Impacts of Resistance Training on Endogenous Antioxidants in Older Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Cellular antioxidant activity and oxidative stress are assumed to be critical factors in the aging process. This study aims to investigate the effects of resistance training (RT) on endogenous antioxidants in healthy older individuals. Design: The records were identified through searches in 5 electronic databases (PubMed, Bireme, Scopus, SPORTDiscus, and Web of Science) in June 2024 for eligible randomized controlled trials that observed older individuals subjected to RT programs that reported endogenous antioxidant outcomes. The Tool for the assEssment of Study qualiTy and reporting in EXercise (ranging from 0 to 15) was used to verify the methodological quality of the studies. Results: Fourteen randomized controlled trials involving 676 healthy older individuals were included in the systematic review. Of these, 10 articles were included in the meta-analysis. The meta-analysis indicated that RT interventions did not have significant effects on improving catalase levels (standardized mean difference = 0.84; 95% CI, -0.61 to 2.29) or antioxidant activity (standardized mean difference = 0.28; 95% CI, -0.41 to 0.98). However, RT was associated with a significant reduction in superoxide dismutase (mean difference = -0.16; 95% CI, -0.29 to -0.04) and glutathione peroxidase increased (standardized mean difference = 0.57; 95% CI, 0.13 to 1.01). Conclusions: Based on available evidence, the meta-analysis suggests potential improvement in glutathione peroxidase gene expression and reduction in gene expression of superoxide dismutase after the intervention physical activity intervention in healthy older individuals.