Moderate-Intensity Exercise May Melt More Pounds   

By Amy Norton

NEW YORK (Reuters Health) - A brisk walk through the park might be better than a fast run when it comes to shedding pounds, a small study suggests.

Researchers found that among 14 women who embarked on a three-month exercise regimen, those who worked out at a moderate pace lost more weight than those who exercised more intensively.

But it's not time for runners to start slowing down, according to the study authors. For one, women in the higher-intensity exercise group did retain more muscle mass than those who worked out more moderately.

More importantly, though, there is no such thing as one "magic exercise," said lead study author Dr. Vassilis Mougios of Aristotle University of Thessaloniki in Greece.

To get the greatest health and fitness benefits, he told Reuters Health, people should strive for a mix of moderate and vigorous cardiovascular exercise, as well as strength training.

Mougios and his colleagues report their findings in the International Journal of Sports Medicine.

Losing weight basically boils down to burning more calories than you take in. But it hasn't been clear whether the intensity of a regular workout makes a difference in body composition - that is, the proportions of fat and lean tissue.

To study the question, Mougios and his colleagues randomly assigned 14 normal-weight and overweight women to one of two groups: one that exercised on a treadmill at a moderate pace, four times a week; and one that worked out at a more vigorous clip, also four times per week.

The researchers set the duration of the workouts so that women in both groups would burn 370 calories each time.

After three months, exercisers in both groups were slimmer, but the lower-intensity group lost more weight -- about 7 pounds, on average, compared with 4 pounds in the high-intensity group.

Fat-free mass decreased slightly (less than half a pound) in the low-intensity exercisers and increased slightly (about 1 pound) in the high-intensity group.

It's possible, according to Mougios, that women in the high-intensity group shed fewer pounds because they ended up eating more, or were so drained by their regimen that they relaxed more in their leisure time.

In turn, the women may have held on to more muscle simply because they lost less weight. On the other hand, the researchers note, high-intensity exercise may actually spur some growth in muscle fibers.

The bottom line, according to Mougios, is that people should stay active with various forms of exercise. But for those who want to know whether they're working hard or moderately, he said a heart rate monitor or some simple pulse checks during the workout will provide that information.

SOURCE: International Journal of Sports Medicine, March 2006.