Talk Transcript: Mary Carmichael on Exercise and the Brain

Last summer, I was pretty much a fat guy getting fatter," says Steve Chugg. The 52-year-old worked a high-stress job as a sales executive, indulging in hefty expense-account meals and finding no time to work them off between long-haul flights and meetings. His weight had ballooned to 240 pounds, and his high blood pressure was out of control. Then, in June, his doctor delivered more bad news: he had type 2 diabetes. "I was basically killing myself," says Chugg.

At this point, most adults would vow to change their habits, only to sink back into the comfort of the living-room couch. Not Chugg. After attending a Senior Olympics event with his son, Ben, a high-school track athlete, he made a drastic change: he quit his six-figure job and decided to devote himself full time to training for this summer's National Senior Games in Louisville, Ky. (For now, he's trying to make ends meet as an amateur art dealer.) After passing a stress test at his doctor's office, he began walking every day, then jogging. Then he hired Ben, 15, as his coach and started running hard. Last September Chugg qualified for Louisville with a bronze medal in the 100-meter dash and a silver in the long jump at a regional meet. More important, his blood pressure is down and he hasn't had a problematic blood-sugar reading in months. "It's changed my life," he says.

Chugg is an example of how high-intensity exercise can rapidly improve your health. Research has shown for decades that people who work out regularly are at lower risk for such health problems as obesity and heart disease. While the benefits of moderate exercise are much greater than little or no exercise, several recent studies have shown that vigorous exercise is even better for you. (Vigorous is defined as working at 60 percent or more of aerobic capacity; moderate is 40 to 60 percent.) 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. "Almost all cardiovascular risk factors respond significantly better to vigorous exercise than to moderate exercise," says Brian Duscha, a clinical researcher who specializes in exercise physiology at the Duke University School of Medicine.

Participating in a competitive sport can help you stick with a high-intensity routine. Many people find it difficult, if not impossible, to make the kinds of lifestyle changes necessary to go from couch potato to gym regular. Joining a team forces you to do things that you might not otherwise do. Not only is it fun, but you have an obligation to show up for practices and events. There are teammates to work out with, and there's usually a coach on hand to keep track of your progress, help set new goals.

William Gillies, 38, used to look forward to frequent after-work pub crawls with friends. But after he joined a marathon training program organized by the New York City running shop Urban Athletics, his priorities shifted. "My coach would give me a hard time whenever I missed a session," he says. He taught Gillies about proper nutrition and "instilled the spirit of competition" in him. Susan von der Lippe, 41, a former Olympic swimmer from Loveland, Colo., does laps with a USA Swimming masters club three mornings a week and competes in meets once a month. "The camaraderie and the competition is what keeps me involved," she says. "I like setting myself goals and seeing how fast I can make this old body move."

In a recent study, Duscha and his co-workers showed exactly how high-intensity exercise can improve health. The Duke group divided 282 overweight and sedentary adults (read: your average American) between the ages of 40 and 65 into four groups and had each group exercise at a different intensity three or four times a week over the course of nine months. One group did a lot of high-intensity exercise—the equivalent of running 20 miles per week fairly quickly. Two other groups did low amounts of high-intensity or moderate-intensity exercise—the equivalent of running 12 miles per week fairly quick-ly or at a moderate pace, respectively. A fourth group, the control, did no ex-ercise. Overall, says Duscha, when compared with fitness improvements in other clinical studies, the group that exercised a lot at a high intensity lowered its risk of dying from a heart attack by 24.5 percent, as compared with 14.5 percent and 8.1 percent for the other exercise groups. Those in the two high-intensity groups also reduced their concentrations of a specific LDL-cholesterol particle that can clog arteries and lowered their body-fat percentages. They also raised their aerobic capacity more than the moderate-intensity group.

Interestingly, moderate exercise appears to lose out to vigorous exercise no matter how many calories it burns. In a review published last year in The American Journal of Cardiology, David Swain, a professor of exercise science at Old Dominion University in Norfolk, Va., and Barry Franklin, director of cardiac rehabilitation at William Beaumont Hospital in Royal Oak, Mich., analyzed a dozen studies like Duscha's that compared exercise intensity with coronary-heart-disease risk. In each case, they controlled for the subjects' total energy expenditure, or the number of calories burned. Those who exercised vigorously had greater improvements in aerobic capacity and glucose control (which predicts one's risk of developing diabetes) and greater reductions in blood pressure.

While doctors know that high-intensity workouts improve health more than low- intensity ones, they don't know exactly why. One clue may lie in the inflammatory process, a cascade of events that can lead to health problems such as clogged coronary arteries. In a pilot study concluded last summer at Columbia University Medical Center, researchers found that moderate and intense aerobic exercise lowered levels of tumor necrosis factor (TNF), which plays a key role in the inflammatory process. Study leader Dr. Richard Sloan, a professor of behavioral medicine at Columbia, is planning a broader study that will examine, among other things, whether high-intensity workouts have a greater impact on inflammation than moderate-intensity ones.

Vigorous exercise also holds benefits that can't be measured in a lab. Since Jessica Kavoulakis, 40, a lawyer from New York City, joined a marathon training program two years ago, she's gained a new sense of purpose, ambition and self-confidence. "I saw my body do things I never thought it could do," she says. Steve Chugg believes his improved fitness has made him a better father, a better friend and "an all-around better person, psychologically." For Marilyn Minnick, 60, who qualified for the 2007 Senior Olympics with her three sisters and two close friends, the experience has brought the group closer. "We do things together all the time now, so it's really fun," she says. "We just laughed our heads off at the state games when we qualified." Minnick's group will compete in cycling and track and field.

How much vigorous exercise does one need? The U.S. Centers for Disease Control and Prevention recommend that adults engage in at least 30 minutes of moderate-intensity exercise—an activity you can do while breathing harder than normal and still carry on a conversation—on five or more days of the week. Another CDC option is 20 minutes of high-intensity exercise—an activity you can do for several minutes at a time but during which you're unable to speak in complete sentences—at least three days per week.

Doctors emphasize, however, that vigorous workouts are not for everyone. Adults with risk factors for heart disease such as diabetes or high blood pressure should take an exercise stress test before starting any activity program, says Swain. Those who are healthy but sedentary should start slow and work up to a more rigorous program over the course of three to six months. "But if you cannot ever make it to a vigorous level, that's fine," says Duscha. "Our study results show low levels of exercise are very beneficial in reducing cardiovascular risks."

Even though she works out with a top coach, Kavoulakis tore a hamstring muscle last year. Now recovered, she's set on not just crossing the finish line of the New York City Marathon in November but running the event quickly enough to qualify for the Boston Marathon in April 2008. For Kavoulakis and many others, the thrill of competitive sports lies in setting goals you never thought you could achieve—then meeting them.