Shoulder External Rotation Research Articles

Range of Motion Adaptations During a Simulated Game Exposure in Softball Pitchers.

Hip and shoulder range of motion (ROM) alterations are correlated with increased risk of injury in softball athletes. The purpose of this study was to investigate bilateral shoulder and hip ROM adaptation during a simulated softball double-header exposure. It was hypothesized that shoulder and hip ROM would decrease after simulated game exposure and would not return to baseline following a 30-minute break. Thirty (14.8±1.9 yrs, 162.5±18.3 cm, 71.79±16.03 kg) adolescent softball pitchers participated. Testing included: bilateral hip and shoulder ROM (preSG), simulated game exposure (100 pitches), bilateral hip and shoulder ROM (postSG), 30-minute break, bilateral hip and shoulder ROM (preDH), pitching first inning of a simulated double header (12 pitches), and bilateral hip and shoulder ROM (postDH). Two separate repeated measures multivariate analyses of variance tests determined differences in ROM between time points. Dominant shoulder internal rotation ROM and non-dominant shoulder internal and external rotation ROM significantly decreased from preDG. Stride hip external rotation ROM and drive hip internal and external rotation ROM significantly decreased from preSG to preDH. Key results revealed the break given between games may not be sufficient recovery time for hip ROM. Thus, assessing ROM as workload progresses can be a useful strategy for monitoring a softball pitcher's injury risk.

Biomechanical Basis of Interval Throwing Programs for Baseball Pitchers: A Systematic Review.

Interval throwing programs are used in rehabilitation of throwing injuries, especially ulnar collateral ligament injuries. Athletes who are rehabilitating begin by throwing on flat ground progressing through increasing distances, number of throws, and intensity of throwing. If the athlete is a baseball pitcher, the flat-ground throwing phase is followed by pitching on a mound at progressively increased effort. The goal is to build back arm strength and capacity with an emphasis on proper mechanics. To determine whether interval throwing progressively builds joint kinetics (specifically, elbow varus torque) to the level required during full-effort baseball pitching. A secondary purpose was to examine the kinematics produced during interval throwing compared to those seen during baseball pitching. Systematic Review. Following PRISMA guidelines, PubMed, Embase, Web of Science, SPORTDiscus, and Google Scholar were systematically searched for biomechanical studies of flat-ground throwing and partial-effort pitching in baseball between 1987 and 2023. Studies that reported the biomechanics of either flat-ground throwing, or partial-effort pitching were included in this review. The AXIS tool was used to assess study quality. Thirteen articles met the inclusion criteria. Ten studies were determined to be of moderate quality, while three studies were deemed high quality. Elbow varus torque during partial-effort pitching was less than during full-effort pitching. Elbow varus torque for most flat-ground throws did not exceed full-effort pitching torque. While most studies showed increased elbow varus torque with increased flat-ground throwing distance, the distance at which elbow varus torque matched or exceeded full-effort pitching elbow varus torque was not consistent.As flat-ground throwing distance increased, shoulder external rotation angle and shoulder internal rotation velocity increased. Arm slot (forearm angle above horizontal) decreased as flat-ground throwing distance increased. For varied effort pitching, shoulder external rotation angle, shoulder internal rotation velocity, elbow extension velocity, and ball velocity increased as effort increased. While the front knee extended slightly from foot contact to ball release in full-effort pitching, the front knee flexed slightly during partial-effort pitching. An interval throwing program progressively builds elbow varus torque up to levels produced in full-effort baseball pitching. While differences exist between interval throwing kinematics and pitching kinematics, the patterns are similar in general. 2.

Observational assessment for determining shoulder fault movements before and after corrective education in participants with chronic shoulder pain: Concurrent validity study

BackgroundMovement faults (MF), described as the alteration of joint position and motion, are an important factor associated with developing shoulder pathologies. However, determining or predicting the exact MF in participants with shoulder pain is limited by the absence of clinical tools and poor validity. PurposeThe aim of the study was to determine the validity of using observational assessment to MFs or controlling MFs in subjects with chronic shoulder pain during shoulder elevation and external rotation. Study DesignConcurrent validity study MethodsTwenty-seven people with chronic shoulder pain were examined. The index test represented three observational assessments of MF during shoulder external rotation, elevation in the frontal plane, and elevation in the sagittal plane. Three-dimensional motion analysis represented the reference test. The movements of both shoulder joints were evaluated simultaneously, and the index and reference tests were performed concurrently. ResultsThe sensitivity and specificity of observational detection were good to excellent (Se: 77.5%, Sp: 81.5%) for MF and excellent (Se: 85.7%, Sp: 100%) for controlling MF. The positive and negative predictive value was (PPV: 93.9, NPV: 57.1) for MF and (PPV: 100%, NPV: 82.8%) for controlling MF. The result of the positive and negative likelihood ratio was (PLR: 5.4, NLR: 0.26) for MF and (PLR: 0, NLR: 0.18) for controlling MF. ConclusionsThe results revealed that the validity of the observational detection approach for identifying MFs was good to excellent. Moreover, the accuracy of this approach in detecting the control of MFs after patient education was excellent. There was good to excellent accuracy in most MFs once classified by their motion trajectories, except for scapula anterior tilt during glenohumeral joint external rotation or elevation.

Injury, Training, Biomechanical, and Physiological Profiles of Professional Breakdancers.

Breakdancing or breaking will enter the Olympics in 2024, however, there is a paucity of literature exploring the epidemiology, demands, and performance. The purpose of this study was to describe injury and training profiles, along with the results of a short performance test battery, in a group of elite breakers. Cross-sectional study (retrospective). Fourteen breakdancers (breakers) (4 Bgirls, 10 Bboys) participated in an interview regarding their injury and training history, endurance test (cycle VO2max testing), counter movement jump, squat jump, drop jump, isometric hip abduction, adduction, shoulder external and internal rotation strength testing on a fixed-frame dynamometer. Breakers were divided into elite (n=10) and developing (n=4) based on their qualification for a world finals competition; Wilcoxen rank sums were used to compare the two groups, or in the case of strength testing between those with and without an injury history. The breakers had a median 11.0 [10.0 - 14.0] years breaking experience and trained 24.4 [20.5 - 30.0] hours per week. The knee was the most commonly injured body part and most frequently injured joint, with the thigh being the most common site for muscle injuries. There were no differences in endurance testing or jump height testing results between elite and developing breakers. There was no difference in shoulder external or internal rotation strength between athletes with a history of shoulder injury and those without. Similarly, there was no difference in hip abduction or adduction strength in those with a history of hip injury and those without. The results of this study should be viewed with caution due to the small sample size. However, this study is the first to publish functional and physiological descriptives on breakers. The authors hope these results support clinicians treating breakers as well as encourages future research related to breaking. 2b.

Outcomes After Double-Layer Repair Versus En Masse Repair for Delaminated Rotator Cuff Injury: A Systematic Review and Meta-analysis.

Delamination of rotator cuff tears during arthroscopic shoulder surgery has an incidence of 38% to 92%. Double-layer (DL) repair and en masse (EM) repair are most commonly used in this situation. To compare the clinical results of the DL versus EM repair techniques for delaminated rotator cuff tears using a meta-analysis. Systematic review; level of evidence, 3. We identified relevant studies comparing the clinical results of DL and EM repair for delaminated rotator cuff injuries in the PubMed, Embase, and Cochrane databases after the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The primary outcomes were the Constant score and retear rate. Additionally, we compared other postoperative shoulder functional scores, shoulder range of motion, and visual analog scale (VAS) pain scores between the 2 suture methods using a meta-analysis. The mean difference (MD) was compared for continuous outcomes, and the odds ratios (ORs) were compared for categorical outcomes. Of the 197 studies initially identified, 6 studies were included in this analysis. There were significant differences in the Constant score (MD, 8.64 [95% CI, 4.47 to 12.8]; P < .05) and external rotation (MD, 5.10 [95% CI, 2.63 to 7.56]; P < .05) between the 2 techniques, with DL repair having superior outcomes. No significant differences were observed between the 2 techniques in forward flexion (MD, 0.62 [95% CI, -1.18 to 2.43]; P = .50), VAS pain (MD, -0.03 [95% CI, -0.34 to 0.27]; P = .84), or retear rate (OR, 0.73 [95% CI, 0.37 to 1.41]; P = .35). Results of this review and meta-analysis suggest that DL repair was more beneficial than EM repair in terms of the Constant score and shoulder external rotation in patients with delaminated rotator cuff injuries.

Reliability and Concurrent Validity of a Markerless, Single Camera, Portable 3D Motion Capture System for Assessment of Glenohumeral Mobility.

Recent technological advancements have enabled medical, sport, and fitness professionals to utilize digital tools that assist with conducting movement examinations and screenings. One such advancement has been the implementation of a single camera, markerless, and portable 3D motion capture system designed to obtain ROM measurements for multiple body parts simultaneously. However, the reliability and validity of a markerless 3D motion capture system that uses a single camera has not been established. The purpose of this study was to investigate the reliability and concurrent validity of this 3D motion capture system compared to a goniometer in assessing ROM of the glenohumeral joint. Quasi-experimental reliability, convenience sampling. Forty healthy volunteers (mean ± SD, age 27.4 ± 12.4 years, height 173.4 ± 11.1 cm, weight 72.1 ± 16.2 kg) participated in this study. Intrarater reliability was analyzed by ICC(2,k) with a 95% CI using two repeated trials for each shoulder movement (flexion, abduction, external rotation, internal rotation) that were recorded simultaneously via two methods: a standard goniometer and a 3D motion capture system. Concurrent validity was analyzed using Pearson Correlation Coefficient (r). The intrarater reliability between the two instruments for glenohumeral motions yielded an overall ICC of 0.82 (95% CI: 0.74-0.88) indicating good reliability for both instruments.The 3D motion capture system demonstrated strong correlations with goniometry for shoulder flexion (r = 0.67), abduction (r = 0.63), and external rotation (r = 0.76), and very strong correlation for shoulder internal rotation (r = 0.84). Results from this study indicated that a markerless, single camera, portable 3D motion capture system can be a reliable and valid tool to assess glenohumeral joint ROM in comparison to a standard goniometer. 3.

The Clinical Outcomes of Spinal Accessory to Suprascapular Nerve Transfer Through a Posterior Approach.

Spinal accessory nerve (SAN) to suprascapular nerve (SSN) transfer can restore function to the rotator cuff following brachial plexus injuries. The traditional anterior approach using the lateral branch of the SAN causes denervation of the lateral trapezius limiting shoulder elevation. Suprascapular nerve pathology at the suprascapular notch may be missed resulting in poor reinnervation of the rotator cuff. The posterior approach uses the medial SAN and allows decompression and visualization of the SSN at the notch and nerve transfer coaptation closer to the target muscles with a shorter reinnervation distance. This is a review of 28 patients from 2014 to February 2020 who underwent SAN to SSN nerve transfer via a posterior approach. Patients were evaluated for SSN pathology, external rotation power, and range of motion. Data were evaluated for high-energy trauma (HET) and low-energy trauma/nontraumatic etiology subsets. A total of 8 HET (40%) patients had pathology identified at the suprascapular notch during the posterior approach, including SSN scarring, ruptures, neuromata-in-continuity, and ossification of ligaments. British Medical Research Council grade greater than or equal to 4 shoulder external rotation was achieved in 75% patients with median range of motion 137.5°. Spinal accessory nerve to SSN transfer using a posterior approach allows visualization of pathology involving the SSN and coaptation of a medial SAN transfer close to the target muscles. Following HET, 8 cases (40%) had posterior pathology identified. Spinal accessory nerve to SSN transfer through a posterior approach shows improved external rotation power and range of motion.

Blood Flow Restriction Training in Patients With Rotator Cuff Tendinopathy: A Randomized, Assessor-Blinded, Controlled Trial.

To investigate the effects of low-load blood flow restriction (BFR) training on shoulder muscle thickness, rotator cuff (RC) strength, and shoulder symptoms in patients with RC tendinopathy. A randomized, assessor-blinded, controlled trial. Physiotherapy clinic at a university. Twenty-eight patients were randomized into an 8-week (2 times/week) shoulder rehabilitation, that is, BFR or non-BFR group. BFR training. (1) RC, deltoid, scapula retractor, and biceps muscle thicknesses and shoulder internal rotation (IR) and external rotation (ER) strengths. (2) Shoulder pain/function. The BFR group had a greater increase in biceps muscle thickness ( P = 0.002) and shoulder IR strength at 60 degrees/s ( P = 0.040) than the non-BFR group. No differences between the 2 groups were observed in other measurements. Significant improvements in supraspinatus, infraspinatus, and scapula retractor muscle thicknesses and in shoulder ER and IR strengths were observed over time in both the groups (all P < 0 .05). Also, shoulder pain decreased and shoulder function increased over time in both the groups (all P < 0 .05). Low-load BFR training resulted in a greater increase in biceps thickness and shoulder IR strength compared with the non-BFR group in patients with RC tendinopathy. However, there was no superiority of either exercise training regarding the RC, scapula retractor, deltoid muscle thicknesses, or improvements in shoulder ER strength and shoulder pain/function. The study was registered in ClinicalTrials.gov named Blood Flow Restriction Training in Patients with Shoulder Pain and the registration number is NCT04333784.

Evaluating the feasibility of implementing the Sup-ER protocol for infants with brachial plexus birth injury

BackgroundThe Sup-ER protocol involves a repositioning program for infants with brachial plexus birth injury to position the shoulder in external rotation (ER) to address progressive loss in passive range of motion (PROM). The British Columbia Children’s Hospital (BCCH) eligibility criteria for this protocol are infants aged 4-8 weeks with decreased shoulder ER PROM and/or Active Movement Scale (AMS) shoulder ER and/or supination scores ≤2. The resources needed to implement this protocol in large clinics have not been studied. PurposeThis study aims to evaluate the BCCH criteria that are used to identify appropriate candidates for the Sup-ER protocol. Study DesignA retrospective cohort study was conducted to identify the percentage of infants who would have been recommended the Sup-ER protocol based on their PROM and AMS scores between 4 and 8 weeks of age. MethodsA sensitivity and specificity evaluation was used to describe the BCCH criteria's ability to identify infants in this historical cohort who went on to have incomplete shoulder function (ie, true positive) vs infants who had functional shoulder outcome at 9 months of age (ie, false positive). ResultsAt a mean of 5.8 weeks (95% confidence interval [CI] 5.3, 6.3), 46 of the 87 (53%) infants satisfied the BCCH Sup-ER protocol criteria. Forty-four (51%) were female, half (n = 45) were left side affected, and 88% had upper plexus injury. The BCCH Sup-ER protocol criteria had sensitivity of 100% and specificity of 71% to identify infants with incomplete shoulder function. Removing the AMS supination ≤2 score criterion from the criteria improves the specificity to 84%, while sensitivity remains high (97%). ConclusionsModifying the BCCH criteria to all infants aged 4-8 weeks with AMS shoulder ER ≤2 and/or decreased shoulder ER PROM improves the precision of identifying infants who would benefit from the Sup-ER protocol.

Correlation between run-up speed and throwing distance of elite javelin athletes

&lt;p&gt;目的：本研究探討台灣優秀標槍選手助跑速度與投擲距離之相關性。方法：8位國內優秀標槍選手 (身高：176.2 &amp;plusmn; 4.5公分，體重：87.7 &amp;plusmn; 10.7公斤，年齡：21.1 &amp;plusmn; 3.7歲，平均投擲距離：68.8 &amp;plusmn; 6.9公尺)，本研究採用實際比賽進行數據收集，本研究使用高速攝影機 (60Hz) 紀錄投擲標槍助跑過程，透過影像分析獲得助跑距離及時間。本研究採用相依樣本t檢定比較預賽及決賽的助跑速度及投擲表現及使用皮爾森積差相關分析比較助跑速度及投擲表現之相關性，顯著水準訂為 &amp;alpha; = .05。結果：研究結果發現，預賽與決賽的投擲表現顯著大於決賽有顯著差異 (p &lt; .05)，但預賽與決賽的助跑速度無顯著差異 (p &gt; .05)，另外，預賽與決賽的投擲距離與助跑速度相關性沒有顯著差異。結論：當助跑速度越快不會增加投擲距離。選手可能會有個別最佳的助跑速度。&lt;/p&gt;&lt;p&gt;The standing throw with run-up is the best approach to evaluate the performance of energy transfer and the efficiency of throwing motions for handball players. Purpose: This research aims at analyzing the usage of the standing throw with run-up among the handball players in Taiwan. The roles of body kinematics, strength of core muscles and standing balance of the drive leg played in the standing throw with run-up are also discussed. Methods: Nine Division I handball players from college went through a series of tests. The motions and the speed of the handball throwing were detected by a 3D electromagnetic motion analysis system and a sports radar gun, respectively. The maximum isometric muscle strength of trunks and hips were measured by a torque sensor and a home-made device of strength measurement. The standing balance of the drive leg was measured by a force plate with a mat. Results: The maximal shoulder external rotation angle in the arm cocking phase, the maximal trunk rotation velocity in the arm acceleration phase and the maximal shoulder horizontal adduction velocity showed moderate positive relationships with the ball velocity. The strength of back muscles had a moderate negative relationship with the ball velocity. The correlation between the balance ability of the drive leg and the ball velocity was not observed. Conclusion: The importance of proximal segments to the standing throw with run-up is analyzed by kinematical analysis. It is suggested that the energy of handball throwing is generated by the upper extremities or other limb segments in the processes of the standing throw with run-up. Our findings can serve as a helpful reference for both coaches and players.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Gender-Specific Patterns of Muscle Imbalance in Elite Badminton Players: A Comprehensive Exploration.

The high-intensity demands of overhead sports exert significant stress on the bilateral shoulder complex, triggering adaptive kinematics and a distinct strength imbalance between internal and external rotators. The imbalance being referred to in the given statement poses a potential risk for humeral head displacement and puts nearby tendons under tension, heightening the vulnerability to injury. This study aims to assess muscle imbalances in badminton athletes. The first hypothesis (H1) suggests that there are differences in internal and external shoulder rotation movements between dominant and non-dominant segments in badminton players. The second hypothesis (H2) proposes that there are variations in muscle imbalances based on gender among elite badminton players. The objectives are to analyze these differences and explore potential gender-related variations in muscle imbalances. The study seeks to contribute to the understanding of muscle imbalances in badminton athletes and potentially guide training and injury prevention strategies in the sport. Using a cutting-edge Hand-Held Dynamometer (HHD), a cohort of 30 elite badminton players underwent an assessment to uncover any bilateral shoulder rotation strength imbalances during a challenging five second isometric maximum contraction. The participants boasted an average age of 17.4 years and a mean playing experience of 7.23 years. The study revealed a notable difference in the ratio of external and internal strength between the dominant and non-dominant shoulders (p = 0.000). This discrepancy amounted to a striking 27.93% muscle imbalance in external rotation/internal rotation strength ratios, favoring the dominant shoulder. Moreover, gender-specific differences were detected, with male players exhibiting a 24.54% muscle imbalance in favor of the dominant shoulder, while female players showcased a more substantial 31.33% imbalance (p = 0.000). In light of these findings, it became evident that elite badminton players possess considerably stronger dominant shoulders compared with their non-dominant counterparts. Furthermore, the study revealed that male players experience less muscular imbalance than their female counterparts.

Shoulder Range of Motion Measurement Using Inertial Measurement Unit-Concurrent Validity and Reliability.

This study aimed to evaluate the reliability of the RSQ Motion sensor and its validity against the Propriometer and electronic goniometer in measuring the active range of motion (ROM) of the shoulder. The study included 15 volunteers (mean age 24.73 ± 3.31) without any clinical symptoms with no history of trauma, disease, or surgery to the upper limb. Four movements were tested: flexion, abduction, external and internal rotation. Validation was assessed in the full range of active shoulder motion. Reliability was revised in full active ROM, a fixed angle of 90 degrees for flexion and abduction, and 45 degrees for internal and external rotation. Each participant was assessed three times: on the first day by both testers and on the second day only by one of the testers. Goniometer and RSQ Motion sensors showed moderate to excellent correlation for all tested movements (ICC 0.61-0.97, LOA < 23 degrees). Analysis of inter-rater reliability showed good to excellent agreement between both testers (ICC 0.74-0.97, LOA 13-35 degrees). Analysis of intra-rater reliability showed moderate to a good agreement (ICC 0.7-0.88, LOA 22-37 degrees). The shoulder internal and external rotation measurement with RSQ Motion sensors is valid and reliable. There is a high level of inter-rater and intra-rater reliability for the RSQ Motion sensors and Propriometer.

A Systematic Review of the Biomechanical Studies on Shoulder Kinematics in Overhead Sporting Motions: Types of Analysis and Approaches

The shoulder is a unique and complex joint in the human body with three bones and four joints, which makes it the most unstable joint in the body due to the amount of motion. To improve approaches toward understanding the performance of overhead throwing movements, this systematic review summarizes the type of analysis related to shoulder biomechanics involving overhead sporting motions. A search of seven databases identified 33 eligible studies, which were subsequently scored using the Modified Coleman Methodology Score scale. A total of nine articles from badminton, seven from baseball, five from volleyball, five from tennis, three from cricket, and one from softball were reviewed. All 33 studies evaluated shoulder kinematics and 12 of them also investigated the forces and torques (kinetics). The most common methods used were 3D motion analysis (76%), digital video cameras (15%), electromagnetic tracking system (6%), and finally 3% used IMU sensors. Overall, shoulder external rotation during the back swing, internal rotation, and elbow extension during the forward acceleration phase were the strongest predictors of high velocity overhead throwing movement. The findings provide some useful insights and guidance to researchers in their future contribution to the existing body of literature on shoulder overhead throwing movement biomechanics.

Enhancing Shoulder External Rotator Electromyography Activity During Sitting External Rotation Exercise: The Impact of Biofeedback Training

Enhancing Shoulder External Rotator Electromyography Activity During Sitting External Rotation Exercise: The Impact of Biofeedback Training

The effects of biofeedback training for efficient activation of infraspinatus on proprioception and EMG activity during shoulder external rotation.

The purpose of this study investigated which biofeedback (BF) training enables efficient activation of the infraspinatus muscle that affect joint position sense (JPS) and force sense (FS) of the shoulder joint. Twenty healthy males participated and performed three external rotation (ER) exercises under three randomly assigned training conditions: 1) non-biofeedback (NBF), 2) BF and 3) force biofeedback (FBF). Each exercise was performed at intervals of one week between training conditions. After performed the ER exercise under each training condition, the relative error (RE) was calculated at shoulder ER 45° and 80°, and then shoulder ER force were measured to determine the JPS error and FS error, respectively. Muscle activity of infraspinatus and posterior deltoid were measured and compared between training conditions. The RE of shoulder ER 45° and 80° were significantly lower under the FBF conditions than other training conditions (P<0.05). The RE of shoulder ER force were also significantly lower under the FBF conditions compared to those under the other training conditions (P<0.05). The activity of the infraspinatus muscle was significantly higher under the FBF conditions during all three ER exercises than other training conditions (p<0.05). We suggest that BF trainings can be useful to improve the proprioception of shoulder joint as well as activation of infraspinatus muscle while performing the ER exercises.

Comparison of isometric strength in rotator cuff and scapulothoracic muscles between elite volleyball athletes versus non-athletes.

Volleyball is an exceptionally popular global sport that involves repetitive, rapid, powerful and wide overhead movements, which can seriously alter normal shoulder kinematics. A recognized hallmark of shoulder muscle balance is the ratio of shoulder external (ER) and internal (IR) rotators. By extension, objective measurement of shoulder muscles' strength could help identify at risk athletes and preempt those injuries by engaging in prescriptive strength training programs. This cross-sectional study measured the isometric strengths of 1) shoulder internal and external rotator muscles, as well as the 2) supraspinatus, 3) rhomboid, and 4) middle and inferior trapezius muscles, in addition to calculation of ER:IR ratios, in professional volleyball players as well as in non-athletes. Measurements were made for dominant- and non-dominant upper limbs, in different position of the body (supine and orthostatic) and in different position of upper limb (adducted and abducted position). Our subject population included 11 male professional volleyball players as well as 14 healthy male orthopedic interns from Orthopedics and Trauma school of University of Milano Bicocca. Strengths were assessed by a handheld dynamometer. Each subject's isometric strength was assessed in triplicate in each limb position through a "make test" procedure; the greatest of each triplicate value was the accepted measure of isometric strength. We observed a gradient in muscle strength in the scapulothoracic complex in both groups; the rhomboid, middle trapezius, and lower trapezius ranked from greatest to least strength, respectively. The data suggest also that intrarotators are stronger in rotation adducted position than in rotation abducted position; however, extrarotators seem to be weaker in rotation adducted position than in rotation abducted position. There is also some indication that force development is enhanced in the supine position compared with the orthostatic position. Our findings indicate a scapulothoracic strength gradient with a rank order of strength of the rhomboid>middle trapezius>lower trapezius. The data further suggest that volleyball players have stronger intrarotation in rotation adducted position than in the rotation abducted position, while extra rotation shows the opposite trend. Finally, our data suggest that force development is greater in the supine position compared to the orthostatic position.

Electromyographic activities of glenohumeral joint muscles during shoulder forward flexion with isometric horizontal abduction loading.

Isometric horizontal abduction loading has been applied to improve imbalanced scapular muscle activities during shoulder exercises; however, the effect on glenohumeral joint muscle activity remains unclear. The purpose of this study was to investigate the changes in electromyographic activity of shoulder muscles during forward flexion with isometric horizontal abduction loading in healthy participants. Thirteen healthy men were recruited for this study. Participants performed shoulder forward flexion with isometric horizontal abduction loading using an elastic band (Flex-band condition) and forward flexion without shoulder loading (Normal-flex condition). Muscle activities were evaluated while maintaining shoulder flexion at 60°, 90°, 120°, and 150° (static task) and during active shoulder flexion from 0° to maximum elevation (dynamic task). Surface electrodes were placed on the deltoid, pectoralis major, infraspinatus, and teres minor muscles to measure the activities of the shoulder muscles during each task. The muscle activities during the static task were compared using a 2-way analysis of variance with repeated measures of the 2 factors, loading condition and flexion position, and a paired t test was used for comparisons between the 2 conditions during the dynamic task (significance level set at P<.05). For the static task, the Flex-band condition significantly increased the deltoid middle and posterior activities by 2-15 times and the infraspinatus and teres minor activities by 2-3 times compared with the Normal-flex condition at all positions. In contrast, the Flex-band condition significantly decreased (by about half) the activities of the deltoid anterior (at 120° and 150°) and pectoralis major (at all positions) compared with the Normal-flex condition. For the dynamic task, the Flex-band condition significantly increased the deltoid middle, deltoid posterior, infraspinatus, and teres minor activities by 2-7 times and decreased the deltoid anterior activity by approximately two-thirds. Applying isometric horizontal abduction loading during shoulder forward flexion may be useful in improving the imbalanced muscle activities of the glenohumeral joint, such as excessive activity of the deltoid anterior and pectoralis major and dysfunction of the deltoid middle, deltoid posterior, and shoulder external rotator muscles. Shoulder forward flexion with horizontal abduction loading could be available for exercise in patients who have massive rotator cuff tears or who have undergone rotator cuff repair and shoulder arthroplasty.

Shoulder structures and strength in competitive preadolescent swimmers: A longitudinal ultrasonographic study.

Repetitive shoulder movements during competitive training may cause changes in the strength of periarticular shoulder structures in preadolescent swimmers. To prospectively determine the effects of training on shoulder periarticular structures and muscle strength in preadolescent swimmers. Prospective cohort study. Community-based natatorium. Twenty-four preadolescent swimmers aged 10-12 years. Not applicable. Measurements were repeated in three periods as preseason, midseason, and postseason. Ultrasonographic measurements (supraspinatus tendon thickness, humeral head cartilage thickness, deltoid muscle thickness, and acromiohumeral distance) were performed using a portable device and a linear probe. Shoulder (flexion, extension, abduction, internal and external rotation) and back (serratus anterior, lower, and middle trapezius) isometric muscle strength were measured with a handheld dynamometer. Supraspinatus tendon thickness and acromiohumeral distance were similar in all periods (all p > .05); however, deltoid muscle and humeral head cartilage thicknesses increased throughout the season (p = .002, p = .008, respectively). Likewise, whereas shoulder muscle strength increased (all p < .05), back muscle strength was similar in all periods (all p > .05). In preadolescent swimmers, acromiohumeral distance and supraspinatus tendon thickness seem to not change; but humeral head cartilage and deltoid muscle thicknesses as well as shoulder muscle strength increase throughout the season.

Relationships between isokinetic knee and shoulder peak strength with maximal punch force in boxing athletes

BACKGROUND: Muscle strength in the upper and lower limbs is a major contributing factor to punch force and is one of the keys to success in boxing. OBJECTIVE: This study aimed to investigate the relationship between knee and shoulder strength and punching force in boxers. METHODS: Twenty-one boxers completed knee flexion, knee extension, shoulder external rotation and internal rotation isokinetic concentric contractions at slow (60∘/s) and fast (180∘/s) angular velocities. Maximal punch force tests included lead and rear straight arm punching were assessed using a force platform. RESULTS: Pearson’s correlation coefficients revealed that knee extension (r= 0.646–0.848) and knee flexion (r= 0.470–0.646) peak torques were moderately to very strongly correlated with maximal punching force in lead and rear arms. The shoulder internal rotation (r= 0.492–0.634) and shoulder external rotation (r= 0.441–0.588) peak torques were moderate to strongly correlated with maximal punching force. Moreover, knee extension peak torques at 60∘/s had higher correlation with maximal punching force. In contrast, shoulder internal rotation peak torques at 180∘/s had a larger correlation with maximal punching force. CONCLUSIONS: The main findings indicated the importance of the capacity to generate maximum knee extension and rapid shoulder internal rotation strength, contributing to punch force production.

A Novel Active Device for Shoulder Rotation Based on Force Control.

This article describes a one-degree-of-freedom haptic device that can be applied to perform three different exercises for shoulder rehabilitation. The device is based on a force control architecture and an adaptive speed PI controller. It is a portable equipment that is easy to use for any patient, and was optimized for rehabilitating external rotation movements of the shoulder in patients in whom this was limited by muscle-skeletal injuries. The sample consisted of 12 shoulder rehabilitation sessions with different shoulder pathologies that limited their range of shoulder mobility. The mean and standard deviations of the external rotation of shoulder were 42.91 ± 4.53° for the pre-intervention measurements and 53.88 ± 4.26° for the post-intervention measurement. In addition, patients reported high levels of acceptance of the device. Scores on the SUS questionnaire ranged from 65 to 97.5, with an average score of 82.70 ± 9.21, indicating a high degree of acceptance. The preliminary results suggest that the use of this device and the incorporation of such equipment into rehabilitation services could be of great help for patients in their rehabilitation process and for physiotherapists in applying their therapies.