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What might explain why there's a link between aerobic exercise and brain development?

This question originally appeared on Quora. Answer by Nicole Gravagna, Neuroscientist. 


Recently, a group of scientists at the University of Ottawa published the newest evidence that getting off your duff makes your brain stronger. It’s sad news for the couch potatoes of the world. For those who wear out a pair of running shoes (or two) every year, it’s one of those studies that isn’t much of a surprise.

Physical exercise and specifically aerobic exercise does some very positive things for the brain. There’s a lot of scientific evidence that exercise allows for neurogenesis which is neuron repair and new neuron formation. Since the brain is heavily made up of neurons, high levels of neurogenesis are a good indication of a healthy brain. It’s like looking at a city and seeing a bunch of cranes and construction teams working on buildings. Only healthy systems have the resources for repairing infrastructure. Disrepair, by contrast, is a mark of wavering health.

Exercise is valuable for the brain in lots of different ways. Learning a new sport, like picking up golf or tennis for the first time, challenges the brain’s ability to remodel its connections. Any kind of exercise is a positive influence on the body, but neurogenesis seems to be triggered most by extended periods of aerobic exercise. High intensity interval training like you might find at cross fit doesn’t seem to provide the same increase in neuron repair.

When you go for a nice long run instead of hitting the weight room, what’s really going on in your noggin?

Extended periods of aerobic exercise positively affect the brain in a few different ways. The most obvious and relatively immediate effect is a runner’s high. When you get an hour or two of aerobic exercise, you feel euphoric for a while afterward. Your troubles melt away and any aches or pains seem to disappear. The effect is unfortunately temporary.

Runner’s high is caused by natural opioid drugs that the body produces during exercise. These chemicals strongly affect the parts of the brain associated with emotional processing. It’s no wonder you can work out your problems on a run. Your body provides a dose of natural anti-depressants to help out.

We all know that feeling good doesn’t necessarily correlate with healthiness. Anyone who’s experienced the euphoria of their third or fourth cocktail on a particularly enjoyable evening knows that some ways of feeling good aren’t necessarily good for you. However, it seems like the positive feelings associated with aerobic activity do tend to correlate with healthy brain tissue growth.

Although we can easily explain runner’s high by looking the accumulation of natural opioids in the frontal lobes in brain scans of athletes who just finished a two hour run, there might be more to feeling good after exercise.  The recent paper published from the scientists at the University of Ottawa saw that another chemical called VGF increased after aerobic exercise. VGF doesn’t stand for anything. That’s just its name.

Scientists haven’t yet pinned down all the things that VGF does. It’s like a secretive musician who might very well be publishing novels under a pseudonym. Chemicals in the body tend to moonlight and it might take decades to uncover all the things they do. VGF was the star of show that the scientists in Ottawa just published. These scientists were working with mice that were not normal. The mice had a genetic dysfunction that caused them to walk and move around in labored ways. The mice also had very short lifespans. Both of these afflictions, difficulty with movement and early death were associated with a genetic degradation of the cerebellum, the part of the brain generally known for control of physical movements.

What the scientists in Ottawa showed was that they could repair the genetic damage to the mouse brains in two ways. They could either give the mice a big dose of VGF, or they could give the mice a treadmill. In both cases the little vermin lived markedly longer, moved more normally, and showed positive infrastructure repair to the tissues in the brain.

For those of you who are clever couch potatoes, I know what you are thinking. You want a VGF pill so you don’t have to go buy a pair of runners or break a sweat. Unfortunately, that’s not a solution. The scientists gave mice a dose of VGF in a way that we can’t treat people. It wasn’t a pill or even an injection. It wasn’t an enema either. VGF was given to the mice through a viral infection. It’s a really common way to do experiments on mice and a very unethical way to give people a brain boost.

You can, however, get the positive effects of increased VGF from getting out and going for a run, which is pretty darned sweet. Remember how I said that we don’t know all the things VGF does when it moonlights? Well, we know that VGF is associated with neurogenesis and neuron repair, but its also known to have anti-depressant properties. So, spending an hour to jog around the park gives you an instant opioid boost plus another slower acting and longer lasting anti-depressant (VGF), that acts as part of a repair process that fixes any wear and tear of the less healthy things you’ve done to yourself lately.

I don’t know about you, but I think it’s time for an afternoon run.

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