Upper Limb Strength and Muscle Volume in Healthy Middle-Aged Adults

• Published in: Journal of applied biomechanics 2015-12, Vol.31 (6), p.484-491
• Main Authors: Saul, Katherine R, Vidt, Meghan E, Gold, Garry E, Murray, Wendy M
• Format: Article
• Language: English
• Subjects: Female; Humans; Isometric Contraction - physiology; Male; Middle age; Middle Aged; Muscle Strength - physiology; Muscle, Skeletal - physiology; Organ Size - physiology; Postural Balance - physiology; Reproducibility of Results; Sensitivity and Specificity; Upper Extremity - physiology
• ISSN: 1065-8483; 1543-2688
• DOI: 10.1123/jab.2014-0177

Our purpose was to characterize shoulder muscle volume and isometric moment, as well as their relationship, for healthy middle- aged adults. Muscle volume and maximum isometric joint moment were assessed for 6 functional muscle groups of the shoulder, elbow, and wrist in 10 middle-aged adults (46-60 y, 5M, 5F). Compared with young adults, shoulder abductors composed a smaller percentage of total muscle volume (P = .0009) and there was a reduction in shoulder adductor strength relative to elbow flexors (P = .012). We observed a consistent ordering of moment-generating capacity among functional groups across subjects. Although total muscle volume spanned a 2.3-fold range, muscle volume was distributed among functional groups in a consistent manner across subjects. On average, 72% of the variation in joint moment could be explained by the corresponding functional group muscle volume. These data are useful for improved modeling of upper limb musculoskeletal performance in middle-aged subjects, and may improve computational predictions of function for this group.