More Information About McArdle’s Disease

McArdle’s Disease is an “Energy Bottleneck”

In McArdle’s Disease, the metabolism of glycogen to glucose does not take place. Because the concentration of glucose in the cell becomes the limiting factor in the formation of ATP needed for muscular contractions, a bottleneck occurs, called “glycogen debt”. This is similar to what a marathon runner may experience after 20 miles or so, when their leg muscles are completely depleted of glycogen and stop responding. ATP powers the concentric and eccentric movement of muscle fibers (contracting and relaxing movements), which is illustrated in a video here of the sliding filament model. When working muscles run out of energy, this results in a very rapid and abrupt onset of fatigue. Any moderate to rigorous physical activity; running, jumping, squatting, walking up stairs, carrying heavy items, swimming and more can result in a failure episode. Injury and damage to muscle tissue can occur as a result.

McArdle’s Disease and Muscle Injury

In addition to premature fatigue or muscle failure during exercise, people with McArdle’s disease are susceptible to muscle injury. The exact nature of this injury has to date not been described, but may be related to eccentric force being placed on “cramped” muscles. The resulting damage to muscle tissue from McArdle’s disease is known as rhabdomyolysis. (Myolysis describes muscle breakdown with resulting release of contents into the bloodstream.) Rhabdomyolysis and associated myoglobinuria (brown urine) can result from damaged muscle tissue, causing pain, weakness and swelling. In addition, damaged muscles spill iron-rich proteins into the bloodstream where they pass through the kidneys into the urine, which can cause renal failure and thus requires medical attention. Help Make This Website Better If anyone with information about this disease wishes to contribute, your help is welcome and greatly appreciated. We can use both anecdotal blog content describing subjective life experiences with McArdle’s disease. If you are a physician and would like to correct or amend some of the descriptions, please write us. Additional links on this page’s topic:

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