Exercise makes our bodies stronger, but can it do the same for our minds? It might, according to several lines of research in animals and humans.

In research with rats, there's evidence that exercise increases the blood supply to their brains. One group of rats got free access to a running wheel and another ran on a treadmill for an hour a day. After 30 days, both groups had a better blood supply to their brains. A group of sedentary rats showed no increase.

An increased blood supply means increased oxygen and energy supply, and that equals better performance.

In the same study, a group of rats learned to run through an obstacle course. Because that was more a learning task than a physical task, these rats developed more connections between the neurons in their brains.

Although these types of studies are only now beginning in humans, the theory is that because sports combine learning and exercise, they may both increase blood supply and enhance brain connections.

Some evidence in humans suggests that being physically fit helps people maintain their cognitive abilities as they age. Many studies have found that physically active elderly people perform better than sedentary elderly people on cognitive tasks such as reasoning, vocabulary, memory, and reaction time. Some studies have found similar differences between physically active and sedentary young people, but results varied from study to study.

Researchers caution that exercise and conditioning have a limited window of effect, we lose that effect quickly if we stop exercising.