ABSTRACT
Necropsy studies involving whole human skeletal muscles have yielded data on fiber type changes with aging, which differ from earlier studies based on biopsies of specific muscles. The reduction of lean muscle mass with aging thus results in decreased mechanical function and also significant adverse metabolic consequences. With the progressive aging of the American population, sarcopenia has emerged as a major public health problem. Severe sarcopenia requires meeting the sarcopenia criteria plus the presence of marked debilitating impairments in muscular strength and mobility, resulting in the so-called fragility syndrome. Research has revealed multiple intrinsic biological, molecular, and biochemical mechanisms involved in the etiology of the aging process, which contribute to the development of sarcopenia. Skeletal muscle mass and strength generally peak by the mid-twenties to 30 years of age. Central nervous system stimulation initiates the electrical and biochemical stimulation required to induce skeletal muscle contractions.
