In the case of primary sarcopenia, there is a wide range of factors that contribute to the development of the condition, which are not entirely understood and largely thought to be natural consequences of aging.[1] These include decreased type II muscle fiber size, loss of motor units (i.e., a motor neuron and the muscle fibers it innervates), hormonal changes (i.e., a decline in serum levels of anabolic hormones like testosterone and insulin-like growth factor 1), anorexia (i.e., decreased or loss of appetite), decreased physical activity, anabolic resistance (i.e., a blunted muscle protein synthesis response to dietary protein and resistance exercise), systemic inflammation, insulin resistance, and increased body fat.[2]
What causes sarcopenia?
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•Last Updated: May 16, 2025
Primary sarcopenia is caused by a variety of factors related to aging, including decreased muscle fiber size, loss of motor units, hormonal changes, decreased appetite, reduced physical activity, anabolic resistance, systemic inflammation, insulin resistance, and increased body fat. These factors contribute to the condition, although their exact roles are not fully understood.