Obesity & chronic disease are on the rise, so determining effective exercise regimens to combat obesity and improve health is necessary. High intensity interval training (HIIT) increases maximal oxygen uptake (VO2max), overall physical function & health status. Yet, little research has investigated HIIT in obese women. We will compare the effects of 2 HIIT regimens on VO2max, cardiac output, body fat, and muscle strength in obese women.