The researchers recruited 44 obese girls between 12 and 18 years old. They separated these volunteers into three groups. One group was assigned to perform 60 minutes of aerobic exercise three days a week for three months, either running on a treadmill or using an elliptical trainer. A second group was assigned to perform the same amount of resistance exercise, but instead participated in aerobic exercise program, doing 10 whole body resistance exercises using weight machines over the course of each hour-long session. A third group was asked not to participate in any structured physical activity program over the course of the study. Before the exercise programs began, all the study participants had a detailed physical exam, which included measuring their total fat, visceral fat, liver fat, and fat embedded in their muscles through various noninvasive means. The researchers also measured the volunteers' insulin sensitivity, a risk factor for diabetes, as well as basic health measures including weight and physical fitness.
The researchers found that those in both exercise groups had less total fat and intramuscular fat by the end of the three-month study period compared to the sedentary group. However, the two exercise groups differed significantly in other measures. Overall, those in the aerobic exercise group lost visceral and liver fat and improved their insulin sensitivity, but those in the other groups didn't.
Importance of the Findings
These findings suggest that for teen girls, aerobic exercise might be superior to resistance exercise for cutting health risks associated with obesity. They also note that, anecdotally, girls in the aerobic exercise group seemed to enjoy their workouts more than those in the resistance exercise group, an oppo
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American Physiological Society