EFFECTS ON MUSCLES OF DIETING WITH OR WITHOUT EXERCISE IN OVERWEIGHT POSTMENOPAUSAL WOMEN

The main aim of this study was to investigate the effect of an energy- restrictive, high-protein diet with or without exercise on muscle morp hology and biochemistry. Moderately overweight postmenopausal women (4 9-58 yr, body mass index: 25-42 kg/m(2)) were randomly assigned to thr ee groups for 12 wk of intervention; namely, a control group, a group on a 4.2 MJ/day diet, and a group on 4.2 MJ/day diet combined with aer obic and anaerobic exercise. Muscle morphology and biochemistry analys is were performed in 69 and 58 women, respectively. In contrast to the diet-only group, the diet-plus-exercise group significantly increased the muscle fiber areas by 20-25%, the number of capillaries per muscl e fiber type I by similar to 20%, and the activities of citrate syntha se by similar to 35% and hexokinase by similar to 20% (P < 0.05). Ther e were no statistically significant changes in any other muscle variab le (P > 0.05). The respiratory exchange ratio decreased in both interv ention groups by 2-4% (P < 0.01). It is concluded that 12-wk period of an energy-restrictive high-protein diet was not associated with major changes in muscle morphology or biochemistry. The addition of exercis e to the diet led to an adaptive increase in muscle fiber areas and in the oxidative capacity of the muscles.