LOSS OF ABDOMINAL FAT AND METABOLIC RESPONSE TO EXERCISE TRAINING IN OBESE WOMEN

Numerous studies have shown that a high accumulation of abdominal fat is associated with metabolic complications and with an increased risk of coronary heart disease. The present study examined the effects of changes in body fatness and in the level of abdominal fat on metabolic variables in a sample of 13 obese premenopausal women, aged 38.8 +/- 5.3 (SD) yr. Women exercised for 90 min at approximately 55% of maximal aerobic power (VO2max) four to five times a week for a period of 14 mo. The training program induced a significant increase in VO2max and a mean reduction in body fat mass of 4.6 kg (P < 0.01), with no change in fat-free mass. Measurement of adipose tissue areas by computed tomography indicated a greater loss of abdominal fat compared with midthigh adipose tissue (P < 0.05). The training program also produced significant reductions in the insulinogenic index measured during an oral glucose tolerance test and in plasma cholesterol (Chol), low-density lipoprotein (LDL)-Chol, and apolipoprotein (apo) B levels (P < 0.05). Training also significantly increased plasma high-density lipoprotein (HDL)-apo A-I and HDL2-Chol levels and decreased plasma HDL3-Chol concentration (P < 0.05). Whereas no change in postheparin plasma lipoprotein lipase activity was noted, a significant decrease in postheparin plasma hepatic triglyceride lipase activity was observed after training (P < 0.005). Metabolic responses were not correlated with changes in VO2max but were significantly correlated with the reduction in body fat mass and/or with the loss of deep abdominal fat. Results of the present study suggest that changes in total body fat and in the level of abdominal fat are more important correlates of aerobic exercise training-induced changes in carbohydrate and lipid metabolism than changes in cardiorespiratory fitness.