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Sarcopenia

Sarcopenia (from Greek) literally translates as poverty of flesh (2) and is used to describe a disease that results in the reduction of skeletal muscle mass and the loss of strength (1,2,3,4,5). In clinical studies, sarcopenia is often a qualitative inspection for small muscle mass and is widely considered one of the major causes of age-related disabilities (1). Sarcopenia reflects a progressive withdrawal of anabolism and an increased catabolism. This disease also reduces the muscles ability to regenerate, due to a decrease in satellite cell numbers (4).

Insulin Resistance in Correlation with Sarcopenia

Loss of muscle mass associated with sarcopenia promotes insulin resistance. This creates a vicious cycle for a person’s health, leading to even further loss of muscle mass and mobility, further insulin resistance, and a risk of developing a metabolic syndrome (4). This is a risk factor for the development of type II diabetes with muscle being the major metabolic organ that’s responsible for disposal of glucose and fatty acids after a meal. With reduced muscle mass, this disposal mechanism is less efficient and contributes to the cause of early hyperglycemia (5). Elderly with early sarcopenia are those who are most likely to benefit form interventions and there is strong evidence that sarcopenia is a reversible cause of disability with the use of resistance exercise and aerobics (1). Studies have shown that if a person is physically inactive, that person can suffer form disuse atrophy and their muscle fibers and cells that are not exercised will begin to shrink, thus making physical inactivity a catalyst for sarcopenia.

Classification of Sarcopenia

Sarcopenic classification of individuals requires a measure that expresses muscle mass in relation to skeletal size and sex-specific criteria to determine a deficit in skeletal muscle mass. The elderly have less muscle mass and less bone mass along with expanded extracellular fluid volumes and a smaller amount of body cell mass compared to that of younger adults (3). A decrease in skeletal muscle mass is associated with a significant decline in the maximum force that can be exerted. This suggests that the quality or efficiency of skeletal muscle is reduced with age (5). In earlier studies, sarcopenia was examined in individuals by observing and testing calf muscle (1), and other muscle cross sectional areas for change in muscle function with aging and how it affected mobility in men and women (1,2,3,4). Also tested were the participants’ knee extension (1,2,4), handgrip strength (1,2,3), plantar flexor and dorsiflexor muscles of the foot (2), and lower extremity muscle power. Sarcopenia is considered to be present when the measurement of each of these indicators was greater than two standard deviations below the mean of the experimental group’s data (1,2,3,4). The loss of skeletal muscle mass directly impacts and is correlated with age-related declines in strength. Studies have shown that between the ages of 20 and 60 years old, total muscle cross section areas (CSA) decreases by about 40%. This includes a reported 25-35% CSA reduction of the quadriceps muscles in the thighs of older men and women when compared to a younger control group (2).