The Most Important Thing We Can Do for Our Brain? Exercise!by Anders Hansen, MD, MSc | October 24, 2017
If I would have guessed ten years ago what the best way to train the brain would be, I would probably have thought about crossword puzzles, sudoku, or cognitive apps. But then I would be wrong. The best way is physical exercise. During the last decade, neuroscience has shown that physical exercise has extraordinary effects on our brain.
Most people know by now that exercise will improve their mood—but few know that it will boost all of their cognitive abilities—memory, attention, creativity, and how we cope with stress. It all gets better in a way unparalleled by any drug, food-supplement, or cognitive training method.
So what happens in our brain when we move? First. the brain gets more blood. Bloodflow is increased by 20% while walking fast compared to sitting. More blood means more oxygen and nutrients. But increased bloodflow is only the beginning. The rate of neurogenesis—the formation of new brain cells—is increased by exercise. The newly born brain cells are formed in the dentate gyrus, a part of the hippocampus known as the “memory center”, and the effect is substantial. The hippocampus actually grew by 2% when a group of sedentary individuals walked regularly for a year. Typically, the hippocampus shrinks by up to 1% per year from our late twenties onwards, contributing to gradual memory loss as we get older. The exercise-based boost of hippocampal growth not only increases memory but improves mood. Exercise has been shown to be as efficient as antidepressants for mild and moderate depression, useful information in an age where more than one in ten adults are prescribed antidepressants in the US.
How about kids? Exercise does wonders to children’s cognitive abilities and their ability to learn. Just 20 minutes of playing increases math and reading test scores. And this isn’t exclusive to tests in the lab, several studies have shown that kids in good shape actually perform better in school. Physical activity even seems to affect IQ! When data from the Swedish military service was analyzed from 1.2 million 18-year old male Swedes a clear pattern emerged—boys in good cardiovascular fitness had higher IQs, a result that was also apparent for identical twins. In a number of identical twins, one brother was in good shape while the other brother was not. The brother in good shape had a higher IQ than his identical twin—even though they, more or less, have identical genes (there can be small differences in identical twins) and have grown up together!
The list goes even further. Exercise can make us more creative. A recent study showed that creativity test results for divergent thinking (“brainstorming”) increased by more than 50% if participants had walked for 45 minutes before the test. The creativity-boost is temporary, we get more creative during 1-2 hours after exercise—probably due to increased blood flow, than we are back to our normal creativity-level. The takeaway message is: if you are stuck with a problem, then go for a walk or jog, and rethink of the problem an hour afterward and increase your chances of coming up with a solution.
But why is exercise so important for the brain? It is not at all obvious from our modern perspective but makes more sense if we look at our history. Our brains are basically the same today as they were 10 000 years ago. It was when our ancestors moved: during hunting, running from predators, and discovering new lands, that they really needed their cognitive abilities. That was when they needed to be attentive and have a memory to remember new experiences. That is why evolution has slowly tailored the brain in such a way that it benefits from exercise and that is why we still benefit from it today as our brains have not grossly changed since our ancestors days on the savanna.
While the human brain is fundamentally unchanged in the past 10 000 or even 20 000 years or so, our lifestyle has changed enormously. Modern sedentary lifestyle deprives many of us from getting enough physical activity, leading to vast consequences not only in terms of obesity and type-2 diabetes but also when it comes to wellbeing and how we function mentally. Exercise is not about sports. It is not about participating in a lifestyle. It is something we need to do for our brain and cognitive abilities since we have evolved for it. Now neuroscience is helping us to rediscover the brain-medicine that we forgot.
 Alvarexz- Bueno C (2017) The Effect of Physical Activity Interventions on Children’s Cognition and Metacognition: A Systematic Review and Meta-Analysis. J Am Acad Child Adolesc Psychiatry. 56(9):729–738. doi:10.1016/j.jaac.2017.06.012
 Oppezzo et al (2014) Give Your Ideas Some Legs: The Positive Effect of Walking on Creative Thinking Journal of Experimental Psychology: Learning, Memory, and Cognition. 40(4):1142–1152. doi:10.1037/a0036577
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