Sarcopenia and Aging

In the last 20 years, there has been a growing clinical and scientific interest in the role of disability related to the loss of muscle mass and strength in the elderly. These muscular modifications were first identified with the term “sarcopenia” in 1989, and the last consensus defined sarcopenia as “a decrease in muscle mass and function (strength and mobility).” The prevalence of muscle loss has been estimated around 20% for people aged under 70 years old, rising up to 40% in subjects aged above 80 years old, with a severe impact on disability and on quality of life and with increased direct and indirect social and health costs in Western countries. Current views consider sarcopenia as the consequence of multiple medical, behavioral, and environmental factors that characterize aged individuals. However, the skeletal and the muscular organ systems are tightly intertwined, and bone fragility is known to depend on several pathogenetic mechanisms leading to the loss of bone mass and strength. Interestingly, the degenerative processes leading to osteoporosis and sarcopenia show many common pathogenic pathways, leading to the same outcomes such as restricted mobility, loss of autonomy, and reduced life expectancy. Thus, they can be summarized in a wider and complex condition called frailty, a geriatric syndrome characterized by reduced homeostatic reserves, which exposes the individual to increased risk of negative health-related events. In this chapter the epidemiology and pathophysiology of sarcopenia, its impact on ADL, and its role in the development of the concept of frailty will be discussed.