Journal of Orthopaedic Sports Physical Therapy
Abnormal scapular kinematics and associated muscle function presumably contribute to shoulder pain and pathology. An understanding of scapular kinematic and electromyographic profiles in asymptomatic individuals can provide a basis for evaluation of pathology. The purpose of this study was to describe normal 3-dimensional scapular orientation and associated muscle activity during humeral elevation. Twenty-five asymptomatic subjects, 19-37 years old, were evaluated. Digitized coordinate data and surface electromyographic signals from the trapezius (upper and lower), levator scapulae, and serratus anterior were collected at static positions of 0°, 90°, and 140° of humeral elevation in the scapular plane. The scapula demonstrated a pattern of progressive upward rotation, decreased internal rotation, and movement from an anteriorly to a posteriorly tipped position as humeral elevation angle increased. Electromyographic activity of all muscles studied increased with increased humeral elevation angles. Differences between mean values at all elevation angles for all variables were significant (p < .05), except for the lower trapezius between the 90° and 140° humeral angles. The results of this study suggest assessment of scapular tipping and internal rotation as well as upward rotation may be necessary to understand pathologies of the shoulder that are related to abnormal scapular kinematics.
Published Article/Book Citation
The article was published in J Orthop Sports Phys Ther , 24:2 (1996), pp. 57-65. http://http://www.jospt.org/issues/articleID.922,type.2/article_detail.asp
Author Posting. Copyright © JOSPT and the Orthopaedic and Sports Physical Therapy Sections of the American Physical Therapy Association. This article is posted here by permission of the publisher for personal use, not for redistribution.
Ludewig PM, Cook TM, Nawoczenski DA. Three-dimensional scapular orientation and muscle activity at selected positions of humeral elevation. J Orthop Sports Phys Ther 24(2):57-65, 1996.