Insulin action after resistive training in insulin resistant older men andwomen

OBJECTIVES: To determine the effects of resistive training (RT) on insulin action and assess the determinants of the changes in insulin action. DESIGN: Longitudinal study. SETTING: Outpatient setting. PARTICIPANTS: Eighteen older men and older postmenopausal women (65-74 year s) with normal (6 men and 5 women) or impaired glucose tolerance (4 men and 3 women). INTERVENTION: Six months of progressive whole-body RT. MEASUREMENTS: Upper and lower body strength was assessed by the one repetit ion maximum test. Total body fat and fat-free mass (FFM) were determined by dual-energy x-ray absorptiometry before and after 6 months of RT. Insulin sensitivity was estimated from the relationship of glucose utilization (M) to the concentration of insulin (I) during the last 30 minutes of 3-hour hy perinsulinemic-euglycemic clamps (240 pmol.m(-2).min(-1)) (M/I) before and after RT. RESULTS: RT significantly improved upper- and lower-body muscular strength (P < .005). FFM increased after RT in the entire group (P < .01) with no si gnificant change in body fat. Although the change in M was larger in men (1 3%) than women (3%), the difference was not significant. The change in M wa s a function of initial M (r = -0.53, P < .05). There was a trend (0.060 +/ - 0.006 vs 0.066 +/- 0.006 <mu>mol.kg(-1).min(-1)/pmol/l, n = 18) for M/I t o increase after RT in the combined group of men and women (P = .06). There were no significant relationships between changes in M or M/I with changes in body composition or strength. CONCLUSION: A 6-month RT program tends to improve insulin action in insulin -resistant older adults. These results suggest that RT may be useful in ame liorating insulin resistance that often occurs with physical inactivity, ob esity, and loss of muscular strength in older insulin resistant men and wom en.