Exercise Helps Your Brain as Much as Your Body
Instead of just asking questions about how exercise helps our bodies, let’s also consider how it helps our brains
Let’s start thinking differently about exercise.
Decades of exercise science research show that when people or animals are given a new exercise routine, they get healthier. But when thinking about the benefits of exercise, most people hold a strong body bias; they focus on how regular exercise builds more lean body mass, helps increase their strength and balance, or improves heart health. Exercise matters even more for our brains, it turns out, in ways that are often overlooked.
Here’s how we know. Animal exercise studies typically run rats for weeks on running wheels. The animals gleefully run every night, sprinting several miles over the course of an evening. There are wonderful health benefits in these studies of voluntary running—improved muscle tone and cardiovascular health, and many brain benefits too. But in some studies, there’s an additional experimental condition where some rats exercise with one crucial difference: it’s no longer voluntary exercise. Instead of a freestanding running wheel, rats run on a mechanized wheel that spins, forcing the animals to cover the same distance as the voluntary runners.
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What happens? When the rats are forced to exercise on a daily basis for several weeks, their bodies become more physically fit, but their brains suffer. Animals regularly forced to exercise have the equivalent of an anxiety disorder, behaving on new tasks in highly anxious and avoidant ways. These animals are more anxious not only compared to the voluntary runners, but also to animals that are not given an opportunity to exercise at all. Yes, forced exercise might be worse than no exercise at all. This work suggests something important about the health benefits of exercise: it is not just about making our muscles work, but what exercise does to our brains. When exercise gives us a sense of control, mastery and joy, our brains become less anxious. If we take that away, by forcing exercise, we can shift it from helpful to harmful.
For us free-ranging humans, there are certainly analogues to this forced running, leaving us feeling like we are in our own rat race: we are forced to run across the airport when late to catch a flight, or we are coerced into doing treadmill tests at the cardiologist’s office. But its more than just feeling forced; studies show that even our everyday attitudes and expectations of exercise shape our health. Studies that manipulate whether exercise is framed as helpful (versus just exercise alone) find that shifting our exercise expectations to be more positive significantly improves mood, and improves some markers of physical health, such as lowering resting blood pressure. Our attitudes toward exercise have even been linked to longevity. For example, the confident belief that one exercises more than others has been associated with greater longevity, an effect that persists even after taking into account actual amount of exercise behavior. But if there is one take-home message from exercise studies in humans, however, it is that exercise significantly improves mental health. A groundbreaking paper out in February looked at hundreds of clinical trials of exercise training for treating major depression. It found that while there are some benefits of taking antidepressant medications, exercise programs such as walking, jogging or dancing had two to three times larger effects on improving mental health.
It’s not just our psychology that shapes the benefits of exercise, the broader social context of exercise is important as well. A study in Denmark collected information on average weekly exercise routines in over 8,000 adults, and then looked to see what types of exercise were associated with greater longevity 25 years later. While physical activities such as cycling, swimming, jogging or going to the gym had some longevity benefits (about 2.4 additional years of longevity relative to people in the sample who didn’t exercise), it was the social sports that were associated with the biggest longevity gains. Tennis and badminton were associated with over three times the longevity benefit, with over eight additional years of longevity.
When I speak to audiences about this study, I often ask them to predict which forms of physical activity are associated with the biggest longevity benefits. There’s usually a heavy body bias; people often pick cycling and jogging as the longevity winners because they are good for our joints or they most rigorously train our cardiovascular systems. We easily forget that exercise is also for our brains, and social connection has all sorts of brain health benefits. Scientific studies of relationships suggest that greater social connectivity is associated with twice the longevity benefit compared to regular physical exercise. But we don’t have to pit them against each other; social sports combine the best of both, linking exercise to social connection. And yes, it is important to remember that all forms of physical activity offer opportunities for social connection. The Denmark longevity study also showed that slower (and less vigorous) forms of jogging were associated with bigger longevity benefits, suggesting that we don’t always need a heart-pumping workout, but that we might also invite a slow jog with a friend. Or maybe a pickleball game.
Modern science reminds us to pay new attention to the old Roman saying, “A sound mind in a sound body.” Instead of just asking questions about how exercise affects our bodies, let’s also consider questions about how it affects our brains. How can I find a way to take my dreaded exercise routine and turn it into something fun? Under what conditions does my exercise provide a sense of mastery and accomplishment? What kind of exercise helps me feel the most mentally strong and in control? Is exercise giving me ways to nurture important relationships with others?
My lab and others show that the mindsets we bring to the challenges and discomforts of life really matter for shaping our resilience and health. Exercise, when done wisely, can become a welcome discomfort that doesn’t just improve the health of our bodies, but also our brains.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.
