Here's How Much Exercise You Need to Give Your Brain a Boost
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Physical activity is good for both the body and mind. Indeed, doctors have long known that exercise improves thinking and slows the rate of cognitive decline, particularly among older adults. But what kind — and how much — exercise is needed to achieve a healthier brain?

The answer seems to be just about any kind of exercise that gets you moving, as long as you stay with it, according to an international study published yesterday (May 30) in the journal Neurology Clinical Practice.

Walking, running, weight training, yoga or tai chi … it's all good, provided you do it a few times a week for at least 52 hours over the course of six months or so. A key finding in the study was that the exercise doesn't need to take place within a set number of hours per day or week. [7 Ways the Mind and Body Change With Age]

"The real-world impact is that you can break that [52 hours] up" into an hour here or there, said lead study author Joyce Gomes-Osman, a clinical neuroscientist at the University of Miami Miller School of Medicine. "This is encouraging, because it tells you that you may not necessarily need an hour a day. If you exercise a few days a week and start racking up those 'points,' and you do this over several months and you get to that 52-hour mark, this is when you can expect that your mind is going to become sharper."

Gomes-Osman noted that low-intensity "mind-body" exercises (such as yoga and tai chi) work just as well as high-intensity, strength-training and aerobic exercises.

The new research examined nearly 100 previously published studies on exercise and cognition, with a total of more than 11,000 participants whose average age was 73. The common denominator across all these studies was that various forms of exercise all led to sharper thinking if the participants achieved this minimum 52-hour target over roughly six months, Gomes-Osman said. Studies with fewer hours of exercise or shorter time scales did not yield positive results.

Gomes-Osman told Live Science that, as a neuroscientist practicing physical therapy, she has long desired to prescribe a "dose" of exercise to her patients, employing the same precision and individualized approach that a physician would use to prescribe a heart medication. Now, she's closer to that goal, she said.

"We often hear advice to be more active" given with the aim of improving thinking, Gomes-Osman said. But, "What does that mean? Does that mean the person needs to do 30 minutes a day every weekday? Or an hour a day? And what kind of exercise?"

Referring back to heart disease, Gomes-Osman said there are recommendations for the precise amount of rigorous or moderate exercise needed to improve heart health. But a corresponding dose of exercise for cognitive health was not known … until now. This is an important new understanding, she said, because there are no drugs to improve or slow cognitive decline. Exercise, for now, is the only approach.

Dr. Douglas Scharre, director of the Center for Cognitive and Memory Disorders at The Ohio State University Wexner Medical Center, who was not involved with new research, agreed with the study's conclusions.

"I believe that the take-home message is that physical exercise should be done consistently for the long term to gain maximum cognitive benefits," Scharre told Live Science. "It does not seem to matter how much or how long or what type of exercise, just that you do it regularly over the long term."

The researchers found that real cognitive gains were in specific areas of thinking — namely, planning and initiation of tasks, processing speed and executive function, which is the ability to focus and manage tasks, Gomes-Osman said. Her team found that participants’ memory improvement was only seen in about half of the studies analyzed, so averaged together, they could not conclude that exercise improved memory.

That makes sense, according to Scharre, because those nonmemory elements of cognition make common use of frontal brain regions that get more of a workout during exercise than brain regions related to memory. [10 Things You Didn't Know About the Brain]

"Exercise is a fabulous brain activity," Scharre said. "The brain is being activated very much during exercise. We have to learn how to control our muscles to do the exercise; we need to focus attention on doing the tasks; we have to determine if we are feeling tired or … plan to go slower the next time to avoid a certain activity that causes pain. Basically, 'use it or lose it,' I believe, is just as true for the brain as it is for muscles."

Scharre added that watching TV and not socializing does not use your brain as much as exercise.

The researchers, who include scientists from Brazil and Spain, wrote that those brain functions that consistently improved with exercise across all studies examined — processing speed, planning and focus — are the very same functions that start to falter with the onset of age-related cognitive decline.

Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.