Effects of HRT and exercise training on insulin action, glucose tolerance,and body composition in older women

The independent and combined effects of exercise training and hormone repla cement therapy (HRT) on body composition, fat distribution, glucose toleran ce, and insulin action were studied in postmenopausal women, aged 68 +/- 5 yr, assigned to control (n = 19), exercise (n = 18), HRT (n = 15), and exer cise + HRT (n = 16) groups. The exercise consisted of 2 mo of flexibility e xercises followed by 9 mo of endurance exercise. HRT was conjugated estroge ns 0.625 mg/day and trimonthly medroxyprogesterone acetate 5 mg/day for 13 days. Total and regional body composition were measured by dual-energy X-ra y absorptiometry. Serum glucose and insulin responses were measured during a 2-h oral glucose tolerance test. There were significant main effects of e xercise on reductions in total and regional (trunk, arms, legs) fat mass, i ncrease in leg fat-free mass, and improvements in glucose tolerance and ins ulin action. There were significant main effects of HRT on the reduction of total fat mass (HRT, -3.0 +/- 4.0 kg; no HRT, -1.3 +/- 2.6 kg), with a str ong trend for reductions in trunk and leg fat mass (both P = 0.07). There w as also a significant improvement in insulin action in response to HRT. The se results suggest that there are independent and additive effects of exerc ise training and HRT on the reduction in fat mass and improvement in insuli n action in postmenopausal women; the effect of HRT on insulin action may b e mediated, in part, through changes in central adiposity.