Abstract
Aging is characterized by a progressive decline in physiological function, driven by intrinsic mechanisms (primary aging) and modifiable factors (secondary aging), ultimately leading to multimorbidity, disability, and mortality. Mitochondrial dysfunction, a major hallmark of aging, plays a central role in the loss of muscle mass and strength observed in frailty and sarcopenia. With age, mitochondrial quality control processes, including biogenesis, mitophagy, and dynamics, become dysregulated, impairing energy metabolism and muscle homeostasis. Mitochondrial dysfunction correlates with clinical biomarkers of sarcopenia and frailty, such as the decrease in walking speed and muscle strength, making it a therapeutic target for mitohormesis-based strategies aimed at preserving functional capacity. Mitohormetic agents induce reversible mitochondrial stress, triggering adaptive responses that enhance function. Among these interventions, physical exercise, particularly endurance and resistance training (RT), has been reported to be among the most effective, as it may modulate mitochondrial biogenesis, dynamics, and mitophagy through increases in proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and mitochondrial transcription factor A (TFAM) expression, mitochondrial deoxyribonucleic acid (mtDNA) copy number, and mitochondrial content. Chronic RT can also elevate fusion and fission markers, potentially as a compensatory mechanism to mitigate mitochondrial damage. Apart from exercise, mitohormetic compounds such as harmol and piceid are emerging as promising supplements in the aging field. By modulating mitochondrial bioenergetics and dynamics, they may complement lifestyle-based interventions to improve mitochondrial fitness and extend health span.