As far back as the Greeks and Romans, humans have documented the belief that there is a strong link between exercise and intelligence. But in the last two decades, neuroscience has begun to catch up with Thales and Juvenal’s idea that a sound mind flourishes in a healthy body. While the studies unite in telling us that running will makes us smarter, it is only partly true. The process is more complicated and reveals more about the wonderful complexities of both the human body and its evolution. Although the science might be helping us to understand how the mechanisms work, an important question remains: why does running make us smarter?
Two studies, one published by Finnish researchers in February and the other in Cell Metabolism in June, have expanded our understanding of the mechanisms involved in running and the ways that it enhances memory and cognition. Before these, it was understood that exercise induced a process called neurogenesis (where new brain cells are created) in a part of the brain involved in memory formation and spatial navigation, known as the hippocampus.
While intense exercise will create brain cells, they are basically stem cells waiting to be put to use. Exercise doesn’t create new knowledge; rather, it gives you the mental equivalent of a sharpened pencil and clean sheet of paper. It prepares you for learning, but you have to actively do some learning yourself, too. Integrating exercise into your working or studying day would seem like a sensible option, if this particular benefit is of interest to you.
What the new research tells us is that it is not just any exercise that will create new brain cells for you. In the study by Finnish researchers, they discovered that only certain kinds of exercise are likely to result in the growth of new brain cells in adults.
According to the researchers, the exercise needs to be “aerobic and sustained”. But they also looked at the neurobiological effects of the currently popular “high intensity interval training” (HIT), as well as resistance training (weightlifting). While the team discovered a minor response after HIT there was no response at all after the resistance training. So HIT will have a small impact on cognitive abilities, while weightlifting, it seems, will definitely not make you smarter. (The weightlifters have Arnold Schwarzenegger in their camp. Runners have the mathematical genius capable of running a marathon in 2 hours 46 minutes, Alan Turing, in theirs. As a committed distance runner, I’m saying nothing …)
Since the 1990s, it has been understood that exercise also assists in learning because the activity produces a protein called brain-derived neurotrophic factor (BDNF). BDNF promotes the growth of new neurons and supports existing ones. John Ratey, a Harvard professor of psychiatry, called it “Miracle-Gro for the brain”.
The Cell Metabolism study examined Cathepsin B (CTSB) protein secretion during running. By assisting in the expression of BDNF, this protein had beneficial effects on cognition, specifically enhanced adult brain cell growth in the hippocampus and spatial memory function.
The science is just settling into its pace and I am sure that in the next few years more and more research will appear to make sense of our deep love for this most simple and natural form of exercise. But there’s still that question: why does the body need to reward us with greater cognitive function and more effective spatial memory and awareness just because we run?