Resistance-based training improves mitochondrial capacity and redox balance in aging adults, independent of polyphenol supplementation.

Abstract

Aging is associated with declines in skeletal muscle function, mitochondrial capacity, and changes in redox balance, which collectively contribute to frailty and chronic disease risk. This study investigated the effects of a 12-week resistance training (RT) program combined with a small dose of high-intensity interval training (HIIT), with or without polyphenol supplementation, on mitochondrial respiratory capacity (MRC) and oxidative stress in middle-aged and older adults (55-70 years). Forty-one participants were randomized to receive either a polyphenol supplement or a placebo for 30 days before the training intervention. Following the training intervention, aerobic capacity, lean mass, and strength improved significantly in both groups. Training also increased MRC in the placebo group but not in the polyphenol group, which displayed higher MRC following the supplementation phase, possibly reflecting either a supplement effect or baseline variation. The training resulted in a 20 % decrease in skeletal muscle H