There are three major types of muscle tissue. One of these is skeletal muscle, also known as striated muscle. Skeletal muscles are those that are under conscious control, as opposed to heart muscle or the muscle tissue associated with internal organs. As with most cells, the genes of skeletal muscle cells are constantly producing a great diversity of substances. What we're becoming increasingly aware of, is which genes are active and how active they are depends strongly on muscle activity. For example, exercised muscle cells produce a substance that allows sugar to enter the muscle cells without the necessity of insulin thus helping to control blood sugar levels. In our border region with a high incidence of diabetes, such control is important in staving off the adult-onset form.
Among other gene products dependent on skeletal muscle activity, many
fluctuate with age. Comparing the muscle tissue of old, inactive people with that of
young, one study found more than 700 genes changed their productivity. The bottom line?
When it comes to muscles, use them or lose them.
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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.