Determinants of body composition in postmenopausal women

Little is known about the effects of different levels of long-term physical activity on total body and regional fat and whether hormone replacement therapy interacts with physical activity level to affect body composition in postmenopausal women.

We determined the associations between different levels of habitual physical activity, hormone replacement therapy (HRT), and total and regional body composition in postmenopausal women. Twenty sedentary, 20 active nonathletic, and 23 endurance-trained women (approximately half on HRT) had total and regional body composition assessed by dual-energy x-ray absorptiometry. The athletes and active nonathletic women had been active for the same number of years and the same number of hours per week.

The athletes and sedentary women weighed the same, but the active nonathletic groups on and not on HRT weighed 3-12 kg more (p < .05). Athletes had less trunk, arm, leg, and total body fat than sedentary and active nonathletic women (p < .05). Women on HRT tended to have lower total body (p = .07), but not regional, fat values. Linear regression analyses indicated that VO2max in ml/kg/min was the major independent determinant of total and regional body fat accounting for 52% to 70% of their variances. Athletes had greater caloric and carbohydrate intake than their less active peers, but all groups had similar protein, fat, saturated fat, monounsaturated fat, and polyunsaturated fat intakes.

Intense training, but not low- to moderate-intensity physical activity, is associated with markedly lower levels of total and regional body fat in postmenopausal women. HRT has less of an effect on body composition than intense exercise training in postmenopausal women.