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Let's Get Physical

Stephens, Stephanie

doi: 10.1097/01.NNN.0000441126.16044.e6
Departments: The Healthy Brain

Exercise is good for the body and the brain.

Staying physically active is good for your body—and your brain.

To listen to a podcast interview with Dr. Kramer about the benefits of exercise for brain health, go to

Courtesy Amie Hoff

Courtesy Amie Hoff

An 85-year-old male client of fitness trainer and consultant Amie Hoff recently told her, “The longer I work out with you, the younger I get.” Hoff, who trains people of all ages in New York City, believes strongly that exercise helps individuals change their mood, energy levels, and attitudes.

“My clients refuse to stop exercising,” Hoff says. “They tell me it helps them stay sharp, that it ‘clears the cobwebs,’ they say. Most come three-to-four times weekly, once they get past thinking that it's drudgery or a chore.”

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Conventional wisdom has long touted the benefits of physical exercise. Now, as evidence mounts from scientific research to support that conventional wisdom, choosing to exercise might seem a no-brainer. In late 1999, a Salk Institute study found physical exercise caused chemical changes that spurred learning in the brains of mice. Salk researchers noted that “similar mechanisms may operate in humans as well.”

More recent studies continue to show that what's good for the body is also good for the brain—in humans as well as mice.

“While all exercise might not provide the ‘easy filigx’ to enhance cognition across the life span, there is ample evidence to support it as one of the most effective means available to improve mental and physical health, without the side effects of many pharmacological treatments,” according to a 2011 review published in the Journal of Applied Physiology of more than 100 scientific articles on the effects of exercise on the human brain.

Still, much more research is needed, experts say. “There are beneficial effects to exercise, yes, but the parameters need to be worked out,” says Arthur Kramer, Ph.D., coauthor of the review, director of the Beckman Institute for Advanced Science and Technology, and the Swanlund Chair and Professor of Psychology and Neuroscience at the University of Illinois at Urbana-Champaign.

Until recently, the majority of research has been on older adults, he says. For example, a 2006 study in the Annals of Internal Medicine and a 2004 report in the Journal of the American Medical Association (JAMA) suggest the probability of being diagnosed with Alzheimer's disease (AD) may be reduced by 30 to 40 percent if a person has exercised substantially more in the past. However, these studies examined correlations between reported exercise and diagnosis of diseases such as AD, Dr. Kramer notes. That doesn't prove exercise causes a decreased probability of being diagnosed with AD.

Much of what Dr. Kramer and his peers know about exercise and the brain still utilizes animals—mainly rats and mice. However, the findings have made experts sit up and take notice. Among other benefits, such as improving heart health, physical activity appears to benefit the brain in a number of ways. For example, exercise seems to increase the birth of new neurons, including those that transmit nerve impulses in the brain's hippocampus. The hippocampus helps form new memories about experienced events as well as memories that can be explicitly verbalized.

According to Dr. Kramer, exercise also seems to improve connections between neurons; improve the health of capillaries that support neurons; increase the production of neurotrophins, which are proteins that influence whether nerve cells live or die; increase the production of certain neurotransmitters—brain chemicals that communicate information throughout our brain and body; increase the efficiency and numbers of mitochondria, which have been described as small energy factories in the brain; and possibly decrease harmful processes that lead to AD, such as the accumulation of amyloid-beta protein that creates brain plaque.

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Before You Start Exercising

The American Council on Exercise says to see your doctor before starting an exercise program if:

  1. You plan to participate in vigorous activities, defined as those which significantly raise both your heart and breathing rates; vigorous activities are those performed for about 20 minutes before fatigue sets in. In contrast, exercises of low to moderate intensity can be sustained relatively comfortably for a long period of time (about 60 minutes), typically begin slowly, progress gradually, and usually aren't competitive in nature.
  2. You're a man over 45 or a woman over 55.
  3. You have a heart condition; experience chest pain, irregular heartbeat, dizziness, orthopedic problems, persistent wounds that don't heal, or unexplained weight loss; or if you take certain blood pressure or heart medications.

The American College of Sports Medicine suggests you choose an exercise that is accessible and enjoyable. Have fun and help both your body and your brain!

For more information on starting an exercise program, visit

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With so much possible benefit and little adverse effects to exercise, experts generally agree that we should get moving.

“We think that, overall, physical activity is good for the brain,” says Jeffrey Burns, M.D., M.S., professor of neurology at the University of Kansas Medical Center, associate director of the university's Alzheimer's Disease Center, and assistant director of the university's Clinical and Translational Science Unit. “Every year, more and more data support this,” he says.

A July report in Frontiers of Aging Neuroscience suggests “aerobic exercise and cardiorespiratory fitness contribute to healthy brain aging.” In June, a study in the Journal of Alzheimer's Disease reported that “exercise may improve neural efficiency during semantic [a type of long-term] memory retrieval in mild cognitive impairment and cognitively intact older adults, and may lead to improvement in cognitive function.”

“We're still short some evidence in different areas about how exercise affects the brain and how we can optimize that—such as what type of exercise are best, and how long you need to exercise,” says Dr. Burns.

To help answer these questions, Dr. Burns hopes for more randomized, controlled trials of the effect of physical exercise on cognition. These types of trials usually involve large numbers of people who are randomly assigned (as by flip of a coin) to receive a new therapy or a placebo. The results of this kind of study are considered the highest level of evidence.

“We want to see more true cause and effect to prove that physical activity prevents dementia,” Dr. Burns says.

At his university's memory clinic, Dr. Burns and colleagues have begun to hand out pedometers to patients so that they can calculate how far they walk or run. Encouraging use of pedometers is more effective than simply telling patients to start exercising, according to Dr. Burns. “If we're looking over patients' shoulders, so to speak, they tend to increase their physical activity,” Dr. Burns says. “Plus, we actually view physical activity levels as a vital sign”—similar to heart rate, breathing rate, temperature, and blood pressure.

“Still, only a certain percentage of patients are receptive to exercise—and can do it consistently and durably over time,” says Dr. Burns. “We need to find ways to increase the percentage of people who can and will change their lifestyles.”

While the individual benefits of exercise are significant, the benefits to society may be even greater, according to Dr. Burns. He believes the effect of physical exercise on brain health deserves more funding for research and program development.

“The field is held back by a lack of definitive proof and the absence of answers to specific questions like how much and what kinds of exercise are best for the brain,” says Dr. Burns. “It's too bad, because we can use this information to reduce heart disease, blood pressure, and potentially AD, which would then also reduce the health burden for Medicare and insurance companies.”

Exercise is simple and cost-effective and almost anyone can do it, Dr. Burns says. “It's a very important intervention with lots of advantages over medications, none of which yet modify brain disease.”

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“Physical activity is the very first recommendation I give older adults who come in with cognitive impairment, depression, or anxiety,” says Helen Lavretsky, M.D., a geriatric psychiatrist at UCLA Health. “The ‘use it or lose it’ rule applies to your brain, your muscle strength, and your ability to walk.”

An avid yoga practitioner, Dr. Lavretsky recommends yoga practice along with tai chi or aerobic exercise to many of her patients. She was lead author on a 2011 study in the American Journal of Geriatric Psychiatry that found use of a mind–body exercise like tai chi may improve outcomes of depressed geriatric patients also treated with medication. In another study she led on yogic meditation in stressed dementia caregivers, yoga practice improved mental health and cognitive performance compared to relaxation activity.

When Dr. Lavretsky spoke recently at a Los Angeles assisted living center, many residents “found all kinds of excuses not to move,” she says. She finds that “young-old adults”—between 60 and 70 years old—tend to be more proactive in using exercise, yoga and meditation, or diet to prevent chronic diseases associated with aging.

“It may be a generational trend showing that aging baby boomers are more aware of reducing dependence upon doctors for pills by being proactive and seeking prevention of disease through active lifestyle,” Dr. Lavretsky notes.

When an elderly individual in a wheelchair objects with “but I can't…,” Dr. Lavretsky hands over a tennis ball or an orange for hand-squeezing and arm flexion. “The brain will wake up,” she says. “Even moving the fingers activates the prefrontal cortex—responsible for cognition and regulation of emotion—and that also increases gray matter.”

She also asks seniors sitting in front of a television to just get up and down from their chairs. “When you move, your brain reacts—increased blood flow shows activation in the brain area responsible for movement,” Dr. Lavretsky says.

Whatever you do, doing something is so much better than doing nothing, say exercise proponents.

“I hear from physicians, ‘Not everybody can run a marathon,’” Dr. Kramer says. “But nobody has to. We run studies with older people ages 60 to 80, and after a course of six months to a year, we get them fitter. Nobody's winning races, but they're making modest changes in cardiorespiratory fitness that engender impressive benefits in cognition—just by coming to the gym three times a week or doing an hour a day of walking. And they haven't been exercising their entire lives.”

There's no time like the present.

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  • For more Neurology Now coverage of exercise and cognition, go to
  • For Neurology Today coverage of exercise and cognitive health, go to
© 2013 American Academy of Neurology