Exercise Training and Glucose Metabolism in Aging

Diabetes and its associated complications affect more than 20 million Americans, and the
prevalence of type 2 diabetes and impaired glucose tolerance rises dramatically with age
such that 40% of Americans over age 60 are affected. In older adults, glucose metabolism may
be affected by reduced skeletal muscle capillary supply, which limits insulin, glucose, and
oxygen delivery to skeletal muscle. Reduced capillary supply to skeletal muscle is found in
older individuals with impaired glucose tolerance and we hypothesize that this is due to
reduced vascular growth factor expression, and chronic inflammation. Further, we hypothesize
that reversal of a sedentary lifestyle through aerobic exercise training will increase
insulin signaling and vascular growth factor expression, as well as decrease inflammation,
to increase capillary supply to skeletal muscle, which contributes to improved glucose
metabolism in older adults with IGT. This study will: 1) Determine the mechanisms underlying
reduced skeletal muscle capillarization in older adults with impaired glucose tolerance; and
2) Determine the effect of aerobic exercise training-induced increases in skeletal muscle
capillarization on glucose metabolism in older adults with impaired glucose tolerance.