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.

Aim:The aim of this study was to retrospectively compare two Circuit Training (CT) programs, one with moderate and one with high intensity, on the body composition, Cardiorespiratory Fitness (CRF), biochemical and physiological markers and isometric strength in apparently healthy obese and overweight individuals.Methods: This is a retrospective comparison of two groups of apparently healthy obese and overweight individuals that participated in two different trials examining the effect of two intermittent CT programs. The experimental groups in both trials were originally compared to a control (no exercise) group. One trial examined the effect of high intensity CT (HCT group) and the other the effect of moderate intensity CT (MCT group, n = 30). Participants on both trials were randomly assigned to the exercise or the control group. Both groups performed two exercise sessions per week for 8 weeks. MCT group performed 2 circuits of 8 exercise stations with 12 repetitions per station, performed for 1min at 50-60% of Heart Rate Reserve (HRR) alternated with 30s active recovery stations at 40-50% of HRR for the whole duration of the 8 weeks. HCT group performed 2 circuits of 6 exercise stations with 10-12 repetitions per station, performed for 1min at 50-60% of HRR alternated with 1min stations of 40-50% of HRR for the first 2 weeks and then progressed to an intensity of 70-85% of HRR, alternated with stations performed at 50-60% of HRR. Body composition, Cardiorespiratory Fitness (CRF), biochemical and physiological markers and isometric strength were measured in both groups using the same methodology.Results: Both programs had a 100% completion rate without any adverse effects. After 8 weeks, HCT group had greater but not significantly different reductions in body weight (BW) (HCT: -3.6%, MCT: -2.5%), body mass index (BMI) (HCT: -3.5%, MCT: -2.7%), in percentage (%) (HCT: -4.5%, MCT: -3.7%), and in kilograms (Kg) (HCT: -7.9%, MCT: -5.9%) of body fat, percentage (%) (HCT: 5%, MCT: 3.3%) and in kilograms (Kg) of lean body mass (LBM) (HCT: 1.9%, MCT: 0.3%), in waist circumference (WC) (HCT: -2.7%, MCT: -1.4%), in hip circumference (HCT: -1.3%, MCT: -0.5%), waist-hip ratio (WHR) (HCT: -1.2%, MCT: -1.1%), heart rate at rest (HR-rest) (HCT: -5%, MCT: -4.3%), mean arterial pressure (MAP) (HCT: -4.8%, MCT: -4.5%) and greater improvement in maximal oxygen uptake (HCT: 16.7%, MCT: 11.1%) (VO 2 peak). Blood lipids did not improve significantly in either group, but reductions in some variables were greater in the HCT group. On the other hand, MCT group appeared to induce greater improvements in Systolic Blood Pressure (SBP) (HCT: -3%, MCT: -5.3%), Diastolic Blood Pressure (DBP) (HCT: -4.6%, MCT: -5.6%), Double Product (RPP) (HCT: -7.2%, MCT: -10 %) and isometric strength of the lower extremity. Conclusion:Short duration CT programs with moderate intensity produce comparable changes in body weight, body composition and other health variables in obese and overweight individuals without comorbidities. This can possibly increase co...

Background: Obesity has become a serious problem in Western societies and is associated with several health problems and reduced quality of life. The purpose of this randomised, clinical trial is to investigate the effects of a moderate-intensity, intermittent, circuit training program on a range of cardiovascular risk factors such as body composition, biochemical and physiological variables and aerobic capacity in obese and overweight individuals. Methods: A total of 30 participants were selected and 15 of them performed a moderate-intensity, intermittent, circuit training program; whereas the rest acted as a control-group. The circuit training program consisted of 10 exercise stations and was performed 2 times per week for 8-weeks in total. The experimental group performed a circuit training program with training cycles at 50-60% of heart rate reserve which were followed by active recovery periods at 40-50% of heart rate reserve. Control-group remained sedentary during the period of 8-weeks and follow-up. Biochemical markers, isometric strength, body composition and physiological parameters were assessed at baseline and 8-weeks post-intervention, whereas maximal oxygen consumption was assessed at baseline, 8-weeks and 2-months follow-up.Results: Significant improvements were demonstrated in BW (2.5%), BMI (~3%), BF% (~4%), BF-Kg (~6%), and LBM% (3.3%), SBP (5.3%), HR-resting (4.3%), MAP (~5%) and cardiorespiratory fitness (~11%) in the exercise group post-intervention. Significant time by group interaction was found for all physiological variables (SBP, DBP, HR, MAP, RPP) in favour of the exercise group. VO2peak improved post-intervention by ~11% in the CT-group, in contrast to 1.7% in the control-group. Conclusion:The present data suggest that a moderate-intensity, intermittent circuit training program for 8-weeks may be effective in reducing cardiovascular risk factors.