The purpose of this study was to determine whether brisk walking improves multi-organ (liver, muscle, adipose tissue) insulin sensitivity in older women. Ten non-obese older women (age: 66.7 ± 1.5 years, mean ± SEM) completed two 2-stage hyperinsulinemic-euglycemic clamp procedures (insulin infusion rate stage 1: 10 mU/m2 body surface area [BSA]/min; stage 2: 50 mU/m2 BSA/min) in conjunction with stable isotope-labeled glucose and palmitate tracer infusions in the morning after either a single, ~1h-bout of brisk treadmill walking or an equivalent period of rest in the late afternoon of the preceding day. We found that basal glucose rate of appearance (Ra) into plasma was not different after rest and after exercise (17.3 ± 0.8 and 17.1 ± 0.4 μmol/kg FFM/min, respectively). The insulin-mediated decrease in glucose Ra during stage 1 of the clamp was also not different after rest and exercise (82.2% ± 3.4% and 77.7% ± 2.1%, respectively), but glucose rate of disappearance (Rd) during stage 2 of the clamp was significantly greater (P < 0.05) after exercise than rest (88.0 ± 5.9 and 78.4 ± 6.5 μmol/kg FFM/min, respectively). There were no differences in palmitate Ra during basal conditions or insulin infusion after exercise and after rest. Therefore, we conclude that a single bout of brisk walking for approximately 1 h improves muscle insulin sensitivity but has no effect on liver and adipose tissue insulin sensitivity in older women.
- insulin sensitivity
- older adults
- Copyright © 2012, Journal of Applied Physiology