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European Journal of Sport Science Jun 2020The current study compared the muscle excitation in free-weight bench press variations and chest press machine. Ten competitive bodybuilders were recruited. The EMG-RMS... (Comparative Study)
Comparative Study
The current study compared the muscle excitation in free-weight bench press variations and chest press machine. Ten competitive bodybuilders were recruited. The EMG-RMS amplitude of clavicular and sternocostal head of , long head of and and was recorded while performing horizontal (BP), inclined (45°) (IBP) or declined (-15°) bench press (DBP) and chest press machine (CP). Four non-exhaustive repetitions were performed using 80% of 1-repetition maximum of each exercise. Both concentric and eccentric phases were recorded. During the concentric phase, [ effect size: 2.78/7.80] clavicular head was more excited in IBP and less excited in CP (: -9.69/-4.39) compared to all other exercises. The sternocostal head was similarly excited in DBP vs. BP and BP vs. CP and more excited (: 2.42/9.92) compared to IBP. excitation was overall greater (: 2.01/6.75) in BP and DBP compared to all other exercises. was less excited (: 3.84/19.77) in DBP compared to all other exercises. excitation was greater (: 0.96/3.10) in BP, IBP and DBP compared to CP. Muscle excitation during the eccentric phase followed a similar pattern, with the exception of the greater (: 3.89/11.32) excitation in the clavicular head in BP compared to all other exercises. The present outcomes showed that the excitation of the clavicular and sternocostal head of depends on the bench inclination angle. The use of BP variations vs. CP allows overall greater and excitation, due to the greater instability.
Topics: Adult; Cross-Sectional Studies; Electromyography; Humans; Male; Muscle Strength; Muscle, Skeletal; Resistance Training; Weight Lifting
PubMed: 31397215
DOI: 10.1080/17461391.2019.1655101 -
Journal of Athletic Training 2013To improve selective infraspinatus muscle strength and endurance, researchers have recommended selective shoulder external-rotation exercise during rehabilitation or...
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 < .001). Furthermore, the SWE elicited the least amount of activity in the middle trapezius muscle (F3,87 = 20.15, P < .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 < .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.
Topics: Analysis of Variance; Cross-Sectional Studies; Electromyography; Exercise Therapy; Female; Humans; Male; Muscle Strength; Muscle, Skeletal; Rotation; Shoulder Joint; Young Adult
PubMed: 23675794
DOI: 10.4085/1062-6050-48.2.18 -
JBJS Essential Surgical Techniques 2019A subscapularis-sparing approach to anatomic total shoulder arthroplasty (TSA) is used for patients with glenohumeral osteoarthritis who have an intact rotator cuff and...
BACKGROUND
A subscapularis-sparing approach to anatomic total shoulder arthroplasty (TSA) is used for patients with glenohumeral osteoarthritis who have an intact rotator cuff and sufficient bone volume.
DESCRIPTION
A 7 to 10-cm anterosuperior incision is made with the patient in the beach chair position. The anterolateral deltoid muscle raphe is split, and the shoulder is externally rotated to bring the rotator interval to the field. A flap of interval tissue is incised, tenodesis of the biceps tendon is performed, and the interval tissue is incised straight back to the glenoid from the upper edge of the subscapularis, creating a triangular piece of tissue referred to as a "trapdoor." Two Darrach retractors are placed to expose the humeral head. An intramedullary guide is placed, and a humeral head osteotomy is performed. The glenoid is exposed, and the glenoid component is placed after sizing, preparation, drilling, and insertion of trial components per the surgical technique. The humeral head size is estimated by measuring, and the humeral stem size is decided by sequentially inserting the trial components. The permanent humeral stem is inserted, and the permanent humeral head is implanted after insertion of trial components. The trapdoor is sutured, the deltoid is reattached, and subcutaneous tissue and skin are sutured.
ALTERNATIVES
The traditional surgical approach for anatomic TSA involves release and reattachment of the subscapularis tendon.
RATIONALE
Nearly all anatomic TSA techniques require the subscapularis to be released, with a peel, tenotomy, or osteotomy, and then repaired on completion of the arthroplasty. Failure of the subscapularis to heal is an unfortunate and potentially devastating complication following anatomic TSA that has been linked to decreased function, instability, and pain. Subscapularis dysfunction following anatomic TSA is seen in one-third to two-thirds of patients, with evidence of complete tears in up to 50% of asymptomatic patients using ultrasound examinations.Sling immobilization with avoidance of excessive passive external rotation and active internal rotation is recommended to help prevent postoperative rupture of the subscapularis repair. However, postoperative motion restrictions to protect the subscapularis may lead to stiffness and may negatively impact function and satisfaction.We describe a subscapularis-sparing TSA, in which we address and improve on 3 technical difficulties identified by Lafosse et al.: (1) difficulty ensuring an anatomic humeral neck cut because of the difficulty visualizing the anterior aspect of the shoulder, (2) inadequate resection of inferior humeral neck osteophytes, and (3) undersizing of the humeral head.
PubMed: 32051788
DOI: 10.2106/JBJS.ST.18.00115 -
Journal of Experimental Orthopaedics Dec 2014There remains controversy on the role of the deltoid on glenohumeral translations during basic and pitching motions. We thus studied the passive effect of the deltoid on...
BACKGROUND
There remains controversy on the role of the deltoid on glenohumeral translations during basic and pitching motions. We thus studied the passive effect of the deltoid on the deltoid glenohumeral joint center (GHJC).
METHODS
Six shoulders were tested using an automated mechanical system. A baseline motion pattern of the intact specimen was contrasted with glenohumeral translation after removal of the deltoid. Each condition was evaluated in abduction (ABD) and an abbreviated throwing motion (ATM) using retro-reflective, bone-embedded markers. The absolute trajectory and the area under the curve (AUC) for each motion were calculated and glenohumeral kinematics with respect to the GH translation were compared.
RESULTS
The removal of the deltoid resulted in significant changes of the GH translation. During 30-60° of ABD, it resulted in a superior and more anterior GH translation, while in the 60-90° segment in a more inferior and medial GH translation. During 90-120°, the GH translation was medialized. In the pitching motion from maximum external rotation to 90° of external rotation (ER), the removal of the deltoid resulted in a more superior, anterior and lateral GH translation. Thus limits anterior translation in the abduction-external rotation position. In the remaining segments (90-80° and 80-45° of ER), it resulted in a lateralization of the GH translation.
CONCLUSIONS
Modelling the throwing shoulder, the deltoid has a significant influence on glenohumeral motion. Athletes with deltoid dysfunction and limited range of motion are at risk for injury due to the resulting change in their throwing mechanics.
PubMed: 26914759
DOI: 10.1186/s40634-014-0014-9 -
Vaccine Aug 2022The mRNA COVID vaccines are only licensed for intramuscular injection but it is unclear whether successful intramuscular administration is required for immunogenicity. (Observational Study)
Observational Study
BACKGROUND
The mRNA COVID vaccines are only licensed for intramuscular injection but it is unclear whether successful intramuscular administration is required for immunogenicity.
METHODS
In this observational study, eligible adults receiving their first Comirnaty/BNT162b2 dose had their skin to deltoid muscle distance (SDMD) measured by ultrasound. The relationship between SDMD and height, weight, body mass index, and arm circumference was assessed. Three needle length groups were identified: 'clearly sufficient' (needle exceeding SDMD by >5 mm), 'probably sufficient' (needle exceeding SDMD by ≤ 5 mm), and 'insufficient' (needle length ≤ SDMD). Baseline and follow-up finger prick blood samples were collected and the primary outcome variable was mean spike antibody levels in the three needle length groups.
RESULTS
Participants (n = 402) had a mean age of 34.7 years, BMI 29.1 kg/m, arm circumference 37.5 cm, and SDMD 13.3 mm. The SDMD was >25 mm in 23/402 (5.7%) and >20 mm in 61/402 (15.2%) participants. Both arm circumference (≥40 cm) and BMI (≥33 kg/m) were able to identify those with a SDMD of >25 mm, the length of a standard injection needle, with a sensitivity of 100% and specificities of 71.2 and 79.9%, respectively. Of 249/402 (62%) participants with paired blood samples, there was no significant difference in spike antibody titres between needle length groups. The mean (SD) spike BAU/mL was 464.5 (677.1) in 'clearly sufficient needle length' (n = 217) compared with 506.4 (265.1) in 'probably sufficient' (n = 21, p = 0.09), and 489.4 (452.3) in 'insufficient needle length' (n = 11, p = 0.65).
CONCLUSIONS
A 25 mm needle length is likely to be inadequate to ensure vaccine deposition within the deltoid muscle in a small proportion of adults. Vaccine-induced spike antibody titres were comparable in those vaccinated with a needle of sufficient versus insufficient length suggesting deltoid muscle deposition may not be required for an adequate antibody response to mRNA vaccines.
Topics: Adult; Antibodies, Viral; BNT162 Vaccine; COVID-19; COVID-19 Vaccines; Deltoid Muscle; Humans; Immunogenicity, Vaccine; RNA, Messenger; Vaccines
PubMed: 35792021
DOI: 10.1016/j.vaccine.2022.06.070 -
Acta Orthopaedica Et Traumatologica... 2014The aim of this study was to identify the anatomical obstacles on the humeral surface which can complicate subcutaneous plate advancement during surgical treatment of...
OBJECTIVE
The aim of this study was to identify the anatomical obstacles on the humeral surface which can complicate subcutaneous plate advancement during surgical treatment of humeral fractures.
METHODS
We dissected twelve upper extremities of six male cadavers, and measured the humeral length, which was defined as the distance between the greater tubercle and the lateral epicondyle. We performed a retrograde advancement of a 4.5 mm plate through the subbrachial tunnel and noted the mechanical obstacles during the procedure. In addition, we recorded the distances between the anatomic obstacles and lateral epicondyle.
RESULTS
The average humeral length was 271.8 mm. We identified anterior insertion of the deltoid muscle and the proximal part of the brachialis muscle as the main anatomic obstacles on the anterior surface of the humerus. The average distances between the lateral epicondyle and the most proximal and distal insertion of anterior deltoid were 188.9 mm and 138.7 mm, respectively. The average distance between the lateral epicondyle and the brachialis origin was 147.4 mm. Proportions of the distances between the lateral epicondyle and proximal of anterior deltoid insertion, the lateral epicondyle and distal of anterior deltoid insertion and the lateral epicondyle and proximal of brachialis origin to humeral length were 69.4%, 51%, and 54.2%, respectively. There was a high interobserver reliability (p<0.001).
CONCLUSION
The deltoid insertion and proximal attachment of the brachialis muscles were identified as mechanical obstacles when performing the percutaneous plating. These sites caused difficulties with the procedure during the retrograde plate advancement through submuscular tunnel on the anterior surface of humerus. It was also noted that for successful plate advancement, it was necessary to release the anterior part of the deltoid insertion.
Topics: Aged; Bone Plates; Cadaver; Dissection; Fracture Fixation, Internal; Humans; Humeral Fractures; Humerus; Male; Middle Aged; Minimally Invasive Surgical Procedures
PubMed: 25429587
DOI: 10.3944/AOTT.2014.3161 -
World Journal of Surgical Oncology Sep 2023Approximately, one-third of patients with tumors of proximal humerus will require an extra-articular resection to achieve oncologic margins. This procedure yields poor...
BACKGROUND
Approximately, one-third of patients with tumors of proximal humerus will require an extra-articular resection to achieve oncologic margins. This procedure yields poor functional outcomes with a considerable rate of revisions. Unconstrained implants are prone to instability hindering also function of the elbow and hand, whereas constrained shoulder reconstructions suffer from early aseptic loosening of the glenoid component due to bone overload. The purpose of this study was to develop a constrained implant suitable for extra-articular resection with loss of function in deltoid and rotator cuff, which would provide both stability and passive motion, whilst also decreasing the risk of aseptic loosening of the glenoid component.
METHODS
In cooperation with Czech Technical University in Prague, we devised an implant consisting of two constrained joints in series connected by a dumbbell piece. The biomechanical analysis showed a reduction of load transfer to the glenoid component with a torque of 8.6 Nm capable of generating an 865-N pulling force on bone screw to just 0.07 Nm, hence shielding the glenoid component from undesired forces and decreasing the risk of aseptic loosening. Three patients with extra-articular resection with a total loss of function of both rotator cuff and deltoid muscle received this type of reconstruction. The average follow-up was 16 months.
RESULTS
The surgical technique is straightforward. The surgery took 175 min on average with average blood loss of 516 ml. There were no surgical- or implant-related complications. All three patients were pain-free and had a stable shoulder joint after the reconstruction. All had fully functional elbow, wrist, and hand joints. The average Musculoskeletal Tumor Society (MSTS) score was 21/30 (70%). All patients were pleased with the results.
CONCLUSION
The presented innovative implant design has demonstrated to be a promising alternative for reconstruction in these challenging cases.
Topics: Humans; Humerus; Postoperative Complications; Scapula; Shoulder; Shoulder Joint; Bone Neoplasms; Arthroplasty, Replacement
PubMed: 37723520
DOI: 10.1186/s12957-023-03173-9 -
BMC Endocrine Disorders Jul 2022In our previous published study, we demonstrated that a qualitatively assessed elevation in deltoid muscle echogenicity on ultrasound was both sensitive for and a strong...
BACKGROUND
In our previous published study, we demonstrated that a qualitatively assessed elevation in deltoid muscle echogenicity on ultrasound was both sensitive for and a strong predictor of a type 2 diabetes (T2DM) diagnosis. This study aims to evaluate if a sonographic quantitative assessment of the deltoid muscle can be used to detect T2DM.
METHODS
Deltoid muscle ultrasound images from 124 patients were stored: 31 obese T2DM, 31 non-obese T2DM, 31 obese non-T2DM and 31 non-obese non-T2DM. Images were independently reviewed by 3 musculoskeletal radiologists, blinded to the patient's category. Each measured the grayscale pixel intensity of the deltoid muscle and humeral cortex to calculate a muscle/bone ratio for each patient. Following a 3-week delay, the 3 radiologists independently repeated measurements on a randomly selected 40 subjects. Ratios, age, gender, race, body mass index, insulin usage and hemoglobin A were analyzed. The difference among the 4 groups was compared using analysis of variance or chi-square tests. Both univariate and multivariate linear mixed models were performed. Multivariate mixed-effects regression models were used, adjusting for demographic and clinical variables. Post hoc comparisons were done with Bonferroni adjustments to identify any differences between groups. The sample size achieved 90% power. Sensitivity and specificity were calculated based on set threshold ratios. Both intra- and inter-radiologist variability or agreement were assessed.
RESULTS
A statistically significant difference in muscle/bone ratios between the groups was identified with the average ratios as follows: obese T2DM, 0.54 (P < 0.001); non-obese T2DM, 0.48 (P < 0.001); obese non-T2DM, 0.42 (P = 0.03); and non-obese non-T2DM, 0.35. There was excellent inter-observer agreement (intraclass correlation coefficient 0.87) and excellent intra-observer agreements (intraclass correlation coefficient 0.92, 0.95 and 0.94). Using threshold ratios, the sensitivity for detecting T2DM was 80% (95% CI 67% to 88%) with a specificity of 63% (95% CI 50% to 75%).
CONCLUSIONS
The sonographic quantitative assessment of the deltoid muscle by ultrasound is sensitive and accurate for the detection of T2DM. Following further studies, this process could translate into a dedicated, simple and noninvasive screening method to detect T2DM with the prospects of identifying even a fraction of the undiagnosed persons worldwide. This could prove especially beneficial in screening of underserved and underrepresented communities.
Topics: Deltoid Muscle; Diabetes Mellitus, Type 2; Glycated Hemoglobin; Humans; Obesity; Ultrasonography
PubMed: 35897066
DOI: 10.1186/s12902-022-01107-2 -
Cureus Mar 2024The infraspinatus muscle (IS) makes a minor contribution to lateral rotation of the arm but mainly serves to stabilize the glenohumeral (GH) joint as part of the rotator...
The infraspinatus muscle (IS) makes a minor contribution to lateral rotation of the arm but mainly serves to stabilize the glenohumeral (GH) joint as part of the rotator cuff. Although reports of variations in the rotator cuff muscles have been documented previously, specific discussions of IS variants are lacking. In this report, we present a novel case of an accessory muscle in the infraspinous fossa and its relationship to the IS, which was normally located. We describe the observed physical features of the muscles and their innervation patterns.
PubMed: 38618436
DOI: 10.7759/cureus.56100 -
Mathematical Biosciences and... Mar 2022Muscle coordination and motor function of stroke patients are weakened by stroke-related motor impairments. Our earlier studies have determined alterations in...
Muscle coordination and motor function of stroke patients are weakened by stroke-related motor impairments. Our earlier studies have determined alterations in inter-muscular coordination patterns (muscle synergies). However, the functional connectivity of these synergistically paired or unpaired muscles is still unclear in stroke patients. The goal of this study is to quantify the alterations of inter-muscular coherence (IMC) among upper extremity muscles that have been shown to be synergistically or non-synergistically activated in stroke survivors. In a three-dimensional isometric force matching task, surface EMG signals are collected from 6 age-matched, neurologically intact healthy subjects and 10 stroke patients, while the target force space is divided into 8 subspaces. According to the results of muscle synergy identification with non-negative matrix factorization algorithm, muscle pairs are classified as synergistic and non-synergistic. In both control and stroke groups, IMC is then calculated for all available muscle pairs. The results show that synergistic muscle pairs have higher coherence in both groups. Furthermore, anterior and middle deltoids, identified as synergistic muscles in both groups, exhibited significantly weaker IMC at alpha band in stroke patients. The anterior and posterior deltoids, identified as synergistic muscles only in stroke patients, revealed significantly higher IMC in stroke group at low gamma band. On the contrary, anterior deltoid and pectoralis major, identified as synergistic muscles in control group only, revealed significantly higher IMC in control group in alpha band. The results of muscle synergy and IMC analyses provide congruent and complementary information for investigating the mechanism that underlies post-stroke motor recovery.
Topics: Electromyography; Humans; Muscle, Skeletal; Shoulder; Stroke; Upper Extremity
PubMed: 35430825
DOI: 10.3934/mbe.2022208