NEW METHODS OF FUNCTIONAL EVALUATION OF PATIENTS WITH METABOLIC MYOPATHIES. THE EFFECTS OF EXERCISE TRAINING.

Mitochondrial myopathies (MM) and myophosphorylase deficiency (McArdle’s disease, McA) are genetic disorders characterized by impairments of the systems which provide the energy utilized by skeletal muscles to contract. These impairments translate into reduced capacity to perform exercise and easy fatigability, which often represent the main symptoms and may significantly affect the patients’ quality of life. In a previous Telethon-UILDM project we applied on MM and McA patients two non-invasive methods specifically aimed at the evaluation of energy metabolism in skeletal muscles. More specifically, we evaluated: A) The capacity by skeletal muscle to take O2 from blood and utilize it for energy provision during exercise, by utilizing a non-invasive optical method based on light absorption by tissues. B) The speed of increase of pulmonary O2 uptake following a sudden increase in work output. In two studies we have demonstrated that these methods allow to identify and quantify the metabolic impairment in MM and McA patients. At present the therapeutic interventions available for these patients are very limited. Previous studies suggest that moderate-intensity aerobic exercise training represents a safe intervention which may benefit MM and McA patients by increasing their capacity to perform exercise. The main aim of the present study will be to utilize the above-mentioned tools in order to evaluate, in MM and McA patients, the effects of a program of home-based moderate-intensity aerobic exercise training. We hypothesize an increased capacity to perform exercise and an improved quality of life after training. We hypothesize that these improvements will be associated with improvements of the proposed variables of functional evaluation of energy metabolism. The results could confirm the utility of the proposed non-invasive methods in the follow-up of patients as well as in the evaluation of the effects of therapies or rehabilitation interventions.