The proposed study is a randomized, open study comparing low-intensity and moderate-intensity aerobic exercise versus non-aerobic (stretching) exercise on direct measurements of insulin resistance and variables associated with the metabolic syndrome. This 6-month intervention will be followed by an additional 6-month follow-up period during which subjects will be encouraged to maintain their exercise regimen (along with their prescribed diet) but without scheduled supervision. Behavioral variables associated with adherence will be analyzed along with changes in the above physiological variables.