ENHANCED INSULIN SENSITIVITY AND LOWER WAIST-TO-HIP RATIO IN MASTER ATHLETES

The effect of long-term aerobic exercise training on insulin action wa s determined in older individuals by comparing insulin sensitivity and maximal responsiveness in 11 master athletes [63.5 +/- 1.9 (SE) yr] a nd 10 age- and body fat-matched sedentary individuals. Maximal aerobic power was higher and the waist-to-hip ratio (WHR) was lower in the at hletes, but there were no differences in body weight, percent body fat , or fat-free mass between groups. Easting plasma glucose levels and g lucose and insulin responses during oral glucose tolerance tests were lower in the athletes. The insulin concentration producing a half-maxi mal increase in glucose disposal (EC(50)) during a three-step hyperins ulinemic-euglycemic glucose clamp was 41% lower in the athletes than i n controls (483 +/- 30 vs. 822 +/- 132 pmol/l, P < 0.05), whereas maxi mal responsiveness was comparable (81.0 +/- 4.4 vs. 85.5 +/- 8.3 mu mo l . kg fat-free mass(-1). min(-1), P = not significant). The EC(50) co rrelated with maximal aerobic power (r = -0.62, P < 0.01) and WHR (r = 0.52, P < 0.05), but in multiple regression analyses WHR was the only variable independently related to EC(50). These results indicate that long-term aerobic exercise training is associated with enhanced insul in sensitivity and a lower WHR in older individuals. This finding sugg ests that regular aerobic exercise may prevent the age-associated incr ease in abdominal obesity and insulin resistance.