[McArdle's disease]

Glycogenosis type V (McArdle disease) is a serious metabolic disorder with an exercise intolerance, myalgia, early fatigue and stiffness of exercising muscles, relieved++ by rest. The authors present a case report of patient with McArdle's disease, and diagnostic procedures which can be used in different diagnostic of metabolic myopathies, especially between myoadenylate deaminase deficiency and different types of gly(geno)lytic myopathies. The importance of "ischemic forearm test" and muscle biopsy is emphasized.