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Thigpen C.A.,Proaxis Therapy | Lynch S.S.,Virginia Commonwealth University | Mihalik J.P.,University of North Carolina at Chapel Hill | Prentice W.E.,University of North Carolina at Chapel Hill | Padua D.,University of North Carolina at Chapel Hill
British Journal of Sports Medicine

Objectives To examine the correction of posture, increase in strength and decrease in shoulder pain and dysfunction in varsity swimmers. Design and Setting Randomised clinical trial Participants Twenty-eight. Source

Thigpen C.A.,Proaxis Therapy | Thigpen C.A.,Duke University | Padua D.A.,University of North Carolina at Chapel Hill | Michener L.A.,Virginia Commonwealth University | And 4 more authors.
Journal of Electromyography and Kinesiology

Forward head and rounded shoulder posture (FHRSP) is theorized to contribute to alterations in scapular kinematics and muscle activity leading to the development of shoulder pain. However, reported differences in scapular kinematics and muscle activity in those with forward head and rounded shoulder posture are confounded by the presence of shoulder pain. Therefore, the purpose of this study was to compare scapular kinematics and muscle activity in individuals free from shoulder pain, with and without FHRSP. Eighty volunteers were classified as having FHRSP or ideal posture. Scapular kinematics were collected concurrently with muscle activity from the upper and lower trapezius as well as the serratus anterior muscles during a loaded flexion and overhead reaching task using an electromagnetic tracking system and surface electromyography. Separate mixed model analyses of variance were used to compare three-dimensional scapular kinematics and muscle activity during the ascending phases of both tasks. Individuals with FHRSP displayed significantly greater scapular internal rotation with less serratus anterior activity, during both tasks as well as greater scapular upward rotation, anterior tilting during the flexion task when compared with the ideal posture group. These results provide support for the clinical hypothesis that FHRSP impacts shoulder mechanics independent of shoulder pain. © 2010 Elsevier Ltd. Source

Thigpen C.,Proaxis Therapy | Namdari S.,University of Pennsylvania | Baldwin K.,University of Pennsylvania
Sports Medicine and Arthroscopy Review

Overhead activities require the shoulder to be exposed to and sustain repetitive loads. The segmental activation of the body's links, known as the kinetic chain, allows this to occur effectively. Proper muscle activation is achieved through generation of energy from the central segment or core, which then transfers the energy to the terminal links of the shoulder, elbow, and hand. The kinetic chain is best characterized by 3 components: optimized anatomy, reproducible efficient motor patterns, and the sequential generation of forces. However, tissue injury and anatomic deficits such as weakness and/or tightness in the leg, pelvic core, or scapular musculature can lead to overuse shoulder injuries. These injuries can be prevented and maladaptations can be detected with a thorough understanding of biomechanics of the kinetic chain as it relates to overhead activity. Copyright © 2012 by Lippincott Williams & Wilkins. Source

Joshi M.,University of Sydney | Thigpen C.A.,Proaxis Therapy | Bunn K.,University of North Carolina at Chapel Hill | Karas S.G.,Emory University | Padua D.A.,University of North Carolina at Chapel Hill
Journal of Athletic Training

Context: Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. Objective: To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Setting: Human performance research laboratory. Design: Descriptive laboratory study. Patients or Other Participants: Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. Intervention(s): We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Main Outcome Measure(s): Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. Results: We found a decrease in ascending-phase and descending- phase lower trapezius activity (F1,25 = 5.098, P =.03) and an increase in descending-phase infraspinatus activity (F1,25 = 5.534, P =.03) after the fatigue protocol. We also found an increase in scapular upward rotation (F1,24 = 3.7, P =.04) postfatigue. Conclusions: The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular and glenohumeral force couples. Fatigue-induced alterations in the lower trapezius might predispose the infraspinatus to injury through chronically increased activation. © by the National Athletic Trainers' Association, Inc. Source

Seitz A.L.,Northeastern University | Reinold M.,Boston Red Sox Baseball | Schneider R.A.,Proaxis Therapy | Gill T.J.,Massachusetts General Hospital | Thigpen C.A.,Proaxis Therapy
Journal of Sport Rehabilitation

Context: Differences in 3-dimensional (3D) scapular motion have been reported between healthy baseball position players and healthy nonoverhead athletic controls, as well as players diagnosed with shoulder impingement syndrome. These alterations are theorized to be the result of adaptations due to the demands of repetitive throwing. However, comparisons between the throwing and nonthrowing shoulders are commonly used to infer normal motion. Objective: The purpose of this study was to compare 3D scapular kinematics between the throwing and nonthrowing shoulders in asymptomatic professional male baseball pitchers. Design: Cross-sectional study. Setting: Laboratory. Participants: 45 asymptomatic professional baseball pitchers participating without restrictions during preseason training. Interventions: An electromagnetic tracking system was used to assess 3D scapular orientation at rest and during weighted (2.3-kg) shoulder flexion across discrete humeral-flexion angles (rest, 30°, 60°, 90°, 120°, and maximum). Main Outcome Measure: 3D scapular upward/downward rotation (UR/DR), anteroposterior (AP) tilt, and internal/external rotation (IR/ER). Separate mixed-model ANOVAs (Side × Angle) for each scapular motion were used to compare the throwing and the nonthrowing shoulder across all angles. Results: There were significant side-to-side differences with scapular UR/DR (P <.001), AP tilt (P <.001), and IR/ER (P <.001). The throwing scapula displayed greater mean UR (increase = 3.6°, SE = 0.50) and anterior/posterior tilt (increase = 2.1°, SE = 0.60) and less mean IR (decrease = 2.1°, SE = 0.66) than the nonthrowing shoulder averaged across all arm angles. Conclusions: In asymptomatic professional pitchers, the throwing shoulder's scapular position differs across all arm angles from that of the nonthrowing shoulder, but the motion does not differ. Scapular asymmetry that is consistent throughout arm elevation may be indicative not of pathology but, potentially, of a normal adaptation of the pitching shoulder. © 2012 Human Kinetics, Inc. Source

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