We all know that exercise is good for us. And this past holiday season, the market was awash with activity monitors like the FitBit and Nike Fuel Band to help you reach your fitness goals from the neck down. But what about from the neck up?

Although it may come as no surprise that exercise is good for your brain, we still do not have the metrics to guide optimal exercise for mental health. Today, the most common explanations for how exercise boosts mental health are that when we exercise we release endorphins that make us feel good and that exercise increases blood flow to our brains. Another explanation is that when we become more “physically fit,” our brains become more fit. But the truth is that scientists still cannot fully explain the numerous mental health benefits of exercise. If we can’t explain it, we don’t know how to suggest the best types of exercise for your brain or how often you should do them, and we don’t know how to biologically mimic exercise when it’s not possible. The good news is that research from our team and others continues to make progress in understanding the connection between exercise and mental health.

Take, for example, the “super” protein BDNF (brain-derived neurotrophic factor). BDNF is thought of as a “super” protein because it seems to improve our brain’s plasticity — how it can change and adapt — and the ability to repair itself following injuries. Researchers have found that muscle contractions that occur with exercise release antioxidants and other molecules into our blood circulation that interact with the brain and can potentially increase the presence of BDNF in the brain.

Although scientists have yet to fully map out how BDNF communicates between the body and the brain, numerous studies have documented that blocking BDNF signaling in the brain also blocks positive effects of exercise on learning and memory. From animal studies, we know these effects occur in a brain region called the hippocampus, which is a brain region that is critical for many types of learning and memory. However, we don’t know if the same happens in humans. This will be important to find out: While on average the hippocampus starts to shrink at around age 60 and does so more dramatically for those who end up developing dementia in older age, it is possible the right dose of exercise-induced BDNF could help delay these age-related declines.

We also know through several studies that exercise results in almost immediate increases in BDNF expression in the brain, with researchers finding higher levels of BDNF in animals within the first hour of exercise and following just several days of running. These findings suggest the rise in BDNF likely plays a role in improved mental health, in addition to changes in physical fitness or blood flow in certain regions of the brain that likely require a more sustained exercise routine…read more

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