Maintaining or increasing exercise linked to fewer depressive symptoms

A new study from South Korea suggests that maintaining or increasing moderate-to-vigorous physical activity over time is associated with lower odds of developing depression and experiencing depressive symptoms. The study, published in the Journal of Affective Disorders, followed nearly four million adults and found that those who were consistently active or became more active had better mental health outcomes over a multi-year period.

Depression is a widespread mental health issue, affecting people across all age groups and cultures. In South Korea, it has emerged as a major public health concern. Depression is typically characterized by persistent sadness, low energy, and loss of interest in activities. Importantly, reduced physical activity is often a symptom of depression. At the same time, research has repeatedly suggested that regular physical activity may help improve mood and protect against depressive symptoms. However, most studies have relied on a single snapshot of a person’s activity level, which fails to capture the ups and downs that occur over time.

The author of this new study aimed to address that gap by investigating whether changes in physical activity over several years were associated with mental health outcomes. They paid special attention to whether the effects differed for people who had already experienced depression versus those who had not.

“I have long been interested in the bidirectional relationship between lifestyle behaviors and mental health outcomes. Given the increasing burden of depression globally, I was motivated to explore how longitudinal changes in physical activity could influence depression risk, especially among individuals with and without pre-existing depressive symptoms,” said study author Yohwan Lim of the CHA University School of Medicine.

The researcher analyzed data from South Korea’s National Health Insurance Service, which provides nearly universal coverage and regularly conducts health screenings. The study began by identifying individuals who participated in screenings in two separate periods: 2014–2015 and 2016–2017.

From a starting pool of more than 24 million people, Lim narrowed the sample to 3.99 million individuals after applying strict eligibility criteria, including consistent data on activity levels, health conditions, and depression status. About 209,000 of the participants had been diagnosed with depression during the initial period, while the remaining 3.78 million had not.

Participants reported their physical activity through a questionnaire that asked how many days per week they engaged in moderate or vigorous activity. Moderate activity included things like brisk walking or cycling, while vigorous activity involved running or other exercises that made breathing hard. Based on their responses, participants were grouped into four categories: inactive, low activity (1–2 days per week), moderate activity (3–4 days), or high activity (5 or more days).

Lim also looked at how people’s activity levels changed over time. For example, someone who went from being inactive to exercising several days a week would be categorized as having increased their activity. These changes were tracked across the two screening periods. In some analyses, a third earlier period (2012–2013) was used to explore patterns before and after a diagnosis of depression.

To measure depression outcomes, Lim used two indicators: official diagnoses (based on health records and prescriptions for antidepressants) and scores from a commonly used depression screening tool (the PHQ-9). They then followed participants from 2018 onward, monitoring whether they developed depression or showed signs of depressive symptoms one and three years later.

The results revealed that among individuals who had already experienced depression, those who became more active or maintained a high level of activity were less likely to be diagnosed with depression again in the future. The same was true for depressive symptoms: those who exercised more frequently were less likely to report high levels of distress on the PHQ-9. For example, depressed participants who became more active had 8–26% lower odds of a future depression diagnosis compared to those who remained inactive. Those who were consistently highly active showed similarly reduced odds over time.

“Our study highlights the importance of maintaining consistent, moderate-to-vigorous physical activity over time to reduce the risk of depression,” Lim told PsyPost. “Notably, individuals who either sustained or increased their activity levels demonstrated a significantly lower likelihood of experiencing depressive symptoms or a new diagnosis of depression.”

Among people who had not previously been diagnosed with depression, the patterns were similar. Increased or consistently high physical activity was linked to a lower likelihood of developing depression or reporting symptoms. Participants in this group who exercised at least five days per week had up to 40% lower odds of depressive symptoms compared to those who did not exercise at all.

Importantly, the study also explored how activity patterns before and after a depression diagnosis affected outcomes. People who were active before their diagnosis and remained active afterward had lower odds of experiencing further depressive episodes. But for those who were inactive before diagnosis, becoming active afterward did not seem to offer the same benefit, at least in terms of future clinical depression diagnoses.

The findings support the idea that sustained physical activity can be a protective factor against depression, both for people with and without a history of the condition. This reinforces earlier studies that found a connection between physical activity and mental health, but it goes a step further by showing how changes in behavior over time matter.

“One surprising finding was that even among individuals who had already been diagnosed with depression, maintaining or increasing physical activity after diagnosis still conferred significant protective effects,” Lim said. “This suggests that it is never too late to benefit from adopting a more active lifestyle.”

There are several possible explanations for the link between physical activity and mental health. Regular exercise may help regulate the body’s stress response, improve sleep, and promote social engagement. On a biological level, physical activity is thought to stimulate brain areas involved in mood regulation and increase levels of chemicals that support brain health, such as brain-derived neurotrophic factor.

While the findings are promising, the study does have some limitations. The physical activity data were based on self-reported questionnaires, which can be subject to bias. The study also focused on leisure-time activity and did not account for physical labor during work hours. Depression diagnoses were based on treatment records, which means that people who experienced depression but did not seek medical help may have been missed. Additionally, depressive symptoms were only measured at specific age intervals, limiting the ability to track changes over time.

Despite these limitations, the study offers one of the most comprehensive looks to date at how patterns of physical activity relate to depression. By following a large, nationally representative sample over multiple years, the researcher was able to highlight the importance of sustained activity and the potential mental health benefits of increasing movement levels over time.

Looking ahead, Lim plans to explore the biological mechanisms behind the relationship between physical activity and mental health in more depth. They are also interested in using wearable devices to capture real-time data on how people move through their day.

“I hope to further explore the mechanisms underlying the relationship between physical activity and mental health, possibly integrating wearable device data to obtain more objective measures of activity,” he explained. “Ultimately, I aim to contribute to developing practical intervention strategies for mental health promotion through lifestyle modification.”

“Given the global mental health crisis, our findings reinforce a simple yet powerful message: staying active can serve as an accessible and effective strategy to support mental well-being, both for individuals currently struggling with depression and for those aiming to prevent it.”

The study, “Longitudinal association between consecutive moderate-to-vigorous physical activity and the risk of depression among depressed and non-depressed participants: A nationally representative cohort study,” was published April 11, 2025.