scholarly journals Regional Electromyography of the Infraspinatus and Supraspinatus Muscles During Standing Isometric External Rotation Exercises

2021 ◽  
pp. 194173812110438
Author(s):  
Rachel L. Whittaker ◽  
Talia Alenabi ◽  
Soo Y. Kim ◽  
Clark R. Dickerson

Background: Whole-muscle electromyography (EMG) data of the rotator cuff support external rotation (ER) strengthening exercises during shoulder rehabilitation. However, distinct neuroanatomic regions in the supraspinatus and infraspinatus exist. Differences in regional muscle activity occur during rehabilitation exercises, but little information is available for ER exertions. Hypothesis: Regional infraspinatus and supraspinatus muscle activity during standing ER exertions will differ with posture and intensity. Study Design: Descriptive laboratory study. Level of Evidence: Level 5. Methods: Twenty healthy individuals (12 men, 8 women) participated. Fine wire electrodes were inserted into 2 supraspinatus and 3 infraspinatus muscle regions. EMG data were recorded during standing isometric ER exertions at 2 intensities (maximal, submaximal) and in 7 postures defined by the angle (0°, 30°, 90°) and plane (abduction, scaption, flexion) of arm elevation. EMG data were normalized to maximum voluntary isometric contraction (% MVIC) to examine the influences of posture, intensity and their interaction on muscle activity. Results: Superior infraspinatus activity was higher in 0° of elevation (50.9% ± 5.7% MVIC) versus 30° of flexion (37.4% ± 3.9% MVIC) at maximal intensity. Inferior infraspinatus activity was higher in 90° of scaption (max = 59.8% ± 2.8% MVIC, submax = 29.4% ± 1.9% MVIC) versus 0° of elevation (max = 42.3% ± 4.5% MVIC, submax = 22.4% ± 2.8% MVIC) ( P = 0.02, P = 0.05, respectively). Anterior supraspinatus activity was highest in 90° of adbuction (max = 61.6% ± 3.1% MVIC; submax = 39.1% ± 3.8% MVIC) and lowest in 30° of flexion (max = 29.0% ± 3.4% MVIC, submax = 15.6% ± 1.7% MVIC) and 90° of flexion (max = 34.6% ± 2.4% MVIC, submax = 14.8% ± 1.9% MVIC). Posterior suprasptinatus activity was lowest in 0° of elevation (34.2% ± 3.0% MVIC), 30° of flexion (33.0% ± 3.6% MVIC) and highest in 90° of abduction (56.2% ± 4.1% MVIC) and 90° of scaption (46.7% ± 2.8% MVIC) (all Ps < 0.04). Conclusion: Regional infraspinatus and supraspinatus muscle activity differed with posture and intensity. Superior and middle infraspinatus muscle activities were similar across postures, but inferior infraspinatus activity was highest in 90° of arm elevation. Anterior and posterior supraspinatus activities were higher in the abduction and scaption planes, especially at 90° of elevation, as compared with the flexion plane. Clinical Relevance: In shoulder rehabilitation of supraspinatus tendon injuries, ER exercises in the flexion plane challenge the whole infraspinatus muscle and require lower supraspinatus muscle activity.

2018 ◽  
Vol 6 (2) ◽  
pp. 232596711775290 ◽  
Author(s):  
Anna Jungwirth-Weinberger ◽  
Christian Gerber ◽  
Glenn Boyce ◽  
Thorsten Jentzsch ◽  
Simon Roner ◽  
...  

Background: Passive glenohumeral range of motion may be characteristically limited to specific shoulder pathologies. While pain associated with loss of range of passive external glenohumeral rotation is recognized as a salient feature in adhesive capsulitis, restriction of glenohumeral range of motion in calcific tendinitis of the supraspinatus tendon has never been studied. Hypothesis: On the basis of clinical observation, we hypothesized that calcific tendinitis of the supraspinatus tendon is associated with loss of passive glenohumeral abduction without loss of external rotation. Study Design: Cohort study; Level of evidence, 3. Methods: Ranges of passive glenohumeral rotation and abduction, which are measured with a standardized protocol in our institution, were retrospectively reviewed and compared for patients diagnosed with either adhesive capsulitis or calcific tendinitis of the supraspinatus tendon. A total of 57 patients met the inclusion criteria for the calcific tendinitis, and 77 met the inclusion criteria for the adhesive capsulitis group. Results: When compared with the contralateral, unaffected shoulder, glenohumeral abduction in the calcific tendinitis group was restricted by a median of 10° (interquartile range [IQR], –20° to –5°) as opposed to glenohumeral external rotation, which was not restricted at all (median, 0°; IQR, 0° to 0°). The adhesive capsulitis group showed a median restriction of glenohumeral abduction of 40° (IQR, –50° to –30°) and a median restriction of passive glenohumeral external rotation of 40° (IQR, –60° to –30°). Conclusion: Calcific tendinitis of the supraspinatus does not typically cause loss of external rotation but is frequently associated with mild isolated restriction of abduction. This finding can be used to clinically differentiate adhesive capsulitis from calcific tendinitis.


2019 ◽  
Vol 28 (3) ◽  
pp. 229-235 ◽  
Author(s):  
Il-young Yu ◽  
Dong-kyu Lee ◽  
Myoung-Joo Kang ◽  
Jae-seop Oh

Context: The infraspinatus muscle plays a particularly important role in producing primary external rotation (ER) torque and dynamic stability of the shoulder joint. Previous studies have reported that prone external rotation with horizontal abduction (PER), side-lying wiper exercise (SWE), and standing external rotation (STER) were effective exercises for strengthening the infraspinatus. However, we do not have enough knowledge about changes in muscle strength and dynamic muscle activity in each exercise under dynamic conditions. Objective: To compare the ER muscle strength, muscle activity among exercise methods and between muscle contraction types during 3 different exercises. Design: Repeated measures design in which ER muscle strength and muscle activities data were collected from subjects under 3 exercise conditions. Setting: Outpatient clinic. Participants: A total of 15 healthy men with no shoulder, neck, or upper-extremity pain were participated. Intervention: The subjects performed 3 different exercises randomly in concentric and eccentric using a Biodex dynamometer at an angular velocity of 60°/s. Main Outcome Measures: The ER peak torque (PT) data was collected and surface electromyography was used to measure the activity of the infraspinatus and posterior deltoid muscles and infraspinatus to posterior deltoid muscle activity ratio. Results: There was significant main effect for muscle contraction type in ER PT (P < .05). The concentric PT was greater during PER (P < .05) and SWE (P < .05) compared with eccentric. The main effect for exercise was found in ER PT and muscle activity (P < .05). The ER PT and infraspinatus muscle activity were the largest increased during PER whereas the lowest during STER in both concentric and eccentric (P < .05). Conclusion: The results of this study suggest that PER is an exercise for strengthening the infraspinatus muscle effectively.


2018 ◽  
Vol 24 (4) ◽  
pp. 295-299
Author(s):  
Fábio Sisconeto de Freitas ◽  
Willy Andrade Gomes ◽  
Paulo Henrique Marchetti

ABSTRACT Introduction: The elastic knee wrap (EKW) is a device used by powerlifters, weightlifters and subjects undergoing strength training with the aim of stabilizing the knee joint and increasing the development of strength (carryover effect). Objective: To compare the effects of elastic knee wrap use on muscular activity of the vastus lateralis (VL) and on knee extension force during maximum voluntary isometric contraction (MVIC) on the knee extensor chair. Methods: The study included 18 healthy male strength trained (>1 year) subjects (age: 25.56 ± 4.84 years, total body mass: 81.83 ± 8.73 kg, height: 176 cm ± 5.17). Three five-second maximum voluntary isometric contractions (MVICs) of the knee extensors were performed with a 10-second interval between attempts, for each experimental condition: control (C), with elastic knee wrap (EKW), and with tensor (T). The performance of the knee extensors and VL muscle activity were evaluated. A repeated measures ANOVA was used to compare the dependent variables (carryover, peak force, IEMG and Impulse). Results: For carryover, the use of EKW presented a higher value (74.21%) than the control condition (p <0.001, d = 0.96) and was 79.37% higher than the tensor (p <0.001, d = 0.97). Peak force was 12.2% higher in condition C compared to EKW (p = .018, d = 0.71). For impulse, the control condition presented an increase of 8% compared to EKW use (p = .015, d = 0.62). No significant differences were observed for IEMG. Conclusion: Elastic knee wrap use increased strength production capacity during knee extension. The removal of the mechanical effect originating from carryover during MVIC reduces the strength performance of the knee extensors, but not the muscular activation of the VL. Level of Evidence I; Therapeutic studies - Investigation of treatment results.


2013 ◽  
Vol 48 (3) ◽  
pp. 346-352 ◽  
Author(s):  
Sung-Min Ha ◽  
Oh-Yun Kwon ◽  
Heon-Seock Cynn ◽  
Won-Hwee Lee ◽  
Su-Jung Kim ◽  
...  

Context: To improve selective infraspinatus muscle strength and endurance, researchers have recommended selective shoulder external-rotation exercise during rehabilitation or athletic conditioning programs. Although selective strengthening of the infraspinatus muscle is recommended for therapy and training, limited information is available to help clinicians design a selective strengthening program. Objective: To determine the most effective of 4 shoulder external-rotation exercises for selectively stimulating infraspinatus muscle activity while minimizing the use of the middle trapezius and posterior deltoid muscles. Design: Cross-sectional study. Setting: University research laboratory. Patients or Other Participants: A total of 30 healthy participants (24 men, 6 women; age = 22.6 ± 1.7 years, height = 176.2 ± 4.5 cm, mass = 65.6 ± 7.4 kg) from a university population. Intervention(s): The participants were instructed to perform 4 exercises: (1) prone horizontal abduction with external rotation (PER), (2) side-lying wiper exercise (SWE), (3) side-lying external rotation (SER), and (4) standing external-rotation exercise (STER). Main Outcome Measure(s): Surface electromyography signals were recorded from the infraspinatus, middle trapezius, and posterior deltoid muscles. Differences among the exercise positions were tested using a 1-way repeated-measures analysis of variance with Bonferroni adjustment. Results: The infraspinatus muscle activity was greater in the SWE (55.98% ± 18.79%) than in the PER (46.14% ± 15.65%), SER (43.38% ± 22.26%), and STER (26.11% ± 15.00%) (F3,87 = 19.97, P &lt; .001). Furthermore, the SWE elicited the least amount of activity in the middle trapezius muscle (F3,87 = 20.15, P &lt; .001). Posterior deltoid muscle activity was similar in the SWE and SER but less than that measured in the PER and STER (F3,87 = 25.10, P &lt; .001). Conclusions: The SWE was superior to the PER, SER, and STER in maximizing infraspinatus activity with the least amount of middle trapezius and posterior deltoid activity. These findings may help clinicians design effective exercise programs.


2021 ◽  
pp. 036354652098868
Author(s):  
Stephen J. Thomas ◽  
Justin Cobb ◽  
Scott Sheridan ◽  
Joseph Rauch ◽  
Ryan W. Paul

Background: Because of the large forces and high frequency of throwing, the upper extremity experiences repetitive stresses that lead to acute and chronic adaptations. While the importance of pennation angle and muscle thickness as predictors of muscle force production has been shown in other populations and other joints, there has been little research done that examines these variables in the shoulders of baseball players. Purpose: (1) To examine the chronic effect pitching has on the rotator cuff muscle architecture (pennation angle and muscle thickness) in healthy professional baseball pitchers, and (2) to examine the correlation between muscle architecture and clinical measures of strength and range of motion (ROM). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Twenty-eight healthy professional pitchers were recruited during the 2019 spring training. Internal rotation (IR) and external rotation (ER) strength were measured with a handheld dynamometer and IR and ER ROM were measured with an inclinometer. A diagnostic ultrasound machine was utilized to capture images of humeral retroversion, as well as the pennation angle and muscle thickness of the infraspinatus and teres minor muscles. ImageJ software was used to quantify the pennation angle and muscle thickness. Results: There were no significant differences between the dominant and nondominant arms for ER or IR strength. Also, no pennation angle and muscle thickness differences were found between the dominant and nondominant arms. A weak positive relationship between infraspinatus muscle thickness (superficial and total) and ER strength ( P = .016, R = 0.287 and P = .009, R = 0.316) and a moderate negative relationship between soft tissue glenohumeral internal rotation deficit (GIRD) and the bilateral difference of the teres minor deep pennation angle ( R = −0.477, P = .008) were observed. No other significant relationships were noted. Conclusion: Our results are contrary to current literature as we expected to see a stronger dominant arm, with a larger pennation angle and greater muscle thickness. Interestingly, we found that ER strength was positively related to only the thickness of the infraspinatus muscle, and that soft tissue GIRD was positively related to only the side-to-side adaptation of the pennation angle within the deep portion of the teres minor. This suggests that when posterior shoulder tightness occurs, specifically the architecture of the teres minor muscle is involved. However, the organization to which these players belonged has a very extensive training protocol throughout the year that emphasizes bilateral training during a large majority of the exercises. Therefore, the results may not be generalizable to all professional players.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Taku Ukai ◽  
Goro Ebihara ◽  
Masahiko Watanabe

Abstract Background This study aims to evaluate postoperative pain and functional and clinical outcomes of anterolateral supine (ALS) and posterolateral (PL) approaches for primary total hip arthroplasty. Materials and methods We retrospectively examined the joints of 110 patients who underwent primary total hip arthroplasty (THA). The ALS group was compared with the PL group using the pain visual analog scale (VAS) and narcotic consumption as pain outcomes. Functional outcomes included postoperative range of motion (ROM) of hip flexion, day on which patients could perform straight leg raising (SLR), day on which patients began using a walker or cane, duration of hospital stay, rate of transfer, and strength of hip muscles. Clinical outcomes included pre and postoperative Harris Hip Scores. Results No significant differences were found in the pain VAS scores or narcotic consumption between the two groups. The PL group could perform SLR earlier than the ALS group (P < 0.01). The ALS group started using a cane earlier (P < 0.01) and had a shorter hospital stay (P < 0.01) than the PL group. Degrees of active ROM of flexion at postoperative day (POD) 1 were significantly lower in the ALS group than in the PL group (P < 0.01). Regarding hip muscle strength, hip flexion was significantly weaker in the ALS group than in the PL group until 1-month POD (P < 0.01). External rotation from 2 weeks to 6 months postoperatively was significantly weaker in the PL group than in the ALS group (P < 0.01). Conclusion The ALS approach was more beneficial than the PL approach because ALS enabled better functional recovery of the strength of external rotation, improved rehabilitation, and involved a shorter hospital stay. Level of Evidence Level IV retrospective observational study.


Author(s):  
Kevin Giordano ◽  
Meredith Chaput ◽  
Adam Anz ◽  
Jeremy Braziel ◽  
James Andrews ◽  
...  

AbstractThe purpose of this study was to describe the knee kinetics of baseball hitting, develop a tool to predict knee kinetics from easily obtainable measures, and to compare knee kinetics to other exercises along the rehabilitation continuum to determine a timeline for when hitting may resume after ACL reconstruction. Nineteen high school baseball athletes (16.3±0.8 yrs, 180.6±5.7 cm, 78.4±10.8 kg) participated. Participants took ten swings off a tee. Kinetic data were recorded using an electromagnetic tracking system. Data from swings with the top three exit velocities were averaged for analysis. Linear regressions were used to determine if predictors of height, mass, age and exit velocity could predict the following torques: bilateral knee net, extension, internal and external rotation, valgus and varus torque; and anterior force. Backwards regression models revealed independent variables could significantly predict front knee net, internal and external rotation, extension, and varus torque, and anterior force; and back knee net and valgus torque. Based on the kinetics of baseball hitting compared to those of rehabilitation exercises, if the involved knee is the front, we suggest tee hitting may be initiated at 13 weeks after ACL reconstruction. If the involved knee is the back, we suggest tee hitting may initiated at 17 weeks after ACL reconstruction.


2021 ◽  
Vol 9 (5) ◽  
pp. 232596712110036
Author(s):  
Jong Geol Do ◽  
Jin Tae Hwang ◽  
Kyung Jae Yoon ◽  
Yong-Taek Lee

Background: Ultrasound is an essential tool for diagnosing shoulder disorders. However, the role of ultrasound in assessing and diagnosing adhesive capsulitis has not been fully studied. Purpose: To evaluate the ultrasound features of adhesive capsulitis and estimate the correlations between clinical impairment and ultrasound parameters. Study Design: Case series; Level of evidence, 4. Methods: A total of 61 patients with clinically diagnosed unilateral adhesive capsulitis were retrospectively reviewed using high-resolution ultrasound. To compare ultrasound parameters, we performed ultrasound examinations on both affected and unaffected shoulders. Ultrasound parameters, including thickness of the coracohumeral ligament (CHL), rotator interval (RI), axillary recess (AR), hypervascularity of the RI, and effusion of the long head of the biceps tendon sheath, were measured. Passive range of motion (PROM), visual analog scale for pain, and the Shoulder Pain and Disability Index were used for clinical assessment. Results: The CHL, the RI, and the AR in affected shoulders were significantly thicker than in unaffected shoulders ( P < .05). CHL thickness in affected shoulders was significantly correlated with PROM limitation, which included forward elevation, abduction, external rotation (ER), and internal rotation (IR) ( P < .05). AR thickness correlated with passive forward elevation limitation and passive IR limitation ( P < .05). The CHL was significantly thicker in stage 2 compared with stage 1, and the RI was thicker in stage 2 compared with stage 3. The diagnostic cutoff values for adhesive capsulitis were 2.2 mm for CHL thickness (77% sensitivity, 91.8% specificity) and 4 mm for AR thickness (68.9% sensitivity, 90.2% specificity). Conclusion: The ultrasound parameters associated with structural changes were correlated with clinical characteristics of adhesive capsulitis. Thickened CHL, RI, and AR were observed in affected shoulders. The cutoff values of 2.2 mm for CHL thickness and 4 mm for AR thickness can be used as cutoff diagnostic values for adhesive capsulitis.


2018 ◽  
Vol 46 (13) ◽  
pp. 3155-3164 ◽  
Author(s):  
Vasanth Seker ◽  
Lisa Hackett ◽  
Patrick H. Lam ◽  
George A.C. Murrell

Background: Massive and irreparable rotator cuff tears are difficult to manage surgically. One technique is to use a synthetic polytetrafluoroethylene (PTFE) patch to bridge the tear. However, there is little information regarding the outcomes of this procedure. Purpose: To determine the ≥2-year outcomes of patients for whom synthetic patches were used as tendon substitutes to bridge irreparable rotator cuff defects. Study Design: Case series; Level of evidence, 4. Methods: This retrospective cohort study used prospectively collected data. Patients included those with a synthetic patch inserted as an interposition graft for large and/or irreparable rotator cuff tears with a minimum 2-year follow-up. Standardized assessment of shoulder pain, function, range of motion, and strength was performed preoperatively, at 6 and 12 weeks, and at 6 months and ≥2 years. Radiograph and ultrasound were performed preoperatively, at 6 months, and ≥2 years. Results: At a mean of 36 months, 58 of 68 eligible patients were followed up, and 53 of 58 (90%) patches remained in situ. Three patches failed at the patch-tendon interface, while 1 patient (2 shoulders/patches) went on to have reverse total shoulder replacements. Patient-ranked shoulder stiffness ( P < .001), frequency of pain with activity and sleep ( P < .0001), level of pain at rest and overhead ( P < .0001), and overall shoulder function improved from bad to very good ( P < .0001) by 6 months. Supraspinatus (mean ± SEM: 29 ± 16 N to 42 ± 13 N) and external rotation (39 ± 13 N to 59 ± 15 N) strength were the most notable increases at the ≥2-year follow-up ( P < .0001). Passive range of motion also improved by 49% to 67%; forward flexion, from 131° to 171°; abduction, from 117° to 161°; external rotation, from 38° to 55°; and internal rotation, from L3 to T10 ( P < .0001) preoperatively to ≥2 years. The most improvement in passive range of motion occurred between 12 months and ≥2 years. The mean (SD) Constant-Murley score was 90 (12), while the American Shoulder and Elbow Surgeons score was 95 (8). Conclusion: At 36 months postoperatively, patients who had synthetic patches used as tendon substitutes to bridge irreparable rotator cuff defects reported less pain and greater overall shoulder function as compared with preoperative assessments. They demonstrated improved range of passive motion and improved strength. The data support the hypothesis that the technique of using a synthetic PTFE patch to bridge a large and/or irreparable tear has good construct integrity and improves patient and clinical outcomes.


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