Muscle power failure in mobility-limited older adults: preserved single fiber function despite lower whole muscle size, quality and rate of neuromuscular activation

摘要: This study investigated the physiological and gender determinants of age-related loss muscle power in 31 healthy middle-aged adults (aged 40–55 years), 28 older (70–85 years) 34 mobility-limited years). We hypothesized that leg extensor would be significantly lower elders relative to both groups sought characterize mechanisms associated with reduction aging. Computed tomography was utilized assess mid-thigh body composition calculate specific strength. Surface electromyography used rate neuromuscular activation biopsies were taken evaluate single fiber contractile properties. Peak power, strength, cross-sectional area, among compared (P ≤ 0.05). Mobility-limited participants had greater deposits intermuscular adipose tissue < 0.001). Single properties type I IIA fibers preserved groups. Male decrements peak participants. Impairments concomitant reductions quality are important contributing deficits mobility limitations. The dissociation between changes at whole level suggest that, even overt problems, surviving an attempt maintain overall function.