Electromyographical Comparison of Four Common Shoulder Exercises in Unstable and Stable Shoulders

This study examines if electromyographic (EMG) amplitude differences exist between patients with shoulder instability and healthy controls performing scaption, prone horizontal abduction, prone external rotation, and push-up plus shoulder rehabilitation exercises. Thirty nine subjects were categorized by a single orthopedic surgeon as having multidirectional instability (n=10), anterior instability (n=9), generalized laxity (n=10), or a healthy shoulder (n=10). Indwelling and surface electrodes were utilized to measure EMG activity (reported as a % of maximum voluntary isometric contraction (MVIC)) in various shoulder muscles during 4 common shoulder exercises. The exercises studied effectively activated the primary musculature targeted in each exercise equally among all groups. The serratus anterior generated high activity (50–80% MVIC) during a push-up plus, while the infraspinatus and teres major generated moderate-to-high activity (30–80% MVIC) during both the prone horizontal and prone external rotation exercises. Scaption exercise generated moderate activity (20–50% MVIC) in both rotator cuff and scapular musculature. Clinicians should feel confident in prescribing these shoulder-strengthening exercises in patients with shoulder instability as the activation levels are comparable to previous findings regarding EMG amplitudes and should improve the dynamic stabilization capability of both rotator cuff and scapular muscles using exercises designed to address glenohumeral joint instability.

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Effect of Glenohumeral Joint Rotation on Serratus Anterior, Pectoralis Major and Upper Trapezius EMG Activity during Push-up Plus Exercise

The Journal of Korean Physical Therapy ◽

10.18857/jkpt.2016.28.2.106 ◽

2016 ◽

Vol 28 (2) ◽

pp. 106-111 ◽

Cited By ~ 3

Author(s):

Young-Hun Shim ◽

Ki-Seok Nam ◽

Ji-Won Park

Keyword(s):

Glenohumeral Joint ◽

Pectoralis Major ◽

Emg Activity ◽

Serratus Anterior ◽

Joint Rotation ◽

Upper Trapezius ◽

Push Up

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EMG ACTIVITY OF THE SERRATUS ANTERIOR AND TRAPEZIUS MUSCLES DURING ELEVATION AND PUSH UP EXERCISES

Journal of Bodywork and Movement Therapies ◽

10.1016/j.jbmt.2021.02.002 ◽

2021 ◽

Author(s):

Thomas Patselas ◽

Stefanos Karanasios ◽

Vasiliki Sakellari ◽

Ioannis Fysekis ◽

Marios I. Patselas ◽

...

Keyword(s):

Emg Activity ◽

Serratus Anterior ◽

Push Up

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Anatomy and Biomechanic of the Shoulder

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967119s00466 ◽

2019 ◽

Vol 7 (11_suppl6) ◽

pp. 2325967119S0046

Author(s):

Troydimas Panjaitan

Keyword(s):

Rotator Cuff ◽

Humeral Head ◽

Glenohumeral Joint ◽

External Rotation ◽

Central Component ◽

Subscapularis Tendon ◽

Glenoid Fossa ◽

Greater Tuberosity ◽

Glenohumeral Ligaments ◽

Shoulder Complex

The shoulder is one of the most complex joints of the human body. Consequently, they are susceptible to injury and degeneration. Mechanical shoulder pathology typically results when overuse, extremes of motion, or excessive forces overwhelm intrinsic material properties of the shoulder complex resulting in tears of the rotator cuff, capsule, and labrum. The fundamental central component of the shoulder complex is the glenohumeral joint. It has a ball-and-socket configuration with a surface area ratio of the humeral head to glenoid fossa of about 3:1 with an appearance similar to a golf ball on a tee. Overall, there is minimal bony covering and limited contact areas that allow extensive translational and rotational ability in all three planes. The glenohumeral joint has 2 groups of stabilizers, which are static (passive) and dynamic (active) restrains. Static stabilizers include the concavity of the glenoid fossa, glenoid fossa retroversion and superior angulation, glenoid labrum, the joint capsule, and glenohumeral ligaments, and a vacuum effect from negative intra-articular pressure. Dynamic stabilization is merely the coordinated contraction of the rotator cuff muscles that create forces that compress the articular surfaces of the humeral head into the concave surface of the glenoid fossa. During upper extremity movement, the effects of static stabilizers are minimized and dynamic or active stabilizers become the dominant forces responsible for glenohumeral stability The simple act of arm elevation is a complex task that occurs via the combination of glenohumeral and scapulothoracic motion, together known as scapulohumeral rhythm. In the first 1200, glenohumeral arm abduction, the supraspinatus and deltoid work together and create a force couple that promotes stability, while raising the arm (deltoid contraction). In addition, the humerus must undergo 450 external rotation to not only clear the greater tuberosity posteriorly but also loosen the inferior glenohumeral ligament (IGHL) to allow maximum elevation. There are several anatomical updates regarding the rotator cuff and capsular footprint. The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus. The superior-most insertion of the subscapularis tendon extends a thin tendinous slip, which attaches to the fovea capitis of the humerus. The teres minor muscle inserts to the lowest impression of the greater tuberosity of the humerus and additionally inserts to the posterior side of the surgical neck of the humerus.

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Muscle Activity of the Latissimus Dorsi after Tendon Transfer in Patients with Rotator Cuff Tears

Journal of Clinical Medicine ◽

10.3390/jcm9020433 ◽

2020 ◽

Vol 9 (2) ◽

pp. 433 ◽

Cited By ~ 1

Author(s):

Pit Hetto ◽

David Spranz ◽

Felix Zeifang ◽

Sebastian I. Wolf ◽

Stefan van Drongelen ◽

...

Keyword(s):

Rotator Cuff ◽

Latissimus Dorsi ◽

Tendon Transfer ◽

Daily Life ◽

External Rotation ◽

Rotator Cuff Tears ◽

Emg Activity ◽

Measurement Protocol ◽

Partial Activity ◽

Perineal Care

Background: Massive irreparable posterosuperior rotator cuff tears may result in the loss of external rotation. Most of the patients with posterosuperior rotator cuff tears suffer from a restriction in their daily life actions. Latissimus dorsi tendon transfer (LDTT) is a method to restore abduction and external rotation in these patients. However, the behavior of the LD after the transfer is not clear yet. Few studies have analyzed the activity of the LD after transfer. The goal of this study was to examine the function of the LD postoperatively in follow-up examinations during activities of daily life (ADLs) and during different movements evaluated by measuring the range of motion (ROM). Methods: We examined 12 patients 4.3 years (1–9 years) after LDTT, using simultaneous 3D motion analysis and surface Electromyography (sEMG) of 12 muscle parts; the opposite, nonaffected side was assessed as a control. The measurement protocol included two standardized movements (exorotation with an adducted arm and exorotation with 90° abduction) as well as two ADLs (combing hair and perineal care). Results: An average of 4.3 years (1–9 years) after LDTT, 9 of the 12 subjects showed EMG activity in the transferred LD during glenohumeral external rotation. During the endorotation phase, either little activity was registered or only the pectoralis major was active. During the ADLs, 6 out of 12 subjects showed EMG activity in the transferred LD while “combing hair”, whereas all subjects showed EMG activity during perineal care. Conclusion: The LD showed partial activity in its new role as an exorotator, but no clear difference was observed between some of the movements as well as in comparison with the healthy shoulder. Further studies will need to be conducted to better differentiate voluntary contractions and co-contractions as well as tension and extension in the muscle.

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Serratus Anterior and Upper Trapezius Electromyographic Analysis of the Push-Up Plus Exercise: A Systematic Review and Meta-Analysis

Journal of Athletic Training ◽

10.4085/1062-6050-237-18 ◽

2019 ◽

Vol 54 (11) ◽

pp. 1156-1164 ◽

Cited By ~ 1

Author(s):

Fu-Jie Kang ◽

Hsiang-Ling Ou ◽

Kun-Ying Lin ◽

Jiu-Jenq Lin

Keyword(s):

Confidence Interval ◽

Lower Extremity ◽

Meta Analysis ◽

Flexion Angle ◽

Emg Activity ◽

Serratus Anterior ◽

Upper Trapezius ◽

Stable Surface ◽

Shoulder Flexion ◽

Push Up

Context Whereas the serratus anterior (SA) and the upper trapezius (UT) work as a force couple for scapular motion, weakness of the SA and overactivation of the UT are often present in overhead athletes with shoulder dysfunction. Therefore, researchers addressing an intramuscular imbalance between the SA and UT have focused on finding exercises that target the weak SA and minimally activate the UT. Objective To compare the effectiveness of push-up plus (PUP) exercise variants based on the electromyographic (EMG) activity of the SA and UT. Data Sources A systematic search of PubMed and Scopus between January 1, 2000, and March 31, 2008. Study Selection Studies of PUP exercises that involved EMG analysis. Data Extraction We assessed study quality using the Critical Appraisal Skills Program. For the systematic analysis, the following data were extracted: (1) author, year, and study design; (2) participant characteristics; (3) type of PUP intervention; (4) EMG outcome measures; and (5) main results. For the meta-analysis, the EMG data of the SA and UT were calculated using the mean difference of EMG activity with a 95% confidence interval. Data Synthesis Based on 19 studies with 356 participants, different hand positions (the distance between the hands, shoulder-flexion angle, and elbow-flexion angle) and different lower extremity positions variably affected the activation of the SA and UT during the PUP exercise. Also, when participants performed the PUP on an unstable surface compared with a stable surface, UT activity increased 2.74% (95% confidence interval = 0.07%, 5.41%). Conclusions The standard PUP exercise elicited high EMG activity of the SA. Participants generated higher SA and lower UT EMG activity when they performed the PUP exercise on a stable surface in full elbow extension, with the hands placed shoulder-width apart, shoulder-flexion angles of 110° or 120°, and the ipsilateral lower extremity lifted.

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Kinematic Differences between Two Types of Forward Elevations of the Shoulder Joint: Flexion and Reaching Elevation

The Open Orthopaedics Journal ◽

10.2174/1874325002014010015 ◽

2020 ◽

Vol 14 (1) ◽

pp. 15-25

Author(s):

Ryo Sahara ◽

Junichiro Hamada ◽

Kunio Yoshizaki ◽

Kazuhiro Endo ◽

Daisuke Segawa ◽

...

Keyword(s):

Rotator Cuff ◽

Elbow Joint ◽

Glenohumeral Joint ◽

External Rotation ◽

Three Dimensional ◽

Coronal Plane ◽

Shoulder Flexion ◽

Joint Flexion ◽

Motion Plane ◽

Teres Minor

Background: Extension of the elbow joint is maintained during shoulder flexion. In contrast, the arm starts from the flexed position of the elbow joint and the joint gradually extends during reaching elevation. Objectives: This study aimed to compare the kinematic elements and electromyographic (EMG) activities of the rotator cuff muscles between flexion and reaching elevation. Methods: The study included 10 healthy young men. (average age, 21.5 ± 3.4 years), and measurements were performed on their dominant arms. A three-dimensional motion analyzer was used to record the following elements during shoulder flexion and reaching elevation: the angles of glenohumeral joint elevation and scapular upward rotation, scapulohumeral rhythm, external rotation of the humerus, and glenohumeral plane shifting from the coronal plane. The EMG activities in the supraspinatus, infraspinatus, subscapularis, and teres minor were recorded simultaneously. Results: The plane of reaching elevation was retained at 60° from the coronal plane. The glenohumeral planes (P < 0 .01) and the external rotation angles of the humerus below 90° of elevation (P < 0.05) were significantly different between both the motions. The EMG activities in the supraspinatus (P < .01), infraspinatus (P < 0.05), and teres minor (P < 0.01) were significantly lower while reaching elevation than those during flexion. Conclusion: The motion plane at 60° from the coronal plane, movement of the humeral external rotation, and EMG activities of the rotator cuff muscles were different during reaching elevation and shoulder flexion.

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The Relationship Between Surface Electromyographic Activity and Torque Production of the Infraspinatus Muscle in Shoulder Rehabilitation Exercises

Journal of Applied Biomechanics ◽

10.1123/jab.2019-0257 ◽

2020 ◽

Vol 36 (3) ◽

pp. 141-147

Author(s):

Bill Stodart ◽

Maria Cup ◽

Curtis Kindel

Keyword(s):

Inverse Relationship ◽

External Rotation ◽

Surface Emg ◽

Joint Torque ◽

Emg Activity ◽

Electromyographic Activity ◽

Maximum Voluntary Isometric Contraction ◽

Relative Value ◽

Torque Values ◽

The Relationship

In current rehabilitation practice, exercise selection is commonly based on the amount of muscle recruitment demonstrated by electromyographic (EMG) analysis. A preponderance of evidence supports the concept that EMG of a muscle and torque output are positively correlated. This study was designed to investigate the relationship between surface EMG activity of the infraspinatus and torque production during exercises involving shoulder external rotation (ER). A total of 30 participants (average age = 24.6 y) performed maximum voluntary isometric contraction of ER at 5 points within the range of motion of 3 shoulder exercise positions with concomitant surface EMG recording. As a maximal internally rotated position was approached, maximum ER torque and minimum or near-minimum EMG recruitment were demonstrated. Conversely, at maximally externally rotated positions, EMG activity was greatest and torque values were lowest. An inverse relationship between joint torque output and EMG activity was established in each of the 3 exercises. The inverse relationship between EMG activity and torque output during Shoulder ER suggests that there may be additional factors warranting consideration during exercise selection. Further research may be needed to determine the relative value of electrical activity versus torque output to optimize the selection of rehabilitative exercises.

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Shoulder Instability and the Labrum

Mayo Clinic Principles of Shoulder Surgery ◽

10.1093/med/9780190602765.003.0007 ◽

2018 ◽

pp. 171-214

Author(s):

Joaquin Sanchez-Sotelo

Keyword(s):

Rotator Cuff ◽

Range Of Motion ◽

Shoulder Instability ◽

Glenohumeral Joint ◽

Biceps Tendon ◽

Posterior Instability ◽

Joint Dislocation ◽

Glenoid Labrum ◽

Multidirectional Instability ◽

Labral Tears

The glenohumeral joint architecture allows for a very ample range of motion. This same architecture, so beneficial for shoulder mobility, also makes the glenohumeral joint particularly prone to instability. Damage to the glenoid labrum is present in many patients with shoulder instability, although the complexity of the pathology involved in shoulder instability goes beyond labral tears. The rotator cuff and the biceps tendon, discussed in chapter 6, The Rotator Cuff and Biceps Tendon, are intimately involved with instability and the labrum; some of the concepts described in chapter 6 will apply here as well. This chapter covers shoulder instability and the labrum, including management of the acute glenohumeral joint dislocation, recurrent posterior instability and posterior labral tears, multidirectional instability, superior labral tears, failed instability surgery, and salvage procedures.

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Shoulder Muscle Activation Levels During the Push-Up-Plus Exercise on Stable and Unstable Surfaces

Journal of Sport Rehabilitation ◽

10.1123/jsr.2016-0050 ◽

2017 ◽

Vol 26 (4) ◽

pp. 281-286 ◽

Cited By ~ 7

Author(s):

Rafaela J.B. Torres ◽

André L.T. Pirauá ◽

Vinícius Y.S. Nascimento ◽

Priscila S. dos Santos ◽

Natália B. Beltrão ◽

...

Keyword(s):

Muscle Activation ◽

Biceps Brachii ◽

Emg Activity ◽

Activity Levels ◽

Triceps Brachii ◽

Serratus Anterior ◽

Upper Trapezius ◽

Unstable Surface ◽

Hands And Feet ◽

Push Up

The aim of this study was to evaluate the acute effect of the use of stable and unstable surfaces on electromyography (EMG) activity and coactivation of the scapular and upper-limb muscles during the push-up plus (with full protraction of the scapula). Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major, biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) levels and coactivation index were determined by surface EMG in 20 young men during push-up plus performed on a stable and unstable condition (2 unstable devices applied to hands and feet). The paired t test and Cohen d were used for statistical analysis. The results showed that during the execution of the push-up plus on the unstable surface an increased EMG activity of the scapular stabilizing muscles (SA, MT, and LT) was observed, while AD and PD muscles showed a decrease. During exercise execution on the unstable surface there was a higher index of coactivation of the scapular muscles (SA–MT and UT–LT pairs). No significant differences were observed in TB–BB and AD–PD pairs. These results suggest that the push-up-plus exercise associated with unstable surfaces produced greater EMG activity levels and coactivation index of the scapular stabilizing muscle. On the other hand, the use of an unstable surface does not promote the same effect for the shoulder muscles.

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