A recent and rapidly growing movement in science is showing that exercise can make people smarter, Newsweek magazine reports in its upcoming issue.

Last week, in a landmark paper, researchers announced that they had coaxed the human brain into growing new nerve cells, a process that for decades had been thought impossible, simply by putting subjects on a three-month aerobic-workout regimen.

Other scientists, the magazine reports, have found that vigorous exercise can cause older nerve cells to form dense, interconnected webs that make the brain run faster and more efficiently. And there are clues that physical activity can stave off the beginnings of Alzheimer's disease, ADHD and other cognitive disorders.

The magazine says it examined with Harvard Medical School, the latest research and findings about how an active body is crucial for building a strong, active mind. "People have been slow to grasp that exercise can really affect cognition," says University of Illinois neuroscientist Charles Hillman.

Armed with brain-scanning tools and a sophisticated understanding of biochemistry, Newsweek reports, researchers are realising that the mental effects of exercise are far more profound and complex than they once thought.

Researchers, the article says, are learning more about how exercise affects mood: it decreases anxiety, improves sleep, improves resilience in the face of stress and raises self-esteem. All these benefits don't come because you notice what you've lost around your waist. Rather, they come from exercise-induced alterations inside your head, Michael Craig Miller, editor in chief of the Harvard Mental Health Letter, is quoted as saying.

If you are a couch potato, you have couch-potato tendencies. There are more opportunities to exercise than many people realise, the magazine says, adding find the time with exercise snacks that last as little as 10 minutes at a time.

Examples are pacing in your office while you're on the phone, taking the stairs instead of the elevator, trekking up the stairs at home during a TV commercial break. Or break up the day with two-minute walks -- to the mailbox, for example, or in a loop around your office corridor.

The magazine says that while moderate exercise is good for you, vigorous exercise is even better. Specifically, it's more effective at lowering blood pressure, improving insulin sensitivity (which can reduce the risk of developing diabetes) and raising one's aerobic capacity.

And one way to stick to a high-intensity routine is to participate in a competitive sport. Not only is it fun, but you have an obligation to show up for practices and events, the report notes.

Reams of research, it says, suggest that exercise -- an activity as old as the human race -- substantially reduces the odds of ever getting breast cancer, lengthens survival and considerably enhances quality of life for women with the disease.