Definitions of Sarcopenia Across the World

Aging is accompanied by the progressive decline of muscle mass and strength; a condition called sarcopenia. During the past three decades, the number of publications with the Medical Subject Heading (MeSH) term "sarcopenia" has been steadily increasing. Several operational definitions of sarcopenia have been proposed over the years by different expert groups and task forces worldwide. The first operational definitions were primarily focused on the evalutation of low muscle mass. Subsequently, as soon as the strong predictive role for negative outcomes of muscle strength emerged, the defining algorithms of sarcopenia evolved to privilege a bidimensional construct to include both the quantity and quality of the muscle. Interestingly, sarcopenia is today a formal nosological condition, having received a specific code in the International Classification of Diseases (ICD-10).