Maximum Voluntary Contraction as a Function of Upper Extremity Posture in Females

Background: Little has been published on the maximum strength of the shoulder girdle as a function of varying postures. Such information may help aid in job design by better assessing the capabilities of workers.Methods: Female subjects (n=12) were required to hold a weight in place for 4 seconds in one of 6 different functional postures: 0/90 (shoulder flexion angle = 0° and included elbow angle = 90°), 30/90, 60/90, 90/120, 120/150 and 150/180. Postures and weights were chosen at random and measurements were repeated. Final weight adjustments were in increments of 0.1 lb. At least 3 minutes of rest between lifts was provided. Maximum voluntary contractions (MVCs) were required to be reproduced within 2 lbs. Dynamic lifting of the weight and holding in place MVCs (“lift and hold”), as well as only holding the weight in place MVCs (“hold only”) were assessed separately. Maximum voluntary torques were also computed and adjusted for arm weight. Ratings of perceived exertion (Borg CR-10) and pain ratings (0–...