Improvement of Symptoms in a Patient With Glycogen Storage Disease Through Nutritional Guidance and Exercise Therapy.

McArdle disease (glycogen storage disease type V) is a rare metabolic disorder caused by a deficiency in muscle phosphorylase, which is encoded by the PYGM gene. This deficiency leads to impaired glycogen metabolism, resulting in exercise intolerance, muscle cramps, and stiffness. This report describes the case of a woman first diagnosed with McArdle disease at age 59 years with genetic testing. The patient experienced lifelong exercise-induced muscle symptoms, which improved through combined preexercise sucrose intake and mild-to-moderate aerobic exercise. Nutritional guidance and structured physical activity remarkably alleviated her symptoms and improved her life quality. The interventions also improved the patient's body composition and grip strength, enhanced exercise tolerance, and reduced fatigue during daily activities. These clinical improvements occurred without any worsening of glucose tolerance, contributing to a meaningful enhancement in the patient's life quality. This case underscores the importance of early diagnosis of McArdle disease and highlights the potential benefits of personalized comprehensive interventions including those targeting lifestyle factors like diet and exercise in clinical management of McArdle disease.