Impact of aerobic exercise training on age-related changes in insulin sensitivity and muscle oxidative capacity

KR Short, JL Vittone, ML Bigelow, DN Proctor… - Diabetes, 2003 - Am Diabetes Assoc
KR Short, JL Vittone, ML Bigelow, DN Proctor, RA Rizza, JM Coenen-Schimke, KS Nair
Diabetes, 2003Am Diabetes Assoc
Insulin resistance increases and muscle oxidative capacity decreases during aging, but
lifestyle changes—especially physical activity—may reverse these trends. Here we report
the effect of a 16-week aerobic exercise program (n= 65) or control activity (n= 37)
performed by men and women aged 21–87 years on insulin sensitivity and muscle
mitochondria. Insulin sensitivity, measured by intravenous glucose tolerance test, decreased
with age (r=− 0.32) and was related to abdominal fat content (r=− 0.65). Exercise increased …
Insulin resistance increases and muscle oxidative capacity decreases during aging, but lifestyle changes—especially physical activity—may reverse these trends. Here we report the effect of a 16-week aerobic exercise program (n = 65) or control activity (n = 37) performed by men and women aged 21–87 years on insulin sensitivity and muscle mitochondria. Insulin sensitivity, measured by intravenous glucose tolerance test, decreased with age (r = −0.32) and was related to abdominal fat content (r = −0.65). Exercise increased peak oxygen uptake (Vo2peak; 10%), activity of muscle mitochondrial enzymes (citrate synthase and cytochrome c oxidase, 45–76%) and mRNA levels of mitochondrial genes (COX4, ND4, both 66%) and genes involved in mitochondrial biogenesis (PGC-1α, 55%; NRF-1, 15%; TFAM, 85%). Exercise also increased muscle GLUT4 mRNA and protein (30–52%) and reduced abdominal fat (5%) and plasma triglycerides (25%). None of these changes were affected by age. In contrast, insulin sensitivity improved in younger people but not in middle-aged or older groups. Thus, the muscle mitochondrial response to 4 months of aerobic exercise training was similar in all age-groups, although the older people did not have an improvement in insulin sensitivity.
Am Diabetes Assoc