Increased aerobic capacity ‘partially explains’ improved insulin sensitivity
Aerobic capacity, measured as peak oxygen consumption (VO2peak), increased by an average 5.7 mL/kg per min among the HIIT patients, significantly more than the mean 3.2 mL/kg per min increase among those in the MICT program.
The insulin sensitivity index rose by a significant, relative 35% among the HIIT patients, but barely budged in the MICT group. Fasting glucose fell significantly and the glucose infusion rate increased significantly among the women who performed HIIT, but again showed little change among those doing MICT.
Analysis showed a significant link between the increase in VO2peak and the increase in insulin sensitivity among the women engaged in HIIT, Ms. Patten reported. The improvement in the insulin sensitivity index was “partially explained” by the increase in VO2peak, she said.
Assessment of hormone levels showed a significant increase in sex hormone–binding globulin in the HIIT patients while those in the MICT group showed a small decline in this level. The free androgen index fell by a relative 39% on average in the HIIT group, a significant drop, but decreased by a much smaller and not significant amount among the women who did MICT. The women who performed HIIT also showed a significant drop in their free testosterone level, a change not seen with MICT.
Women who performed the HIIT protocol also had a significant improvement in their menstrual cyclicity, and significant improvements in depression, stress, and anxiety, Ms Patten reported. She next plans to do longer follow-up on study participants, out to 6 and 12 months after the end of the exercise protocol.
“Overall, the findings suggest that HIIT is superior to MICT for improving fitness and insulin sensitivity in the short term. Results from a number of studies in individuals without PCOS suggest that HIIT is superior to MICT for improving fitness short term,” commented Dr. Dunaif. “This study makes an important contribution by directly investigating the impact of training intensity in women with PCOS. Larger studies will be needed before the superiority of HIIT is established for women with PCOS, and study durations of at least several months will be needed to assess the impact on reproductive outcomes such as ovulation,” she said in an interview. She also called for assessing the effects of HIIT in more diverse populations of women with PCOS.
Ms. Patten had no disclosures. Dr. Dunaif has been a consultant to Equator Therapeutics, Fractyl Laboratories, and Globe Life Sciences.