Confirmation of the efficacy of vitamin B6 supplementation for McArdle disease by follow-up muscle biopsy.

No effective treatment for McArdle disease exists.We report a Japanese patient with McArdle disease who was treated with vitamin B(6) supplementation (60-90 mg/day). After treatment, increased muscle phosphorylase activity was confirmed by follow-up muscle biopsy (3.8 times higher than pretreatment levels). Increased lactate levels were seen on the forearm exercise test, and regular work activities could be resumed. Vitamin B(6) supplementation can enhance residual phosphorylase activity and improve insufficient anaerobic glycolysis of skeletal muscle.

Physical training for McArdle disease.

BACKGROUND: McArdle disease is a rare metabolic myopathy caused by a complete absence of the enzyme muscle glycogen phosphorylase. Affected people experience symptoms of fatigue and cramping within minutes of exercise and are at risk for acute muscle injury (rhabdomyolysis) and acute renal failure. If the first few minutes of exercise are paced, a 'second wind' will occur enabling exercise to continue. This is due to mobilisation and utilisation of alternative fuel substrates. Aerobic training appears to improve work capacity by increasing cardiovascular fitness. OBJECTIVES: To assess the effects of aerobic training in people with McArdle disease. SEARCH METHODS: We searched the Cochrane Neuromuscular Disease Group Specialized Register (11 January 2011), CENTRAL (2010, Issue 4), MEDLINE (January 1966 to January 2011) and EMBASE (January 1980 to January 2011). SELECTION CRITERIA: All randomised and quasi-randomised controlled studies of aerobic exercise training in people of all ages with McArdle disease. DATA COLLECTION AND ANALYSIS: Two authors identified possible studies for inclusion and assessed their methodological quality. Had more than one study of sufficient methodological quality been identified we would have undertaken a meta-analysis. MAIN RESULTS: There were no randomised or quasi-randomised controlled trials of aerobic training in people with McArdle disease. However, three open studies using small numbers of participants provided some evidence that aerobic training improves fitness without adverse events in people with McArdle disease. AUTHORS' CONCLUSIONS: Evidence from non-randomised studies using small numbers of patients suggest that it would be safe and worthwhile for larger controlled trials of aerobic training to be undertaken in people with McArdle disease.

McArdle disease: another systemic low-inflammation disorder?

McArdle disease is caused by inherited deficit of human muscle glycogen phosphorylase with subsequent blockade in muscle glycogenolysis. Patients usually experience severe exercise intolerance and 'chronic' skeletal muscle damage. We determined circulating levels of 27 cytokines in a group of 31 adult McArdle patients (15 male 16 female; mean (+/-S.E.M.) age: 39+/-3 years) and 29 healthy sedentary controls (14 male, 15 female) before and after an acute exercise bout involving no muscle damage (cycling). Patients had an ongoing state of muscle breakdown even when following a sedentary lifestyle (serum creatine kinase activity at baseline of 2590+/-461 Ul(-1) vs. 97+/-5 Ul(-1) in controls). Under resting conditions, neutrophil count (+20%) and circulating levels of several cytokines were significantly higher (P

Resistance (weight lifting) training in an adolescent with McArdle disease.

Owing to the risk of severe rhabdomyolysis, clinicians advise McArdle disease patients to refrain from strenuous exercise, particularly weight lifting. A 15-year-old male McArdle disease patient performed a 6-week, supervised, light- to moderate-intensity (~65-70% of one-repetition-maximum) resistance (weight lifting) training program (2 sessions/week). Training resulted in ~27% and ~6% increase in one-repetition-maximum bench press and multipower squat performance while inducing no myoglobinuria. The patient changed to a lower disease severity class, that is, he became virtually asymptomatic in terms of exercise limitations. The authors' preliminary data suggest that supervised, light to moderate resistance training is feasible in children with McArdle disease and has potential clinical benefits.

Double trouble (McArdle's disease and myasthenia gravis): how can exercise help?

We report a 29-year-old patient with McArdle's disease and myasthenia gravis. She had been debilitated with McArdle's disease since childhood (with marked rhabdomyolysis) and was obese. Myasthenia gravis was diagnosed at 24 years of age. After 3 months of aerobic exercise training, her exercise capacity increased significantly and she regained the ability to live independently. We conclude that even patients with profound neuromuscular diseases may benefit from carefully prescribed exercise training.