Absent Exercise-Induced Improvements in Fat Oxidation in Women With Polycystic Ovary Syndrome After High-Intensity Interval Training

Abstract

Background: Polycystic ovary syndrome (PCOS) and metabolic inflexibility are linked to insulin resistance, and women with PCOS appear to be metabolic inflexible in the rested, insulin-stimulated state. Exercise training is a primary lifestyle intervention in PCOS. Exercise training improves whole-body fat oxidation during submaximal exercise in healthy women, yet little is known about the effect on this outcome in women with PCOS.Methods: We measured whole-body fat oxidation rates during sub maximal exercise before and after 16 weeks of high-intensity interval training (HIT) in women with PCOS randomly allocated to either: low- or high-volume HIT (n = 41; low-volume HIT, 10 × 1 min work bouts at maximal, sustainable intensity and high-volume HIT, 4 × 4 min work bouts at 90–95% of maximal heart rate) or non-exercise control (n = 23), and in women without PCOS (Non-PCOS) allocated to low- or high volume HIT (n = 15). HIT was undertaken three times weekly. In a subset of women with and without PCOS, we measured mitochondrial respiration in abdominal and gluteal subcutaneous adipose tissue using high-resolution respirometry, as well as fat cell sizes in these tissues.Results: At baseline, women with PCOS had lower whole-body fat oxidation and mitochondrial respiration rates in abdominal adipose tissue compared to Non-PCOS. Peak oxygen uptake (mL/min/kg) increased in women with PCOS (~4%, p = 0.006) and Non-PCOS (~6%, p = 0.003) after 16 weeks of HIT. Whole-body fat oxidation only improved in Non-PCOS after HIT. No changes were observed in mitochondrial respiration and cell size in abdominal and gluteal adipose tissue after HIT in either group of women.Conclusion: We observed exercise-induced improvements in whole-body fat oxidation during submaximal exercise in Non-PCOS, but not in women with PCOS, after 16 weeks of HIT, suggesting metabolic inflexibility in women with PCOS.Clinical Trial Registration:www.clinicaltrials.gov, identifier NCT02419482 and NCT02943291.

HIIT'ing or MISS'ing the Optimal Management of Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of High- Versus Moderate-Intensity Exercise Prescription

“…Our results deviate from previous studies where significant improvements inVO 2max were evident following HIIT interventions in obesity (Chin et al, 2020), cardiometabolic disease (de Nardi et al, 2018;Boff et al, 2019) and PCOS (Lionett et al, 2021). This deviation may be a result of a significant publication bias toward studies reporting increases inVO 2max in the MISS literature which was not evident within the HIIT literature included in our analyses.…”

“…In our analysis, neither HITT nor MISS significantly improved HOMA-IR. Similar results have been reported recently, with no improvement in HOMA-IR or fasting insulin following 16 weeks of HIIT exercise (Lionett et al, 2021) and equivocal results following MISS exercise (Shele et al, 2020) in individuals with PCOS. However, we did observe a significant reduction in fasting insulin following MISS exercise, which may suggest improved insulin sensitivity, as a reduced amount of insulin is required to act upon a given concentration of glucose in order to maintain normal metabolic homeostasis (Iaccarino et al, 2021).…”

HIIT’ing or MISS’ing the optimal management of Polycystic Ovary syndrome: A systematic review and meta-analysis of high-versus moderate-intensity exercise prescription

“…Our results deviate from previous studies where significant improvements in VO 2max were evident following HIIT interventions in obesity (Chin et al, 2020), cardiometabolic disease (de Nardi et al, 2018;Boff et al, 2019) and PCOS (Lionett et al, 2021). This deviation may be a result of a significant publication bias toward studies reporting increases in VO 2max in the MISS literature which was not evident within the HIIT literature included in our analyses.…”

The mitochondrial profile in women with polycystic ovary syndrome: impact of exercise

“…It is important to note that cardiorespiratory fitness, insulin sensitivity and mitochondrial characteristics were all improved following training in the women with PCOS. The only study which has examined the effect of HIIT on mitochondrial function was performed in adipose tissue of overweight and lean women with PCOS (Lionett et al 2021). In this study, IR in both women with PCOS and BMI and age-matched controls did not change following HIIT.…”