Acute effect of moderate-intensity concentric and eccentric exercise on cardiac effort, perceived exertion and interleukin-6 level in physically inactive males.

BACKGROUND: Muscle-derived interleukin-6 (IL-6) not only enhances glucose and fat metabolism but also has an anti-inflammatory effect that can prevent the development of cardiovascular disease (CVD) and metabolic syndrome. Dynamic resistance exercise comprises a muscle shortening and a lengthening phase known as concentric and eccentric contraction respectively. We compared an acute bout of concentric exercise (CE) with eccentric exercise (EE) for the serum IL-6 concentration, myocardial oxygen consumption (MVO2) and rating of perceived exertion (RPE).

METHODS: The present non-randomized crossover study involved 24 physically inactive but apparently healthy males, aged 18-25 years with body mass index of 18.5-23 kg/m2. Each participant performed an acute bout of moderate intensity CE followed by an EE bout after two weeks of rest. Exercise bout lasted for about 45 minutes that involved brisk walking on a treadmill at ±21% gradient for approximately 30 minutes, followed by the dumbbell exercises for biceps, triceps, quadriceps and hamstring muscles. MVO2 and IL-6 were estimated by the rate pressure product (RPP) and ELISA (enzyme-linked immunosorbent assay) kit respectively. Participants told their RPE after the workout. Wilcoxon or paired-t test were applied appropriately to compare the means. P<0.05 was considered significant.

RESULTS: RPP, RPE, and serum IL-6 were significantly less after EE (164.4 ±16.3, 12, 11.0±5.0 respectively) than CE (191.2±22.9, 13, 12.0±6.3 respectively). A significant, strong and positive correlation of RPE was obtained with post-exercise heart-rate and RPP.

CONCLUSIONS: Regular EE might be beneficial for individuals having a low tolerance to exertion or at risk of developing CVD.