Physical activity improves cognitive and mental health. Here are ways to reap its myriad benefits and maximise gains

Whether exercise can cause new neurons to grow in adult humans — a feat previously thought impossible, yet a tantalising prospect to treat neurodegenerative diseases — is still up for debate. But even if it’s not possible, physical activity is still excellent for your brain, improving mood and cognition through a plethora of cellular changes, said Henriette van Praag, a professor at Florida Atlantic University, US.

THE BENEFITS?

Exercise offers short-term boosts in cognition. Studies show that immediately after a bout of physical activity, people perform better on tests of working memory. This may be in part because movement increases the release of neurotransmitters in the brain, most notably epinephrine and norepinephrine, which are needed for paying attention to information.

The neurotransmitters dopamine and serotonin are also released during exercise, which is thought to be a main reason people often feel so good after going for a run.

But to gain benefits over time, we have to work out consistently. People who exercise several times a week, for instance, have higher cognitive test scores than those who were more sedentary.

However, the effects on cognition aren’t huge, and not everyone improves to the same degree. “You cannot acquire a super memory just because you exercised,” said Marc Roig, an associate professor at McGill University, Canada.

The other impact of physical activity is on mood. People who work out regularly report having better mental health than people who are sedentary. Exercise can even be effective in treating people’s depression.

Perhaps most remarkably, exercise offers protection against neurodegenerative diseases. “Physical activity has been shown to be beneficial for cognitive function and reducing risk of Alzheimer’s and dementia,” said Michelle Voss, an associate professor of psychological and brain sciences at the University of Iowa, US.

HOW DOES EXERCISE HELP?

It starts with the muscles. When we work out, they release molecules that travel through the blood up to the brain. Some, such as the hormone irisin, have “neuroprotective” qualities and have been shown to be linked to the cognitive health benefits of exercise, said Christiane Wrann, an associate professor of medicine at Massachusetts General Hospital, US.

Good blood flow is essential to obtain the benefits of physical activity. Exercise improves circulation and stimulates the growth of new blood vessels in the brain. “It’s not just that there’s increased blood flow,” Voss said. “There’s also a greater chance for signalling molecules coming from the muscle to get delivered to the brain.”

Once these signals are in the brain, other chemicals are released locally. A greater number of blood vessels and connections between neurons can actually increase the size of different brain areas. This is especially noticeable in older adults because it can offset the loss of brain volume that happens with age. The hippocampus, an area important for memory and mood, “shrinks with age”, Roig said. “[But] if we exercise regularly, we can prevent this decline.”

Exercise’s effect on the hippocampus may be one way it helps protect against Alzheimer’s and depression; the hippocampus is smaller in people who are depressed, and effective treatments, including medications and exercise, increase its size.

THE BEST EXERCISE?

The type of activity doesn’t seem to matter, though most of the research has involved aerobic exercise. However, higher-intensity workouts do confer a bigger benefit, experts have said. Improving your overall cardiovascular fitness appears to be key. “The more you can improve your cardiorespiratory fitness, the better,” Wrann said. NYT

Did You Know?

The US Center for Disease Control and Prevention recommends 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity per week