Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement.
ABSTRACT 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.
Fifty-two subjects were recruited from a population of construction workers with routine exposure to overhead work.
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().
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.
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.
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ABSTRACT: This study aimed to characterize scapular muscle timing in stroke patients with and without shoulder pain. Muscle activity of upper trapezius, lower trapezius, serratus anterior, infraspinatus, and anterior deltoid (AD) was measured (Delsys Trigno surface EMG system, USA) in 14 healthy controls (dominant side) and 30 stroke patients (hemiplegic side) of whom 10 had impingement-like shoulder pain. Participants performed 45° and full range anteflexion, in two load conditions. The impact of group, anteflexion height, load condition, and muscle was assessed for onset and offset of the different muscles relative to the onset and offset of AD, using a 3 (group) × 2 (height) × 2 (load) × 4 (muscle) mixed model design. Recruitment patterns were additionally described. Across all load conditions and groups, serratus anterior had a significantly earlier onset and, together with lower trapezius, a significantly later offset in 45° compared to full range anteflexion tasks (p < 0.001). In stroke patients without pain, lower trapezius had furthermore a significantly earlier onset in comparison to stroke patients with shoulder pain (all tasks, p = 0.04). Serratus anterior also showed a significantly earlier offset in stroke patients with shoulder pain in comparison to controls (p = 0.01) and stroke patients without pain (p < 0.001). Analysis of muscle recruitment patterns indicated that for full range tasks, stroke patients without pain used early and prolonged activity of infraspinatus. In stroke patients with shoulder pain, recruitment patterns were characterized by delayed activation and early inactivity of serratus anterior. These timing results can serve as a reference frame for scapular muscle timing post-stroke, and when designing upper limb treatment protocols and clinical guidelines for shoulder pain after stroke.Frontiers in Human Neuroscience 11/2014; 8:933. · 2.90 Impact Factor
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ABSTRACT: Background: There are various methods for rehabilitating round-shoulder posture (RSP), including strengthening exercises, stretching, and using a shoulder brace or taping to correct the altered posture. However, no study has determined which intervention is the most effective of the three methods to decrease RSP (intervention #1: scapular posterior tilting exercise alone [hereafter, SPT], intervention #2: the scapular posterior tilting exercise after PM stretching [PM stretch+SPT], and intervention #3: the scapular posterior tilting exercise with use of a shoulder brace [SPT+brace]). Objectives: The purpose of this study was to compare the SPT, PM stretch+SPT, and SPT+brace on RSP, PM index (PMI), and lower trapezius (LT) and serratus anterior (SA) activity in subjects with RSP. Methods: In total, fifteen young men with RSP, participated in the study (21.46±2.30years old). RSP was confirmed using a caliper measure. Surface electromyography (SEMG) data for LT and SA activity were collected during the three interventions, and the SEMG data are expressed as a percentage of the maximal voluntary isometric contraction (%MVIC). Results: RSP was significantly less in the PM stretch+SPT and SPT+brace than in the SPT (P<0.05). PMI was significantly greater in the PM stretch+SPT and SPT+brace than in the SPT (P<0.05). LT activity was significantly greater in the PM stretch+SPT than in the SPT or SPT+brace in subjects with RSP (P<0.05). Conclusions: The PM stretching exercise and application of a shoulder brace may help correct RSP and restore the length of the PM. The posterior tilting exercise after PM stretching was the most effective method for eliciting greater LT muscle activation among the interventions tested. Copyright © 2014 Elsevier Ltd. All rights reserved.Journal of Electromyography and Kinesiology 10/2014; xxx(xxx). · 1.73 Impact Factor
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ABSTRACT: The normal function of the shoulder is deeply dependent on the adequate and proper motion of the scapula. In its turn, the abnormal alignment of the thoracic and cervical portions of the spine, like the excessive thoracic kyphosis and cervical lordosis, alters the resting position of the scapula. Therefore, the comparison between the spine's curvatures and the blades’ position can be an important contribution for the identification and prevention of pathologies related to the shoulder.The Vertebral Metrics is an innovative instrument that aims at the global evaluation of the spinal column. Noninvasively and semi-automatically, this image processing based system allows the measurement of the x, y, and z positions of each spinous process, on a standing position. This project aims at the evolution of this device, in order to provide the measurement of the three-dimensional position of the scapulae.According to Dr José Machado, physiatrist, the results show that the Vertebral Metrics has sufficient detection efficiency for the global and simultaneous analysis of the spinal column and the shoulder girdle, since it was able to acquire the x, y and z coordinates of each spinous process and of scapular references located on each scapula.Procedia Technology. 11/2014;