We’re finding out more and more about the link between exercise and healthy brains

Everyone knows exercise is good for your body, but a growing body of evidence suggests it helps keep your brain sharp, too.

And these benefits are especially noticeable as we age.

As The New York Times reported, a new study compared the brain activity of younger and older adults in Japan while they completed a task that requires significant concentration. The brains of older adults who performed better on fitness tests looked more like the young people’s brains, according to the study, to be published next month in the journal NeuroImage.

The benefits of exercise

The CDC recommends that Americans do two hours and 30 minutes of moderate-intensity aerobic activity (such as brisk walking) or 1 hour and 15 minutes of vigorous-intensity aerobic activity (jogging or running) each week, as well as muscle-strengthening activities that work all major muscle groups on two or more days a week.

Sadly, only about 20% of adults actually meet these recommendations.

But exercise isn’t only important for our bodies.

Numerous studies have found a link between exercise and brain health. One recent study looked at lifetime physical activity and cognitive function in middle-aged and older adults, and found there was a strong correlation.

Another study looked at ten sets of identical twins where one twin exercised regularly and the other didn’t. It found that the twins who exercised not only had less body fat and more endurance than their less active sibling, but their brains also had more grey matter — the darker tissue that contains nerve cell bodies, which perform most of the mental processing — especially in regions involved in coordination and motor control.

Exercise has also been found to be helpful for boosting your mood and improving your sleep schedule.

In the new study, exercise scientist Hideaki Soya of the University of Tsukuba in Japan and his colleagues studied 60 Japanese men between the ages of 64 and 75 who did not have dementia or other forms of cognitive impairment.

First, the researchers tested the men’s aerobic fitness. Then, they monitored the men’s brains while they performed a computer task that involved reading the name of a colour word that was printed in a different hue (for example, the word “green” written in purple).

The researchers measured the men’s brain activity by placing tiny probes on their heads and using infrared light to visualise blood flow and oxygen consumption in different parts of the brain, a technique known as functional near infrared spectroscopy.

The colour naming task requires a lot of attention, and in younger adults, previous studies have found that it boosts brain activity in the left hemisphere of the prefrontal cortex. In older adults, this same task is known to require more effort, producing activity in the prefrontal cortex of both brain hemispheres. Neuroscientists have dubbed this effect hemispheric asymmetry reduction in older adults, or “Harold.”

Ageing bodies, younger brains

Indeed, what Soya and his team found was consistent with these earlier studies. Most of the older adults in the study showed the “Harold” pattern of brain activity while completing the colour-naming task.

But interestingly, those who performed better on the fitness test showed little or no extra activity in their right hemisphere — just like younger people, they didn’t need both sides of their brain to complete the task. The fitter participants also hit the computer keys faster and more accurately, the results showed.

However, as the Times pointed out, the study does not show a cause-and-effect relationship between fitness and cognitive health; it merely shows a link. In addition, the researchers did not take into account exercise habits, only at fitness. Moreover, this study and others do not show that the Harold effect is a sign of cognitive decline, just that certain tasks require more mental resources.

Still, the findings are one more piece of evidence that exercising can keep your brain young, and that’s probably a good thing.

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