Effects of High-Intensity Circuit Training in Obese and Overweight Population: A Randomized Clinical Trial

Abstract

Background: Obesity is a serious risk for various cardiovascular diseases and is often managed with increased physical activity and exercise. The purpose of this study is to investigate the effects of a minimal dose, High-Intensity Circuit Training (HICT) program on a range of cardiovascular risk factors in obese and overweight individuals. Methods:The trial was prospectively registered with Cyprus National Bioethics Committee ΕΕΒΚ/ΕΠ/2017/38 29 th October 2017. A total of 30 participants were randomly allocated to or to a no exercise control-group (n = 15). Participants in the HICTgroup trained for 36-minutes, twice a week (18-minutes per session) for 8 weeks in total. The program consisted of 2 circuits of 6 exercise stations of 1min at 50-60% of Heart Rate Reserve (HRR) which progressed to 70-85% of HRR after the first two weeks, alternating with 1min active rest at 40-50% of HRR which progressed to 50-60% of HRR. Approximately 12 repetitions were performed per station. Body composition, blood markers and physiological variables, cardiorespiratory fitness and isometric strength were measured at baseline and post-intervention.Findings: Significant and meaningful improvements were demonstrated in cardiorespiratory fitness, several body composition variables, isometric strength of the left (nondominant) lower limb and several physiological variables. No significant changes were revealed to the biochemical parameters or the strength of the right (dominant) limp. Conclusion:The results of the study suggest that a lowfrequency, circuit training program with high intensity lasting only for 18-minutes twice a week is the minimum required dose in reducing at least some of the cardiovascular risk factors, in obese and overweight population.