What is McArdle disease (Glycogen storage disease type V)?

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McArdle disease patients should adopt a moderate exercise routine with proper warm-up periods, avoid intense anaerobic activities, and take frequent rest breaks during physical exertion, as there is no cure for the disease but management focuses on lifestyle modifications to improve quality of life and reduce morbidity and mortality. The disease is caused by a deficiency of the enzyme myophosphorylase, which prevents muscles from properly using stored glycogen during exercise, leading to exercise intolerance, muscle pain, cramping, and fatigue during physical activity 1. Some key features of the disease include:

  • Exercise intolerance, with reversible, acute crises triggered by static muscle contractions or dynamic exercise 1
  • The "second wind" phenomenon, where symptoms temporarily improve after brief rest during exercise 1, 2
  • Frequent exercise-induced rhabdomyolysis and myoglobinuria episodes, with muscle damage also occurring under basal conditions 2
  • Early appearance of fatigue and contractures 2 Management of the disease should focus on lifestyle modifications, including:
  • A diet with complex carbohydrates and consuming a small amount of simple carbohydrates (like fruit juice) before exercise to provide alternative energy sources 3, 1
  • Regular monitoring by specialists, including neurologists and exercise physiologists 1
  • Medically supervised aerobic training of low to moderate intensity 1
  • Avoiding intense anaerobic activities and taking frequent rest breaks during physical exertion 3, 1 While there is no cure for McArdle disease, these lifestyle modifications can help improve quality of life and reduce morbidity and mortality. It is also important to note that some studies have investigated the use of pharmacological and nutritional treatments, such as creatine supplementation and oral sucrose, but the evidence is limited and inconclusive 4, 5, 3. Therefore, a moderate exercise routine with proper warm-up periods, a diet with complex carbohydrates, and regular monitoring by specialists are the most effective management strategies for McArdle disease patients.

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