Inclusion Criteria:

• Friedreich ataxia diagnosis confirmed by evidenced mutation expansion of Frataxin gene
• Ambulatory patient, with depressed tendon reflexes and pyramidal syndrome associated or not to a loss of position or vibration senses or dysarthria
• Patient able to perform the tests of the study

Exclusion Criteria:

• Severe cardiac disease as assessed by echocardiography performed at least within 6 months before screening or during the wash out period (4 weeks)
• Absolute contra-indication to NMR examination: iron and any magnetic objects implanted in the whole body, e.g. some neurostimulators, cardiac pace-makers, vascular clips and other implanted orthopaedic prosthesis
• Patient who did not deplete at baseline PCr pool by more than 40 % during the exercise bout
• Any continuous use of the following forbidden medications:
• other antioxidant such as idebenone, coenzyme Q, vitamin E/C taken for less than 4 weeks prior study treatment start (ie for antioxidant drugs a mandatory wash-out period of 4 weeks prior study drug start has to be observed),
• any other vasodilators
• tranquilizer such as benzodiazepine, meprobamate or buspirone, and/or antidepressant (only one), at non stable dose