It was established that exercise training improved clinical outcomes in women with PCOS, but it was unknown whether HIIT results in better health outcomes than traditional MICT.  Researchers conducted a randomized clinical trial with 2 arms in which 29 overweight women with PCOS were enrolled between May 2016 and November 2019.  About 18–45-year-old women with PCOS were randomly assigned to 12 weeks of MICT (60–75% peak heart rate, N=14) or HIIT (>90% peak heart rate, N=15), each performed 3 times per week. The key clinical outcomes were aerobic capacity (VO2peak) and insulin sensitivity (euglycemic–hyperinsulinemic clamp). Hormonal profiles, menstrual cyclicity, and body composition were secondary outcomes. Both HIIT and MICT increased VO2peak (HIIT; Δ5.8±2.6 ml/kg/min, P<0.001 and MICT; Δ3.2±2 ml/kg/min, P<0.001); however, the HIIT group experienced a larger increase in aerobic capacity than the MICT group (β=2.73 ml/kg/min, P=0.015). HIIT enhanced insulin sensitivity index relative to baseline (Δ 2.3 ±4.4 AU, P=0.007) and MICT (β=0.36 AU, P=0.030) and induced greater increases in sex hormone-binding globulin relative to MICT (β=0.25 nmol/l, P=0.002). Participants in the HIIT group were 7.8 times more likely than those in the MICT group to report improved menstrual cyclicity (odds ratio 7.8, P=0.04). The study had a small sample size, and the outcomes of the efficacy of the exercise interventions were restricted to overweight women of reproductive age who did not have any comorbidities requiring medication.