Muscle and bone health in adult males with muscular dystrophy

Muscular Dystrophy (MD) results in muscle atrophy, loss of ambulation and reduced physical activity through chronic inflammation leading to muscle damage and derangement of muscle physiology. Reduced physical activity relating to muscle weakness and reduced muscle anatomical cross-sectional area (ASCA) due to atrophy lead to a reduction in tensile and compression strain required to maintain bone mineral density (BMD), resulting in adverse bone health. Studies have demonstrated reductions in BMD and muscle size, primarily in children with Duchenne Muscular Dystrophy (DMD) – a severe variant – however there is no extant data describing muscle size in adults with MD, and data describing BMD in adults with other variants of MD is sparse (e.g. Becker‟s (BeMD), Limb Girdle (LGMD), and Fascioscapluohumeral dystrophy (FSHD)). The aim of this study was to measure BMD, tibialis anterior (TA) muscle ASCA, grip strength and physical activity in adult male individuals with four distinct variants of MD compared to unaffected adult male controls. TA ASCA was measured via B-mode ultrasound; BMD was measured using speed-of-sound ultrasound of midshaft Tibia (MST) and distal Radius (DR). Grip strength was assessed through isometric dynamometer contraction; and physical activity through use of two questionnaires. 40 adult males with MD and 10 unaffected male controls were measured for demographic information, T- & Z-scores of BMD, TA ASCA, maximum grip strength and physical activity. BMD assessed by Z-score was lower in DMD individuals compared to all other participants in tibia and radius and lower in BeMD and FSHD individuals compared to CTRL (P