Alterations in Shoulder Kinematics and Associated Muscle Activity in People With Symptoms of Shoulder Impingement

Abstract

Background and Purpose. Treatment of patients with impingement symptoms commonly includes exercises intended to restore "normal" movement patterns. Evidence that indicates the existence of abnormal patterns in people with shoulder pain is limited. The purpose of this investigation was to analyze glenohumeral and scapulothoracic kinematics and associated scapulothoracic muscle activity in a group of subjects with symptoms of shoulder impingement relative to a group of subjects without symptoms of shoulder impingement matched for occupational exposure to overhead work. Subjects. Fifty-two subjects were recruited from a population of construction workers with routine exposure to overhead work. Methods. Surface electromyographic data were collected from the upper and lower parts of the trapezius muscle and from the serratus anterior muscle. Electromagnetic sensors simultaneously tracked 3-dimensional motion of the trunk, scapula, and humerus during humeral elevation in the scapular plane in 3 handheld load conditions: (1) no load, (2) 2.3-kg load, and (3) 4.6-kg load. An analysis of variance model was used to test for group and load effects for 3 phases of motion (31°-60°, 61°-90°, and 91°-120°). Results. Relative to the group without impingement, the group with impingement showed decreased scapular upward rotation at the end of the first of the 3 phases of interest, increased anterior tipping at the end of the third phase of interest, and increased scapular medial rotation under the load conditions. At the same time, upper and lower trapezius muscle electromyographic activity increased in the group with impingement as compared with the group without impingement in the final 2 phases, although the upper trapezius muscle changes were apparent only during the 4.6-kg load condition. The serratus anterior muscle demonstrated decreased activity in the group with impingement across all loads and phases. Conclusion and Discussion. Scapular tipping (rotation about a medial to lateral axis) and serratus anterior muscle function are important to consider in the rehabilitation of patients with symptoms of shoulder impingement related to occupational exposure to overhead work. [Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther. 2000;80:276 -291.]

Comparing the Isometric Strength of the Shoulder and Scapulothoracic Muscles in Volleyball and Futsal Athletes

“…Research has shown that one-side sports such as volleyball causes accommodative changes in muscle strength within the dominant side [26]. The strength of the upper trapezius muscle of the dominant side in volleyball athletes was more than that in futsal athletes, which was in accordance with the findings of Ludewig [8]. In volleyball players, during the cocking and acceleration phases, the upper trapezius and serratus anterior play a significant role throughout the course of throwing movements that places the scapula in an elevation and upper rotation position [27].…”

“…Muscle weakness and muscle imbalance can cause impingement of the shoulder joint syndrome, therefore, evaluation of the ratio of antagonist-agonist of the scapulothoracic muscle on one side can help diagnose and treat [2,8,[22][23][24]. To measure the elevation to depression ratio of the scapula, the upper trapezius muscle was considered for elevation and the lower trapezius for depression [15].…”

“…Research in glenohumeral abnormalities has shown that serratus anterior, rhomboids, middle and lower trapezius are weak or inhibited [7]. In the impingement syndrome, there are decreased scapular upward rotation, increased anterior tipping, and increased scapular medial rotation [8]. In baseball athletes, there was an increase in external rotation range and a decrease in muscle strength, particularly the supraspinatus muscles [5].…”

Impairment severity selectively affects the control of proximal and distal components of reaching movements in children with hemiplegic cerebral palsy

“…Thus, aspects of the transport component such as activation related to the scapular movement (i.e. an essential component for arm elevation) 22 may be affected, even in less severely impaired children. Furthermore, for children with moderate HCP, the impairment clearly impinges on proximal as well as distal transport components.…”

Ultrasound imaging of the serratus anterior muscle at rest and during contraction

“…Critical to the movement of the scapula are the trapezius and serratus anterior muscles, both considered important in normal kinematics of the scapula (Ebaugh et al, 2005). Dysfunction of these muscles is thought to be related to shoulder pathology with evidence of differences in the activation patterns between subjects with shoulder pain and those who do not complain of shoulder symptoms (Cools et al, 2002;Lin et al, 2005;Ludewig & Cook, 2000). Clinically, scapular muscle function can be assessed by observing the position of the scapula, palpating scapular position and visualizing scapular changes during dynamic movement (Kibler & Sciascia, 2010;Mottram, 1997;Myers et al, 2005;Tate et al, 2008).…”