Effects of high intensity interval training in women with polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrinopathy found in reproductive-age women. Physical inactivity and visceral adiposity aggravate insulin resistance that predisposes these women to long term health risks. Lifestyle (combined exercise plus diet modification) management is the first line of treatment and minimal weight loss of 2–5%, can restore their metabolic and reproductive profile. However, PCOS women exercise less frequently and have a greater inclination towards higher fat intake, and a high dietary glycaemic index.
Exercise training, either as an individual treatment or in combination with diet, is effective in managing PCOS symptoms when either intervention is meticulously applied. Physiological benefits of exercise are well documented, but an optimal prescription for PCOS is lacking. Multiple exercise prescriptions improve PCOS symptoms, but they are time-consuming. High intensity interval training (HIIT) utilises less time and improves insulin resistance, glucose homeostasis and lipid metabolism. Therefore, it is likely that HIIT will improve the anthropometric, cardiorespiratory, lipid, glycaemic, inflammatory and endocrine profile, in PCOS women.
The primary aims of this research were
• To conduct a systematic review and meta-analysis to evaluate/update the effectiveness of exercise only or exercise combined with diet treatments, on the hallmark features of PCOS.
• To conduct a subsequent meta-analysis to evaluate various exercise protocols using the frequency, intensity, time and type principle for PCOS women.
• To evaluate the effects of 17 minutes of HIIT, 3 sessions/week for 12 weeks on the anthropometric profile, cardiorespiratory fitness, lipids, glycaemic index, inflammatory and endocrine measures in PCOS women.
Results of the systematic review (SR) and meta-analysis (MA) supported the effectiveness of exercise only (EO) in improving body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), VO2max, resting heart rate (HR), power maximum (Pmax), high-density lipoprotein (HDL), low-density lipoprotein (LDL), fasting insulin (FI), homeostasis model assessment-estimated insulin resistance, total testosterone, dehydroepiandrosterone sulfate (DHEAS) and androstenedione versus sedentary controls. Additionally, exercise plus diet (ED) may be effective on the parameters of weight, BMI, WHR, VO2max, LDL and FI.
Findings of the secondary MA using intensity, supported EO with low-intensity training for improvements in free androgen index, Ferriman-Gallwey score for hirsutism and follicle stimulating hormone in PCOS women. Additionally, moderate intensity exercise training (MIET) improved BMI, WC, WHR, VO2max, resting HR, Pmax, HDL, LDL, total cholesterol, triglycerides and FI, whereas, HIIT showed significant effects on fasting blood glucose. Moreover, combined ED using MIET induced improvements in BMI, WHR, VO2max and LDL.
Findings of the controlled pilot study revealed the effectiveness of HIIT in reducing visceral adiposity (WC) and improving cardiorespiratory fitness measures (VO2max and Pmax). Moreover, HIIT showed a recommended minimum effect size change representing a “practically” significant effect for SHBG, free testosterone and DHEAS.
Exercise holds the potential to reduce PCOS symptoms when applied for a longer duration utilising supervision, the progression of exercise intensity and individualised protocols. Aerobic exercise training of frequency ≥3 sessions/week and progressive MIET (60–70% VO2max or 60–85% MHR), for 30–60 minutes/session, either in isolation or combined with diet, seems effective in improving PCOS symptoms. Furthermore, the mode of exercise is not as important as the intensity. Additionally, HIIT or progressive resistance training may also potentially ameliorate the extent of PCOS symptoms versus aerobic MIET, but more research is required to confirm their effects. The findings of the HIIT study reinforces the effectiveness of HIIT in improving cardiorespiratory fitness and reducing central adiposity in PCOS women without any dietary changes. Additionally, just 17 minutes/week of HIIT may also potentially improve the hyperandrogenic profile in PCOS women.