Sarcopenia: assessment of disease burden and strategies to improve outcomes

Abstract

Life expectancy is increasing worldwide, with a resultant increase in the elderly population. Aging is characterized by the progressive loss of skeletal muscle mass and strength - a phenomenon called sarcopenia. Sarcopenia has a complex multifactorial pathogenesis, which involves not only age-related changes in neuromuscular function, muscle protein turnover, and hormone levels and sensitivity, but also a chronic pro-inflammatory state, oxidative stress, and behavioral factors - in particular, nutritional status and degree of physical activity. According to the operational definition by the European Working Group on Sarcopenia in Older People (EWGSOP), the diagnosis of sarcopenia requires the presence of both low muscle mass and low muscle function, which can be defined by low muscle strength or low physical performance. Moreover, biomarkers of sarcopenia have been identified for its early detection and for a detailed identification of the main pathophysiological mechanisms involved in its development. Because sarcopenia is associated with important adverse health outcomes, such as frailty, hospitalization, and mortality, several therapeutic strategies have been identified that involve exercise training, nutritional supplementation, hormonal therapies, and novel strategies and are still under investigation. At the present time, only physical exercise has showed a positive effect in managing and preventing sarcopenia and its adverse health outcomes. Thus, further well-designed and well-conducted studies on sarcopenia are needed.

Keywords: assessment; elderly; sarcopenia; therapy.

Figure 1

Sarcopenia assessment flowchart. Note: (*) Body mass index (BMI)-adjusted values were used as a cutoff point to classify “Low” muscle strength (BMI ≤24 kg/m², 24.1–28 kg/m², and <28 kg/m² was 29 kg/m², ≤30 kg/m², and ≤32 kg/m² for men and BMI ≤23 kg/m², 23.1–26 kg/m², 26.1–29 kg/m², and <29 kg/m² was 17 kg/m², ≤17.3 kg/m², ≤18 kg/m², and ≤21 kg/m² for women, respectively). Abbreviations: BIA, bioelectrical impedance analysis; DEXA, dual energy X-ray absorptiometry; CT, computed tomography; MRI, magnetic resonance imaging.

Figure 2

Relationship between sarcopenia and frailty (see the text for details).

Figure 3

Sarcopenia: pathogenesis and relative therapeutic approaches. Abbreviations: NMJ, neuromuscular junction; SARMs, selective androgen receptor modulators; GH/IGF, growth hormone and insulin-like growth factor; mAbs, monoclonal antibodies.