Losses in limb muscle mass and increased fatigability compromise the ability of older adults (≥65 yrs) to generate the power necessary to maintain mobility and perform daily activities. Recently, we showed that the age-related increase in fatigability during dynamic contractions is due to a greater accumulation of metabolites, hydrogen (H+), inorganic phosphate (Pi) and diprotonated phosphate (H2PO4-), eliciting greater disruptions in contractile function within the muscle. However, the mechanisms for the greater metabolite accumulation are unknown. 

Our central hypothesis is that the greater accumulation of metabolites and increased fatigability are due to age-related impairments in skeletal muscle bioenergetics and/or vascular function. To test this hypothesis, we will use cutting-edge techniques to assess whole-muscle and single fiber bioenergetics and macro- and micro-vascular function. Additionally, we will study the effectiveness of a novel exercise-training intervention in older men and women aimed at improving contractile economy, vascular function, muscle power and fatigability.