Effects of Exercise Training Intensity on Pancreatic -Cell Function

OBJECTIVE — Insulin resistance and -cell dysfunction both are important contributors to the pathogenesis of type 2 diabetes. Exercise training improves insulin sensitivity, but its effects on -cell function are less well studied. RESEARCHDESIGNANDMETHODS — Sedentary, overweight adults were random-ized to control or one of three 8-month exercise programs: 1) low amount/moderate intensity, 2) low amount/vigorous intensity, or 3) high amount/vigorous intensity. Of 387 randomized, 260 completed the study and 237 had complete data. Insulin sensitivity (Si), acute insulin response to glucose (AIRg), and the disposition index (DI SiAIRg) were modeled from an intravenous glucose tolerance test. RESULTS — Compared with control subjects, all three training programs led to increases in DI. However, the moderate-intensity group experienced a significantly larger increase in DI than either of the vigorous-intensity groups and through a different mechanism. The high-amount/ vigorous-intensity group improved Si and had a compensatory reduction in AIRg, whereas the moderate-intensity group had a similar improvement in Si but almost no reduction in AIRg. Importantly, the inactive control group experienced a significant increase in fasting glucose