Titre : | Appraisal of muscular impairments associated to effort-related fatigability (abstract : congrès international de Myologie, 2005) |
contenu dans : | |
Auteurs : | Congrès international de myologie 2005 (International Congress of Myology 2005; 9-13 mai 2005; Nantes, France) ; Boerio D ; Lefaucheur JP ; Creange A ; Hogrel JY |
Type de document : | Article |
Année de publication : | 2005 |
Pages : | p. 99 |
Langues: | Anglais |
Mots-clés : | colloque ; contraction isométrique ; contraction volontaire ; électrodiagnostic ; exercice musculaire ; fatigue ; muscle squelettique ; sclérose en plaques |
Résumé : |
Communication n° 234. INTRODUCTION : The achievement of a motor task induces an effort-related fatigability implying several mechanisms. Fatigability can be due to either central (central drive, reflex activity) or peripheral (peripheral nervous system, muscle) impairments or a combination of both components. OBJECTIVES : The aim of the present study was to quantify muscular contribution during effort-related fatigability in healthy subjects and patients. METHODS : Twenty healthy subjects and patients suffering from multiple sclerosis and myopathies participated to this study. Electrophysiological data were collected using high spatial resolution surface electrodes. The fatiguing task consisted in maintaining an isometric contraction of adductor digitorum minimi (ADM) for 45 s at 60% of maximal voluntary contraction (MVC). Previously and after this effort, electrophysiological tests were performed. The testing sessions consisted in 10 electrically evoked twitches by applying single pulses on the ulnar nerve at wrist to obtain compound muscle action potential (CMAP) of ADM and 2 MVC of ADM. The CMAP were analyzed in terms of area, duration, amplitude and conduction velocity (CV). The root mean square (RMS) and CV were observed in MVC. Finally, RMS, CV and spectral analysis in term of mean power frequency (MPF) were calculated to quantify the fatiguing task. RESULTS : A sub-maximal isometric effort induces impairments of the muscular component expressed by CV and MPF reductions whereas RMS increases during the effort. The post tests data are significantly affected by the effort. Effort-related fatigability is more important in patients compared to healthy subjects. CONCLUSIONS : High spatial resolution surface electrodes allow to obtain a lot of information related to muscular component implication during fatigue. This non painful exam could be easily applied in clinical neurophysiology in order to facilitate longitudinal care of patients, to observe inter-individual variations, the effects of a given pathology and also to quantify the benefits of a therapeutic agent on effort-related fatigability. Acknowledgements: This work was supported by the Association Française contre les Myopathies (AFM). |