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

A 12-week resistance training program combined with HIIT significantly improved aerobic capacity, lean mass, and strength in middle-aged and older adults regardless of supplementation group.

• Participants were middle-aged and older adults aged 55-70 years
• 41 participants were included in the study
• Improvements occurred in both the polyphenol supplementation group and the placebo group
• The training program consisted primarily of resistance training with a small dose of high-intensity interval training (HIIT)

Training increased mitochondrial respiratory capacity (MRC) in the placebo group but not in the polyphenol group.

• The polyphenol group displayed higher MRC following the supplementation phase prior to training
• The authors suggest the lack of training-induced MRC increase in the polyphenol group possibly reflects either a supplement effect or baseline variation
• 41 participants were randomized to receive either polyphenol supplement or placebo for 30 days before the training intervention

Training resulted in a 20% decrease in skeletal muscle H2O2 emission across both groups.

• The decrease in H2O2 emission was observed across both the polyphenol and placebo groups
• The authors suggest this finding reflects enhanced mitochondrial efficiency or antioxidant defenses
• Gene expression of selected antioxidants was unchanged despite the reduction in H2O2 emission

Plasma oxidative stress marker malondialdehyde (MDA) increased with training while 3-nitrotyrosine (3-NT) remained unchanged.

• MDA is a marker of lipid peroxidation and oxidative stress
• 3-nitrotyrosine (3-NT) showed no significant change following the training intervention
• These plasma markers showed a different pattern from the skeletal muscle H2O2 emission findings

Circulating antioxidants showed distinct and group-specific changes following training.

• Ascorbic acid increased with training in both groups
• α-tocopherol increased only in the placebo group, not in the polyphenol group
• β-cryptoxanthin and retinol declined in the polyphenol group
• The authors suggest these patterns indicate potential supplement-nutrient interactions

Uric acid increased in both groups following the training intervention.

• The increase in uric acid was observed in both the polyphenol supplementation group and the placebo group
• The authors attribute this increase to exercise-induced purine turnover
• This finding was consistent regardless of polyphenol supplementation status

Polyphenol supplementation was administered for 30 days prior to the 12-week training intervention.

• Participants were randomized to receive either a polyphenol supplement or a placebo
• The supplementation phase preceded the exercise training intervention
• The study design allowed examination of both supplementation effects and training effects separately and in combination
• Polyphenol supplementation did not augment training-induced adaptations in mitochondrial bioenergetics or muscle redox balance

Aging is associated with declines in skeletal muscle function, mitochondrial capacity, and changes in redox balance that contribute to frailty and chronic disease risk.

• This background rationale motivated the investigation of exercise and polyphenol supplementation as interventions
• The study population of 55-70 year olds was selected to target this aging-related decline
• The study addressed whether exercise training and/or polyphenol supplementation could counter these age-related changes