ISOMETRIC STRENGTH IN FLEXORS, ABDUCTORS, AND EXTERNAL ROTATORS OF THE SHOULDER

The aim of this study was to map the isometric shoulder muscle strengt h of 96 men and 90 women randomized from the population register of St ockholm citizens (reference groups), and of 83 male furniture removers and 89 female secretaries (aged 19-65 years, all four groups). Maximu m isometric strength of the right-side shoulder flexors (90-degrees jo int angle), abductors, and external rotators (0-degrees) was recorded with the subject sitting in a standardized position in an adjustable c hair. Women had 43, 55, and 56% of the men's strength in the abductors , flexors, and external rotators respectively. Neither of the female t est groups showed any change in maximum isometric strength with increa sing age. Men from the reference group showed an age-related differenc e only in shoulder flexor strength, where the older men (45-65 years) had 89% of the younger men's (19-44 years) strength. The strength valu es of older furniture removers were 77-83% of the younger colleagues' values in ali muscle groups tested. The muscular strength utilization ratio (MUR%) when holding the arm without external load at 90-degrees shoulder flexion was 22-25 MUR% for the male groups and 34 MUR% for th e female groups, which shows that the muscular load on the shoulder ca used by the weight of the arm is of great importance.