This Is Your Brain on Exercise

Human beings evolved to move. Our bodies, including our brains, were fine-tuned for endurance activities over millennia of stalking and chasing down prey. “We’ve engineered that out of our lives now,” says Charles Hillman, a psychology professor at Northeastern University who has spent decades studying the link between exercise and cognition. The toll our relatively new sedentary lifestyle takes on our bodies is clear: For the first time in U.S. history, younger generations are expected to live shorter, unhealthier lives than their parents.

While the myriad ways exercise can shape our bodies are well known, researchers have long suspected the same might be true of the brain. Decades of research have gone into examining the effect of exercise on attention, memory, and visual sensitivity, according to Richard Maddock, a professor of psychiatry at the University of California, Davis. “There is a very consistent finding that the brain works better after exercise,” Maddock says. But why that is has been harder to figure out.

“Few studies have really looked at what’s actually going on in the brain while we’re moving,” says Tom Bullock, a postdoc at the University of California, Santa Barbara. Only recently has technology given scientists the tools to zero in on the mechanisms at play. Aerobic exercise appears to lead to changes in both the structure of the brain and the way it operates, which together bolster learning in kids, give adults an edge on cognitive tasks, and protect against the cognitive declines that often come with age.

Here, we outline exactly what we know happens in your head when your heart rate rises.

Brain Waves Get a Boost

Your brain becomes much more active during exercise, “perhaps more active than at any other time,” says Maddock. One way neurons communicate is with electrical pulses, and sometimes entire networks of neurons fire in unison, like a group of soccer fans chanting together at a game. These synchronized pulses are known colloquially as brain waves. Different kinds of brain waves, characterized by the number of times they oscillate in a single second, are linked to one’s mental state and mood. Lower-frequency waves occur when we’re running on autopilot: brushing our teeth, driving, or sleeping, for example. Higher-frequency waves, known as beta waves, occur when we’re awake and mentally engaged and are associated with attention, memory, and information processing.

Using tools like an electroencephalogram (EEG), which pick up on these electrical pulses, researchers have found that aerobic exercise causes a shift in the amplitude and frequency of brain waves. More beta waves, in other words, means that exercisers may be in a more alert state. “The brain is in a different gear when the human being is in motion,” Maddock says.