Effects of age and exercise training on coronary microvascular smooth muscle phenotype and function

Radiation Biology & DNA Damage

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Study examining effects of age and exercise training on coronary. Microgravity causes rapid skeletal muscle atrophy, particularly affecting slow-twitch fibers. Protein synthesis decreases while breakdown increases, and muscle phenotype shifts toward faster fibers. Despite exercise countermeasures, significant muscle loss occurs, along with mitochondrial dysfunction and reduced oxidative capacity.

Study examining effects of age and exercise training on coronary. Skeletal muscle atrophy progressed rapidly in microgravity with 10-20% mass loss within first month. Type I slow-twitch fibers were preferentially affected. Protein synthesis decreased while proteolytic pathways upregulated. Myosin heavy chain isoforms shifted toward faster phenotypes. Exercise countermeasures attenuated but did not prevent muscle loss. Mitochondrial function declined with reduced oxidative capacity.