We’ve heard it a million times — You’re just depressed because you sit there all day and don’t exercise!
After all, it seems like every day there’s a new article talking about how people who exercise are less depressed.
Well, no, it could simply mean that people who are feeling good about life are more likely to exercise. After all, the more motivated you are to live life, the more you’ll exercise, the more you’ll work, engage with your community, the more you’ll, you know, live.
And we know, from research, that depression can strip people of their motivation (chronic, low-grade inflammation from depression disrupts dopamine, which drives our motivation). So depression can kill our desire to exercise.
Thus, the big question has always been this — does exercise actually fight depression, or is exercise just something happier people do because they’re happier?
Well, thanks to a massive new review of 49 studies, following 267,000 people, we have a better idea (Brad Stulberg has a great review).
Exercise does, indeed, provide some level of protection against developing depression.
To try to solve the correlation/causation situation, researchers only looked at people who didn’t have any signs of depression, then followed them for a period of time, monitoring their exercise (among other things).
In the end, they found that exercise reduced the chance of developing depression by between 17-41%.
Now remember — this is a study of studies, so that’s why the variability is so high.
So it appears exercise does help ward off depression for some people.
Now what about people who already have depression?
Well, in another review of studies, the authors found that exercise helped between 40-50% of people with depression, which is similar to therapy and medication (And cheaper and less side-effecty. But perhaps research would suggest the best thing to do is pop a pill, and then ride your bike to your therapy session).
So what’s the point of all this?
Well, if you’re not depressed, exercise makes it 17-41% less likely you’ll get depressed. That’s pretty good at the high end, but 17% underwhelms me, at the low end, a bit.
But if you are already depressed, a 40-50% response rate is pretty good.
However, this means between 50-60% of people’s depression don’t respond to exercise.
That’s something you certainly won’t hear from those memes that promise you an active life is a happy life and will cure you of wanting to sit inside all day and then walk a few feet to bed, and lie there all night.
So exercise definitely can help protect you from depression and deal with its symptoms, but keep in mind that if it doesn’t help you, you’re not alone.
[Painting: Dynamism of a Cyclist, Boccioni (1913).
