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How physical exercise acts as an antidepressant

In conversation with Garcia Ashdown-Franks on the effects of exercise on depression
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Exercising regularly could function effectively as an antidepressant, according to a recent review paper co-authored by U of T researchers.

One of the researchers, Garcia Ashdown-Franks, a PhD student in exercise science, spoke with The Varsity on how the psychosocial mechanisms of exercise could cause antidepressant effects.

The impact of exercise on self-esteem

Self-esteem is the extent to which one’s conception of themself is positive. According to multiple studies over the past decade, sustained low self-esteem is a predictor of depression.

Symptoms of depression, according to the American Psychiatric Association, include a loss of interest in activities one once enjoyed, mood shifts to sadness, increased fatigue, and feelings of worthlessness. These are indicators of depression when experienced for two weeks or longer.

Low self-esteem may result in depressive symptoms, which could further erode self-esteem. According to the co-authors, this creates a cyclical relationship between the two.

Poor self-perception of one’s physical body is one factor that can impact self-esteem, and thus create depressive symptoms. According to the review, exercise can break the cycle by boosting physical self-perception, and thus self-esteem.

Increase in muscle mass and fat loss are two possible mechanisms that could drive the effect, according to the review. However, according to The New York Times, fat acceptance advocates and academics promote feeling self-confident at any weight. Learning to feel comfortable with one’s body weight may be another pathway to increasing self-esteem, aside from exercise.

Interestingly, two studies in the review also suggest that even if body composition remains the same, exercise may still increase self-esteem.

Ashdown-Franks noted, “Just the act of performing exercise or activity or sport can make us feel better about our body, even if there are no actual changes in our body composition.”

How exercise can change your social life

“There’s evidence that people with depression report feeling less social support in their lives, or [fewer] people [who] they can go to for support, which also can [worsen] their symptoms,” Ashdown-Franks said to The Varsity.

The co-authors noted that physical engagement is associated with emotional support from friends and family, and further suggested that the social benefits of exercise could be pronounced in team sports.

Ashdown-Franks said that the evidence is limited regarding whether solitary sports — such as running and weightlifting — could also result in social support. However, she noted that interaction with others, such as fellow runners or coaches, could provide a sense of community.

Team sport activities are prevalent at U of T. For example, there are drop-in basketball sessions at UTSG, UTSC, and UTM. Drop-in tennis, volleyball, and yoga are alternative options on campus.

Social impacts underpinned by biological mechanisms

Long-term exercise also induces biological changes, which could play a role in the antidepressant effects of exercise as well.

According to the co-authors, these biological mechanisms include changes to structures in the brain. The findings of animal studies report that the growth of neurons in the hippocampus, an area of the brain relevant to depression, can be stunted by the condition.

Exercise may be a long-term way to improve the growth of neurons, with studies finding that exercise can specifically increase the volume of the hippocampus. Further factors that boost neural growth include increased blood flow to the brain.

Inflammation in the body is another possible cause of depression. Evidence shows that exercise can lower the levels of pro-inflammatory markers associated with depression, as exercise may be responsible for the release of anti-inflammatory biochemicals.

Future steps of research

“I think there’s a lot more research that needs to be done,” said Ashdown-Franks, regarding research on the relationship between exercise and depression.

Understudied research areas, according to Ashdown-Franks, include determining the optimal exercise routine for combating depression. Other limitations of studies on overcoming depression include their reliance on self-reports, which have limited power, and on animal studies, which may not be applicable to humans.

Despite a lack of clarity of the research, Ashdown-Franks emphasized that it’s clear that some exercise is better than none at all. She said, “For someone who’s struggling with depression or symptoms of depression, they might think going to the gym [can be] a monumental task. But… [taking] a few minutes every day just to go for a walk [can make you] feel better.”