For some time, researchers have known that exercise changes the structure of the brain and affects thinking. Ten years ago scientists at the Salk Institute in California published the groundbreaking finding that exercise stimulates the creation of new brain cells. What sort of exercise is most beneficial. Should it be aerobic? What about weight lifting? And are the cognitive improvements permanent or fleeting?

Other recent studies provide some preliminary answers. In an experiment published in the journal of the American College of Sports Medicine, 21 students at the University of Illinois were asked to memorize a string of letters and then pick them out from a list flashed at them. Then they were asked to do one of three things for 30 minutes — sit quietly, run on a treadmill or lift weights — before performing the letter test again.  The students were noticeably quicker and more accurate on the retest after they ran compared with the other two options.

“There seems to be something different about aerobic exercise,” Charles Hillman, an associate professor in the department of kinesiology at the University of Illinois and an author of the study, says.

Similarly, in other work by scientists at the University of Illinois, elderly people were assigned a six-month program of either stretching exercises or brisk walking. The stretchers increased their flexibility but did not improve on tests of cognition. The brisk walkers did. Why should exercise need to be aerobic to affect the brain?

“It appears that various growth factors must be carried from the periphery of the body into the brain to start a molecular cascade there,” creating new neurons and brain connections, says Henriette van Praag, an investigator in the Laboratory of Neurosciences at the National Institute on Aging. For that to happen, “you need a fairly dramatic change in blood flow,” like the one that occurs when you run or cycle or swim. Weight lifting, on the other hand, stimulates the production of “growth factors in the muscles that stay in the muscles and aren’t transported to the brain,” van Praag says.

Researchers are finding that brisk walking or running is more intense and leads to improvements in “muscle aerobic capacity,” and this increased aerobic capacity, in turn, affects the brain more than something that is less strenuous for the individual.

Do we have to really go outside our aerobic “comfort zone” in order to gain the cognitive benefits of exercise? Researchers conclude that any form of regular exercise, if it is aerobic, should be able to maintain or even increase our brain functions. Give it a try, and stay with the physical activity.  Your entire wellness will benefit along with your cognition.

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