Successful Aging: A Neuroscientist Explores the Power and Potential of Our Lives

by Daniel J. Levitin

Our brains were built to move our bodies toward food and mates, and away from predators. Exercise is important for two reasons. The obvious one is that it oxygenates the blood. The brain runs on oxygenated glucose, carried by hemoglobin in the blood, and a fresh supply of oxygen is good. The nonobvious reason is that our brains, because they were built to navigate in unfamiliar surroundings, don’t do well when they’re not challenged by having to problem solve. Every step you take on a treadmill or elliptical is helping you with the first of these two imperatives—getting your blood oxygenated—but they don’t help your brain to keep its navigational skills and memory systems honed. Every minute you walk on an unpaved trail, whether in a park or in the wilderness, requires you to make hundreds of microadjustments to foot pressure, angle, and pace. These adjustments stimulate the neural circuitry of your brain in the precise way that it evolved to be used. The area that is most stimulated is your hippocampus, that seahorse-shaped structure that is critical to memory formation and retrieval. This is why so many studies show that memory is enhanced by physical activity. This way of looking at things is known as embodied cognition, the idea that physical properties of the human body, particularly the perceptual and motor systems, play an important role in cognition (thinking, problem solving, action planning, and memory). In this way of thinking, the sensation of movement is inext...