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The Exercise–Brain Connection

Feb 01, 2012

Fitness Handout

Did you know that your brain is incredibly dynamic? It can change its structure and function by adding new neurons, making new connections between neurons and even creating brand-new blood vessels, all in response to exercise.

Jeffrey A. Kleim, PhD, associate professor in the Arizona State University School of Biological and Health Systems Engineering, shares the following insights on how exercise impacts the brain.

Exercise Improves Cognitive Function

A sedentary lifestyle affects the brain—and in turn lessens mental capacity. Sibley and Etnier (2003) found a clear connection between how much schoolchildren exercised and their cognitive performance: the more aerobic exercise the children engaged in, the better they performed on verbal, perceptual and mathematical tests. The same pattern of results was found in older adults: aerobic training improved cognitive performance (Colcombe & Kramer 2003), and active lifestyles decreased age-related risks for cognitive impairment and dementia (Yaffe et al. 2009). Not surprisingly, these cognitive effects were accompanied by clear changes in brain structure and function.

Exercise Changes Brain Function

Research shows that exercise changes brain function in a lasting manner. For example, the reduced cognitive capacity in sedentary individuals is associated with different patterns of brain activity—both at rest and while performing mentally challenging tasks—than those observed in active subjects.

Plus, compared with sedentary people, active individuals show greater baseline levels of cortical activity (Dustman et al. 1990). (The cerebral cortex helps with complex cognitive tasks.)

Exercise Changes Brain Structure

The structure of the brain can be broken down into two general components. Gray matter contains the neurons and supporting cells, while white matter consists of the axons of these neurons (nerve cell fibers) that carry signals from one area to another.

Magnetic resonance imaging (MRI) allows for the measurement of gray and white matter. MRI scans have shown that exercise boosts overall brain volume (Colcombe et al. 2006), increasing both gray matter (Colcombe et al. 2006) and white matter (Gordon et al. 2008). These changes can occur over relatively short periods of time. After learning to juggle for only a few weeks, for example, study subjects showed increases in gray matter within regions of the brain concerned with integrating visual and motor information (Draganski et al. 2004).


Colcombe, S., & Kramer, A. F. 2003. Fitness effects on the cognitive function of older adults: A meta-analytic study. Psychological Science, 14 (2), 125–30.

Colcombe, S.J., et al. 2006. Aerobic exercise training increases brain volume in aging humans. Journal of Gerontology, Series A Biological Sciences and Medical Sciences, 61 (11), 1166–70.

Draganski, B., et al. 2004. Neuroplasticity: Changes in grey matter induced by training. Nature, 427, 311–12.

Dustman, R.E., et al. 1990. Age and fitness effects on EEG, ERPs, visual sensitivity, and cognition. Neurobiology of Aging, 11 (3), 193–200.

Gordon, B.A., et al. 2008. Neuroanatomical correlates of aging, cardiopulmonary fitness level, and education. Psychophysiology, 45 (5), 825–38..

Sibley, B.A. & Etnier, J.L. 2003. The relationship between physical activity and cognition in children: A meta-analysis. Pediatric Exercise Science, 15 (3), 243–56.

van Praag, H., Kempermann, G., & Gage, F.H. 1999. Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. Nature Neuroscience, 2 (3), 266–70.

Vaynman, S., & Gomez-Pinilla, F. 2006. Revenge of the “sit”: How lifestyle impacts neuronal and cognitive health through molecular systems that interface energy metabolism with neuronal plasticity. Journal of Neuroscience Research, 84 (4), 699–715.

Yaffe, K., et al. 2009. Predictors of maintaining cognitive function in older adults: The Health ABC study. Neurology, 72 (23), 2029–35.

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