Sarcopenia, or the aging-related loss of muscle mass, affects a large number of older adults. The presence of sarcopenia is associated with physical disability, poor quality of life, and all-cause mortality, in part because sarcopenic adults have low muscle skeletal muscle capillarization and may lack the adequate perfusion needed to maintain muscle mass and function. This study will test the effects of increasing skeletal muscle capillarization through aerobic exercise training on responses to resistance training in older adults. Eligible participants will be randomized to one of two groups, resistance training preceded by aerobic exercise training (AEX-RT), or resistance training followed by aerobic exercise training (RT-AEX). Participants in the AEX-RT group will undergo 3 months of aerobic exercise training to increase skeletal muscle capillarization, followed by 3 months of resistance training. Participants in the RT-AEX group will undergo 3 months of resistance training, followed by 3 months of aerobic exercise training. Before and after the interventions, participants will undergo assessments of muscle size, strength, and capillarization, as well as assessments of physical function.
