INS and polycystic ovary syndrome: When observing studies on high-intensity interval training (HIIT) involving high intensity intervals (i.e., ≥ 90% of HRmax) separated by low intensity active rest periods (i.e., ≤ 75% of HRmax), it was found that it helped in improving insulin sensitivity and cardiorespiratory fitness in clinical populations, including women with PCOS [8–10].