Résumé :
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Communication n° 281. Introduction : McArdle's disease is a metabolic myopathy of genetic origin. It is characterised by a severe effort intolerance due to myophosphorylase deficiency. Patients present, often from childhood, an excessive fatigue, painful muscular cramps during exercise, delayed-onset muscle soreness and a second wind phenomenon. Objectives : This study assess, on patients with McArdle's disease, the effects of a moderate aerobic training program on ergocycle (8 weeks, 3 sessions of 45 minutes per week at 60-70% of maximal heart rate) on the physiological response during exercise. Methods : The effects of training were evaluated on 4 patients with McArdle's disease and 5 healthy subjects from a multiparametric approach focussed on the evolution of blood metabolic, hormonal and cardio-respiratory parameters. Nuclear magnetic resonance (31P spectroscopy) and surface electromyography (EMG) measures were also included in the protocol. Serum creatine kinase (CK) was measured weekly. Results : In the beginning of exercise, EMG activity (-62%), cardiac frequency (-9%), the rate of perceived exertion (-80%) and the time of second-wind apparition (-14%) are reduced with the training for the patients. The oxygen uptake is normal. The glucose utilisation and the mitochondrial function to exercise are improved. Serum CK during training was unchanged or lower than before training. Moreover, the training response of patients is similar to healthy subjects. Conclusion : A moderate aerobic training program induces muscle, cardiac and metabolic adaptations to physical exercise. These adaptations improve the effort tolerance of patients with McArdle's disease.
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