post-pandemic world where isolation has become a more pressing issue than ever before.

The motivation for this new research stemmed from the increased societal challenge of social isolation and loneliness, further accelerated by the COVID-19 pandemic. Previous studies conducted by the research team had explored the effects of social contact and physical activity on mental health resilience. However, the pandemic presented a unique opportunity to investigate potential strategies that could counteract the growing problem of isolation.

Given the known risks associated with social isolation — including its potential to increase human mortality on par with obesity, excessive alcohol consumption, or smoking 15 cigarettes a day — the study aimed to explore physical activity as a viable strategy to combat these effects.

“Our main interest in this topic stems from prior studies from our research groups, which investigated the influence of social contact and physical activity on mental health resilience. The COVID-19 pandemic increased our motivation to delve into the investigation of strategies that could potentially counteract the increasing social isolation and loneliness,” explained study authors Anastasia Benedyk and Markus Reichert from the Department of Psychiatry and Psychotherapy at the Central Institute of Mental Health.

The study involved a cohort of 317 healthy young adults aged 18-28 years, monitored over a week, and a replication sample of 30 healthy adults aged 18-63 years, observed over six months during the pandemic in Germany. Participants in both studies were equipped with accelerometers, either worn on their hip or wrist, to measure physical activity in an objective and quantifiable manner.

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Alongside physical activity monitoring, the study utilized smartphone-based electronic diaries (e-diaries) for participants to report their real-life social contacts and their mood at various times throughout the day. To assess mental well-being, the study focused on affective valence, a measure of mood that ranges from feelings of unwellness to wellness.

The researchers found that an hour of moderate physical activity, equivalent to walking at a pace of three miles per hour, could effectively counteract the negative mood effects of being alone. This positive impact of physical activity on mood was consistently observed across both study groups.

“The key takeaway from our study is that physical activity may be a feasible and effective strategy to alleviate adverse effects of aloneness on affective well-being in everyday life,” Benedyk and Reichert told PsyPost. “By highlighting the potential of physical activity as a public health strategy, our findings can contribute to enhancing evidence-based recommendations for managing social isolation in the post-pandemic world.”

In addition, a subset of participants from the first study underwent resting-state functional magnetic resonance imaging (fMRI) scans. These scans were used to assess the connectivity within the default mode network (DMN), a brain network associated with self-referential thought and emotion regulation, and identified as a neurobiological marker of risk for social isolation and depression.

Individuals with higher connectivity within the DMN showed a greater beneficial response to physical activity in terms of mood improvement. This suggests that physical activity may have a more pronounced positive effect on individuals who are neurobiologically predisposed to loneliness or depression.

Further exploratory analyses underscored physical activity’s benefits under restrictive conditions, such as curfews and closed gyms, during the pandemic. Even light physical activity and exercises performed at home were found to be beneficial. This demonstrates that the mood-enhancing effects of physical activity are not confined to high-intensity workouts or exercises done in specific settings but can also be achieved through more accessible forms of movement.

“Throughout our research, we were intrigued to discover that even smaller doses of physical activity at home could compensate for a social-affective deficit of aloneness,” Benedyk and Reichert said. “This finding supports the feasibility of integrating physical activity into everyday life to promote mental well-being.”

But the study has certain limitations, including the reliance on self-reported mood assessments and the observational nature of the research.

“While our observational study provides valuable insights, it does not establish causal relationships,” Benedyk and Reichert explained. “It’s essential to acknowledge that our findings demonstrate correlations which do not prove causality. Future studies should incorporate experimental designs to establish causality and validate our observations.”

“Our long-term goals involve investigating the causality of the findings by implementing short physical activity interventions delivered by smartphone applications,” the researchers added. “Through integrating innovative daily life research designs, e.g., prompting participants to engage in specific physical activities, we aim to uncover optimal strategies for leveraging physical activity as a treatment target in daily life.”

The study, “Real-life behavioral and neural circuit markers of physical activity as a compensatory mechanism for social isolation,” was authored by Anastasia Benedyk, Markus Reichert, Marco Giurgiu, Irina Timm, Iris Reinhard, Carina Nigg, Oksana Berhe, Alexander Moldavski, Christoph von der Goltz, Urs Braun, Ulrich Ebner-Priemer, Andreas Meyer-Lindenberg, and Heike Tost.