Effects of aerobic exercise on mitochondrial function in older adults

Thesis Abstract

The decline in mitochondrial function is a hallmark of aging that contributes significantly to the diminished physical and metabolic health observed in older adults, accentuating the need for interventions that can preserve or enhance mitochondrial health. Despite growing evidence linking physical activity to improved mitochondrial outcomes, the specific effects of aerobic exercise on mitochondrial function in the elderly population remain insufficiently elucidated. This study aims to investigate the impact of structured aerobic exercise on mitochondrial function among older adults aged 60 to 75 years, with a focus on both mitochondrial density and enzymatic activity, utilizing a comprehensive empirical approach. The primary objectives are to assess changes in mitochondrial DNA (mtDNA) copy number as a marker of mitochondrial density, evaluate alterations in citrate synthase activity and mitochondrial respiratory capacity, and determine the correlation between these mitochondrial parameters and physical performance metrics, such as gait speed and grip strength. The research further seeks to explore whether improvements in mitochondrial function are associated with changes in oxidative stress markers, including malondialdehyde (MDA) and superoxide dismutase (SOD) activity, and to compare outcomes between male and female participants to identify possible sex-specific responses. Employing a quasi-experimental design with pre- and post-intervention assessments, the study recruited 120 community-dwelling older adults through stratified random sampling from local health centers. Participants were randomly assigned to an intervention group engaging in supervised aerobic exercise, consisting of moderate-intensity treadmill walking at 60-70% of maximum heart rate for 45 minutes, three times per week for 12 weeks, or a control group receiving health education. Data collection involved blood samples for biochemical analysis of mitochondrial DNA, enzymatic activity, and oxidative stress markers, alongside physical performance tests conducted at baseline and post-intervention. Validity and reliability of laboratory assays were ensured through calibration, standardized protocols, and repeated measures, while data analysis employed repeated-measures ANOVA to detect within- and between-group differences, multiple regression to explore predictors of mitochondrial adaptation, and mediation analysis to examine the role of oxidative stress. Expected findings include statistically significant increases in mtDNA copy number, citrate synthase activity, and mitochondrial respiratory capacity in the aerobic exercise group compared to controls. It is anticipated that these mitochondrial enhancements will correlate with improved physical performance and reduced oxidative stress markers, suggesting a potential mechanistic link between aerobic activity and mitochondrial health. Furthermore, the study expects to find sex-based differences in the magnitude of mitochondrial response, contributing to personalized intervention approaches. This research contributes to existing knowledge by providing robust mechanistic insights into how aerobic exercise modulates mitochondrial function in aging populations, clarifying biological pathways underpinning exercise-induced health benefits in older adults. It advances the theoretical understanding of aging-related mitochondrial decline, grounded in the mitochondrial-nuclear communication framework, and empirically tests these concepts in a practical, community-based setting. The study concludes that regular aerobic exercise is a viable and effective strategy to counteract age-related mitochondrial deterioration, with implications for designing targeted interventions aimed at promoting healthy aging. Recommendations include integrating structured aerobic programs into routine health maintenance for older adults and emphasizing the importance of early intervention, with future research suggested to explore long-term sustainability and the combined effects of aerobic and resistance training on mitochondrial health.