Shoulder Muscles Research Articles

Scapulohumeral rhythm, posterior capsule stiffness, shoulder muscle strength and flexibility in young unilateral and bilateral overhead athletes.

Scapulohumeral rhythm, posterior capsule stiffness, shoulder muscle strength and flexibility in young unilateral and bilateral overhead athletes.

Clinical Validation of a Computed Tomography Image-Based Machine Learning Model for Segmentation and Quantification of Shoulder Muscles

Introduction: We developed a computed tomography (CT)-based tool designed for automated segmentation of deltoid muscles, enabling quantification of radiomic features and muscle fatty infiltration. Prior to use in a clinical setting, this machine learning (ML)-based segmentation algorithm requires rigorous validation. The aim of this study is to conduct shoulder expert validation of a novel deltoid ML auto-segmentation and quantification tool. Materials and Methods: A SwinUnetR-based ML model trained on labeled CT scans is validated by three expert shoulder surgeons for 32 unique patients. The validation evaluates the quality of the auto-segmented deltoid images. Specifically, each of the three surgeons reviewed the auto-segmented masks relative to CT images, rated masks for clinical acceptance, and performed a correction on the ML-generated deltoid mask if the ML mask did not completely contain the full deltoid muscle, or if the ML mask included any tissue other than the deltoid. Non-inferiority of the ML model was assessed by comparing ML-generated to surgeon-corrected deltoid masks versus the inter-surgeon variation in metrics, such as volume and fatty infiltration. Results: The results of our expert shoulder surgeon validation demonstrates that 97% of ML-generated deltoid masks were clinically acceptable. Only two of the ML-generated deltoid masks required major corrections and only one was deemed clinically unacceptable. These corrections had little impact on the deltoid measurements, as the median error in the volume and fatty infiltration measurements was <1% between the ML-generated deltoid masks and the surgeon-corrected deltoid masks. The non-inferiority analysis demonstrates no significant difference between the ML-generated to surgeon-corrected masks relative to inter-surgeon variations. Conclusions: Shoulder expert validation of this CT image analysis tool demonstrates clinically acceptable performance for deltoid auto-segmentation, with no significant differences observed between deltoid image-based measurements derived from the ML generated masks and those corrected by surgeons. These findings suggest that this CT image analysis tool has potential to reliably quantify deltoid muscle size, shape, and quality. Incorporating these CT image-based measurements into the pre-operative planning process may facilitate more personalized treatment decision making, and help orthopedic surgeons make more evidence-based clinical decisions.

Risk Contributors for Shoulder Injuries Among Adolescent Tennis Participants: A Prospective Group Study

Background:Tennis is a popular sport among adolescents, but the repetitive overhead motions can lead to shoulder injuries. The risk factors for shoulder injuries in this population are not well understood.Purpose:To identify risk factors for shoulder injuries in adolescent tennis players and examine potential interactions between these factors.Study Design:Cohort study; Level of evidence, 2.Methods:Adolescent tennis players (N = 350; aged 12-18 years) were followed for 24 months. Baseline data on demographics, tennis experience, training volume, physical characteristics, and psychological factors were collected. Shoulder injuries (defined as any shoulder pain or dysfunction requiring ≥48 hours of time loss from tennis participation and medical attention) were recorded monthly. Cox proportional HR analysis with univariate and multivariate models was used to identify risk factors, with statistical significance set at P < .05.Results:A total of 88 players (25.1%) sustained shoulder injuries. Significant risk factors included age (hazard ratio [HR], 1.42; 95% CI, 1.16-1.74), years of playing tennis (HR, 1.25; 95% CI, 1.10-1.42), weekly training hours (HR, 1.18; 95% CI, 1.09-1.28), shoulder external/internal rotation strength ratio (HR, 3.12; 95% CI, 1.63-5.98), scapular dyskinesis (HR, 2.76; 95% CI, 1.46-5.22), and high levels of competitive anxiety (HR, 2.15; 95% CI, 1.24-3.73). Playing on hard courts increased injury risk compared with clay (HR, 1.68; 95% CI, 1.05-2.69) or grass courts (HR, 1.92; 95% CI, 1.14-3.24). Significant interactions were found between age and training volume (P = .01) and between shoulder strength ratio and scapular dyskinesis (P = .02).Conclusion:Our study demonstrated that multiple interacting factors contribute to shoulder injury risk in adolescent tennis players. Age, tennis experience, training volume, shoulder muscle imbalance, scapular dyskinesis, competitive anxiety, and playing surface were identified as significant risk factors. These findings can guide the development of targeted prevention strategies to reduce shoulder injury risk in adolescent tennis players.

Comparative analysis of high-intensity resistance training and blood flow restriction training on enhancing upper limb muscle strength and mass

PurposeTo investigate the effects of blood flow restriction training with fixed pressure combined with low-intensity resistance training (BFRT-F) and progressive pressure combined with low-intensity resistance training (BFRT-P) in enhancing upper limb muscle strength and mass, and to compare their effects with high-intensity resistance training (HIRT).MethodsA stratified randomized controlled trial was conducted, where 34 participants were randomly assigned to the HIRT, BFRT-F, and BFRT-P groups. The 8-week intervention included thrice-weekly training sessions.Results1) All groups showed significant 1RM increases, with HIRT and BFRT-P superior BFRT-F. 2) HIRT significantly improved isokinetic muscle strength indicators, including peak torque of shoulder, elbow joints, and trunk and back muscle groups, compared with BFRT-F and, in some measurements, BFRT-P. BFRT-P also significantly increased peak torque compared to BFRT-F. BFRT-F demonstrated significant gains in peak torque for multiple joint flexors and extensors. 3) Muscle circumference increased significantly in HIRT and BFRT-P groups, with the highest gain in HIRT. 4) Only HIRT and BFRT-P significantly increased muscle mass, with HIRT demonstrating the highest growth in both arms.ConclusionThe efficacy hierarchy was HIRT &amp;gt; BFRT-P &amp;gt; BFRT-F. While HIRT is optimal for strength and hypertrophy, BFRT-P is a viable alternative for individuals contraindicated to high-intensity training.

The Association between Excessive Glenohumeral External Rotation and Risk for Shoulder and Elbow Injury in Left-Handed High School Baseball Pitchers: A Prospective Cohort Study

Background:Left-handed baseball pitchers exhibit unique throwing biomechanics, yet the risk factors for shoulder and elbow injuries in this population remain unclear.Purpose:To prospectively investigate preseason risk factors for shoulder and elbow injuries in left-handed high school baseball pitchers.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 160 left-handed high school baseball pitchers were enrolled. Preseason evaluations included age, height, weight, shoulder muscle strength, and range of motion of the shoulder and elbow. Participants completed a self-recorded questionnaire on shoulder and elbow pain and associated pitching limitations during the subsequent season. Participants were categorized into the noninjured or injured group. The Mann-Whitney U test, chi-square test, logistic regression analysis, and receiver operating characteristic curve analysis were used to identify injury risk factors and cutoff values for shoulder and elbow injuries.Results:Shoulder and elbow injuries occurred in 27 participants (16.9%). The injured group had significantly greater abduction–external rotation (ABER) in the dominant shoulder (114.8°± 11.9° vs 107.5°± 13.0°; P = .008) and a greater total arc of the dominant shoulder (166.4°± 25.1° vs 156.0°± 23.4°; P = .039). Logistic regression analysis showed that ABER in the dominant shoulder was an independent risk factor for injuries (P = .031; OR, 1.04). Receiver operating characteristic curve analysis determined that an ABER ≥109° predicted injury (P = .017). Pitchers with ABER ≥109° had a 3.3 times higher incidence of injury than those with ABER <109° (P = .005).Conclusion:Increased shoulder ABER was significantly associated with shoulder and elbow injuries among left-handed high school baseball pitchers. Pitchers with ABER ≥109° are at higher risk.

Screening Tests to Identify Injury Risk in Competitive Swimmers: A Scoping Review

Introduction: Swimming places unique demands on athletes, encompassing repetitive, high-intensity movements in a challenging aquatic environment, which predisposes them to a higher risk of injuries. Early identification through screening tests is essential for injury prevention in swimmers. Several screening tests are available to assess injury risk in swimmers, highlighting the need to identify effective, clinically relevant tools. Aim: To review existing literature on screening tools that identify the risk of injury in competitive swimmers. Materials and Methods: An electronic search of the PubMed database, as well as secondary sources like Google Scholar, was conducted for relevant studies from the earliest available date until February 2024. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. A population, concept, and context framework was used to select and collect data. Peer-reviewed full-text studies involving competitive swimmers across different age categories were included, while studies that were reviews or in non English languages were excluded. Data were extracted using Excel, and the following factors were summarised: study design, population, screening tools, and major findings. A quality rating for the selected studies was conducted using the National Institutes of Health (NIH) study-quality assessment tool. Results: A total of 7,255 articles were identified, from which 16 full-text studies reported the use of various screening tools to assess injury risk. The majority of the studies (n=12) were rated as fair quality according to NIH standards. Shoulder horizontal abduction Range of Motion (ROM), posterior shoulder endurance, and the isokinetic functional strength ratio (EccER: ConIR) were most effective in identifying shoulder injuries. However, limited evidence exists regarding the identification of injury risk in other body regions, such as the knee and spine. Conclusion: Screening tools identified decreased shoulder rotation strength ratio, Posterior Shoulder muscle Endurance (PSE), and shoulder horizontal abduction ROM as causative risks for swimming injuries. However, it is also evident that screening needs to be comprehensive and should include robust outcomes to effectively determine injury risk.

Preliminary Analysis of the Contribution of Shoulder Muscle Strength to Bowling Speed in University-Level Male Cricketers

Preliminary Analysis of the Contribution of Shoulder Muscle Strength to Bowling Speed in University-Level Male Cricketers

Effect of international scientific exercise guidelines on illness perception in patients with chronic spinal cord injury

Introduction. The aim of this study was to analyze the effect of the International Scientific Exercise Guidelines on illness perception in patients with chronic spinal cord injury (SCI). Methods. Sixteen patients with chronic SCI (AIS B/C/D, NLI at T1 or lower) were randomized into treatment and control groups. The treatment group received exercise interventions based on the International Scientific Exercise Guidelines for 12 weeks, including 20 minutes of moderate-intensity cardiovascular fitness exercises twice a week, followed by three sets of shoulder muscle strengthening exercises at home twice a week. The control group received no specific intervention and continued with their usual daily activities, but were allowed to perform exercises other than those outlined in the guidelines. The Brief Illness Perception Questionnaire (B-IPQ) score was analyzed before and after the intervention. Results. A significant improvement in the B-IPQ score was observed in the treatment group (p = 0.028) after the intervention. The difference (Δ) in B-IPQ scores between the two groups was also significant (p = 0.008). Conclusion. A 12-week exercise program based on the International Scientific Exercise Guidelines can improve illness perception in patients with chronic SCI (AIS B/C/D, NLI T1 or lower).

Differences in Glenohumeral Range of Motion, Shoulder Strength, and Humeral Torsion Between Right- and Left-handed High School Baseball Pitchers

Background:Differences in shoulder range of motion (ROM), shoulder muscle strength, and humeral torsion between left- and right-handed high school baseball pitchers remain poorly characterized.Hypothesis:Similar differences in shoulder ROM, strength, and humeral torsion between right-handed pitchers (RHPs) and left-handed pitchers (LHPs) observed in professionals will also be present in high school pitchers, with potential variations due to developmental stages.Study Design:Cross-sectional study; Level of evidence, 3.Methods:The authors included 921 high school baseball pitchers (706 RHPs and 215 LHPs) and evaluated their age, height, weight, body mass index, baseball experience, shoulder ROM, and muscle strength. Humeral torsion was measured in 211 RHPs and 57 LHPs. The Mann-Whitney U test was performed to determine the differences between the RHPs and LHPs and between the dominant and nondominant sides in each group. Pearson correlation analysis was performed to test the relationship between humeral torsion and shoulder ROM. Logistic regression analysis was conducted to determine the independent factors associated with LHP.Results:LHPs exhibited increased nondominant external rotation (ER) (103.1° vs 100.0°; P = .004), dominant horizontal adduction (HA) (23.0° vs 19.6°; P = .015), and side-to-side ratio in prone internal rotation (PIR) strength (107.6% vs 98.3%; P < .001) compared with RHPs. Additionally, LHPs were shorter (171.4 vs 172.9 cm; P = .002) with lower side-to-side differences in ER (5.7° vs 8.9°; P < .001) and HA (–6.5° vs −11.3°; P < .001), dominant prone ER (PER) strength (15.4 vs 16.8 kgf; P = .040), side-to-side ratio in PER strength (93.1% vs 103.7%; P < .001), and side-to-side differences in humeral torsion (5.8° vs 9.9°; P = .011) compared with RHPs. After adjusting for confounding factors, a smaller side-to-side ratio in PER strength (P < .001; OR, 0.911) and larger side-to-side ratio in PIR strength (P < .001; OR, 1.031) were independent factors associated with being an LHP.Conclusion:LHPs have a decreased side-to-side ratio in PER strength and increased side-to-side ratio in PIR strength compared with RHPs. These findings suggest that shoulder-related biomechanical differences between right- and left-handed pitchers are evident in high school athletes.

Immediate Effectiveness of Percussor Massage Therapyon Pain, Cervical Range of Motion in Forward Head Posture among Janitors: Single Arm Clinical Trial

Background: Forward Head Posture (FHP) is increasingly prevalent among janitors due to repetitive physical tasks, often resulting in chronic neck pain and limited cervical mobility. This study evaluates the immediate effectiveness of Percussor Massage Therapy (PMT) in alleviating pain and improving cervical range of motion (ROM) in this high-risk occupational group.  Methodology: An experimental single-arm study was conducted on 12 janitors aged 35–50 years, diagnosed with FHP (craniovertebral angle &gt;49°). Participants underwent a single 15-minute PMT session targeting cervical and upper shoulder muscles. Pre- and post-intervention assessments were conducted using the Numerical Pain Rating Scale (NPRS), Neck Pain and Disability Scale (NPAD), and goniometric cervical ROM measurements.  Results: Statistical analysis using paired t-tests revealed significant reductions in pain scores (NPRS: pre 4.82, post 2.27; p &lt; 0.001) and improvements in cervical flexion, extension, and functional scores (NPAD: pre 64.36, post 40.00; p &lt; 0.001).  Conclusion: PMT demonstrated immediate and significant benefits in reducing pain and improving cervical ROM in janitors with FHP. Its non-invasive nature and practicality suggest its utility as an effective ergonomic intervention in occupational settings.

Spinal accessory nerve palsy and winged scapula caused by repetetive strain: a case report

Scapular winging is a rare disorder that causes functional limitation of the upper extremity. It may develop due to many pathological conditions that can cause paralysis in the serratus anterior, trapezius and rhomboid muscles (which are innervated by the long thoracic nerve, spinal accessory nerve and dorsal scapular nerve, respectively). Diagnosis is made by imaging and electrodiagnostic studies after physical examination. In this case, it is aimed to present the diagnosis and treatment stages of the patient who developed shoulder pain, muscle weakness and scapular winging, due to injury to the spinal sccessory nerve, which is the 11th cranial nerve and provides pure motor innervation to the trapezius muscle. Although scapular winging is not a condition we frequently encounter in clinical practice, it is important due to its potential for disability that may affect the quality of life.

Abstract P5-09-09: Prospective Evaluation of Shoulder Morbidity in Patients with Lymph Node-Positive Breast Cancer Receiving Regional Nodal Irradiation

Abstract Purpose/Objective(s): Many women with axillary node-positive breast cancer benefit from regional nodal irradiation (RNI) in terms of improved cancer control outcomes. RNI unintentionally exposes the shoulder structures to radiation, which can lead to morbidity. We previously demonstrated that intensity modulated radiation therapy (IMRT) results in less radiation dose to the shoulder compared to 3D conformal radiation therapy (3DCRT). We set to determine if the dosimetric advantage of IMRT translates into a clinically meaningful reduction in shoulder morbidity. Materials/Methods: This study is registered on clinicaltrials.gov (NCT03786354). We enrolled patients that were to receive RNI after mastectomy (Mx) or lumpectomy (Lump) with axillary staging (axillary lymph node dissection [ALND] or sentinel node biopsy [SNB]). All patients received 50 Gy in 25 fractions to the breast or chestwall and RNI. Patients were non-randomly assigned to either Arm IMRT or Arm B 3DCRT on the basis of a treatment planning algorithm that defaults to 3DCRT but transitions to IMRT based on dosimetric criteria. The primary endpoint was shoulder/arm morbidity at 1 year post-RNI in IMRT patients using the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Based on limited existing data at the time, we estimated that the 1-year DASH score would be 20 in patients that had undergone RNI with 3DCRT and that IMRT would reduce the 1-year DASH to ≤10. A sample size of 27 patients would have 80% power to detect this 10-point difference in DASH score. We enrolled 27 patients on Arm 3DCRT to establish the average DASH score in this cohort. Results: Patients were enrolled from 1/2019-3/2022. After loss to follow-up, there were 29 patients evaluable for the primary endpoint in Arm IMRT and 27 patients in Arm 3DCRT with similar ages (median age=50 years vs. 51 years, p=0.83) but trend towards higher rates of Mx (72% vs. 51%, p=0.11) and ALND (90% vs.78%, p=0.23) in Arm IMRT vs. Arm 3DCRT. In arm IMRT, the mean baseline (post-surgery/pre-RNI) DASH was 12.8(SD 11.0) and increased to a mean of 15.4(SD 15.1) at 1-year. In arm 3DCRT, the mean baseline DASH was 14.0(SD 12.9) and increased to a mean of 14.8(SD 13.2) at 1-year. Decrease in DASH scores was more frequent in Arm IMRT vs. 3DCRT (51.7% vs. 37.0%, p=0.27). In the entire cohort, patients treated with Mx and patients treated with ALND tended to have worse 1-year DASH scores: 17.6 (SD 15.9) Mx vs. 11.0(SD 9.4) Lump, p=0.06; 16.4(SD 14.7) ALND vs. 8.4(SD 8.0) SNB, p=0.03. Conclusion: This study did not meet its primary endpoint but the similar 1-year DASH scores in Arm IMRT and Arm 3DCRT may reflect IMRT compensating for the more extensive axillary and breast surgery in that arm. More than 50% of patients in Arm IMRT experienced a decrease in DASH score. These findings suggest that prospective investigation of IMRT for RNI in the setting of SNB remains worthy of study. Analysis of secondary endpoints including objective range of motion assessments and shoulder muscle dosimetry are forthcoming. Citation Format: Jose Bazan, Julie Stephens, Sachin R. Jhawar, Sasha Beyer, Karen Hock, Julia R. White. Prospective Evaluation of Shoulder Morbidity in Patients with Lymph Node-Positive Breast Cancer Receiving Regional Nodal Irradiation [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P5-09-09.

Size matters ̶ effect of screen setup on muscle activity and posture in computer work

This research aims to investigate and compare how computers work on five different workstation setups of multiple or large screens and viewing distances (27-inch and 49-inch at 70 or 90 cm viewing distance) affect muscular load in neck/shoulders, working postures, and perceived exertions of non-presbyopic participants. The electrical activity in the trapezius shoulder and trapezius neck muscles, and work postures of the head and back were recorded with objective, technical methods. The perceived exertions in the neck/shoulder and eyes, and the participants' opinions of the different workstations, were collected. Overall, the 49-inch curved screen with a viewing distance of 90 cm was quantitatively recorded and qualitatively rated as the best setup of all five workstations included in the study. The 49-inch screen was also objectively and subjectively rated to be better than 2 × 27-inch screens. The 2 × 27-inch V-formation setup was subjectively favoured compared to the 2 × 27-inch L-formation setup.

Transcutaneous Electrical Neurostimulation at the Second Stage of Medical Rehabilitation in Ischemic Stroke: a Controlled Randomized Study

INTRODUCTION. Patients who have suffered a stroke require long-term and intensive rehabilitation measures to restore both vital and motor, cognitive, psycho-emotional and other functions of the body. Along with the use of physiotherapy methods, transcutaneous electrical neurostimulation can be used already at the stage of the patient’s stay in the intensive care unit; however, due to the lack of modern information on its effectiveness, this method is extremely rarely included in rehabilitation programs at the early stages. AIM. To evaluate the clinical effectiveness of using electrotherapy with different durations of procedures at the II stage of medical rehabilitation, including the period of patients with stroke in the intensive care unit. MATERIALS AND METHODS. A randomized controlled trial was conducted at the National Medical Research Center for Rehabilitation and Balneology between 2024 and 2025, involving 61 patients who had suffered an ischemic stroke. All patients were divided into 4 groups, which underwent a standard medical rehabilitation scheme, as well as additional electrotherapy with a duration of 10, 20 and 30 minutes, a course of 14 procedures. BEFORE the start of the course of procedures, as well as after its completion, muscle strength in the affected limbs was assessed on a five-point scale, as well as an assessment on the Rivermead, Rankin, NIHSS, and rehabilitation routing scales. RESULTS AND DISCUSSION. A total of 61 patients of both sexes (27 men (44 %) and 34 women (56 %)) took part in the study. The average age of the patients was 59 years. All patients suffered from acute cerebrovascular accident (ACVA) of the ischemic type in the basin of the right/left middle cerebral artery. At the end of the course of electrotherapy procedures in the main group, with an exposure of 30 minutes, muscle strength in the affected limbs in the distal sections increased (shoulder muscles 1.9b. (1.0; 2.3); forearm/hand muscles 1.5b. (0.5; 1.8); thigh muscles 2.2b. (1; 2.5); lower leg/foot muscles 1.5b. (1.1; 1.8)) compared to the control group (0.9b. (0; 1.5); 0.3b. (0; 1); 1.1b. (0; 2); 0b. (0; 0.5), respectively) (p 0.05). CONCLUSION. Additional physiotherapeutic treatment in the form of transcutaneous electrical neurostimulation of patients who have suffered a stroke, initiated during their stay in the intensive care unit at the second stage of medical rehabilitation, proved to be more effective in improving the motor activity of paretic limbs compared to the standard rehabilitation programme. The best results were in the group with a duration of electrotherapy of 30 minutes, significantly improving muscle strength in the affected limbs in the distal sections (shoulder muscles 1.9b. (1.0; 2.3); forearm/hand muscles 1.5b. (0.5; 1.8); thigh muscles 2.2b. (1; 2.5); calf/foot muscles 1.5b. (1.1; 1.8)) (p 0.05) at the end of the rehabilitation course lasting 20 days.

Arm Differences in Muscle Activity Characteristics During a Bilateral Simulated Overhead Work in Right-Handed and Ambidextrous Individuals

Occupational Applications In this study, healthy adults performed repetitive bilateral overhead shoulder flexion to fatigue-failure while we measured electromyography of shoulder muscles. We found that ambidextrous and right-handed individuals, especially females, exhibit asymmetrical muscle activation patterns during the task. To enhance worker health and safety, handedness and sex should be considered when implementing workplace changes. For instance, our results may imply that job rotation strategies that alternate use of hands would be easier to implement for males. Moreover, to minimize risk of injury, bilateral asymmetry in muscle activity could be monitored using wearable technology. In our experiment, the mean time to fatigue-failure was under 5 min, which was enough to elicit asymmetry of muscle activation. Therefore, we recommend frequent breaks after a few minutes of work when feasible, in order to avoid asymmetrical loadings during bilateral manual work, especially among females, who both have higher injury risk and more bilateral asymmetry.

Muscle synergy analysis during badminton forehand overhead smash: integrating electromyography and musculoskeletal modeling.

This study aimed to quantify shoulder muscle synergies during badminton forehand overhead smash (BFOS) via non-negative matrix factorization (NMF), validate musculoskeletal (MSK) models for high-speed movements by comparing electromyography (EMG)-derived synergies with simulation results, and explore the potential of NMF-based MSK models in advancing sports science. Twenty elite badminton players (age: 24 ± 4 years; experience: 15 ± 4 years) performed maximal-effort BFOS while EMG signals from fifteen shoulder muscles were recorded. Three-dimensional motion analysis with a ten-camera Vicon system captured kinematic data at 100 Hz. A validated OpenSim upper extremity model was implemented to simulate muscle activations via static optimization. NMF extracted synergy vectors and activation coefficients from both experimental EMG and MSK modeling data. Three muscle synergies accounted for >90% variance in both analyses with no significant differences in global VAF (p = 0.12). The first synergy (trapezius-dominant) showed 95% EMG and 97% MSK variance; the second synergy (pectoralis/anterior deltoid) exhibited 97% EMG and 94% MSK variance; the third synergy (posterior muscles) demonstrated 95% EMG and 98% MSK variance. Strong agreement between approaches was observed for both weight vectors (W1:0.81 ± 0.04, W2:0.87 ± 0.01, W3:0.88 ± 0.03) and activation coefficients (C1:0.95 ± 0.02, C2:0.98 ± 0.01, C3:0.98 ± 0.01), with differences primarily in lower trapezius activation (similarity: 0.77 ± 0.05), likely due to challenges in recording deep muscle activity through surface electromyography. These findings validate the combined experimental-computational approach for analyzing complex, high-velocity movements. The strong correspondence between experimental and computational synergies validates MSK modeling for analyzing neuromuscular control during high-velocity overhead movements. The identified synergies provide a framework for understanding muscle coordination during BFOS, with potential applications in targeted training program optimization and injury prevention strategies in overhead sports.

The Effect of Photo biomodulation Therapy on Shoulder Muscle Activation, Motor Function, Pain Reduction, and Quality of Life in Hemiplegia: A Systematic Review

Background: Hemiplegic shoulder dysfunction is a common and debilitating complication following stroke, often leading to impaired motor function, chronic pain, and reduced quality of life. Photo biomodulation therapy (PBMT), a non-invasive modality using low-level laser or light therapy, has emerged as a potential intervention for neuromuscular rehabilitation. This systematic review aimed to evaluate the effectiveness of PBMT in improving shoulder muscle activation, motor function, pain reduction, and quality of life in hemiplegic patients. Methods and Materials: A comprehensive literature search was conducted across PubMed, Scopus, Web of Science, and Google Scholar databases for studies primarily published between 2014 and 2025. Inclusion criteria were clinical trials, cohort studies, or quasi-experimental studies, and review studies that evaluated PBMT effects on post-stroke hemiplegic patients. A total of eighteen studies were included based on predefined inclusion and exclusion criteria. Data extraction focused on study design, sample size, PBMT parameters, and clinical outcomes. Results: The included studies demonstrated consistent evidence that PBMT significantly enhances shoulder muscle activation, improves motor function, reduces pain, and contributes positively to quality of life. Most studies utilized wavelengths between 650–850 nm with positive therapeutic outcomes and minimal adverse effects. Some variability existed in PBMT protocols and patient populations, but overall findings were favourable. Conclusion: PBMT shows promise as an effective adjunct therapy for improving shoulder function and reducing pain in hemiplegic patients. While current evidence is encouraging, further large-scale studies with standardized protocols are needed to confirm its long-term efficacy and optimize clinical application.

Shoulder kinematics and muscle synergy during multi-plane humeral elevation and lowering.

Shoulder kinematics and muscle synergy during multi-plane humeral elevation and lowering.

Shoulder girdle muscle activity at rest and during jaw and shoulder movements in participants with and without temporomandibular disorders: A cross-sectional observational study.

Shoulder girdle muscle activity at rest and during jaw and shoulder movements in participants with and without temporomandibular disorders: A cross-sectional observational study.

Modified arthroscopic-assisted reduction and internal fixation for treatment of Ideberg type III scapular glenoid fracture associated with acromioclavicular joint injury.

Modified arthroscopic-assisted reduction and internal fixation for treatment of Ideberg type III scapular glenoid fracture associated with acromioclavicular joint injury.