ABSTRACT
            Background and Objectives: Coronary artery disease (CAD) is the leading cause of death worldwide. It is well established that low level of high-density lipoprotein-cholesterol (HDL-C) is a strong and independent risk factor for CAD. Apolipoprotein M (apoM) is a component of HDL, which is involved in pre-β-HDL formation and cholesterol efflux to HDL. It is believed that resistance and aerobic exercise can significantly reduce risk of cardiovascular disease, especially by increasing serum levels of HDL-C. However, little is known about effects of these activities on HDL-apoM levels. The aim of this study was to investigate effects of circuit resistance training at different intensities on HDL-associated apoM levels in young untrained men.
            Methods: Forty-five age- and weight-matched healthy untrained men were randomly assigned to a control group (n=10) and four training groups: 20% 1-repetition maximum (1RM) (n=9), 40% 1RM (n=8), 60% 1RM (n=7) and 80% 1RM (n=8). The subjects performed circuit resistance training consisting of barbell bench press, underarm flab, seated barbell curl, triceps exercise with chains, lying leg curl, squats, hyperextension, abs workout, sit-ups and quadriceps workouts (30 seconds each) in three bouts without rest between stations and with active rest (3 minutes) between sets or bouts. The training protocol was carried out for 45 minutes per session, three sessions a week, for five weeks. Venous blood samples were taken 48 hours before the first exercise session and 48 hours after the last training session. After separating plasma, HDL-associated apoM was measured using commercial ELISA kits. SPSS 16 was used for analysis of data using two-way ANOVA and Tukey's post hoc test at significant level of 0.05.
            Results: After the training intervention, the exercise groups had higher apoM levels in total HDL and HDL-2 compared to the control group (P>0.05). However, no significant difference in HDL-associated apoM level was observed between the study groups.
            Conclusion: The results of this study indicate that various intensities of circuit resistance training can alter HDL-associated apoM levels. The decreased HDL-3-associated apoM level could indicate increased rate of apoM transfer to HDL-2, which could potentially prevent development of atherosclerosis and CAD by enhancing the antioxidant effects of HDL.
            Keywords: Circuit Resistance Training, Total HDL-M, HDL3-M, HDL2-M.