The Epidemiology of Sarcopenia

Abstract

The aim of this review is to describe the epidemiology of sarcopenia, specifically prevalence, health outcomes, and factors across the life course that have been linked to its development. Sarcopenia definitions involve a range of measures (muscle mass, strength, and physical performance), which tend to decline with age, and hence sarcopenia becomes increasingly prevalent with age. Less is known about prevalence in older people in hospital and care homes, although it is likely to be higher than in community settings. The range of measures used, and the cutpoints suggested for each, presents a challenge for comparing prevalence estimates between studies. The importance of sarcopenia is highlighted by the range of adverse health outcomes that strength and physical performance (and to a lesser extent, muscle mass) have been linked to. This is shown most strikingly by the finding of increased all-cause mortality rates among those with weaker grip strength and slower gait speed. A life course approach broadens the window for our understanding of the etiology of sarcopenia and hence the potential intervention. An example is physical activity, with increased levels across midadulthood appearing to increase muscle mass and strength in early old age. Epidemiologic studies will continue to make an important contribution to our understanding of sarcopenia and possible avenues for intervention and prevention.

Keywords: Epidemiology; Muscle strength; Physical performance; Sarcopenia.

Figure 1

A life course approach to sarcopenia On average, peak muscle mass and strength are reached in early adult life prior to decline. The dashed line shows the use of the normal range encountered in young adult life (analogous to the T-score approach in osteoporosis) to produce cut-points for low muscle mass or strength. The prevalence below this cut-point inevitably rises with age, as average mass or strength declines.

Figure 2

Sarcopenia: major health outcomes and risk factors Several factors across the life course have been associated with muscle mass and strength and hence are likely to contribute to the development of sarcopenia, which in turn is recognised as having a range of adverse health outcomes.