Brain Rules

Exercise Boosts Brain Power

Jack LaLanne once celebrated his 70th birthday by swimming 1.5 miles through a harbor while handcuffed and shackled, towing 70 boats behind him. Even in his 90s, he remained incredibly sharp, witty, and energetic. His vitality points to a fundamental truth: there is a direct, powerful link between physical movement and mental alertness. Our minds were not designed for the sedentary lives we lead today; they were forged in an environment of constant motion. Our ancestors walked up to 12 miles every day, meaning the human brain evolved while the body was working out. We are the descendants of marathon runners who had to think on their feet to find food and avoid predators.

This evolutionary legacy explains why exercise is the single greatest predictor of how well we age. Consider two men in their 80s: one sits in a wheelchair, staring blankly, while the other—like the architect Frank Lloyd Wright—is still designing masterpieces. The difference often comes down to a sedentary versus an active lifestyle. Exercise improves almost every measure of cognitive performance, from long-term memory and reasoning to the ability to think abstractly and solve new problems.

The brain is an incredibly hungry organ. Although it makes up only two percent of our body weight, it consumes twenty percent of our total energy. This massive energy consumption creates a lot of toxic waste in the form of "free radicals" that can damage our DNA. To stay healthy, the brain needs a constant supply of oxygen to act as a sponge for this waste. Exercise acts like a road-building project for the brain, increasing the number of blood vessels in our tissues. This process allows more oxygen and glucose to reach deep into the brain while more efficiently hauling away toxic trash.

Beyond improving blood flow, physical activity acts like a fertilizer for our neurons. It stimulates a protein called BDNF, which keeps existing brain cells healthy and encourages the growth of new ones, particularly in the hippocampus—the region responsible for memory. The more we move, the more of this brain fertilizer we produce, making our neurons more willing to connect and communicate. The benefits are not just for the elderly; children who are physically fit concentrate better and allocate more cognitive resources to their tasks than their sedentary peers. Even a short 20-minute walk can significantly reduce the risk of stroke and dementia, while regular aerobic activity can be as effective as medication for treating depression and anxiety.

We are currently living through a traffic wreck of a lifestyle. Our brains are supported by bodies built for the Serengeti, yet we spend hours a day sitting in cubicles or classrooms. Integrating movement back into our daily routines—through walking meetings or treadmill desks—is not about becoming superhuman. It is about returning to a state of normalcy that our biology expects. When we move, we are not just training our muscles; we are feeding our minds.