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Fitter bodies = fitter brains. True at all ages?

Posted Oct 04 2010 9:24am

The results of recently published studies suggest that fitter children also have fitter brains. It looks like exer­cis­ing your body pro­motes brain health. Is this true at all ages? How does it work? How much exercise should we do?

Physical activity and brain health in children

An emerging literature suggests that physical activity and high levels of aerobic fitness during childhood  may enhance cognition. In the 2 most recent studies by Kramer and colleagues (2010), the cognitive performance and the brains of higher-fit and lower-fit 9– and 10-year-old children were examined.

In one study, fitter children did better than less fit children in a task requiring to ignore irrelevant information and attend to relevant cues. Fitter children also had larger basal ganglia (more specifically dorsal striatum) than less fit children. The basal ganglia play a key role in cognitive control (e.g. preparing, initiating, inhibiting, switching responses).

In another study, fitter children did better than less fit children in a task requiring to memorize information. Fitter children also had larger hippocampi than less fit children. The hippocampus is a structure in the brain that is key to the formation of new memories.

These studies suggest that physical fitness in children is related or associated with a) better cognitive performance and b) larger brain structures (usually the ones responsible for the performance difference). The results do not show a causation relationship between physical fitness and cognitive performance but as we examine the results coming from the adult population, it seems likely that the causal effect is here.

Physical activity and brain health in adults

In 2003, Col­combe and Kramer, ana­lyzed the results of 18 sci­en­tific stud­ies pub­lished between 2000 and 2001. These were not correlation studies. Researchers ran­domly assigned participants to either an aer­o­bic train­ing group or a con­trol group. Cognitive performance in both groups was assessed before and after the training period. The results of this meta-analysis clearly showed that fit­ness train­ing increased cog­ni­tive per­for­mance in healthy adults between the ages of 55 and 80. Given the design of the studies, results suggest a causal relation between more physical exercise and better cognitive performance.

Another meta-analysis pub­lished in 2004 by Heyn and col­leagues showed sim­i­lar ben­e­fi­cial effects of fit­ness train­ing for peo­ple over 65 years old who had cog­ni­tive impair­ment or dementia.

In 2006, Col­combe and col­leagues ran­domly assigned 59 older adults to either a car­dio­vas­cu­lar exer­cise group, or a non­aer­o­bic exer­cise con­trol group (stretch­ing and ton­ing exer­cise). Par­tic­i­pants exer­cised 3h per week for 6 months. Col­combe et al. scanned the par­tic­i­pants’ brains before and after the train­ing period. After 6 months, the brain vol­ume of the aer­o­bic exer­cis­ing group increased in sev­eral areas com­pared to the other group. Vol­ume increase occurred prin­ci­pally in frontal and tem­po­ral areas of the brain involved in exec­u­tive con­trol and mem­ory processes.

More recent studies confirm that aerobic exercise is related to the size of regions responsible for memory processes (such as the hippocampus) in elderly humans (Erickson et al., 2009).

How does it work?

As you know neuroplasticity is the brain’s ability to reorganize itself throughout life. This reorganization occurs through the generation of new neurons (neurogenesis) and new connections (synapses) between neurons. Neuroplasticity is triggered by our experiences, by what happens in our life.

It seems that physical exercise triggers some neuroplastic changes in the brain.

Numerous animal studies have shown that physical exercise has a multitude of effects on the brain: neurogenesis, creation of synapses, increase in various neurotransmitters and nerve growth factor levels, and angiogenesis (the formation of new blood vessels).

In human studies,  researchers suspect that the increased brain volumes observed following fitness training may be due to an increased num­ber of blood ves­sels and an increased num­ber of con­nec­tions between neurons.

Neuroplasticity slows down as we age but does not disappear. Clearly the brain can benefit from physical exercise at all ages.

The guidelines

Aerobic exercise, at least thirty to sixty minutes per day, three days a week, has been shown to have a positive impact on brain functions. As pointed out in the SharpBrains Guide to Brain Fitness , the exercise does not have to be strenuous: Walking have been shown to have positive effects too.

As we all know it is not always easy to integrate physical exercise in our busy lives. Two things may help:

·       Set a goal that you can achieve. Do something you enjoy for even just 15 minutes a day; you can always add more time and variety later.

·       Schedule exercise into your daily routine. It will become a habit faster if you do.

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