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ACSM'S Health & Fitness Journal:
doi: 10.1249/FIT.0b013e318201c21b
DEPARTMENTS: You Asked For It: Question Authority

You Asked for It: Question Authority

Nieman, David C. Dr.P.H., FACSM

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David C. Nieman, Dr.P.H., FACSM, is professor and director of the Human Performance Laboratory, Appalachian State University, Boone, North Carolina, an active researcher; and author of several textbooks on health and fitness. Send your questions


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A:You are not alone in your belief regarding the "cerebral satisfaction" of exercise. The ancient Greeks maintained that exercise made the mind more lucid. Aristotle started his "Peripatetic School" in 335 B.C. - so named because of Aristotle's habit of walking up and down (peripaton) the paths of the Lyceum in Athens while thinking or lecturing to his students. Plato and Socrates also practiced the art of peripatetics, as did the Roman Ordo Vagorum or walking scholars. Centuries later, Oliver Wendell Holmes explained that "in walking, the will and the muscles are so accustomed to working together and perform their task with so little expenditure of force that the intellect is left comparatively free." Albert Einstein, when asked how he came up with the theory of relativity, quipped, "I thought of that while riding my bike."

The part of the brain that enables us to exercise, the motor cortex, is located only a few millimeters away from the part of the brain that deals with thought and reason. Might this proximity mean that when the motor cortex generates impulses to control exercise, it has a parallel effect in stimulating improved cognition?

There is growing research support for the linkage between acute exercise and enhanced cognition, but only under certain conditions (3,5,9). For example, moderate physical activity improves cognitive function, whereas high-intensity exercise in most people impairs the ability to think and reason during the bout (3). The optimal exercise intensity for cognitive function is below the level where lactic acid accumulates (3). Cognitive benefits are better during cycling compared with running and after 20 minutes into the workout (5). The "golden" moment for improved cognition is during the recovery period from exercise, even when fatigued from a vigorous bout of running or cycling (5). The length of time cognitive function is improved after exercise has not yet been defined. In general, the arousal induced by exercise helps people perform mental tasks more rapidly and efficiently, and then store and retrieve facts from memory.

A recent study used functional near-infrared spectroscopy to pinpoint the area of the brain influenced by both a moderate 25-minute bout of cycling and a mental challenge (9). Functional near-infrared spectroscopy is a noninvasive neuroimaging system that monitors changes in blood oxygen levels in specific areas of the brain. Mental cognition was significantly improved after the moderate exercise bout, and this benefit was detected in the left area of the prefrontal cortex. Moderate cycling activated the left prefrontal cortex, improving performance in a mental challenge that required this specific brain area.

The prefrontal cortex is the anterior part of the frontal lobes of the brain and lies just in front of the motor and premotor areas that help control muscle movement. This brain region is involved in complex mental tasks, personality expression, decision making, and correct social behavior. The authors of this study speculated that as individuals engage in moderate exercise day after day, week after week, the acute exercise-induced activation of the left part of the prefrontal cortex may result in both an acute and chronic improvement in mental cognition (9).

The ancient Greeks maintained that a physically fit and strong body leads to a sound mind. Evidence, however, on the chronic benefits of exercise training on mental cognition for young and middle-aged adults is lacking. This linkage is much stronger for older adults whose cognitive function is below peak levels (1,2,4,6-8). Interestingly, adults who adopt physically active lifestyles experience a delay in the onset of cognitive decline and Alzheimer disease as they age (8). Among the elderly, regular physical activity improves or maintains cognitive function, with the specific improvements seen in speed of cognition and attention (1,4,6,7). Even in those at risk for Alzheimer disease or other dementias, regular physical activity improves cognitive function or reduces symptoms of dementia (6,8).

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How does physical activity improve cognitive performance in older adults? Limited human and animal studies suggest several pathways, including reduced inflammation, enhanced brain perfusion with blood through a buildup of extra brain capillaries, improved neural connections between brain regions, and an enhanced caffeine-like arousal (5,6,8).

Taken together, the best evidence shows that most adults should experience improved cognition during and for some time after moderate physical activity bouts lasting 20 minutes or longer. This may not translate to a higher level of cognition all the time, except for older adults and those with dementia. However, as younger adults maintain a near-daily schedule of 30 to 60 minutes moderate physical activity, a "summation" effect may occur as new ideas and creative thoughts are generated, memorized, and then acted upon during and soon after exercise. Thus, a chronic enhancement of cognition through physical activity may not be as important as taking advantage of the creative thoughts and ability to think that occur during and after each bout.

John F. Kennedy once proclaimed:

"Physical fitness is not only one of the most important keys to a healthy body, it is the basis of dynamic and creative intellectual activity. Intelligence and skill can only function at the peak of their capacity when the body is strong. Hardy spirits and tough minds usually inhabit sound bodies."

This statement echoes the beliefs of many fitness enthusiasts and is endorsed by scientists who have shown that the brain can better accomplish mental tasks during and after moderate physical activity. Perhaps the "dynamic and creative intellectual activity" of many people is more dependent on their physical activity habits than they are aware of.

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1. Angevaren M, Aufdemkampe G, Verhaar HJ, Aleman A, Vanhees L. Physical activity and enhanced fitness to improve cognitive function in older people without known cognitive impairment. Cochrane Database Syst Rev. 2008;(3):CD005381.

2. Hillman CH, Motl RW, Pontifex MB, et al. Physical activity and cognitive function in a cross-section of younger and older community-dwelling individuals. Health Psychol. 2006;25:678-87.

3. Kashihara K, Maruyama T, Murota M, Nakahara Y. Positive effects of acute and moderate physical exercise on cognitive function. J Physiol Anthropol. 2009;28:155-64.

4. Klusmann V, Evers A, Schwartzer R, et al. Complex mental and physical activity in older women and cognitive performance: a 6-month randomized controlled trial. J Gerontol A Biol Sci Med Sci. 2010;65:680-8.

5. Lambourne K, Tomporowski P. The effect of exercise-induced arousal on cognitive task performance: a meta-regression analysis. Brain Res. 2010;1341:12-24.

6. Lautenschlager NT, Cox KL, Flicker L, et al. Effect of physical activity on cognitive function in older adults at risk for Alzheimer disease: a randomized trial. JAMA. 2008;300:1027-37.

7. Middleton LE, Mitnitski A, Fallah N, Kirkland SA, Rockwood K. Changes in cognition and mortality in relation to exercise in late life: a population based study. PLoS ONE. 2008;3:e3124.

8. Scarmeas N, Luchsinger JA, Schupf N, et al. Physical activity, diet, and risk of Alzheimer disease. JAMA. 2009;302:627-37.

9. Yanagisawa H, Dan I, Tsuzuki D, et al. Acute moderate exercise elicits increased dorsolateral prefrontal activation and improves cognitive performance with Stroop test. Neuroimage. 2010;50:1702-10.

© 2011 American College of Sports Medicine


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