Effects of a Circuit Training Program on Myokine Levels in Insulin-Resistant Women: A Randomised Controlled Trial

Introduction: Circuit training is a form of body conditioning with endurance and resistance components. Given the function of skeletal muscle as an endocrine organ secreting various myokines involved in maintaining glucose metabolism homeostasis, our study focused on estimating the impact of the implemented training program on the direction of changes in myokines such as interleukin (IL)-6, IL-10, fibroblast growth factor 21 (FGF21), and irisin in women newly diagnosed with insulin resistance. Methods: This prospective controlled trial randomly divided 42 women into two groups. The training group performed circuit training combining strength (50%-80% of one-repetition maximum) and endurance (50%-75% of heart rate reserve) exercises for 3 months, three 33-min sessions weekly. Exercises were performed on five weight and two cardio machines. The control nontraining group did not change their previous activity. Body composition indicators and IL-6, IL-10, FGF21, and irisin levels were measured before and after the intervention. The data for 27 patients were analysed using two-way repeated measures analyses of variance. Results: The pattern of change in serum IL-6 levels over time differed significantly between the groups (p < 0.05). The patterns of change did not differ significantly between groups for IL-10, FGF21, and irisin. Conclusion: The circuit training program implemented in women newly diagnosed with insulin resistance significantly increased their serum IL-6 and not their IL-10, FGF21, and irisin levels. Trial Registration: ClinicalTrials.gov: NCT04528693.