Shoulder-Muscle Activation in Individuals With Previous Shoulder Injuries

2015 ◽  
Vol 24 (3) ◽  
pp. 278-285 ◽  
Author(s):  
Alyssa Muething ◽  
Shellie Acocello ◽  
Kimberly A. Pritchard ◽  
Stephen F. Brockmeier ◽  
Susan A. Saliba ◽  
...  
Keyword(s):  
Shoulder Pain ◽  
Outcome Measures ◽  
Muscle Activation ◽  
Treatment Plan ◽  
Isometric Contractions ◽  
Shoulder Injuries ◽  
Upper Trapezius ◽  
History Of ◽  
Anterior Deltoid ◽  
Lower Trapezius

Context:Understanding how muscles activate in a population with a previous glenohumeral-joint (GH) injury may help clinicians understand how to build a conservative treatment plan to strengthen or activate the specific muscles in an attempt to reduce recurrent shoulder injury and development of GH laxity.Objective:To investigate muscle-activation differences between the previously injured limb of individuals with a history of GH-joint injury and healthy matched controls during functional isometric contractions.Design:Case control.Setting:University research laboratory.Participants:17 individuals (8 women, 9 men; age 22.3 ± 2.6 y, height 172.4 ± 8.8 cm, mass 75.4 ± 16.5 kg) with previous unilateral shoulder pain and 17 (8 women, 9 men; age 22.9 ± 3.9 y, height 170.9 ± 11.3 cm, mass 73.6 ± 22.9 kg) with no history of shoulder pain or injury.Intervention(s):Diagnostic ultrasound measurements of the supraspinatus were completed in both resting and contracted states to assess changes in muscle thickness. Manual muscle tests (anterior deltoid, upper trapezius, infraspinatus, lower trapezius, serratus anterior) and functional isometric contractions (forward flexion, scaption, abduction) were measured using electromyography.Main Outcome Measures:Peak, normalized activation of each muscle and supraspinatus thickness activation ratio were compared between groups and bilaterally within groups using separate ANOVAs.Results:The anterior deltoid was significantly less activated during all functional isometric tasks in previously injured subjects than in healthy subjects (P = .024). In previously injured subjects, the involved limb-lower trapezius was significantly less activated during scaption and abduction tasks than the contralateral side (P = .022 and P = .031, respectively).Conclusions:There were decreases in muscle activation in the anterior deltoid between previously injured and healthy people, as well as in the lower trapezius, in previously injured subjects. Understanding the source of muscle-activation deficits can help clinicians focus rehabilitation exercises on specific muscles.

scholarly journals Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

2011 ◽  
Vol 46 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Mithun Joshi ◽  
Charles A. Thigpen ◽  
Kevin Bunn ◽  
Spero G. Karas ◽  
Darin A. Padua
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
External Rotation ◽  
Shoulder Injuries ◽  
Serratus Anterior ◽  
Overhead Athletes ◽  
Scapular Kinematics ◽  
Fatigue Protocol ◽  
Upper Trapezius ◽  
Lower Trapezius

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.

scholarly journals Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Elisa Raulino Silva ◽  
Nicola Maffulli ◽  
Filippo Migliorini ◽  
Gilmar Moraes Santos ◽  
Fábio Sprada de Menezes ◽  
...  
Keyword(s):  
Shoulder Pain ◽  
Surface Electromyography ◽  
Shoulder Joint ◽  
Muscle Activation ◽  
National Registry ◽  
Kinetic Chain ◽  
Balance Test ◽  
Cross Sectional ◽  
Significant Difference ◽  
Lower Trapezius

Abstract Background The shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain. Methods We divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report. Results The function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038). Conclusion Crossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius. Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

Evaluation of an adjustable support shoulder exoskeleton on static and dynamic overhead tasks

2018 ◽  
Vol 62 (1) ◽  
pp. 804-808 ◽  
Author(s):  
Logan Van Engelhoven ◽  
Nathan Poon ◽  
Homayoon Kazerooni ◽  
Alan Barr ◽  
David Rempel ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Peak Torque ◽  
Industrial Workers ◽  
Human Engineering ◽  
Shoulder Injuries ◽  
Flexor Muscle ◽  
Work Related ◽  
Upper Trapezius ◽  
Shoulder Complex

Introduction: Overhead tasks increase the risk of work related musculoskeletal disorders to industrial workers. A shoulder supporting exoskeleton with adjustable and angle dependent torque (referred to as shoulderX in this paper for brevity) was designed and built at the University of California Berkeley Human Engineering and Robotics Laboratory for workers performing overhead tasks. shoulderX was designed specifically to reduce the exposure to large muscle exertion forces on the shoulder complex from overhead work. Methods: We evaluated shoulderX by measuring the muscle activation of the upper trapezius (UT), anterior deltoid (AD), triceps long head (TR), and infraspinatus (IF) during static and dynamic overhead tasks. Thirteen male subjects with experience in the construction or manufacturing industries were recruited to perform overhead tasks using light (.45 kg) and heavy (2.25 kg) weight tools with four exoskeleton support levels (0, 8.5, 13.0, 20.0 Nm peak torque). Results: During all conditions, the wearer’s shoulder flexor muscle activity of UT, AD were reduced with increasing strength of shoulderX by up to 80%. Subjects unanimously preferred the use of shoulderX over the unassisted condition for all task types (static and dynamic overhead tasks) and tool weights (.45 kg and 2.25 kg). Conclusion: shoulderX reduces the wearer’s primary muscle activity in overhead static and dynamic work and results in a more desirable and balanced pattern of shoulder complex activation. This investigation indicates that shoulderX reduces the risk of work related shoulder injuries during overhead tasks.

Hip-Abduction Torque and Muscle Activation in People With Low Back Pain

2015 ◽  
Vol 24 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Mark A. Sutherlin ◽  
Joseph M. Hart
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Muscle Function ◽  
Muscle Activation ◽  
Low Back ◽  
Hip Muscle ◽  
Hip Abduction ◽  
History Of

Context:Individuals with a history of low back pain (LBP) may present with decreased hip-abduction strength and increased trunk or gluteus maximus (GMax) fatigability. However, the effect of hip-abduction exercise on hip-muscle function has not been previously reported.Objective:To compare hip-abduction torque and muscle activation of the hip, thigh, and trunk between individuals with and without a history of LBP during repeated bouts of side-lying hip-abduction exercise.Design:Repeated measures.Setting:Clinical laboratory.Participants:12 individuals with a history of LBP and 12 controls.Intervention:Repeated 30-s hip-abduction contractions.Main Outcome Measures:Hip-abduction torque, normalized root-mean-squared (RMS) muscle activation, percent RMS muscle activation, and forward general linear regression.Results:Hip-abduction torque reduced in all participants as a result of exercise (1.57 ± 0.36 Nm/kg, 1.12 ± 0.36 Nm/kg; P < .001), but there were no group differences (F = 0.129, P = .723) or group-by-time interactions (F = 1.098, P = .358). All participants had increased GMax activation during the first bout of exercise (0.96 ± 1.00, 1.18 ± 1.03; P = .038). Individuals with a history of LBP had significantly greater GMax activation at multiple points during repeated exercise (P < .05) and a significantly lower percent of muscle activation for the GMax (P = .050) at the start of the third bout of exercise and for the biceps femoris (P = .039) at the end of exercise. The gluteal muscles best predicted hip-abduction torque in controls, while no consistent muscles were identified for individuals with a history of LBP.Conclusions:Hip-abduction torque decreased in all individuals after hip-abduction exercise, although individuals with a history of LBP had increased GMax activation during exercise. Gluteal muscle activity explained hip-abduction torque in healthy individuals but not in those with a history of LBP. Alterations in hip-muscle function may exist in individuals with a history of LBP.

Acute Effects of Posture Shirts on Rounded-Shoulder and Forward-Head Posture in College Students

2016 ◽  
Vol 25 (4) ◽  
pp. 309-314 ◽  
Author(s):  
John Manor ◽  
Elizabeth Hibberd ◽  
Meredith Petschauer ◽  
Joseph Myers
Keyword(s):  
College Students ◽  
Shoulder Pain ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Acute Effects ◽  
Contributing Factors ◽  
Student Body ◽  
Forward Head Posture ◽  
Head Posture ◽  
History Of

Context:Rounded-shoulder and forward-head posture can be contributing factors to shoulder pain. Corrective techniques such as manual therapy and exercise have been shown to improve these altered postures, but there is little evidence that corrective garments such as posture shirts can alter posture.Objectives:To determine the acute effects of corrective postureshirt use on rounded-shoulder and forward-head posture in asymptomatic college students.Design:Repeated-measures intervention study with counterbalanced conditions.Setting:Research laboratory.Participants:24 members of the general student body of a university, 18–25 y old, with a forward shoulder angle (FSA) >52° and no history of upper-extremity surgery, scoliosis, active shoulder pain, or shoulder pain in the previous 3 mo that restricted participation for 3 consecutive days.Interventions:Photographic posture assessment under a control condition, under a sham or treatment condition (counterbalanced), under another control condition, and treatment or sham.Main Outcome Measures:FSA and forward head angle (FHA) calculated from a lateral photograph.Results:FSA decreased relative to the control condition while participants wore the sham shirt (P = .029) but not the corrective posture shirt (P = 1.00). FHA was unchanged between groups (P = .371).Conclusions:Application of a corrective posture shirt did not acutely alter FSA or FHA, while application of a sham shirt may decrease FSA at rest.

Effects of Kinesiology Taping on Scapular Reposition Accuracy, Kinematics, and Muscle Activity in Athletes With Shoulder Impingement Syndrome: A Randomized Controlled Study

2018 ◽  
Vol 27 (6) ◽  
pp. 560-569 ◽  
Author(s):  
Yi-Fen Shih ◽  
Ya-Fang Lee ◽  
Wen-Yin Chen
Keyword(s):  
Muscle Activation ◽  
Position Sense ◽  
Joint Position Sense ◽  
Controlled Study ◽  
Shoulder Impingement ◽  
Scapular Kinematics ◽  
Randomized Controlled ◽  
Upper Trapezius ◽  
Posterior Tilt ◽  
Lower Trapezius

Context:Scapular proprioception is a key concern in managing shoulder impingement syndrome (SIS). However, no study has examined the effect of elastic taping on scapular proprioception performance.Objective:To investigate the immediate effect of kinesiology taping (KT) on scapular reposition accuracy, kinematics, and muscle activation in individuals with SIS.Design:Randomized controlled study.Setting:Musculoskeletal laboratory, National Yang-Ming University, Taiwan.Participants:Thirty overhead athletes with SIS.Interventions:KT or placebo taping over the upper and lower trapezius muscles.Main Outcome Measures:The primary outcome measures were scapular joint position sense, measured as the reposition errors, in the direction of scapular elevation and protraction. The secondary outcomes were scapular kinematics and muscle activity of the upper trapezius, lower trapezius, and serratus anterior during arm elevation in the scapular plane (scaption).Results:Compared with placebo taping, KT significantly decreased the reposition errors of upward/downward rotation (P = .04) and anterior/posterior tilt (P = .04) during scapular protraction. KT also improved scapular kinematics (significant group by taping effect for posterior tilt,P = .03) during scaption. Kinesiology and placebo tapings had a similar effect on upper trapezius muscle activation (significant taping effect,P = .003) during scaption.Conclusions:Our study identified the positive effects of KT on scapular joint position sense and movement control. Future studies with a longer period of follow-up and clinical measurement might help to clarify the clinical effect and mechanisms of elastic taping in individuals with SIS.

scholarly journals Volitional Preemptive Abdominal Contraction and Upper Extremity Muscle Latencies During D1 Flexion and Scaption Shoulder Exercises

2018 ◽  
Vol 53 (12) ◽  
pp. 1181-1189 ◽  
Author(s):  
Ramonica Scott ◽  
Hyung Suk Yang ◽  
C. Roger James ◽  
Steven F. Sawyer ◽  
Phillip S. Sizer
Keyword(s):  
Serratus Anterior ◽  
Movement Initiation ◽  
Open Chain ◽  
Cross Sectional ◽  
Upper Trapezius ◽  
Shoulder Muscle ◽  
Onset Timing ◽  
Asymptomatic Volunteers ◽  
Anterior Deltoid ◽  
Lower Trapezius

Context The abdominal-bracing maneuver, a volitional preemptive abdominal contraction (VPAC) strategy, is commonly used during resisted shoulder exercises. How VPAC affects shoulder-muscle function during resisted shoulder exercise is unknown. Objective To identify the effects of VPAC on selected parascapular and glenohumeral muscles during specific shoulder exercises with or without resistance. Design Cross-sectional study. Setting Clinical biomechanics research laboratory. Patients or Other Participants Twenty-two asymptomatic volunteers between 18 and 40 years of age. Intervention(s) Participants performed arm elevation in scaption and D1 shoulder-flexion (D1F) patterns with and without resistance and VPAC. Main Outcome Measure(s) Electromyography was used to test the muscle-contraction amplitudes and onset timing of the anterior deltoid, posterior deltoid, upper trapezius, lower trapezius, and serratus anterior. Muscle-response amplitudes were quantified using root mean square electromyography. Shoulder-muscle relative-onset timing was quantified in reference to kinematic elbow-movement initiation. Results The VPAC increased serratus anterior amplitude during D1F (P &lt; .001) and scaption (P &lt; .001) and upper trapezius amplitude (P &lt; .001) in scaption. All muscle amplitudes increased with resistance. The VPAC decreased muscle-onset latencies for the anterior deltoid (P &lt; .001), posterior deltoid (P = .008), upper trapezius (P = .001), lower trapezius (P = .006), and serratus anterior (P = .001) during D1F. In addition, the VPAC decreased muscle-onset latencies for the anterior deltoid (P &lt; .001), posterior deltoid (P = .007), upper trapezius (P &lt; .001), lower trapezius (P &lt; .001), and serratus anterior (P &lt; .001) during scaption. Conclusions The VPAC affected only the parascapular muscles that had the greatest scapular-stabilizing roles during the specific open chain movement we tested. It decreased latencies in all muscles. These neuromuscular changes may enhance the stability of the shoulder during D1F and scaption exercises.

Differences in trapezius muscle activation patterns in office workers with and without chronic neck-shoulder pain, as quantified through exposure variation analysis

2018 ◽  
Vol 62 (1) ◽  
pp. 962-966
Author(s):  
Denean Kelson ◽  
Divya Srinivasan ◽  
Svend Erik Mathiassen
Keyword(s):  
Chronic Pain ◽  
Shoulder Pain ◽  
Muscle Activation ◽  
Trapezius Muscle ◽  
Variation Analysis ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Upper Trapezius ◽  
Exposure Variation Analysis ◽  
And Control

The purpose of this study was to quantify upper-trapezius muscle activation patterns using exposure variation analysis (EVA) in healthy computer workers and those with chronic neck-shoulder pain. Eight healthy and five chronic pain participants were asked to complete three computer-based tasks (TYPE, CLICK, and FORM) in two pacing conditions (self-paced and control-paced). EVA was used to quantify variation using five amplitude classes and five duration classes. Performance in each task was also quantified. Healthy workers and those with chronic pain did not differ in performance, and they both exhibited similarly low levels of muscle activation amplitude. Pain participants, however, were found to spend less time in lower duration classes across tasks and conditions. These results indicate that individuals with chronic neck-shoulder pain utilize movement strategies involving sustained durations of continuous muscle activation. This may be suggestive of decreased temporal variation in muscle activation patterns in those with chronic pain.

scholarly journals Scapular Muscle Tests in Subjects With Shoulder Pain and Functional Loss: Reliability and Construct Validity

2005 ◽  
Vol 85 (11) ◽  
pp. 1128-1138 ◽  
Author(s):  
Lori A Michener ◽  
N Douglas Boardman ◽  
Peter E Pidcoe ◽  
Angela M Frith
Keyword(s):  
Construct Validity ◽  
Shoulder Pain ◽  
Muscle Activity ◽  
Trapezius Muscle ◽  
Muscle Performance ◽  
Serratus Anterior ◽  
Functional Loss ◽  
Upper Trapezius ◽  
Lower Trapezius ◽  
Isometric Muscle

Abstract Background and Purpose. Scapular muscle performance evaluated with a handheld dynamometer (HHD) has been investigated only in people without shoulder dysfunction for test-retest reliability of data obtained with a single scapular muscle test. The purpose of this study was to assess the reliability, error, and validity of data obtained with an HHD for 4 scapular muscle tests in subjects with shoulder pain and functional loss. Subjects and Methods. Subjects (N=40) with shoulder pain and functional loss were tested bymeasuring the kilograms applied with an HHD during 3 trials for muscle tests for the lower trapezius, upper trapezius, middle trapezius, and serratus anterior muscles. Concurrently, surface electromyography (sEMG) data were collected for the 4 muscles. The same procedures were performed 24 to 72 hours after the initial testing by the same tester. Muscle tests were performed 3 times, and the results were averaged for data analysis. Results. Intraclass correlation coefficients for intratester reliability of measurements of isometricforce obtained using an HHD ranged from .89 to .96. The standard error of the measure (90% confidenceinterval [CI]) ranged from 1.3 to 2.7 kg; the minimal detectable change (90% CI) ranged from 1.8 to 3.6 kg. Construct validity assessment, done by comparing the amounts of isometric muscle activity (sEMG) for each muscle across the 4 muscle tests, revealed that the muscle activity of the upper trapezius and lower trapezius muscles washighest during their respective tests. Conversely, the isometric muscle activity of the middle trapezius and serratus anterior muscles was not highest during their respective tests. Discussion and Conclusion. In people with shoulder pain and functional loss, the intrarater reliability and error over 1 to 3 days were established using an HHD for measurement of isometric force for the assessment of scapular muscle performance. Error values can be used to make decisions regarding individual patients. Construct validity was established for the lower and upper trapezius muscle tests; therefore, these tests are advocated for use. However, construct validity was not demonstrated for the serratus anterior and middle trapezius muscle tests as performed in this study. Further investigation of these muscle tests is warranted.

Analysis of neck and back muscle activity during the application of various pillow designs in patients with forward head posture

2021 ◽  
pp. 1-9
Author(s):  
Sirirat Kiatkulanusorn ◽  
Bhornluck Paepetch Suato ◽  
Phurichaya Werasirirat
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Trapezius Muscle ◽  
Back Muscle ◽  
Forward Head Posture ◽  
Sleeping Position ◽  
Head Posture ◽  
Upper Trapezius ◽  
Activation Response ◽  
Lower Trapezius

BACKGROUND: There are currently no reports of biomechanical changes in patients with forward head posture (FHP) that result in altered muscle activation throughout various functions with muscle activation response during diverse sleep postures. OBJECTIVE: This study investigated neck and back muscle activity in individuals with and without FHP during a maintained side-sleeping position by incorporating various pillow designs. METHODS: Thirty-four participants (i.e. 17 in each group) were enrolled. The muscle activity was investigated via surface electromyography during the use of three trial pillows: orthopedic pillow, hollow pillow, and Thai neck support pillow. RESULTS: With the application of all three trial pillows the FHP group demonstrated significantly greater lower trapezius muscle activity than the normal head posture group (p< 0.05). Sternocleidomastoid and upper trapezius (UT) muscle activity were similar between the two groups (p> 0.05). Only UT muscle activity was affected by variations in pillow design. In the normal group no difference was observed in the muscle activity between all three pillows (p> 0.05). CONCLUSIONS: Feasibly, the ability to appropriately modify a pillow configuration without creating undesired muscle activation was limited to those exhibiting FHP. Therefore, specially designed pillows or mattresses should be investigated in terms of their relevance to muscle fatigue and potential musculoskeletal pain in FHP patients.

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