Alterations in upper extremity muscle coordination resulting from muscle dystrophy and gravity compensation

Introduction
Facioscapulohumeral Dystrophy (FSHD) is a neuromuscular disorder characterized by muscles strength loss in the upper extremity and compensatory muscle activations [1]. Dynamic arm supports compensate for gravity thus reducing muscle efforts and enhancing task performance. It is postulated that the use of an arm support in persons with FSHD leads to larger individual-specific alterations of muscle coordination than in healthy controls. To clarify this effect, we investigate the effect of muscular weakness and support on muscle coordination in persons with FSHD, when performing functional tasks. We hypothesize firstly, that the FSHD population presents less consistent muscle coordination than healthy controls and secondly, that the support greatly improves consistency of muscle coordination within the FSHD population.