The Effect of Exercise Intensity and Duration on Oxidative Stress and Antioxidant Enzymes Activity among Sedentary Healthy Adults: A Repeated Measures Study

Abstract

\n Background Aerobic exercise can increase oxidative stress, but it can produce the necessary stimulus for physiological adaptation of exercise. However, the effects of intensity and duration of exercise on oxidative stress status are unclear. This study aimed to compare the effects of exercise intensity (I) and duration (D) on the oxidative stress [malondialdehyde (MDA)], and the responses of the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), antioxidant enzymes ratio (AE)] among sedentary adults. Methods In a randomized crossover design, 25 sedentary adults, performed nine cycling exercise sessions with a constant load of 50%, 60% and 70% VO2peak for 10-, 20- and 30- minutes duration. Plasma MDA, CAT, GPx and SOD activity were measured before exercise (baseline) and immediately after each session (post). Results The interaction effect of intensity and duration was significant for percentage changes of MDA (FIxD=3.59, df=4, p<0.05) and CAT activity (FIxD =3.38, df=2.146, p<0.05). Repeated Measures ANOVA analysis revealed that intensity is the major controlling factor for MDA (FI =54.24, df=2, p<0.05 vs FD=8.62, df=2, p<0.05), and CAT responses (FI =14.24, df=1.619, p<0.05 vs FD = 5.96, df=1.347, p<0.05). However, the main determinant factor for SOD (FD =11.82, df=1.166, p<0.05 vs FI =5.58, df=1.289, p<0.05) and AE (FD =11.63, df=1.201, p<0.05 vs. FI =3.035, df=1.32, p>0.05) is exercise duration. Conclusions These findings suggest that exercise intensity was an essential factor of acute oxidative stress and antioxidant enzyme responses compared with the duration of exercise.