Sarcopenia is the loss of skeletal muscle mass and function with aging. Although 
the term sarcopenia was first coined in 1989, its etiology is still poorly 
understood. Moreover, a consensus for defining sarcopenia continues to elude us. 
Sarcopenic changes in the muscle include losses in muscle fiber quantity and 
quality, alpha-motor neurons, protein synthesis rates, and anabolic and sex 
hormone production. Other factors include basal metabolic rate, increased 
protein dietary requirements, and chronic inflammation secondary to age-related 
changes in cytokines and oxidative stress. These changes lead to decreased 
overall physical functioning, increased frailty, falls risk, and ultimately the 
loss of independent living. Because the intertwining relationships of these 
factors are complex, effective treatment options are still under investigation. 
The published data on sarcopenia are vast, and this review is not intended to be 
exhaustive. The aim of this review is to provide an update on the current 
knowledge of the definition, etiology, consequences, and current clinical trials 
that may help address this pressing public health problem for our aging 
populations.