From the time you are born to around the time you turn 30, your muscles grow larger and stronger. But at some point in your 30s, you begin to lose muscle mass and function, a condition known as age-related sarcopenia or sarcopenia with aging. Age-related muscle weakness dramatically increases the risk for elderly falling. A large number of those elderly who fall will not continue living in the community. One half of accidental deaths among individuals age 65 and older are related to falls.

Though diet and exercise can reduce the rate of muscle and strength loss, even active seniors will experience decline in muscle function. In 2010, The European Working Group on Sarcopenia in Older People (EWGSOP) has defined sarcopenia as Low muscle mass with Low muscle strength OR Low gait speed. The rationale for use of two criteria is: muscle strength does not depend solely on muscle mass, and the relationship between strength and mass is not linear.

EWGSOP Appendicular skeletal muscle mass (ASM) was obtained by adding skeletal muscle mass of both arms and legs. A skeletal muscle mass index (SMI), which is used for the diagnosis of sarcopenia, was calculated by dividing the ASM by the height squared. To be diagnosed sarcopenic, the SMI must be below 7.25 kg/m² for men and 5.67 kg/m² for women.