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Why Is Physical Activity So Good for Your Brain?

Exercise improves the structure, function, and connectivity of your brain.

Neuroscientists around the globe agree that physical activity is the best medicine to maintain brain health throughout your lifespan. Why is physical activity so good for your brain?

There are many reasons that exercise is good for your brain. These include: increased blood flow, which improves cerebrovascular health; the release of neurotrophic factors like BDNF, which stimulates the growth of new neurons; and the benefits of glucose and lipid metabolism which bring nourishment to the brain.

Recently, researchers at the Beckman Institute at the University of Illinois at Urbana-Champaign found that physical activity is also associated with improved white matter integrity. In two separate studies—released within the past month—researchers found that physical activity improved the white matter integrity of physically fit children aged 9 to 10 and also in “low fit” participants aged 60 to 78.

The researchers found that physical activity improves the microstructures of white matter in the brain. White matter integrity is linked to faster neural conduction between brain regions and superior cognitive performance.

Multiple Sclerosis (MS) directly affects the integrity of white matter. In MS lesions the myelin sheath around the axons gradually deteriorates. Changes in white matter, known as amyloid plaques, are associated with Alzheimer's disease and other neurodegenerative diseases.

What is the White Matter of Your Brain?

White matter connectivity on MRI. (Wikipedia)

White matter consists mostly of glial cells and myelinated axons that act as communication lines between various regions of gray matter in the cerebrum. White matter also allows communication between the cerebrum and lower brain centers including the cerebellum.

When white matter tissue is freshly cut in a living brain, it actually appears pinkish because myelin is composed largely of lipid tissue that is veined with capillaries for vascularization. According to Arthur Kramer, the director of the Beckman Institute, one reason that exercise might improve white matter integrity is that physical activity gets the blood pumping through the brain and improves vascularization of these capillaries. There is also the possiblilty that physical activity improves myelination.

White matter carries nerve signals between the gray matter in one brain region to another brain region. The more streamlined and compact your white matter is, the faster and more efficiently your brain functions.

These new studies show that physical activity appears to make the axons in white matter more tightly bundled and compact. Exercise appears to improve white matter integrity which is correlated with more efficient communication between brain regions from childhood into our golden years.

Aerobic Fitness in Children Linked to White Matter Integrity

The first new study from the Beckman Institute, “Aerobic Fitness is Associated with Greater White Matter Integrity in Children,” was published August 2014 in in the open-access journal Frontiers in Human Neuroscience. In this study U. of I. kinesiology and community heatlh professor Charles Hillman, postdoctoral researcher Laura Chaddock-Heyman and their colleagues found that physically fit children had more fibrous and compact white matter tracts in the brain than their less fit peers.

In a press release, University of Illinois researcher Laura Chaddock-Heyman said, "Previous studies suggest that children with higher levels of aerobic fitness show greater brain volumes in gray matter brain regions important for memory and learning. Now for the first time we explored how aerobic fitness relates to white matter in children's brains."

Chaddock and her colleagues used a technique called diffusion tensor imaging (DTI) to look at five white matter tracts that play a role in attention and memory. The findings revealed significant fitness-related improvements in the integrity of several white matter tracts.

For this study, the researchers didn't specifically test for cognitive differences in the children. A wide range of studies over the past decades have found a link between aerobic fitness levels, improved cognitive function, and higher academic test scores. "Previous studies in our lab have reported a relationship between fitness and white matter integrity in older adults," Kramer said. "Therefore, it appears that fitness may have beneficial effects on white matter throughout the lifespan."

Avoiding a Sedentary Lifestyle Benefits White Matter Integrity As You Age

The second new study from the Beckman Institute, “Physical Activity and Cardiorespiratory Fitness Are Beneficial for White Matter in Low-Fit Older Adults” was published September 2014 in the journal PLOS ONE. Postdoctoral researcher Agnieszka Burzynska conducted the research with Art Kramer and kinesiology and community health professor Edward McAuley.

In this study, the researchers found a strong link between the structural integrity of white matter tracts and an older person's level of daily activity. Interestingly, it wasn't the extent to which the person engaged in moderate or vigorous exercise, but simply if someone spent most of the day being sedentary. Avoiding a sedentary lifestyle can have dramatic effects on your brain health by maintaining the integrity of your white matter throughout a lifespan.

Hippocrates was right when he said, “Walking is man’s best medicine.” Art Kramer has spent decades researching the brain benefits of physical activity. In a recent conversation, Kramer said that the best news about the latest findings is that you don’t have to be running marathons or winning triathlons to reap the brain benefits of physical activity. I agree.

In our conversation, Art Kramer and I spoke about the difficulty of motivating people to break a sweat. He emphasized that the most exciting aspect of this new study is that it shows that the real enemy is sedentarism. This study indicates that just a little bit of movement every day helps preserve the integrity of your brain’s white matter.

Conclusion: Physical Activity Improves Brain Health and Cognitive Function at Any Age

These results come at a critical time. In a digital age, our society has become increasingly unfit and sedentary. As the father of a 6-year-old, I am passionate about public health and education policies that affect children's brain health and overall development.

As adults we can make daily lifestyle choices that include physical activity. Unfortunately, most children are subject to policies that tend to reduce or eliminate opportunities for physical activity during the school day.

Reducing the time and availability for children to be physically active during the school day could have negative impacts on the integrity of white matter tracts, which might reduce brain efficiency and could lead to lower test scores.

One of the most interesting findings from recent research is that white matter microstructure in the corona radiata is linked to mathematics performance (van Eimeren et al., 2008). Ironically, in an attempt to prepare children for the Common Core Standards and No Child Left Behind testing by forcing them to sit still in a chair we may actually be sabotaging a child's brain from optimizing white matter integrity.

Laura Chaddock-Heyman and co-authors sum up the importance of physical activity in the conclusion of their study when they say, “In fact, our study raises the possibility that greater white matter integrity, perhaps via greater myelination, is one pathway by which higher fit children excel in cognitive and academic performance compared to their less fit peers. Hopefully these findings will reinforce the importance of aerobic fitness during development and lead to additional physical activity opportunities in and out of the school environment.”

If you'd like to read more on this topic, check out my Psychology Today blog posts:

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