Another reason why you should exercise: It helps your brain
David Raichlen’s research looks at the effects of a range of human movement, such as squatting and kneeling and strenuous physical activity. (Photo: Courtesy of David Raichlen.)

Another reason why you should exercise: It helps your brain

Evolutionary biologist David Raichlen of USC Dornsife talks about how our brains developed when we began moving long distances and the “runner’s high.” [2¾ min read]
ByPaul McQuiston

Finding the links between brain and physical health motivates David Raichlen, professor of biological sciences and anthropology at the USC Dornsife College of Letters, Arts and Sciences. His research into human movement spans a broad range of activities, from the long-term benefits of squatting and kneeling to how your body rewards strenuous physical activity to the effects of exercising in highly polluted areas.

Raichlen recently spoke about his research, and why he’s grumpy when he doesn’t work out.

Why is fitness so important?

At this point, I think most people know that physical activity is important for their health. The key question now is how do you get people to change their behavior? From an evolutionary perspective, I’m focused on why physical activity makes some people feel good and that … comes from my experience. I wanted to figure out why I felt so much better when I worked out and why I wasn’t very pleasant on days that I didn’t exercise.

Something like endorphins and the ‘runner’s high’?

Exactly. Only what we found out was that it’s also tied to a reward system in the body called the endocannabinoid system. It’s like our body’s endogenous form of marijuana. Over a series of projects, we looked at endocannabinoid signaling in humans, dogs and ferrets while they ran. It turns out that while ferrets — which don’t generally engage in endurance activity — didn’t show much activity, humans and dogs did, suggesting perhaps evolutionary processes at work. That led to further projects where we found that the endocannabinoid system may have developed to encourage and reduce pain during physical activity and may even play a role in the cognitive benefits of exercise.

What else have you learned about how exercise benefits humans?

The whole point of our work at this point is taking our evolutionary history and applying it to the massive health problems we’re dealing with today. Two million years ago, we evolved and adopted a hunting and gathering lifestyle which required our ancestors to start being much more physically active to forage. While we engaged in physically active foraging, we also were navigating and doing other cognitive tasks utilizing executive functions and memory — remembering where to find certain foods and making decisions while on the move, things like that. We think the evolution of these foraging behaviors linked high levels of physical activity with cognitive needs and may explain why physical activity is so good for brain health. So, the concurrent evolution of high physical activity and cognitive function became a fertile ground for us to start thinking about how we can actually enhance the impact of physical activity on health today.

What are the best exercises for cognitive health?

That is absolutely the question I get asked the most and unfortunately, it’s a question I don’t have a great answer for. In terms of the kind of activities available to people right now, there’s not been a good comparative work. However, we’ve produced a game that you can play while you’re on an exercise bike that’s includes a maze and other cognitive challenges. We showed for that task, there was an enhanced effect of exercising while playing the game versus just exercising alone. There have also been metanalyses that show that simultaneous exercise and gaming lead to better results than just exercise alone. Unfortunately, most of those games aren’t available to the public right now.

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