What is McArdle's disease?

Answer 1

McArdle's disease is a metabolic disease of skeletal muscle. People with this condition are unable to properly metabolize energy during exercise due to a missing enzyme, glycogen phosphorylase, which is required to convert glycogen (muscle starch) to glucose. As a consequence of this missing or non-functional enzyme, people with McArdle's disease experience muscle fatigue and failure prematurely during even moderately intense exercise. In addition, due to the muscles' inability to properly contract, painful and damaging cramping may occur, which can pose a serious health risk due to tissue damage. People with McArdle's disease experience difficulty jogging, walking up flights of stairs, swimming, carrying things, and many other normal activities of moderate intensity. However, it has been observed in some individuals with the disease that a "second wind" can be achieved following a careful warm-up period, after which activities such as walking can be sustained without difficulty. McArdle's disease is most commonly caused by a genetic mutation with a recessive inheritance pattern. At the present, there is cure for the disease and treatments which involve diet and exercise are the subject of debate. For additional information and anecdotal information from patients with the disease, visit mcardlesdisease.org.