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.

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 Ergonomics Analysis for Subjective and Objective Fatigue Between Laparoscopic and Robotic Surgical Skills Practice Among Surgeons

2019 ◽  
Vol 27 (1) ◽  
pp. 81-87
Author(s):  
Priscila Rodrigues Armijo ◽  
Chun-Kai Huang ◽  
Tyson Carlson ◽  
Dmitry Oleynikov ◽  
Ka-Chun Siu
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activation ◽  
Surgical Skills ◽  
Learning Center ◽  
Training Systems ◽  
Upper Trapezius ◽  
Shoulder Muscles ◽  
Anterior Deltoid ◽  
Robotic Surgical Training ◽  
Objectively Measured

Introduction. Our aim was to determine how self-reported and objectively measured fatigue of upper limb differ between laparoscopic and robotic surgical training environments. Methods. Surgeons at the 2016 SAGES Conference Learning Center and at our institution were enrolled. Two standardized surgical tasks (peg transfer [PT] and needle passing [NP]) were performed twice in each surgical skills practical environments: (1) laparoscopic training-box environment (Fundamentals of Laparoscopic Surgery [FLS]) and (2) Mimic dV-trainer (MIMIC). Muscle activation of upper trapezius (UT), anterior deltoid (AD), flexor carpi radialis, and extensor digitorum were recorded using surface electromyography (EMG; Trigno, Delsys, Inc, Natick, MA). Subjective fatigue was self-reported using Piper Fatigue Scale-12. Analysis was done using SPSS v25.0, α = .05. Results. Demographics were similar between FLS (N = 14) and MIMIC (N = 12). For PT, MIMIC had a significant increase in EMGRMS of UT ( P < .001) and AD ( P < .001). Conversely, FLS led to significant decreased muscle fatigue in UT ( P = .015). For NP, MIMIC had a significant increase in EMGRMS for UT ( P = .034) and AD ( P = .031), but FLS induced more muscle fatigue for AD ( P = .004). There was significant decrease in self-reported fatigue after performing FLS tasks ( P = .030) but not after MIMIC ( P = .663). Conclusion. Our results showed that practice with MIMIC resulted in greater activation of shoulder muscles, while FLS caused more significant muscle fatigue in the same muscles. This could be due to ergonomic disadvantages and nonoptimal ergonomic settings. Further studies are needed to understand the optimal ergonomics and its impact on fatigue and muscle activation during use of both the FLS and MIMIC training systems.

scholarly journals The comparison of the shoulder muscle activation in patients with rotator cuff tear under an abduction brace among the three postures

2021 ◽  
pp. 14
Author(s):  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Tear ◽  
Supine Position ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Biceps Brachii ◽  
Sitting Position ◽  
Cuff Tear ◽  
Upper Trapezius ◽  
Anterior Deltoid

Background: Immobilization using an abduction brace is essential for the relaxation of the rotator cuff and scapular muscles and the prevention of a retear in patients with rotator cuff tear after arthroscopic rotator cuff repair (ARCR). However, thus far, the comparison of the scapular muscle activities has not been compared among different postures under an abduction brace in patients after ARCR. Objectives: The purpose of our study was to compare the scapular muscle activities among the supine position, sitting position, and walking under an abduction brace before and after ARCR Study Design: Observational, repeated measures study. Methods: Twelve patients with full-thickness rotator cuff tears were studied. The mean patient age was 64.7 years. The scapular muscle activations of the ipsilateral limbs were measured using surface electromyography in three postures: supine position, sitting position, and walking. The integrated electromyography relative values of the upper trapezius, anterior deltoid, middle deltoid, and biceps brachii were compared preoperatively and at two weeks after ARCR. Results: The trapezius, biceps brachii, and middle deltoid in the walking showed significantly higher integrated electromyography relative values than those in the supine position, preoperatively and at two weeks after surgery. The anterior deltoid in the sitting position had significantly higher integrated electromyography relative values than those in the supine position. Conclusions: Postures affected the scapular muscle activities in ARCR patients under an abduction brace. Understanding the influence of posture on the scapular muscle activity after ARCR will help rehabilitation accurately and appropriately.

Comparison of Shoulder Protraction Strength and Electromyography Activity of Serratus Anterior and Pectoralis Major in Subjects With or Without a Winged Scapula

2019 ◽  
Vol 28 (3) ◽  
pp. 272-277 ◽  
Author(s):  
Jun-Seok Kim ◽  
Moon-Hwan Kim ◽  
Duk-Hyun Ahn ◽  
Jae-Seop Oh
Keyword(s):  
Muscle Activity ◽  
Cross Sectional Study ◽  
Pectoralis Major ◽  
Serratus Anterior ◽  
Cross Sectional ◽  
Winged Scapula ◽  
Upper Trapezius ◽  
Shoulder Muscles ◽  
Strengthening Exercises ◽  
Anterior Deltoid

Context:A winged scapula (WS) is associated with faulty posture caused by weakness of the serratus anterior (SA), which mainly acts as a scapular stabilizer muscle. It is important to accurately assess and train the SA muscle with a focus on scapula stabilizers during musculoskeletal rehabilitation of individuals with a WS.Objective:The authors examined muscle activity in the SA and pectoralis major (PM), upper trapezius (UT), and anterior deltoid (AD) as well as shoulder protraction strength during isometric shoulder protraction in individuals with and without a WS.Design:Cross-sectional study.Setting:A clinical biomechanics laboratory.Participants:In total, 27 males with no shoulder, neck, or upper-extremity pain participated.Main Outcome Measures:Isometric shoulder protraction strength was collected and surface electromyography used to measure the activity of the SA, PM, UT, and AD muscles and selective SA activity ratio to other shoulder muscles.Results:Electromyography activity of the SA muscle and shoulder protraction strength were significantly lower in individuals with a WS compared with the non-WS group (P < .05). In contrast, PM muscle activity and the PM-to-SA, UT-to-SA, and AD-to-SA ratios were significantly greater in individuals with a WS than in individuals without winging (P < .05).Conclusions:Isometric shoulder protraction for measuring SA strength in individuals with a WS should focus on isolated muscle activity of the SA, and SA strengthening exercises are important for individuals with a WS.

Impulses of activation but not motor modules are preserved in the locomotion of subacute stroke patients

2011 ◽  
Vol 106 (1) ◽  
pp. 202-210 ◽  
Author(s):  
Leonardo Gizzi ◽  
Jørgen Feldbæk Nielsen ◽  
Francesco Felici ◽  
Yuri P. Ivanenko ◽  
Dario Farina
Keyword(s):  
Healthy Subjects ◽  
Muscle Activation ◽  
Central Pattern Generators ◽  
Dependent Manner ◽  
Healthy Controls ◽  
Stroke Patients ◽  
Unaffected Side ◽  
Subacute Stroke ◽  
The Central Nervous System ◽  
Pattern Generators

It has been hypothesized that the coordinated activation of muscles is controlled by the central nervous system by means of a small alphabet of control signals (also referred to as activation signals) and motor modules (synergies). We analyzed the locomotion of 10 patients recently affected by stroke (maximum of 20 wk) and compared it with that of healthy controls. The aim was to assess whether the walking of subacute stroke patients is based on the same motor modules and/or activation signals as healthy subjects. The activity of muscles of the lower and upper limb and the trunk was measured and used for extracting motor modules. Four modules were sufficient to explain the majority of variance in muscle activation in both controls and patients. Modules from the affected side of stroke patients were different from those of healthy controls and from the unaffected side of stroke patients. However, the activation signals were similar between groups and between the affected and unaffected side of stroke patients, and were characterized by impulses at specific time instants within the gait cycle, underlying an impulsive controller of gait. In conclusion, motor modules observed in healthy subjects during locomotion are different from those used by subacute stroke patients, despite similar impulsive activation signals. We suggest that this pattern is consistent with a neuronal network in which the timing of activity generated by central pattern generators is directed to the motoneurons via a premotor network that distributes the activity in a task-dependent manner determined by sensory and descending control information.

scholarly journals Motor Outputs From the Primate Reticular Formation to Shoulder Muscles as Revealed by Stimulus-Triggered Averaging

2004 ◽  
Vol 92 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Adam G. Davidson ◽  
John A. Buford
Keyword(s):  
Reticular Formation ◽  
Latissimus Dorsi ◽  
Upper Trapezius ◽  
Shoulder Muscles ◽  
Muscle Pair ◽  
Anterior Deltoid ◽  
Motor Outputs ◽  
Behaving Monkeys ◽  
Stimulus Triggered Averaging ◽  
Effective Site

The motor output of the medial pontomedullary reticular formation (mPMRF) was investigated using stimulus-triggered averaging (StimulusTA) of EMG responses from proximal arm and shoulder muscles in awake, behaving monkeys ( M. fascicularis). Muscles studied on the side ipsilateral (i) to stimulation were biceps (iBic), triceps (iTri), anterior deltoid (iADlt), posterior deltoid (iPDlt), and latissimus dorsi (iLat). The upper and middle trapezius were studied on the ipsilateral and contralateral (c) side (iUTr, cUTr, iMTr, cMTr). Of 133 sites tested, 97 (73%) produced a poststimulus effect (PStE) in one or more muscles; on average, 38% of the sampled muscles responded per effective site. For responses that were observed in the arm and shoulder, poststimulus facilitation (PStF) was prevalent for the flexors, iBic (8 responses, 100% PStF) and iADlt (13 responses, 77% PStF), and poststimulus suppression (PStS) was prevalent for the extensors, iTri (22 responses, 96% PStS) and iLat (16 responses, 81% PStS). For trapezius muscles, PStS of upper trapezius (iUTr, 49 responses, 73% PStS) and PStF of middle trapezius (iMTr, 22 responses, 64% PStF) were prevalent ipsilaterally, and PStS of middle trapezius (cMTr, 6 responses, 67% PStS) and PStF of upper trapezius (cUTr, 46 responses, 83% PStS) were prevalent contralaterally. Onset latencies were significantly earlier for PStF (7.0 ± 2.2 ms) than for PStS (8.6 ± 2.0 ms). At several sites, extremely strong PStF was evoked in iUTr, even though PStS was most common for this muscle. The anatomical antagonists iBic/iTri were affected reciprocally when both responded. The bilateral muscle pair iUTr/cUTr demonstrated various combinations of effects, but cUTr PStF with iUTr PStS was prevalent. Overall, the results are consistent with data from the cat and show that outputs from the mPMRF can facilitate or suppress activity in muscles involved in reaching; responses that would contribute to flexion of the ipsilateral arm were prevalent.

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.

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.

Estimating Muscle Forces for Breast Cancer Survivors During Functional Tasks

2020 ◽  
Vol 36 (6) ◽  
pp. 408-415
Author(s):  
Angelica E. Lang ◽  
Soo Y. Kim ◽  
Stephan Milosavljevic ◽  
Clark R. Dickerson
Keyword(s):  
Breast Cancer ◽  
Cancer Survivors ◽  
Analysis Of Variance ◽  
Repeated Measures ◽  
Breast Cancer Survivors ◽  
Muscle Activation ◽  
Muscle Forces ◽  
Upper Trapezius ◽  
Shoulder Muscles ◽  
Shoulder Loading

Breast cancer survivors have known scapular kinematic alterations that may be related to the development of secondary morbidities. A measure of muscle activation would help understand the mechanisms behind potential harmful kinematics. The purpose of this study was to define muscle force strategies in breast cancer survivors. Shoulder muscle forces during 6 functional tasks were predicted for 25 breast cancer survivors (divided by impingement pain) and 25 controls using a modified Shoulder Loading Analysis Module. Maximum forces for each muscle were calculated, and 1-way analysis of variance (P < .05) was used to identify group differences. The differences between maximum predicted forces and maximum electromyography were compared with repeated-measures analysis of variance (P < .05) to evaluate the success of the model predictions. Average differences between force predictions and electromyography ranged from 7.3% to 31.6% but were within the range of previously accepted differences. Impingement related pain in breast cancer survivors is associated with increased force of select shoulder muscles. Both pectoralis major heads, upper trapezius, and supraspinatus peak forces were higher in the pain group across all tasks. These force prediction differences are also associated with potentially harmful kinematic strategies, providing a direction for possible rehabilitation strategies.

scholarly journals An Electromyographic Analysis of Lateral Raise Variations and Frontal Raise in Competitive Bodybuilders

2020 ◽  
Vol 17 (17) ◽  
pp. 6015
Author(s):  
Giuseppe Coratella ◽  
Gianpaolo Tornatore ◽  
Stefano Longo ◽  
Fabio Esposito ◽  
Emiliano Cè
Keyword(s):  
Confidence Interval ◽  
Effect Size ◽  
Muscle Activation ◽  
External Rotation ◽  
Pectoralis Major ◽  
Mean Square ◽  
Triceps Brachii ◽  
Upper Trapezius ◽  
Anterior Deltoid ◽  
Electromyographic Analysis

The present study examined the muscle activation in lateral raise with humerus rotated externally (LR-external), neutrally (LR-neutral), internally (LR-internal), with flexed elbow (LR-flexed) and frontal raise during both the concentric and eccentric phase. Ten competitive bodybuilders performed the exercises. Normalized surface electromyographic root mean square (sEMG RMS) was obtained from anterior, medial, and posterior deltoid, pectoralis major, upper trapezius, and triceps brachii. During the concentric phase, anterior deltoid and posterior deltoid showed greater sEMG RMS in frontal raise (effect size (ES)-range: 1.78/9.25)) and LR-internal (ES-range: 10.79/21.34), respectively, vs. all other exercises. Medial deltoid showed greater sEMG RMS in LR-neutral than LR-external (ES: 1.47 (95% confidence-interval—CI: 0.43/2.38)), frontal raise (ES: 10.28(95% CI: 6.67/13.01)), and LR-flexed (ES: 6.41(95% CI: 4.04/8.23)). Pectoralis major showed greater sEMG RMS in frontal raise vs. all other exercises (ES-range: 17.2/29.5), while upper trapezius (ES-range: 2.66/7.18) and triceps brachii (ES-range: 0.41/3.31) showed greater sEMG RMS in LR-internal vs. all other exercises. Similar recruitment patterns were found during the eccentric phase. When humerus rotates internally, greater activation of posterior deltoid, triceps brachii, and upper trapezius occurs. Humerus external rotation increases the activation of anterior and medial deltoid. Frontal raise mainly activates anterior deltoid and pectoralis major. LR variations and frontal raise activate specifically shoulders muscles and should be proposed accordingly.

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