scholarly journals Construct Validity of Muscle Force Tests of the Rotator Cuff Muscles: An Electromyographic Investigation

2010 ◽  
Vol 90 (4) ◽  
pp. 572-580 ◽  
Author(s):  
Rebecca L. Brookham ◽  
Linda McLean ◽  
Clark R. Dickerson
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Muscle Force ◽  
Test Group ◽  
Clinical Test ◽  
Shoulder Muscles ◽  
Frequent Use ◽  
Medial Rotation ◽  
Generating Capacity ◽  
Teres Minor

Background Manual muscle tests (MMTs) are used in clinical settings to evaluate the function and strength (force-generating capacity) of a specific muscle in a position at which the muscle is believed to be most isolated from other synergists and antagonists. Despite frequent use of MMTs, few electromyographic evaluations exist to confirm the ability of MMTs to isolate rotator cuff muscles. Objective This study examined rotator cuff isolation during 29 shoulder muscle force tests (9 clinical and 20 generic tests). Design An experimental design was used in this study. Participants and Measurements Electromyographic data were recorded from 4 rotator cuff muscles and 10 additional shoulder muscles of 12 male participants. Maximal isolation ratios (mean specific rotator cuff muscle activation to mean activation of the other 13 recorded muscles) defined which of these tests most isolated the rotator cuff muscles. Results Three rotator cuff muscles were maximally isolated (obtained highest isolation ratios) within their respective clinical test groups (lateral rotator test group for the infraspinatus and teres minor muscles and abduction test group for the supraspinatus muscle). The subscapularis muscle was maximally isolated equally as effectively within the generic ulnar force and clinical medial rotation groups. Similarly, the supraspinatus and teres minor muscles were isolated equally as effectively in some generic test groups as they were in their respective clinical test groups. Limitations Postural artifact in the wire electrodes caused exclusion of some channels from calculations. The grouping of muscle force tests based on test criteria (clinical or generic tests and muscle action) may have influenced which groups most isolated the muscle of interest. Conclusions The results confirmed the appropriateness of 9 commonly used clinical tests for isolating rotator cuff muscles, but suggested that several other muscle force tests were equally appropriate for isolating these muscles.

scholarly journals Electromyography of the Shoulder Musculature during Passive Rehabilitation Exercises

2020 ◽  
Vol 4 ◽  
pp. 247154922096004
Author(s):  
Janelle A Cross ◽  
John deVries ◽  
Mason Mocarski ◽  
Nicholas C Ketchum ◽  
Eileen Compty ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
Muscle Activation ◽  
Biceps Brachii ◽  
Emg Activity ◽  
Maximum Voluntary Isometric Contraction ◽  
Subscapularis Muscle ◽  
Shoulder Muscles ◽  
Cuff Repair ◽  
Teres Minor

Background Medical professionals remain conflicted about the best rehabilitation protocol a patient should perform after rotator cuff repair surgery. Exercises deemed passive may be activating the shoulder muscles to a moderate level, thus putting the surgical repair construct at risk for re-injury. The purpose of this study was to measure the activation of the rotator cuff and surrounding musculature during exercises used in physical therapy following rotator cuff repair surgery using electromyography (EMG). Methods Muscle activation was recorded in fourteen participants performing sixteen exercises. Four fine wire electrodes (supraspinatus, infraspinatus, subscapularis, teres minor) and six surface electrodes (upper and middle division of the trapezius, anterior, medial and posterior head of the deltoid, biceps brachii) were utilized. EMG activity values for each muscle were normalized to the maximum voluntary isometric contraction and activation levels were assessed. Results Twelve of the sixteen exercises tested were moderately active in the subscapularis muscle. The results show the subscapularis muscle was activated in all three planes of motion. Discussion Most exercises were found to have low activation levels for the supraspinatus, infraspinatus and teres minor muscles. While the exercises examined in this study appear to be safe for the more commonly repaired supraspinatus, caution should be used when administering exercises to individuals with repairs involving the subscapularis.

Muscle Activity Before and After Subacromial Injection

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.

scholarly journals Evaluation of a New Rotator Cuff Trainer Based on Oscillating Hydraulic Damping

Healthcare ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 24
Author(s):  
Yinghao Wang ◽  
Jianfeng Wu ◽  
Hongchun Yang ◽  
Zhichuan Tang ◽  
Guozhong Chai
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Muscle Force ◽  
Movement Speed ◽  
Training Methods ◽  
Muscle Work ◽  
Traditional Training ◽  
Testing Experiment ◽  
Axis Rotation ◽  
Semg Signals

In order to provide a convenient way to strengthen the rotator cuff muscles and prevent rotator cuff injury, this study designed an innovative strength trainer specifically for shoulder rotator cuff based on oscillating hydraulic damping. We carried out a myoelectric testing experiment to evaluate the shoulder rotation training effect and compared the results with traditional training equipment to verify the feasibility and validity of the new rotator cuff trainer (RCT). Then, we further explored the influence of different training postures and motion speeds on shoulder rotation training. In the experiment, subjects used three types of equipment (RCT, dumbbells and elastic bands) to perform shoulder rotation training under two movement speeds and two motion postures. The surface electromyography (sEMG) signals of targeted muscles were collected in real time and then further analyzed. The experimental results showed that when using the RCT, the muscle force generation sequence was more aligned with the biomechanical principles of shoulder rotation than using the other two training methods, and the target training muscles had the higher percentage of muscle work. During RCT training, a higher speed of movement (120°/s) led to a higher degree of muscle activation; coronal axis rotation was better for the infraspinatus training, and sagittal axis rotation was better for teres minor training. Based on these results, the RCT was proved to be more effective than traditional training methods. In order to exercise the different muscles of rotator cuff more comprehensively and extensively, different postures should be selected. Furthermore, the movement speed can be appropriately increased within the safe range to improve muscle activation.

scholarly journals Muscle Fiber Contribution to Rotator Cuff Moment Arms During Abduction for Intact Rotator Cuff, Complete Supraspinatus Tear, Superior Capsular Reconstruction, and Reverse Shoulder Arthroplasty. (225)

2021 ◽  
Vol 9 (10_suppl5) ◽  
pp. 2325967121S0033
Author(s):  
Martine Dolan ◽  
Michael Patetta ◽  
Sonia Pradhan ◽  
Danil Rybalko ◽  
Aimee Bobko ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Muscle Fiber ◽  
Moment Arm ◽  
Moment Arms ◽  
Shoulder Muscles ◽  
Supraspinatus Tear ◽  
Significant Difference ◽  
The Moment ◽  
Multiple Fibers ◽  
Teres Minor

Objectives: The Rotator Cuff (RC) is formed from the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and their tendinous extensions. The 4 RC tendons insert on the humeral head such that they contribute to the dynamic stability of the glenohumeral joint along with their rotational actions on the shoulder. The moment arm can be used to demonstrate the work effort potential that a specific muscle is contributing to a musculoskeletal joint rotation. The objective of this study was to break out RC muscles into multiple fibers, providing more clarity as to how individual fibers contribute to a muscle’s overall moment arm during abduction. The aims of this study are: 1.) to illustrate within each RC muscle how multiple muscle fiber lines of action work together to produce abduction in an intact shoulder 2.) to estimate the moment arm changes that take place when the intact rotator cuff goes through surgical repair with either SCR or RSA after complete supraspinatus tear. We hypothesized that the rotator cuff muscles work differently and in combination at the fiber level to bring about a resultant movement that can be assessed through the proposed method of moment arm calculation for intact RC, complete supraspinatus tear, SCR and RSA. Methods: Five fresh cadaveric shoulder specimens were used in an apparatus where each muscle was maintained in tension with the line of action towards its origin on the scapula (Figure 1). An Optotrack camera kept track of digitized points along both the origin and insertion of the rotator cuff muscles as the shoulder was abducted. Using these digitized points, multiple lines of action were created across the breadth of each muscle. Each muscle force action line was then used to calculate moment arm values during 0-90º abduction (Figure 2). Results: Moment arms calculated for multiple fiber lines spanning the tendon attachment site displayed the variance of fiber contribution and function within each muscle during abduction. Our results indicate that rather than providing a return to anatomical shoulder muscle function, RSA and SCR models produce moment arms that vary between muscles, with some contributing more to abduction and some contributing less. Highlighted below are the infraspinatus results for moment arms of individual fiber lines of action (Figure 3) and calculated mean moment arms (Figure 4) over abduction.ANOVA testing demonstrated a significant difference (p<0.001) when analyzing moment arms of intact, complete supraspinatus tear, SCR, and RSA models in teres minor and infraspinatus. There was no significant difference in moment arm values between the models in the subscapularis (p=0.148). Highlighted in Table 1 are the ANOVA testing results for infraspinatus. Conclusions: Our biomechanical analysis demonstrated sufficient sensitivity to detect differences in moment arms of the four rotator cuff muscles across a variety of models, suggesting changes to even one muscle of the shoulder will have significant implications on the function of other shoulder muscles. Furthermore, our analysis of fiber divisions within the same muscle illustrates the complex nature of the shoulder muscles themselves, and future studies should aim to better explore and model their function. The calculated percent differences from intact beautifully illustrated this complexity, as corrective RSA and SCR procedures provided better resemblance of intact anatomy within some rotator cuff muscles while creating a larger percent difference in other muscle groups. By breaking out RC muscles into multiple fibers, more clarity can be gained as to how individual fibers contribute to a muscle’s overall moment arm during abduction. This may further aid surgical decision-making, specifically for RSA where there is continued debate about whether to reconstruct portions of the RC. Given that the supraspinatus tendon is the most frequently torn tendon in the rotator cuff, especially for athletes who apply repetitive stress to the tendon, the results of this study may help inform post-operative rehabilitation by illustrating how abduction and stability are achieved after SCR and RSA.

Rotator-Cuff Muscle-Recruitment Strategies During Shoulder Rehabilitation Exercises

2011 ◽  
Vol 20 (4) ◽  
pp. 471-486 ◽  
Author(s):  
Kathleen A. Swanik ◽  
Kellie Huxel Bliven ◽  
Charles Buz Swanik
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Glenohumeral Joint ◽  
Neuromuscular Control ◽  
Muscle Recruitment ◽  
Individual Muscle ◽  
Muscle Activation Patterns ◽  
Outcomes Measures ◽  
Rehabilitation Exercises ◽  
Teres Minor

Context:There are contradictory data on optimal muscle-activation strategies for restoring shoulder stability. Further investigation of neuromuscular-control strategies for glenohumeral-joint stability will guide clinicians in decisions regarding appropriate rehabilitation exercises.Objectives:To determine whether subscapularis, infraspinatus, and teres minor (anteroposterior force couple) muscle activation differ between 4 shoulder exercises and describe coactivation ratios and individual muscle-recruitment characteristics of rotator-cuff muscles throughout each shoulder exercise.Design:Crossover.Setting:Laboratory.Participants:healthy, physically active men, age 20.55 ± 2.0 y.Interventions:4 rehabilitation exercises: pitchback, PNF D2 pattern with tubing, push-up plus, and slide board.Main Outcomes Measures:Mean coactivation level, coactivation-ratio patterns, and level (area) of muscle-activation patterns of the subscapularis, infraspinatus, and teres minor throughout each exercise.Results:Coactivation levels varied throughout each exercise. Subscapularis activity was consistently higher than that of the infraspinatus and teres minor combined at the start of each exercise and in end ranges of motion. Individual muscle-recruitment levels in the subscapularis were also different between exercises.Conclusion:Results provide descriptive data for determining normative coactivation-ratio values for muscle recruitment for the functional exercises studied. Differences in subscapularis activation suggest a reliance to resist anteriorly directed forces.

Blood Flow Restriction Training for the Shoulder: A Case for Proximal Benefit

2021 ◽  
pp. 036354652110175
Author(s):  
Bradley Lambert ◽  
Corbin Hedt ◽  
Joshua Daum ◽  
Carter Taft ◽  
Kalyan Chaliki ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rotator Cuff ◽  
Lean Mass ◽  
Muscle Activation ◽  
Acute Exercise ◽  
Blood Flow Restriction ◽  
Analysis Of Covariance ◽  
Muscular Endurance ◽  
Flow Restriction ◽  
Shoulder Muscles

Background: Although blood flow restriction (BFR) is becoming increasingly popular in physical therapy and athletic training settings, little is known about the effects of BFR combined with low-intensity exercise (LIX) on muscles proximal to the site of occlusion. Hypothesis/Purpose: Determine whether LIX combined with BFR applied distally to the shoulder on the brachial region of the arm (BFR-LIX) promotes greater increases in shoulder lean mass, rotator cuff strength, endurance, and acute increases in shoulder muscle activation compared with LIX alone. We hypothesized that BFR-LIX would elicit greater increases in rotator cuff strength, endurance, and muscle mass. We also hypothesized that the application of BFR would increase EMG amplitude in the shoulder muscles during acute exercise. Study Design: Controlled laboratory study. Methods: 32 healthy adults were randomized into 2 groups (BFR group, 13 men, 3 women; No-BFR group, 10 men, 6 women) who performed 8 weeks of shoulder LIX (2 times per week; 4 sets [30/15/15/fatigue]; 20% maximum) using common rotator cuff exercises (cable external rotation [ER], cable internal rotation [IR], dumbbell scaption, and side-lying dumbbell ER). The BFR group also trained with an automated tourniquet placed at the proximal arm (50% occlusion). Regional lean mass (dual-energy x-ray absorptiometry), isometric strength, and muscular endurance (repetitions to fatigue [RTF]; 20% maximum; with and without 50% occlusion) were measured before and after training. Electromyographic amplitude (EMGa) was recorded from target shoulder muscles during endurance testing. A mixed-model analysis of covariance (covaried on baseline measures) was used to detect within-group and between-group differences in primary outcome measures (α = .05). Results: The BFR group had greater increases in lean mass in the arm (mean ± 95% CI: BFR, 175 ± 54 g; No BFR, –17 ± 77 g; P < .01) and shoulder (mean ± 95% CI: BFR, 278 ± 90 g; No BFR, 96 ± 61 g; P < .01), isometric IR strength (mean ± 95% CI: BFR, 2.9 ± 1.3 kg; No BFR, 0.1 ± 1.3 kg; P < .01), single-set RTF volume (repetitions × resistance) for IR (~1.7- to 2.1-fold higher; P < .01), and weekly training volume (weeks 4, 6-8, ~5%-22%; P < .05). Acute occlusion (independent of group or timepoint) yielded increases in EMGa during RTF (~10%-20%; P < .05). Conclusion: Combined BFR-LIX may yield greater increases in shoulder and arm lean mass, strength, and muscular endurance compared with fatiguing LIX alone during rotator cuff exercises. These findings may be due, in part, to a greater activation of shoulder muscles while using BFR. Clinical Relevance: The present study demonstrates that BFR-LIX may be a suitable candidate for augmenting preventive training or rehabilitation outcomes for the shoulder.

Effect of acute inflation on the mechanics of the inspiratory muscles

2009 ◽  
Vol 107 (1) ◽  
pp. 315-323 ◽  
Author(s):  
André De Troyer ◽  
Theodore A. Wilson
Keyword(s):  
Adverse Effect ◽  
Muscle Activation ◽  
Muscle Force ◽  
Radius Of Curvature ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Respiratory Effect ◽  
Inspiratory Muscles ◽  
Generating Capacity ◽  
Very High

When the lung is inflated acutely, the capacity of the diaphragm to generate pressure, in particular pleural pressure (Ppl), is impaired because the muscle during contraction is shorter and generates less force. At very high lung volumes, the pressure-generating capacity of the diaphragm may be further reduced by an increase in the muscle radius of curvature. Lung inflation similarly impairs the pressure-generating capacity of the inspiratory intercostal muscles, both the parasternal intercostals and the external intercostals. In contrast to the diaphragm, however, this adverse effect is largely related to the orientation and motion of the ribs, rather than the ability of the muscles to generate force. During combined activation of the two sets of muscles, the change in Ppl is larger than during isolated diaphragm activation, and this added load on the diaphragm reduces the shortening of the muscle and increases muscle force. In addition, activation of the diaphragm suppresses the cranial displacement of the passive diaphragm that occurs during isolated intercostal contraction and increases the respiratory effect of the intercostals. As a result, the change in Ppl generated during combined diaphragm-intercostal activation is greater than the sum of the pressures generated during separate muscle activation. Although this synergistic interaction becomes particularly prominent at high lung volumes, lung inflation, either bilateral or unilateral, places a substantial stress on the inspiratory muscle pump.

scholarly journals What is the Best Clinical Test for Assessment of the Teres Minor in Massive Rotator Cuff Tears?

2015 ◽  
Vol 473 (9) ◽  
pp. 2959-2966 ◽  
Author(s):  
Philippe Collin ◽  
Thomas Treseder ◽  
Patrick J. Denard ◽  
Lionel Neyton ◽  
Gilles Walch ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Tears ◽  
Clinical Test ◽  
Massive Rotator Cuff Tears ◽  
Teres Minor

scholarly journals Delayed Anticipatory Muscle Activation in Rotator Cuff Tendinopathy

2021 ◽  
Vol 9 (7) ◽  
pp. 232596712110193
Author(s):  
Samuel Baek ◽  
Se-Young Ki ◽  
Seok Won Chung ◽  
Seoung-Joon Lee ◽  
Young Chang Cho ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Onset Time ◽  
Unaffected Side ◽  
Number Count ◽  
Upper Trapezius ◽  
Affected Side ◽  
Shoulder Muscles ◽  
The Central Nervous System ◽  
Anterior Deltoid

Background: Previous research investigating rotator cuff (RC) tendinopathy has usually focused on pathoanatomy. The pathologic response to anticipatory postural adjustments (APAs) has not yet been investigated. Purpose/Hypothesis: To explore changes in APAs as detected by pre-emptive activation of shoulder muscles during ball catching. It was hypothesized that anticipatory muscle activation (AMA) would be present in the unaffected shoulder but delayed or absent in the affected shoulder in patients with RC tendinopathy. Study Design: Controlled laboratory study. Methods: This study included 21 RC tendinopathy patients with a mean age of 49.5 years. Patients were required to grab a ball embedded with an electromyography sensor when it dropped on their hand, and surface electromyography signals were recorded from the infraspinatus, upper trapezius, anterior deltoid, and biceps. The trials utilized 2 balls, weighing 200 g and 500 g. Each ball was used in 2 trials, 1 involving a number count preceding the ball drop (predictable) and the other involving a sudden drop (unpredictable). The onsets of AMA between the affected and unaffected limbs were compared. Results: Regardless of the experimental condition, significantly delayed AMA onsets were identified in all investigated muscles of the affected side compared with those of the unaffected side, except for the biceps muscle in the 500-g predictable trial. For the infraspinatus, the mean onset time in the 200-g predictable trial was –141.0 ± 60.2 ms on the affected side and –211.9 ± 67.1 ms on the unaffected side ( P < .001); in the 200-g unpredictable trial this value was –139.5 ± 54.9 ms on the affected side and –199.5 ± 56.2 ms on the unaffected side ( P < .001). Conclusion: Delayed AMA was observed in the affected shoulder compared with the unaffected shoulder in patients with RC tendinopathy, not only in the RC muscle but also in the periscapular and upper arm muscles. This may indicate that central hypoexcitability is partly responsible. Clinical Relevance: The basis for RC tendinopathy treatment should not be limited to the tendon pathoanatomy. Delayed AMA around the shoulder joint could provide insight into potential mechanisms related to the central nervous system.

Sign in / Sign up

Export Citation Format

Share Document