A regular exercise routine can make both body and brain fit.

In a new study, previously sedentary adults were put through four months of high-intensity interval training. At the end, their cognitive functions–the ability to think, recall and make quick decisions–had improved significantly, says Dr. Martin Juneau, director of prevention at the Montreal Heart Institute, in a press release from the Heart and Stroke Foundation of Canada.

“If you talk to people who exercise, they say they feel sharper. Now we’ve found a way to measure that,” says Juneau.

Blood flow to the brain increases during exercise. The more fit you are, the more that increases. The pilot study looked at adults, average age 49, who were overweight and inactive. Juneau and his colleagues measured their cognitive function with neuropsychological testing, as well as their body composition, blood flow to the brain, cardiac output and their maximum ability to tolerate exercise.

The subjects then began a twice-a-week routine with an exercise bike and circuit weight training. After four months, their weight, body mass index, fat mass and waist circumference were all significantly lower. Their cognitive function had also increased, based on follow-up testing.

These improvements were proportional to the changes in exercise capacity and body weight. Essentially, the more people could exercise, and the more weight they lost, the sharper they became.

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