Normalization to Maximal Voluntary Contraction is Influenced by Subacromial Pain

In this study, we aimed to determine if electromyography (EMG) normalization to maximal voluntary isometric contractions (MVIC) was influenced by subacromial pain in patients with subacromial impingement syndrome. Patients performed MVICs in unique testing positions for each shoulder muscle tested before and after subacromial injection of local anesthetic. In addition to collection of MVIC data, EMG data during an arm elevation task were recorded before and after injection. From a visual analog pain scale, patients had a 64% decrease in pain following the injection. Significant increases in MVICs were noted in 4 of the 7 shoulder muscles tested: anterior, middle and posterior deltoid, and lower trapezius. No significant differences were noticed for the upper trapezius, latissimus dorsi, or serratus anterior. MVIC condition (pre and post injection) had a significant influence on EMG normalization for the anterior deltoid and lower trapezius muscle. Results indicate that subacromial pain can influence shoulder muscle activity, especially for the deltoid muscles and lower trapezius. In addition, normalization to MVIC in the presence of pain can have unpredictable results. Caution should be taken when normalizing EMG data to MVIC in the presence of pain.

Download Full-text

Shoulder Muscle Activity in Sport Climbing in Naturally Chosen and Corrected Shoulder Positions

The Open Sports Sciences Journal ◽

10.2174/1875399x01710010107 ◽

2017 ◽

Vol 10 (1) ◽

pp. 107-113

Author(s):

Jiří Baláš ◽

Alena Duchačová ◽

David Giles ◽

Kateřina Kotalíková ◽

David Pánek ◽

...

Keyword(s):

Muscle Activity ◽

External Rotation ◽

Voluntary Contraction ◽

The Other ◽

Electromyographic Activity ◽

Serratus Anterior ◽

Upper Trapezius ◽

Shoulder Muscle ◽

Sport Climbing ◽

Lower Trapezius

Objective:The aim of the study was to determine electromyographic activity of the scapula stabilizing muscles in naturally chosen and corrected shoulder positions in typical static climbing postures.Methods:Six male participants undertook surface electromyography measurement in four climbing postures for two different shoulder positions. The activity of the lower, middle and upper trapezius, serratus anterior, pectoralis major, and sternocleidomastoid was recorded. Electromyographic activity was expressed as the percentage of maximal voluntary contraction (MVC) for each muscle.Results:Climbing postures induced higher activation of middle and lower trapezius in corrected shoulder positions (35.3 ± 11.8 and 61.7 ± 15.4% MVC respectively) than in naturally chosen shoulder positions (18.4 ± 8.9 and 30.1 ± 13.8% MVC respectively). The highest activity of the middle and lower trapezius was found in postures with the arm in external rotation and 90° abduction and in an overhanging posture. Low activation was stated for the other muscles in both shoulder conditions.Conclusion:Results showed that climbers naturally elevate the shoulder during typical static postures. Corrected shoulder positions induce higher activation of the scapula stabilizing muscles than naturally chosen shoulder positions.

Download Full-text

Muscle Activity Before and After Subacromial Injection

Journal of Sport Rehabilitation ◽

10.1123/jsr.2020-0524 ◽

2021 ◽

pp. 1-7

Author(s):

Lucas Ettinger ◽

Matthew Shaprio ◽

Andrew Karduna

Keyword(s):

Rotator Cuff ◽

Muscle Activation ◽

Rotator Cuff Tears ◽

Subacromial Impingement ◽

Upper Trapezius ◽

Subacromial Injection ◽

Shoulder Muscle ◽

Shoulder Muscles ◽

Before And After ◽

Arm Elevation

Context: Shoulder muscle activation in patients with subacromial impingement is highly cited and variable in the literature. Differences between studies could be due to artifacts introduced by normalization practices in the presence of pain. Ultimately, this lack of knowledge pertaining to pathogenesis limits the clinical treatment and restoration of muscular function. Design: A total of 21 patients with stage 2 subacromial impingement and 21 matched controls were recruited for EMG testing of their affected shoulder during an arm elevation task. The patients were tested before and after receiving an injection to their subacromial bursa. Methods: The EMG from 7 shoulder muscles were measured before and after treatment during humeral motion in the scapular plane. Results: Our findings indicate an increase in anterior deltoid, middle deltoid, and upper trapezius activity following the injection; further, this trend extended to the controls. The control subjects had a greater activation of the latissimus dorsi at peak arm elevation when compared with the patient group postinjection. Conclusions: Our results indicate that a reduction in subacromial pain is associated with changes in shoulder muscle recruitment, primarily of the deltoid. This change in deltoid activity may lend evidence to rotator cuff function in patients without rotator cuff tears.

Download Full-text

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

Journal of Athletic Training ◽

10.4085/1062-6050-255-17 ◽

2018 ◽

Vol 53 (12) ◽

pp. 1181-1189 ◽

Cited By ~ 2

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 < .001) and scaption (P < .001) and upper trapezius amplitude (P < .001) in scaption. All muscle amplitudes increased with resistance. The VPAC decreased muscle-onset latencies for the anterior deltoid (P < .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 < .001), posterior deltoid (P = .007), upper trapezius (P < .001), lower trapezius (P < .001), and serratus anterior (P < .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.

Download Full-text

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

Physical Therapy ◽

10.1093/ptj/85.11.1128 ◽

2005 ◽

Vol 85 (11) ◽

pp. 1128-1138 ◽

Cited By ~ 78

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.

Download Full-text

Rehabilitation of Scapular Muscle Balance

The American Journal of Sports Medicine ◽

10.1177/0363546507303560 ◽

2007 ◽

Vol 35 (10) ◽

pp. 1744-1751 ◽

Cited By ~ 265

Author(s):

Ann M. Cools ◽

Vincent Dewitte ◽

Frederick Lanszweert ◽

Dries Notebaert ◽

Arne Roets ◽

...

Keyword(s):

External Rotation ◽

Trapezius Muscle ◽

Electromyographic Activity ◽

Shoulder Injury ◽

Serratus Anterior ◽

Upper Trapezius ◽

Strengthening Exercises ◽

Muscle Balance ◽

Lower Trapezius ◽

Balance Rehabilitation

Background Strengthening exercises for the scapular muscles are used in the treatment of scapulothoracic dysfunction related to shoulder injury. In view of the intermuscular and intramuscular imbalances often established in these patients, exercises promoting lower trapezius (LT), middle trapezius (MT), and serratus anterior (SA) activation with minimal activity in the upper trapezius (UT) are recommended. Hypothesis Of 12 commonly used trapezius strengthening exercises, a selection can be performed for muscle balance rehabilitation, based on a low UT/LT, UT/MT, or UT/SA muscle ratio. Study Design Controlled laboratory study. Methods Electromyographic activity of the 3 trapezius parts and the SA was measured in 45 healthy subjects performing 12 commonly described scapular exercises, using surface electromyography. Results For each intramuscular trapezius ratio (UT/LT, UT/MT), 3 exercises were selected for restoration of muscle balance. The exercises side-lying external rotation, side-lying forward flexion, prone horizontal abduction with external rotation, and prone extension were found to be the most appropriate for intramuscular trapezius muscle balance rehabilitation. For the UT/SA ratio, none of the exercises met the criteria for optimal intermuscular balance restoration. Conclusion In cases of trapezius muscle imbalance, some exercises are preferable over others because of their low UT/LT and UT/MT ratios. Clinical Relevance In the selection of rehabilitation exercises, the clinician should have a preference for exercises with high activation of the LT and MT and low activity of the UT.

Download Full-text

Prevalence of Upper Cross Syndrome in Different Occupations

Pakistan Journal of Physical Therapy (PJPT) ◽

10.52229/pjpt.v0i0.980 ◽

2021 ◽

pp. 04-08

Author(s):

Rizmi Naseer ◽

Sana Tauqeer

Keyword(s):

Rating Scale ◽

Neck Disability Index ◽

Trapezius Muscle ◽

Cross Sectional Study ◽

Study Data ◽

Pectoralis Major ◽

Serratus Anterior ◽

Cross Sectional ◽

Upper Trapezius ◽

Lower Trapezius

Upper crossed syndrome is caused by weak lower and middle trapezius, tight upper trapezius and levator scapulae, weak deep-neck flexors, tight sub occipital muscles and sternocleidomastoid, weak serratus anterior, and tight pectoralis major and minor Objective: To find prevalence of upper cross syndrome in different occupations Methodology: In this cross sectional study data was collected from department of physical therapy Hamza Medical Centre, Islamabad. Study was conducted in 6 months (June 2019 to December 2019).Sample size was 37 that was collected through Epitool calculator. Participants were made aware of the study Pectoralis major contracture test was performed to check the pectoral muscles tightness. After that, trapezius weakness test was performed. In this test weakness of middle and lower trapezius muscle was assessed Verbal consent form was taken. Data collection tools were Numeric pain rating scale (NPRS) and Neck disability index (Pain).Data was analyzed by using SPSS version 20. Results: Total 37 participants were recruited for this The mean age for the participants was 32.11+ 5.606.There were 54.5% male participants and 45.95 female participants.%. Prevalence of upper cross syndrome in desk workers was (12)32.43%.Pravalence of Upper Cross syndrome in Drivers was (9)924.325.Pravalence of upper cross syndrome in House wives was (10)27.035.Pravalence of Upper cross syndrome in teachers was (6)16.22%. Conclusion: This research concluded that there is prevalence of upper cross syndrome in different occupations. This study also concluded that rest and medicine are reliving factors for upper cross syndrome participants

Download Full-text

Role of the kinetic chain in shoulder rehabilitation: does incorporating the trunk and lower limb into shoulder exercise regimes influence shoulder muscle recruitment patterns? Systematic review of electromyography studies

BMJ Open Sport & Exercise Medicine ◽

10.1136/bmjsem-2019-000683 ◽

2020 ◽

Vol 6 (1) ◽

pp. e000683

Author(s):

Eleanor Richardson ◽

Jeremy S Lewis ◽

Jo Gibson ◽

Chris Morgan ◽

Mark Halaki ◽

...

Keyword(s):

Systematic Review ◽

Lower Limb ◽

Trapezius Muscle ◽

Cochrane Central Register ◽

Muscle Recruitment ◽

Kinetic Chain ◽

Serratus Anterior ◽

Significant Difference ◽

Recruitment Patterns ◽

Lower Trapezius

ObjectiveTo investigate the influence of trunk and lower limb motion on electromyography (EMG) muscle activity and recruitment patterns around the shoulder.DesignSystematic review.Data sourcesMEDLINE, CINAHL, PEDro, AMED, PubMed, Cochrane Central Register of Controlled trials, Cochrane Database of Systematic reviews, SportsDiscuss and PROSPERO.Eligibility criteriaStudies investigating both multiregional kinetic chain (KC) shoulder exercises and localised non-kinetic chain (nKC) shoulder exercises in healthy subjects under the same experimental conditions were included in this review.ResultsKC exercises produced greater EMG activation levels in 5 of 11 studies for the lower trapezius. Of the remaining studies, five found no difference between the exercise types and one favoured nKC exercises. KC exercises produced greater EMG activation levels in 5 of 11 studies for the serratus anterior. Of the remaining studies, three reported the opposite and three found no significant difference between the exercise types. nKC exercises produced greater EMG activation in infraspinatus in three of four studies. KC exercises produced the lowest trapezius muscle ratios in all studies. Studies investigating the upper trapezius, middle trapezius, supraspinatus, subscapularis, biceps brachii, latifissimus dorsi, pectoralis major, deltoid, and trapezius and serratus anterior ratios showed inconsistency.ConclusionThis review found evidence that integrating the KC during shoulder rehabilitation may increase axioscapular muscle recruitment, produce lower trapezius muscle ratios and reduce the demands on the rotator cuff. Stepping appears preferable to squatting.PROSPERO registration numberCRD42015032557, 2015.

Download Full-text

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

Physical Therapy ◽

10.1093/ptj/80.3.276 ◽

2000 ◽

Vol 80 (3) ◽

pp. 276-291 ◽

Cited By ~ 900

Author(s):

Paula M Ludewig ◽

Thomas M Cook

Keyword(s):

Occupational Exposure ◽

Muscle Activity ◽

Load Condition ◽

Trapezius Muscle ◽

Electromyographic Activity ◽

Serratus Anterior Muscle ◽

Serratus Anterior ◽

Shoulder Impingement ◽

Upper Trapezius ◽

Load Conditions

AbstractBackground 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 hand-held 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.

Download Full-text

Scapula Muscle Activations During Overhead Throwing Holds

International Journal of Athletic Therapy & Training ◽

10.1123/ijatt.2015-0038 ◽

2016 ◽

Vol 21 (3) ◽

pp. 42-46 ◽

Cited By ~ 1

Author(s):

Gretchen Oliver ◽

Lisa Henning ◽

Hillary Plummer

Keyword(s):

Surface Electromyography ◽

Serratus Anterior ◽

Upper Trapezius ◽

Overhead Throwing ◽

Muscle Activations ◽

Lower Trapezius

The purpose of this study was to examine activations of selected scapular stabilizing musculature while performing an overhead throw with a hold (not releasing the ball) in two different throwing positions—standing with a crow hop and kneeling on the ipsilateral knee. Surface electromyography was used to examine activations of throwing side lower trapezius (LT), middle trapezius (MT), serratus anterior (SA), and upper trapezius (UT). Muscle activations were recorded while performing the overhead throw with holds while in two throwing positions. MANOVA results revealed no significant differences between the two throwing conditions and muscle activations of LT, MT, SA, and UT: F(8,124) = .804, p = .600; Wilks’s Λ = .904, partial η2 = .049. Although no significant differences were observed in the scapular stabilizers between the two conditions, moderate (21–50% MVIC) to high (> 50% MVIC) activations of each muscle were present, indicating that nonrelease throws may be beneficial for scapular stabilization in throwers.

Download Full-text