Exercise is beneficial: but how and why?

Effects of physical exercise on biomarkers of oxidative stress in healthy subjects: A meta-analysis of randomized controlled trials

This meta-analysis investigated the effect of physical exercise (PE) on the levels of oxidative biomarkers in randomized controlled trials (RCTs) involving healthy subjects. We searched five databases for articles until May 1, 2023. A random-effect meta-analysis, subgroup analysis, meta-regressions as well as trim and fill method were conducted using STATA 11.0, involving ten articles. According to the results of the meta-analysis, PE had no significant effect on superoxide dismutase (SOD), glutathione peroxidase, and catalase levels. PE induced significant increase in total antioxidant status (standardized mean difference [SMD] 1.53, 95% CI 0.73-2.32), and PE could significantly reduce the level of malondialdehyde (MDA) (SMD -1.11, 95% CI -2.15 to -0.06). Sensitivity analyses and subgroup analyses showed that male participants, body mass index (BMI) <25, exercise duration between 1 and 12 weeks, resistance exercise or multicomponent exercise, and exercise of low or moderate intensity were associated with a significant PE-induced decrease in MDA concentrations. Meta-regression analysis identified the age of the participants as a confounder of the effect of PE on SOD levels. The older age of the subjects was associated in a gradient fashion with incident SOD levels. Further RCTs are required to investigate the optimal PE protocol for people of different ages and BMI as well as the effect of PE on oxidative stress.

Effects of Exercise-Induced ROS on the Pathophysiological Functions of Skeletal Muscle

Oxidative stress is the imbalance of the redox system in the body, which produces excessive reactive oxygen species, leads to multiple cellular damages, and closely relates to some pathological conditions, such as insulin resistance and inflammation. Meanwhile, exercise as an external stimulus of oxidative stress causes the changes of pathophysiological functions in the tissues and organs, including skeletal muscle. Exercise-induced oxidative stress is considered to have different effects on the structure and function of skeletal muscle. Long-term regular or moderate exercise-induced oxidative stress is closely related to the formation of muscle adaptation, while excessive free radicals produced by strenuous or acute exercise can cause muscle oxidative stress fatigue and damage, which impacts exercise capacity and damages the body's health. The present review systematically summarizes the relationship between exercise-induced oxidative stress and the adaptions, damage, and fatigue in skeletal muscle, in order to clarify the effects of exercise-induced oxidative stress on the pathophysiological functions of skeletal muscle.