Abstract
Glucagon has been reported to improve exercise tolerance in some patients with myophosphorylase deficiency (McArdle's disease) but a placebo effect was not excluded in previous trials. A single-blind controlled trial of glucagon in a patient with myophosphorylase deficiency is described. Although an improved exercise endurance of the forearm muscles was demonstrated with both short-acting and depot-glucagon, this was not statistically significant when compared with placebo or no treatment.