Since the ability of exercise to lower weight and fat was demonstrated without any changes in diet, the researchers also believe a focus on dietary intake can only add to the benefits of exercise in reducing weight.

For the trial, researchers randomized 120 participants into one of four groups: no exercise, low dose/moderate intensity (equivalent of 12 miles of walking per week), low dose/vigorous intensity (equivalent of 12 miles of jogging per week) or high dose/vigorous intensity (equivalent of 20 miles of jogging per week). The exercise was carried out on treadmills, elliptical trainers or cycle ergometers in a supervised setting.

Participants in the high dose/vigorous intensity group saw reductions in all measures when compared to the two lower exercise and control groups.

Specifically, the high dose/vigorous intensity group experienced a 3.5 percent weight loss, while the two low-dose exercise groups experienced slightly greater than a 1 percent weight loss. During the same period, the inactive control group showed a 1.1 percent weight gain.

Interestingly, the two vigorous intensity groups saw similar increases in lean body mass, or muscle, which were twice as high as the 0.7 percent increase for the low-intensity group.

"The higher exercise intensity groups resulted in greater increases in lean body mass, which if confirmed by other studies, could have significant implications," Slentz said. "This finding suggests that while the amount of exercise determines total body weight change and fat mass loss, exercise intensity would appear to be the primary determinant of gain in lean body mass."

In terms of body fat mass, the inactive group experienced a 0.5 percent increase, while all the exercise groups saw important decre
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Contact: Richard Merritt
merri006@mc.duke.edu
919-684-4148
Duke University Medical Center
12-Jan-2004