The most common disorders are related to glycogen storage problems.
Cramps are a prominent complaint.
The episodic occurrence of the complaints does not necessarily signify a benign outcome. As the disease progresses, the patient may develop a progressively worsening permanent muscle weakness. The diagnosis of glycogen-storage metabolic muscle diseases can be quite challenging. They are first suspected when a history of intermittent exercise-induced muscle cramps and myalgias is given. Not all muscle cramps, however, are related to metabolic muscle diseases and can be due to benign etiologies.