Spark: The Revolutionary New Science of Exercise and the Brain

by John J. Ratey

In his book Racing the Antelope: What Animals Can Teach Us about Running and Life, biologist Bernd Heinrich describes the human species as an endurance predator. The genes that govern our bodies today evolved hundreds of thousands of years ago, when we were in constant motion, either foraging for food or chasing antelope for hours and days across the plains. Heinrich describes how, even though antelope are among the fastest mammals, our ancestors were able to hunt them down by driving them to exhaustion—keeping on their tails until they had no energy left to escape. Antelope are sprinters, but their metabolism doesn’t allow them to go and go and go. Ours does. And we have a fairly balanced distribution of fast-twitch and slow-twitch muscle fibers, so even after ranging miles over the landscape we retain the metabolic capacity to sprint in short bursts to make the kill. Today, of course, there’s no need to forage and hunt to survive. Yet our genes are coded for this activity, and our brains are meant to direct it. Take that activity away, and you’re disrupting a delicate biological balance that has been fine-tuned over half a million years. Quite simply, we need to engage our endurance metabolism to keep our bodies and brains in optimum condition. The ancient rhythms of activity ingrained in our DNA translate roughly to the varied intensity of walking, jogging, running, and sprinting. In broad strokes, then, I think the best advice is to follow our ancestors’ routine: walk ...