The primary aim of the trial is to determine the effects of varying exercise dose (energy expenditure, kcal) or intensity (relative to VO2max (cardiorespiratory fitness)) on waist circumference and glucose tolerance. The investigators will test the following hypotheses: 1) That the reduction in waist circumference and improvement in glucose tolerance in response to all treatments will be greater than controls. 2) That reduction in waist circumference and improvement in glucose tolerance in HVLI and LVHI will be greater than LVLI. 3) That hypotheses 1 and 2 are true independent of gender.