Quick and Sweaty Workouts

While researching a book on exercise and the brain, John Ratey learned that intense exercise releases a hormone that burns belly fat and adds muscle fibers. So the Harvard Medical School psychiatrist swapped out 40-minute jogging sessions on the treadmill for something less time consuming but more vigorous: Twice a week, he now jogs for a total of 20 minutes and includes five exhausting sprints of 20 to 30 seconds apiece. After a month, he was amazed at the results.

Katherine Hobson

August 27, 2009