March 3, 2006

Pump It Up: Women May Prevent or Delay “Middle-aged Spread” by Lifting Weights
Penn Researcher Presents Findings at the AHA’s 46th Annual Conference
on Cardiovascular Disease Epidemiology and Prevention

(Phoenix, AR) – Women who lift weights twice a week can prevent or at least slow down “middle-age spread” and weight gain, a University of Pennsylvania School of Medicine researcher reported today at the American Heart Association’s 46th Annual Conference on Cardiovascular Disease Epidemiology and Prevention.

A study of 164 overweight and obese (body mass index of 25-35) women between 24 and 44 years of age, found that strength training with weights dramatically reduced the increase in abdominal fat in pre-menopausal participants compared to similar women who merely received advice about exercise.

“On average, women in the middle years of their lives gain one to two pounds a year and most of this is assumed to be fat,” said lead author Kathryn H. Schmitz, PhD., Assistant Professor, Center for Clinical Epidemiology and Biostatistics. “This study shows that strength training can prevent increases in body fat percentage and attenuate increases in the fat depot – or ‘belly fat’ – most closely associated with heart disease. While an annual weight gain of one to two points doesn’t sound like much, over 10 to 20 years, the gain is significant.”

Women in the two-year weight-training program decreased their body fat percentage by 3.7 percent, while body fact percentage remained stable in the controls. The strength-training reduced intra-abdominal fat, which is more closely associated with heart disease and metabolic disturbances. More specifically, the women who did strength-training experienced only a 7 percent increase in intra-abdominal fat compared to a 21 percent increase in intra-abdominal fat among controls.

The study – dubbed The SHE study, for The Strong, Healthy, and Empowered – examined whether twice-weekly strength-training would prevent increases in intra-abdominal and totally body fat in women who were overweight or obese. The women initially were separated by baseline percentage body had booster session four times yearly with certified fitness professionals over two years. The control fat and age. The strength-training group participated in supervised strengthening classes for 16 weeks, and group received a brochure recommending 30 minutes to an hour of exercise most. days of the week. All of the women were asked not to change their diets in ways that might lead to weight changes while they were participating in the study.

The weight-training sessions took about an hour, and the women were encouraged to steadily increase the amount of weight they lifted. The weight training included exercises for all major muscle groups, including the chest, upper back, lower back, shoulders, arms, buttocks and thighs. The maximal amount of weight women could lift once – called a one-repetition maximum test – increased by an average of 7 percent in bench pressing and 13 percent in leg press exercises.

Researchers measured the participants’ body composition with a dual energy X-ray absorptiometry (DEXA) scan and measurements of abdominal and total body fat by single slice CT scan at baseline, and again at one and two years.

“This study showed that strength training is a fairly time efficient method to prevent the small increases in weight that come with aging and may increase an adults’ risk for heart disease and diabetes,” said Schmitz.

The average age of participants was 36 years. Approximately 40 percent of the sample was non-Caucasian. About two-thirds were college educated and about half had children under the age of five at home. All had similar caloric intakes. On average, the women completed 70 percent of all prescribed exercise sessions over two years.

“There was marginal treatment effects on total fat mass and subcutaneous abdominal fat,” said Schmitz. “However, since there was no dietary intervention in this protocol, it’s not surprising that total body weight and body mass indexes were not altered.”

Strength training to increase muscle mass has been demonstrated to allow older persons to delay functional declines associated with aging. “It can also increase muscle strength to allow aerobic activity in overweight people,” adds Schmitz. “Making women stronger and more confident behaviorally, may serve as a gateway to getting overweight women to be more active.”

For her research, Schmitz will be awarded the 2006 Trudy Bush Fellowship for Cardiovascular Research in Women’s Health from the American health Association’s Council on Epidemiology and Prevention.

The National Institutes of health funded the study, which was co-authored by Peter J. Hannan, Michael D. Jensen, MD, and MStat.

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This release is available online at http://www.uphs.upenn.edu/news/News_Releases/mar06/SHE.htm