Assessment of posterior shoulder muscle stiffness related to posterior shoulder tightness in college baseball players using shear wave elastography

Acute Effects of Local High-Frequency Percussive Massage on Deep Fascial and Muscular Stiffness and Joint Range of Motion in Young Adult Men

BACKGROUND

Local high-frequency percussive (HFP) massage has recently found widespread application in physical therapy. Although HFP massage reportedly improves range of motion (ROM), the mechanism underlying its action has not yet been proven. This study aimed to clarify whether a 5-minute percussive massage regimen affects muscular or connective tissues, such as the deep fascia and deep intermuscular fascia and the change in joint ROM.

METHOD

The study sample was calculated using G*Power analysis program, and this study enrolled 15 healthy men who underwent 5-minute HFP massage to the medial gastrocnemius muscle. Shear-wave elastography was used to measure tissue stiffness in the deep fascia, muscle, and deep intermuscular fascia through shear-wave velocity as well as the ROM of the volunteers' ankle joint dorsiflexion before and after the HFP massage. A value of P < .05 was used to declare statistical significance, and post hoc was used to calculate the effect size using G*Power.

RESULTS

Shear-wave velocity revealed a significant change in the deep fascia (P = .003; shear-wave velocity: -0.7 m/s) and significant increase in ROM of ankle dorsiflexion (P = .002; increase in ROM: 3.0°) after 5 minutes of HFP massage. However, the muscle and deep intermuscular fascia did not exhibit any significant changes.

CONCLUSIONS

HFP massage for 5 minutes modified the stiffness of the deep fascia and concurrently improved the ankle joint-dorsiflexion ROM. This method can be used as an intervention to decrease stiffness of the deep fascia and increase the ROM efficiently.

Investigation of the limiting factors of shoulder joint complex motion in college baseball players: motion analysis of the humeral head and rotator cuff using ultrasound

Background

The relationship between lower mobility, as measured by the elbow forward translation motion (T-motion) test, a new indicator of shoulder joint complex movement that measures elbow position when both dorsal hands are placed on the iliac crest while in a sitting position, and the parameters calculated by ultrasonography is unknown. The purpose of this study was to investigate the limiting factors of T-motion through motion analysis of the humeral head and rotator cuff muscles using ultrasonography in college baseball players.

Methods

Thirteen college baseball players participated in this cross-sectional study. The shortest distance from the posterior edge of the glenoid to the humeral head was measured in the static and T-motion positions, and the difference was calculated as the humeral head translation. The velocity of the infraspinatus was calculated during shoulder internal/external rotation using the particle image velocimetry method. These parameters were compared between the throwing and nonthrowing sides to examine the limiting factors of T-motion.

Results

This study indicated moderate-to-good reliability for the parameters calculated by ultrasonography. The mean anterior translation distance was significantly greater on the throwing side than on the nonthrowing side (r = 0.56, P = .015). The mean velocity of infraspinatus during internal rotation was significantly lower on the throwing side than on the nonthrowing side (r = 0.51, P = .028).

Conclusion

Increased anterior translation of the humeral head and decreased the velocity of infraspinatus are likely correlated with reduced T-motion mobility in college baseball players. These methods showed potential for physical therapy assessment and intervention to prevent shoulder dysfunction.

Stiffness Changes in Shoulder Muscles between Pitchers and Position Players after Throwing Overhead Using Shear Wave Elastography and Throwing Motion Analysis

Objectives: The objective is to compare stiffness changes around the shoulder muscles between pitchers and position players after throwing overhead using shear wave elastography (SWE) in relation to throwing motion analysis and muscle strength. Methods: A total of 32 male college baseball players (12 pitchers and 20 position players) were observed throwing 20 times, and SWE was performed to evaluate 13 shoulder muscle items-tendons (supraspinatus, infraspinatus, subscapularis, and teres minor), muscles (supraspinatus, infraspinatus [transverse and oblique part], teres minor, lower trapezius, latissimus dorsi, and pectoralis minor), and capsules (posterior and posteroinferior). Motion analysis was used to assess elbow torque, forearm angle, forearm rotation speed, and maximum external rotation angle of the shoulder. Muscle strength was measured using a dynamometer for abduction, internal/external rotation of the shoulder at an abduction of 0°, internal/external rotation of the shoulder at an abduction of 90°, and internal/external rotation of shoulder at a flexion of 90°. Results: In the pitcher group, SWE values for the teres minor muscle and latissimus dorsi muscle increased significantly after throwing. In the position player group, SWE values for the teres minor muscle significantly increased, and SWE values of the pectoralis minor muscle decreased after throwing. In the pitcher group, positive correlations were found between the teres minor muscle and forearm rotation speed and between the latissimus dorsi muscle and forearm angle. No significant difference was found in muscle strength after throwing in any of the groups. Conclusions: Stiffness changes occurred after throwing and were related to the motion analysis, but the regions in which stiffness occurred varied between pitchers and position players.

Emerging Quantitative Imaging Techniques in Sports Medicine

This article describes recent advances in quantitative imaging of musculoskeletal extremity sports injuries, citing the existing literature evidence and what additional evidence is needed to make such techniques applicable to clinical practice. Compositional and functional MRI techniques including T2 mapping, diffusion tensor imaging, and sodium imaging as well as contrast-enhanced US have been applied to quantify pathophysiologic processes and biochemical compositions of muscles, tendons, ligaments, and cartilage. Dual-energy and/or spectral CT has shown potential, particularly for the evaluation of osseous and ligamentous injury (eg, creation of quantitative bone marrow edema maps), which is not possible with standard single-energy CT. Recent advances in US technology such as shear-wave elastography or US tissue characterization as well as MR elastography enable the quantification of mechanical, elastic, and physical properties of tissues in muscle and tendon injuries. The future role of novel imaging techniques such as photon-counting CT remains to be established. Eventual prediction of return to play (ie, the time needed for the injury to heal sufficiently so that the athlete can get back to playing their sport) and estimation of risk of repeat injury is desirable to help guide sports physicians in the treatment of their patients. Additional values of quantitative analyses, as opposed to routine qualitative analyses, still must be established using prospective longitudinal studies with larger sample sizes.

Functional and morphological changes in shoulder girdle muscles after repeated climbing exercise

This study aimed to investigate the acute effect of repeated climbing actions on functional and morphological measures of the shoulder girdle. Fifteen male indoor climbers participated in this study. All the climbers declared route level 6a+, as the best climbing grade (French climbing grade scale). Functional (range of motion - ROM and muscle strength), and morphological measurements (muscle/tendon stiffness and thickness) after a repeated climbing exercise protocol were analysed. The ROM and muscle strength showed significant decreases from baseline to Immediate-Post (IA) as well as significant increases from IA to 1 h-Post for all movements (p ≤ .001 for all). Muscle stiffness showed significant increases from baseline to IA after as well as significant decreases from IA to 1 h-Post for all muscles (p ≤ .001 for all). However, the thickness showed significant increases from baseline to IA for supraspinatus tendon and muscle thickness and occupation ratio (p ≤ .001 for all), while a significant decrease was observed in acromiohumeral distance (p ≤ .001). Significant decreases from IA to 1 h-Post were found for muscles/tendons and occupation ratio (p ≤ .001 for all), while a significant increase for AHD (p ≤ .001). Our data demonstrated acute alterations in tendon thickness due to acute signs of implement symptom in climbers.

Relationship Between Posterior Shoulder Tightness and Lower-Limb Flexibility in College Baseball Players

CONTEXT

Posterior shoulder tightness evaluated as limited glenohumeral internal rotation and horizontal adduction is a risk factor for throwing-related shoulder and elbow injuries. Given that the throwing motion uses the entire body kinematics, limited lower-limb flexibility might be associated with posterior shoulder tightness. Therefore, we aimed to investigate the relationships between posterior shoulder tightness and lower-limb flexibility in college baseball players.

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Twenty-two college baseball players (20 right-handed and 2 left-handed).

METHODS

To investigate the relationships between glenohumeral range of motion and lower-limb flexibility using simple linear regression analysis, we measured passive range of motion of glenohumeral internal rotation and horizontal adduction, hip internal/external rotation in the prone/sitting position, ankle dorsiflexion, and quadriceps and hamstrings flexibility from both shoulders and legs.

RESULTS

Our analysis indicated that decreases in the lead leg hip external rotation in the prone position were moderately associated with limitations in glenohumeral internal rotation (R2 = .250, β [95% confidence interval, CI] = 0.500 [0.149 to 1.392], P = .018) and horizontal adduction (R2 = .200, β [95% CI] = 0.447 [0.051 to 1.499], P = .019) on the throwing shoulder. Furthermore, there were significant moderate relationships between decreases in glenohumeral internal rotation and limited lead leg quadriceps flexibility (R2 = .189, β [95% CI] = 0.435 [0.019 to 1.137], P = .022), and between decreases in glenohumeral horizontal adduction and limited stance leg ankle dorsiflexion (R2 = .243, β [95% CI] = 0.493 [0.139 to 1.438], P = .010).

CONCLUSION

College baseball players with limited lower-limb flexibilities including the lead leg hip external rotation in the prone position, the lead leg quadriceps flexibility, and the stance leg ankle dorsiflexion showed excessive posterior shoulder tightness. The current results support the hypothesis that lower-limb flexibility is associated with posterior shoulder tightness in college baseball players.

The Acute Effects of Pectoralis Major Foam Ball Rolling on Shoulder Extension Range of Motion, Isometric Contraction Torque, and Muscle Stiffness

Although it is well known that foam rolling (FR) of the lower extremities can increase the range of motion (ROM) of a joint while likely having no detrimental effect on muscle performance, to date, this is not clear if this is the case for the upper body. Therefore, the purpose of this study was to analyze the effects of a 2-min FR intervention of the pectoralis major (PMa) muscle on muscle stiffness of the PMa, shoulder extension ROM, and maximal voluntary isometric contraction (MVIC) peak torque. Thirty-eight (n = 15 females) healthy, physically active participants were randomly assigned to either an intervention (n = 18) or a control group (n = 20). The intervention group performed a 2-min foam ball rolling (FBR) intervention of the PMa muscle (FB-PMa-rolling), while the control group rested for 2 min. Before and after the intervention, muscle stiffness of the PMa was measured with shear wave elastography, while shoulder extension ROM was recorded with a 3D-motion capture system, and shoulder flexion MVIC peak torque was measured with a force sensor. MVIC peak torque decreased in both groups (time effect: p = 0.01; η2 = 0.16), without any difference between groups (interaction effect: p = 0.49, η2 = 0.013). ROM (p = 0.24; η2 = 0.04) and muscle stiffness (FB-PMa-rolling p = 0.86; Z = -0.38; control group p = 0.7, Z = -0.17) did not change due to the intervention. The lack of changes in ROM and muscle stiffness following the FBR intervention might be explained by the small area of applied pressure with the FBR on the PMa muscle. Moreover, the decrease in MVIC peak torque is likely more related to the uncommon test situation of the upper limbs, rather than the FBR intervention itself.

Assessment of the Ulnar Collateral Ligament of the Elbow Using Ultrasonic Shear Wave Elastography in Professional Baseball Players

BACKGROUND

Injury to the ulnar collateral ligament (UCL) of the elbow can cause chronic pain and loss of throwing ability. Ultrasonic shear wave elastography (SWE) is a new imaging method that can be used for quantitative assessment of tissue elasticity.

PURPOSE

To evaluate the properties of the UCL in professional baseball players using SWE.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This study included 35 professional baseball players (mean age, 23.0 years) without elbow injuries. Both elbows of each player were examined using ultrasound, and comparisons between the dominant and nondominant arms were conducted. The thickness of the anterior bundle of the UCL at its midportion was measured in the resting position on ultrasound. We also measured the difference in the ulnohumeral joint space with and without gravity stress on the forearm. Tissue elasticity was evaluated using a built-in software program. The relationship between UCL elasticity and ultrasound findings was analyzed using the Pearson correlation coefficient.

RESULTS

The mean ± SD thickness of the UCL was significantly greater in the dominant arm versus the nondominant arm (6.0 ± 1.4 vs 5.3 ± 1.3 mm; P = .004). The mean joint space difference was significantly wider in the dominant arm as compared with the nondominant arm (0.81 ± 0.42 vs 0.52 ± 0.31 mm; P = .002), and the mean UCL elasticity was lower in the dominant arm than in the nondominant arm (34.9 ± 11.6 vs 43.3 ± 10.6 kPa; P = .002). UCL elasticity was negatively correlated with UCL thickness (r = -0.27; P = .02) and joint space difference (r = -0.34; P = .003).

CONCLUSION

In professional baseball players, the elbow UCL of the dominant arm demonstrated increased thickness, with a larger joint space gap on gravity stress and lower elasticity in SWE as compared with the nondominant arm. Greater medial joint laxity can be predicted by assessing the elasticity of the UCL using SWE.

Increased external rotation related to the soft tissues is associated with pathologic internal impingement in high-school baseball players

BACKGROUND

Changes in soft-tissue structures such as anterior laxity and posterior tightness are thought to contribute to the development of pathologic internal impingement in baseball players. Although side-to-side differences in shoulder rotational range of motion (ROM) is commonly used in clinical practice to quantify the soft-tissue changes, the ROM does not accurately reflect the soft-tissue changes because the ROM is affected not only by the soft tissues, but also by the bone. Increased retroversion of the humeral head is often observed in the dominant shoulder of throwing athletes. The purpose of this study was to determine the relationship between the soft-tissue-related (STR) ROM and pathologic internal impingement in baseball players.

METHODS

Bilateral humeral retroversion and ranges of glenohumeral external rotation (ER) and internal rotation (IR) were investigated in 81 high-school baseball players. The players were divided into two groups: the internal impingement group (19 players) and the control group (62 players). Humeral retroversion was measured using the ultrasound-assisted technique to assess the bone-related ER and IR. The STR ER and IR were defined as subtracting the amount of humeral retroversion from the measured ER and IR.

RESULTS

The side-to-side difference (throwing shoulder - nonthrowing shoulder) in humeral retroversion showed no significant difference between the internal impingement group (6° ± 10°) and control group (11° ± 11°) (P = .064). The side-to-side difference in STR ER was significantly greater in the internal impingement group (12° ± 12°) than that in the control group (1° ± 14°) (P = .002). No significant difference was observed in the side-to-side difference in STR IR between the internal impingement group (-7° ± 16°) and control group (-5° ± 15°) (P = .696). Pathologic internal impingement was significantly associated with the side-to-side difference of STR ER (odds ratio, 1.06 for increase of 1°; 95% confidence interval, 1.02-1.11; P = .008).

CONCLUSION

In high-school baseball players, the increased STR ER in the throwing shoulder may be associated with pathologic internal impingement. An increase of 10° in side-to-side difference in STR ER would increase the risk of pathologic internal impingement by 1.8 times.

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography

PURPOSE

To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing.

METHODS

Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1 month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis.

RESULTS

Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing.

CONCLUSIONS

The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Disabled Throwing Shoulder 2021 Update: Part 1-Anatomy and Mechanics

The purpose of this article is to provide updated information for sports health care specialists regarding the Disabled Throwing Shoulder (DTS). A panel of experts, recognized for their experience and expertise in this field, was assembled to address and provide updated information on several topics that have been identified as key areas in creating the DTS spectrum. Each panel member submitted a concise presentation on one of the topics within these areas, each of which were then edited and sent back to the group for their comments and consensus agreement in each area. Part 1 presents the following consensus conclusions and summary findings regarding anatomy and mechanics, including: 1) The current understanding of the DTS identifies internal impingement, resulting from a combination of causative factors, as the final common pathway for the great majority of the labral pathoanatomy; 2) intact labral anatomy is pivotal for glenohumeral stability, but its structure does not control or adapt well to shear or translational loads; 3) the biceps plays an active role in dynamic glenohumeral stability by potentiating "concavity compression" of the glenohumeral joint; 4) the ultimate function of the kinetic chain is to optimize the launch window, the precise biomechanical time, and position for ball release to most effectively allow the ball to be thrown with maximum speed and accuracy, and kinetic chain function is most efficient when stride length is optimized; 5) overhead throwing athletes demonstrate adaptive bony, capsular, and muscular changes in the shoulder with repetitive throwing, and precise measurement of shoulder range of motion in internal rotation, external rotation, and external rotation with forearm pronation is essential to identify harmful and/or progressive deficits. LEVEL OF EVIDENCE: Level V, expert opinion.

Reciprocal inhibition improves posterior shoulder tightness and shoulder range of motion in youth baseball players

Background

The aim of this study was to evaluate the efficacy of reciprocal inhibition for posterior shoulder tightness (PST), internal rotation at 90° abduction (ABIR) limitation, and subacromial impingement in elementary and junior high school baseball players.

Methods

The present study included 290 elementary school and junior high school baseball players who were members of an organized baseball team and attended a medical checkup in 2014. Seventeen participants were excluded because they were left-handed. We applied a sit-up exercise as a tool of reciprocal inhibition to all participants. Before and after the sit-up exercise, we evaluated the shoulder range of motion (ROM) in external rotation at 90° abduction (ABER), ABIR, and horizontal flexion (HF) in both shoulders and the prevalence of subacromial impingement in the dominant shoulder. We defined PST as a ≧15°decrease in the HF angle of the dominant shoulder in comparison to the nondominant shoulder before the sit-up exercise and divided participants into two groups (the PST group and the non-PST groups). An independent t-test was performed to compare the shoulder ROM, and a chi-squared test was performed to compare the prevalence of subacromial impingement between the two groups. A dependent t-test was performed to compare intragroup changes in the shoulder ROM. The McNemar test was performed to compare intragroup changes in the prevalence of subacromial impingement.

Results

Fifty-six of 273 participants had PST in the initial examination. The initial examination revealed that the ROM of ABIR and HF in the dominant shoulder were significantly lower in the PST group than those in the non-PST group, whereas the ROM of ABER and total arc were significantly higher in the PST group. The prevalence of subacromial impingement in the PST group was significantly higher than that in the non-PST group. The sit-up exercise improved ABER, ABIR, total arc, HF, and the prevalence of subacromial impingement in both groups. However, the amount of ROM change did not differ between the two groups for any parameter with the exception of HF.

Conclusion

The presence of PST affects the prevalence of subacromial impingement but was not related to the loss of ABIR or the prevalence of pathological glenohumeral internal rotation deficit. The sit-up exercise, as reciprocal inhibition, can transiently improve the prevalence of subacromial impingement via the improvement of PST.

Relationship between glenohumeral internal rotation deficit and shoulder conditions in professional baseball pitchers

BACKGROUND

Previous studies have reported that glenohumeral internal rotation deficit (GIRD) may increase the risk of throwing-shoulder injuries. The purpose of this study was to analyze the conditions of the throwing shoulder in professional baseball pitchers with GIRD by comparing with those in pitchers without GIRD.

METHODS

In total, 26 male professional baseball pitchers participated in this study. We evaluated passive range of motion (ROM) and isometric muscle strength at internal rotation (IR) and external rotation (ER) at 90° of abduction, as well as the muscle thickness of the supraspinatus (SSP) and infraspinatus (ISP) by ultrasound. The pitchers were divided into 2 groups: those who exhibited a loss of IR of ≥20° in the throwing shoulder (GIRD group) and those who did not (non-GIRD group).

RESULTS

In the GIRD group, the total ROM deficit (throwing side - non-throwing side) (P < .001), the muscle thickness ratio (throwing to non-throwing) of the SSP and ISP (P = .017 and P = .014, respectively), and the muscle strength ratio (throwing to non-throwing) of ER (P = .028) were significantly lower than those in the non-GIRD group. In contrast, the muscle strength ratio (throwing to non-throwing) of IR was significantly higher in the GIRD group than in the non-GIRD group (P = .0064).

CONCLUSIONS

We have shown that GIRD has significant correlations with several conditions, such as atrophy of the SSP and ISP, weakness of ER strength, enhancement of IR strength, limitation of total ROM, and throwing side, all of which could be important factors for throwing-shoulder injuries.

Sequential Changes in Posterior Shoulder Muscle Elasticity After Throwing as Assessed via Ultrasound Shear Wave Elastography

Background

Improvements in ultrasound diagnostic equipment and techniques can enable muscle stiffness to be measured quantitatively as muscle elasticity using ultrasound shear wave elastography (USWE), where high muscle elasticity values represent muscle stiffness.

Purpose

To use USWE to analyze the sequential changes in muscle elasticity in the posterior shoulder before and after pitching.

Study Design

Descriptive laboratory study.

Methods

The authors evaluated 14 baseball players who had played in high school or college at an intermediate level. The elasticity of the supraspinatus, infraspinatus (ISP), middle trapezius, lower trapezius (LT), rhomboideus, and serratus anterior muscles of the throwing shoulder was measured using USWE at 3 time points: before, immediately after, and 24 hours after a throwing session of 100 pitches. The authors analyzed the sequential changes in the mean elasticity values of the respective muscles at the 3 time points.

Results

The mean elasticity values before, immediately after, and 24 hours after throwing were as follows: supraspinatus: 32.9, 53.4, 43.8 kPa; ISP: 22.7, 44.8, 43.7 kPa; middle trapezius: 45.1, 70.3, 59.9 kPa; LT: 32.8, 45.5, 46.5 kPa; rhomboideus: 29.1, 47.5, 38.8 kPa; and serratus anterior: 19.2, 36.9, 26.5 kPa, respectively. The mean elasticity values for all tested muscles were significantly higher immediately after throwing compared with before throwing (P ≤ .0086 for all), and elasticity values in the ISP and LT remained significantly higher 24 hours after throwing compared with before throwing (P ≤ .019 for both).

Conclusion

The study results indicated that pitching significantly increased ISP and LT muscle elasticity even after 24 hours.

Effect of Forearm Position on Glenohumeral External Rotation Measurements in Baseball Players

BACKGROUND

Alterations in glenohumeral internal rotation (GIR), glenohumeral external rotation (GER), and the total arc of motion (TAM) have been linked with increased injury risk in the shoulder and elbow. These motions have been routinely measured with the forearm in neutral rotation (GIRN, GERN, TAMN). GER capacity appears to be especially important. The throwing motion, however, requires forearm pronation as GER occurs to achieve optimal cocking (GERP). No previous studies have evaluated GERP to determine GER capacity or pronated TAM (TAMP) values.

HYPOTHESIS

There would be significant differences between GERN and TAMN and between GERP and TAMP.

STUDY DESIGN

Cross-sectional.

LEVEL OF EVIDENCE

Level 3.

METHODS

Sixty asymptomatic male Minor League Baseball players (32 pitchers, 28 position players) participated in the study and were tested on the first day of spring training. Passive range of motion measurements were recorded using a long-arm bubble goniometer for GIRN, GERN, and GERP on both arms. TAM was calculated separately as the sum of internal and external rotational measurements under neutral and pronated conditions.

RESULTS

Within pitchers and position players, all measurements were statistically reduced for the throwing arm (P ≤ 0.03) except for GERN of the pitchers. GERP measures were significantly less than GERN for both arms of each group (P < 0.01): pitchers throwing arm +11.8°/nonthrowing arm +4.8°, position players throwing arm = +8.6°/nonthrowing arm +4.0°.

CONCLUSION

The forearm position of pronation, which appears to be mediated by tightness of the biceps, decreases GER capacity and TAM. GER and TAM should be calculated in neutral and pronated positions, considering that 80% of the players have a demonstrated difference between 8° and 12°.

CLINICAL RELEVANCE

Measurement of GERP more accurately reflects the GER required in throwing, allows better quantification of the motion capacity necessary to withstand the loads in throwing, and may suggest interventions for at risk athletes.

Supraspinatus Tendon Changes and Glenohumeral Range of Motion in College Baseball Players

Baseball players commonly show altered glenohumeral range of motion during internal rotation, external rotation, total rotation, and horizontal adduction. These altered ranges of motion appear to be associated with throwing shoulder injuries, which frequently involve the supraspinatus tendons; thus, we aimed to examine the relationship between altered glenohumeral range of motion and supraspinatus tendon changes in collegiate baseball players. To investigate this association using the Pearson correlation coefficient, we measured glenohumeral internal rotation, external rotation, total rotation, and horizontal adduction ranges of motion and supraspinatus tendon thickness in 22 college baseball players. Consequently, there was a significant relationship between increase in supraspinatus tendon thickness and greater deficit of internal rotation (r=-0.520, P=0.013). Increased supraspinatus tendon thickness tended to be associated with greater external rotation gain (r=0.394, P=0.073). No other range of motion had any relationship with supraspinatus tendon changes. These results might indicate that restricted glenohumeral internal rotation and excessive gain in external rotation increase the risk of supraspinatus tendon abnormalities in baseball players.

Shoulder ranges of motion and humeral torsions of injured baseball players have different characteristics depending on their pitching sides

Background

Right- and left-side throwers in baseball may have different shoulder conditions and throwing biomechanics. This study aimed to compare the passive range of motion, humeral torsion, and clinical findings between right- and left-handed throwers who sustained throwing shoulder injuries and confirm the differences in the characteristics between throwing sides.

Methods

A total of 52 pitchers diagnosed with throwing shoulder injuries were included in this study: 27 patients were right-side throwers (R group), and 25 were left-side throwers (L group). We measured the bilateral passive external and internal rotation angles in abduction position (ABIR) and total arc at their first visit. To assess posterior shoulder tightness, the internal rotation angles in forward flexion (FIR), and the abduction angle (AA) and horizontal flexion angle (HFA) without scapula motion were measured. The bilateral humeral torsion angles were also measured using ultrasonography. These values were compared between the participants' throwing and non-throwing sides and between the R and L groups' throwing sides. Furthermore, several physical findings in the shoulders were assessed, and the positive ratio was compared between the R and L groups.

Results

On comparing the throwing and non-throwing sides, the R group had significantly greater external rotation angles in the abduction position and humeral torsion angle, and smaller ABIR, total arc, FIR, AA, and HFA in the throwing side, while the L group showed no significant differences, except for a smaller ABIR and larger HFA in the throwing side. On comparing the throwing side between the R and L groups, the R group had a smaller FIR, AA, and FHA than the L group. Regarding the physical findings, the posterior jerk test, Kim test, anterior and posterior drawer sign, sulcus sign, and scapular winging in the L group were significantly more positive than in the R group.

Conclusion

The range of motion and humeral torsions differed between the left- and right-side throwers, as did the pathology between their throwing sides. Clinicians should consider the possibility that the pathological condition differs between left- and right-side throwers.

Comparison of specific and non-specific treatment approaches for individuals with posterior capsule tightness and shoulder impingement symptoms: A randomized controlled trial

BACKGROUND

Posterior capsule tightness (PCT) is associated with shoulder pain and altered shoulder kinematics, range of motion (ROM), external rotation (ER) strength, and pain sensitization.

OBJECTIVE

To assess the effects of two interventions on shoulder kinematics, Shoulder Pain and Disability Index (SPADI) scores, ROM, strength, and pressure pain threshold (PPT) in individuals with PCT and shoulder impingement symptoms.

METHODS

In this prospectively registered randomized controlled trial 59 individuals were randomized to either an Experimental Intervention Group (EIG, n=31) or a Control Intervention Group (CIG, n=28). The low flexion (LF) test was used to determine the presence of PCT. Shoulder kinematics, SPADI scores, internal rotation (IR) and ER ROM, ER strength, and PPT were measured pre- and post-treatment. Those in the EIG received an intervention specific to pain and PCT and those in the CIG received a non-specific intervention, both 4 weeks in duration.

RESULTS

Individuals in the EIG demonstrated more scapular upward rotation (P=.03; mean difference (MD)=3.3°; 95% Confidence Interval (CI)=1.3°, 4.9°) and improved value on the LF test (P=.02; MD=4.6°; 95%CI=0.7°, 8.6°) than those in the CIG after treatment. Both groups presented less anterior (P<.01; MD=-0.7mm; 95%CI=-1.3mm, -0.2mm) and superior (P<.01; MD=-0.5mm; 95%CI=-0.9mm, -0.2mm) humeral translations, decreased SPADI score (P<.01; MD=-23.6; 95%CI=-28.7, -18.4), increased IR ROM (P<.01; MD=4.6°; 95%CI=1.8°, 7.8°) and PPTs for upper trapezius (P<.01; MD=60.1kPa; 95%CI=29.3kPa, 90.9kPa), infraspinatus (P=.04; MD=47.3kPa; 95%CI=2.1kPa, 92.5kPa), supraspinatus (P<.01; MD=63.7kPa; 95%CI=29.6kPa, 97.9kPa), and deltoid (P<.01; MD=40.9kPa; 95%CI=12.3kPa, 69.4kPa) after treatment.

CONCLUSION

The experimental intervention was more effective at improving PCT as measured through changes in the LF test. No benefit of the specific approach over the non-specific intervention was noted for the remaining variables.