Effects of two stretching methods on shoulder range of motion and muscle stiffness in baseball players with posterior shoulder tightness: a randomized controlled trial

Novel Posterior Shoulder Stretching With Rapid Eccentric Contraction and Static Stretching in Patients With Subacromial Pain Syndrome: A Randomized Trial

BACKGROUND

In subacromial pain syndrome (SPS), it is unknown whether posterior shoulder stretching exercises (PSSE) with rapid eccentric contraction, a muscle energy technique, improve clinical and ultrasonographic outcomes more than no stretching or static PSSE.

HYPOTHESIS

PSSE with rapid eccentric contraction is superior to no stretching and static PSSE in improving clinical and ultrasonographic outcomes in SPS.

STUDY DESIGN

Randomized controlled trial.

LEVEL OF EVIDENCE

Level 1.

METHODS

Seventy patients with SPS and glenohumeral internal rotation deficit were randomized into the modified cross-body stretching with rapid eccentric contraction group (EMCBS; n = 24), static MCBS group (SMCBS; n = 23), or control group (CG; n = 23). In addition to 4-week physical therapy, EMCBS received PSSE with rapid eccentric contraction, SMCBS static PSSE, and CG no PSSE. The primary outcome was internal rotation range of motion (ROM). Secondary outcomes were posterior shoulder tightness, external rotation ROM (ERROM), pain, modified Constant-Murley score, short form of the disabilities of the arm, shoulder, and hand questionnaire (QuickDASH), rotator cuff strength, acromiohumeral distance (AHD), supraspinatus tendon thickness, and supraspinatus tendon occupation ratio (STOR).

RESULTS

Shoulder mobility, pain, function and disability, strength, AHD, and STOR improved in all groups (P < 0.05).

CONCLUSION

In patients with SPS, PSSE with rapid eccentric contraction and static PSSE were superior to no stretching in improving clinical and ultrasonographic outcomes. Stretching with rapid eccentric contraction was not superior to static stretching, but improved ERROM compared with no stretching.

CLINICAL RELEVANCE

In SPS, both PSSE with rapid eccentric contraction and static PSSE included in physical therapy program are beneficial to improve posterior shoulder mobility and other clinical and ultrasonographic outcomes. In the case of ERROM deficiency, rapid eccentric contraction might be preferred.

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.

Acute effects of static stretching on passive stiffness in older adults: A systematic review and meta-analysis

BACKGROUND

Static stretching has been demonstrated to improve the health of older adults. One of its goals is to decrease passive stiffness of the muscle-tendon unit (MTU) and/or muscles. Decreased passive stiffness in older adults could increase the range of motion and movement efficiency. Herein, we conducted a meta-analysis of the acute effects of static stretching on passive stiffness in older adults as well as a meta-analysis of differences in these effects between older and young adults.

BACKGROUND

PubMed, Web of Science, and EBSCO were searched for studies published before June 28, 2023. Manual searches were performed to identify additional studies. All included studies were critically reviewed by five authors. Meta-analyses of muscle and tendon injuries were performed using a random effect model. Of 4643 identified studies, 6 studies were included in the systematic review.

RESULTS

The main meta-analysis in older adults showed that static stretching could decrease the passive stiffness of the MTU or muscles (effect size, 0.55; 95 % confidence interval, 0.27 to 0.84; p < 0.01; and I2 = 0.0 %). Moreover, for the comparison between young and old adults, three studies were included in the meta-analysis. The results revealed no significant difference in the effects of static stretching interventions on stiffness between older and young adults (effect size, 0.136; 95 % confidence interval, -0.301 to 0.5738; p = 0.541; and I2 = 17.4 %). Static stretching could decrease the passive stiffness of the MTU and/or muscles in older adults to a small magnitude, and the effects were comparable between older and young adults.

Developing the Singapore youth shoulder overuse injury prevention program

OBJECTIVES

To develop the Singapore Youth Shoulder Overuse Injury Prevention Program specifically for competitive overhead youth athletes in Singapore.

DESIGN

Two-round online Delphi technique with experts and a feasibility assessment questionnaire with youth athletes who represented end-users.

SETTING

Volleyball for youth athletes.

PARTICIPANTS

Experts were recruited through purposive sampling based on their knowledge and experience. Youth athletes were recruited though a volleyball club.

MAIN OUTCOME MEASURES

The main outcome measure was the level of consensus on the proposed (1) exercise program for the overhead youth athletes, (2) education program regarding overuse injuries for coaches of overhead youth athletes, and (3) education program regarding overuse injuries for overhead youth athletes. Consensus was set at 75% agreement in this study.

RESULTS

Eighteen experts completed the two Delphi rounds with 100% response rate. Consensus was achieved for the exercise program and both education programs. Twelve youth athletes completed the feasibility assessment questionnaire and found the exercises to be feasible in terms of usefulness, practical use, instructions, duration, and ease of execution.

CONCLUSION

Consensus was reached for the Singapore Youth Shoulder Overuse Injury Prevention Program, and feasibility of execution by end-users was successfully determined.

Comparative Analysis of Various Rotator Cuff Stretching Techniques: Efficacy and Recommendations for Gym Enthusiasts

Shoulder pain is a common complaint among gym-going individuals, particularly those engaged in upper limb workouts. The rotator cuff, comprising four muscles, plays a crucial role in stabilizing the shoulder joint during movements and supporting its mobility. Imbalances or weaknesses in these muscles can lead to shoulder injuries, affecting performance and overall well-being. The main aim of this review is to explore the benefit of one of the approaches in preventing shoulder pain and improving performance among gym-going individuals. Specific rotator cuff stretching exercises target the entire shoulder complex to enhance the mobility, control, and stabilization of the joint. The dynamic warm-up routine will actively engage the relevant muscles in various planes of motion, promoting the increased range of motion and reduced inflammation. Ultimately, the results from this review can serve as important knowledge for gym-going individuals, trainers, and fitness enthusiasts, guiding them in incorporating evidence-based warm-up strategies to optimize their workouts. Empowering individuals to take proactive measures in caring for their shoulder health can lead to improved overall performance and a better training experience in the gym.

Posterior deltoid shoulder tightness and greater contralateral lower limb muscle strength are associated with swimmers' shoulder pain

OBJECTIVES

To identify factors associated with shoulder pain in swimmers based on elastic muscle modulus, joint range of motion, and isometric muscle strength.

DESIGN

Cohort study.

METHODS

Forty-eight competitive swimmers without shoulder pain (age: 18-28 years; men: 29) were followed-up for 6 months. Baseline measurements of the elastic modulus of the pectoralis minor, supraspinatus, infraspinatus, posterior deltoid, and pectoralis minor muscles were obtained using shear wave elastography. Range of motion and isometric strength were measured using a goniometer and a hand-held dynamometer, respectively. A questionnaire was administered weekly for 6 months to determine shoulder pain occurrence. Each item was compared between shoulders with and without pain at baseline. For participants with shoulder pain exceeding 2 weeks, shear wave elastography and range of motion at baseline (pre pain) and during follow-up (post pain) were compared.

RESULTS

Of 46 swimmers followed-up for 6 months, 20 reported shoulder pain. 14 swimmers with pain were evaluated twice. Participants with shoulder pain during follow-up had significantly higher posterior deltoid and pectoralis minor stiffness at baseline and high lower extremity isometric muscle strength contralateral to the shoulder with pain compared to those without pain (p < 0.05). Swimmers with pain exceeding 2 weeks exhibited no differences in ultrasound shear wave elastography and range of motion at baseline and after pain onset.

CONCLUSIONS

Posterior deltoid and pectoralis minor muscle stiffness, and high isometric lower extremity strength contralateral to the shoulder with pain may be associated with shoulder pain development, thereby indicating the importance of maintaining posterior deltoid and pectoralis minor muscle flexibility during conditioning.

Acute and Long-Term Effects of Static Stretching on Muscle-Tendon Unit Stiffness: A Systematic Review and Meta-Analysis

Static stretching can increase the range of motion of a joint. Muscle-tendon unit stiffness (MTS) is potentially one of the main factors that influences the change in the range of motion after static stretching. However, to date, the effects of acute and long-term static stretching on MTS are not well understood. The purpose of this meta-analysis was to investigate the effects of acute and long-term static stretching training on MTS, in young healthy participants. PubMed, Web of Science, and EBSCO published before January 6, 2023, were searched and finally, 17 papers were included in the meta-analysis. Main meta-analysis was performed with a random-effect model and subgroup analyses, which included comparisons of sex (male vs. mixed sex and female) and muscle (hamstrings vs. plantar flexors) were also performed. Furthermore, a meta-regression was conducted to examine the effect of total stretching duration on MTS. For acute static stretching, the result of the meta-analysis showed a moderate decrease in MTS (effect size = -0.772, Z = -2.374, 95% confidence interval = -1.409 - -0.325, p = 0.018, I2 = 79.098). For long-term static stretching, there is no significant change in MTS (effect size = -0.608, Z = -1.761, 95% CI = -1.284 - 0.069, p = 0.078, I2 = 83.061). Subgroup analyses revealed no significant differences between sex (long-term, p = 0.209) or muscle (acute, p =0.295; long-term, p = 0.427). Moreover, there was a significant relationship between total stretching duration and MTS in acute static stretching (p = 0.011, R2 = 0.28), but not in long-term stretching (p = 0.085, R2 < 0.01). Whilst MTS decreased after acute static stretching, only a tendency of a decrease was seen after long-term stretching.

Long-term static stretching can decrease muscle stiffness: A systematic review and meta-analysis

Stretch training increases the range of motion of a joint. However, to date, the mechanisms behind such a stretching effect are not well understood. An earlier meta-analysis on several studies reported no changes in the passive properties of a muscle (i.e., muscle stiffness) following long-term stretch training with various types of stretching (static, dynamic, and proprioceptive neuromuscular stretching). However, in recent years, an increasing number of papers have reported the effects of long-term static stretching on muscle stiffness. The purpose of the present study was to examine the long-term (≥2 weeks) effect of static stretching training on muscle stiffness. PubMed, Web of Science, and EBSCO published before December 28, 2022, were searched and 10 papers met the inclusion criteria for meta-analysis. By applying a mixed-effect model, subgroup analyses, which included comparisons of sex (male vs. mixed sex) and type of muscle stiffness assessment (calculated from the muscle-tendon junction vs. shear modulus), were performed. Furthermore, a meta-regression was conducted to examine the effect of total stretching duration on muscle stiffness. The result of the meta-analysis showed a moderate decrease in muscle stiffness after 3-12 weeks of static stretch training compared to a control condition (effect size = -0.749, p < 0.001, I2  = 56.245). Subgroup analyses revealed no significant differences between sex (p = 0.131) and type of muscle stiffness assessment (p = 0.813). Moreover, there was no significant relationship between total stretching duration and muscle stiffness (p = 0.881).

Effects of modified sleeper stretch and modified cross-body stretch on upper limb functions and shoulder ROM in tennis players: a randomized trial

Tennis players often experience posterior shoulder pain due to restricted internal rotation (IR) range of motion (ROM) of the glenohumeral joint. No research has compared the effects of modified sleeper stretch (MSS) versus modified cross-body stretch (MCBS) on tennis players' upper limb functions and IR ROM. The study aimed to compare the efficacy of modified sleeper and cross-body adduction stretch in improving shoulder IR ROM and upper limb functions in tennis players. Thirty male lawn tennis players (aged 20 to 35 years) with more than 15° glenohumeral IR deficiency on the dominant side compared to the non-dominant side were recruited and divided into two groups: Modified sleeper stretch group (MSSG) and modified cross-body stretch group (MCBSG). MSSG received MSS, and MCBSG received MCBS, 3-5 repetitions once daily for 4 weeks. Upper limb functions were measured using the Disability of the Arm, Shoulder, and Hand (DASH) scale, and the IR ROM of the shoulder joint was measured using a universal goniometer. Both groups observed significant (p < 0.05) DASH scores and IR ROM improvements. DASH scores decreased by 85% in MSSG and 79.60% in MCBSG. IR ROM increased by 94.64% in MSSG and 89.52% in MCBSG. No significant differences (p > 0.05) were found in post-intervention DASH scores and IR ROM values between both groups. MSS and MCBS improved upper limb functions and IR ROM of the shoulder joint in the selected sample population of lawn tennis players. No difference was observed between both stretching techniques in improving upper limb functions and IR ROM of the shoulder joint.

High elasticity of the flexor carpi ulnaris and pronator teres muscles is associated with medial elbow injuries in youth baseball players

OBJECTIVES

The purpose of the present study was to measure the elasticities of the forearm flexor-pronator muscles in youth baseball players and examine their relationships with medial elbow injuries.

METHODS

We examined the strain ratios (SR) of the flexor digitorum superficialis (FDS), flexor carpi ulnaris (FCU), and pronator teres (PT) in 89 youth baseball players with medial epicondylar fragmentation (injury group) and in 142 healthy baseball players (control group). An index of muscle elasticity was determined using ultrasound strain elastography. The SR of each muscles was compared between the injury and control groups, and the SR of the both side arms was compared within group. Moreover, multivariable logistic regression analyses were conducted to examine the association of forearm muscle elasticity with medial elbow injuries.

RESULTS

The SR of the FCU and PT of the throwing arm were significantly higher in the injury group than in the control group (both P < .001). In the injury group, the SR of the FCU was higher in the throwing arm than in the non-throwing arm (P < .001), but no difference was noted for the PT. Multivariable logistic regression analyses showed that a 0.1 increase of the SR of the FCU of the throwing arm (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.14-1.48) and PT of the throwing arm (OR 1.41, 95% CI 1.19-1.67) and the non-throwing arm (OR 1.31, 95% CI 1.12-1.54) was significantly associated with an increased prevalence of medial elbow injuries.

CONCLUSION

High elasticities of the FCU of the throwing arm and PT of both the arms were observed in individuals with medial elbow injuries, and were associated with increased prevalence of medial elbow injuries. These findings may be characteristic of medial elbow injuries in youth baseball players.

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.

Glenohumeral Internal Rotation Deficit in the Adolescent Overhead Athlete: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this review was to investigate the average glenohumeral internal rotation deficit (GIRD) in the dominant arm of adolescent overhead athletes and to examine the association with shoulder and elbow injuries.

DESIGN

Systematic review and meta-analysis.

SETTING

MEDLINE, Embase, and PubMed were searched from inception to August 1, 2020.

PARTICIPANTS

Adolescent overhead athletes with glenohumeral range of motion (ROM) measurements.

INTERVENTIONS

Nonoperative treatments of GIRD.

MAIN OUTCOME MEASURES

Glenohumeral ROM measurements comparing the dominant and nondominant extremities were pooled in a meta-analysis.

RESULTS

Twenty-five studies were included in this review, which involved 2522 overhead athletes. Pooled internal rotation (IR) deficit of the dominant arm was 9.60° (95% confidence interval [CI] 7.87°-11.32°, P < 0.00001), with an external rotation (ER) gain of 6.78° (95% CI 4.97°-8.59°, P < 0.00001) and a total ROM (TROM) deficit of 1.78° (95% CI -0.70° to 4.26°, P = 0.16). The association between GIRD and shoulder or elbow injury was not clearly defined. Two studies reported treatment, and both used nonoperative treatment in the form of physiotherapy and sleeper stretches.

CONCLUSIONS

The adolescent overhead athlete has roughly 10° of IR deficit in their dominant arm, accompanied by nearly 7° of ER gain, with similar ROM measurements for injured and uninjured athletes. Those with pathological GIRD have a greater degree of IR deficit, but without an accompanying compensatory increase in ER, leading to a TROM deficit of nearly 15°. Surgical treatment in the absence of other indications is rare, whereas physiotherapy and sleeper stretches remain the first-line treatment.

Elasticity of the Scalene Muscles in Collegiate Baseball Pitchers Using Shear Wave Elastography

Background:

Thoracic outlet syndrome is more common in overhead athletes. The anterior and middle scalene muscles have been associated with thoracic outlet syndrome; however, the relationship between the elastic moduli of the scalene muscles and the overhead-throwing position has not been evaluated.

Purpose:

To investigate the elastic moduli of the anterior and middle scalene muscles in simulated throwing positions using shear wave elastography.

Study Design:

Descriptive laboratory study.

Methods:

We enrolled collegiate baseball players who underwent preseason medical checkups in January and February 2020. The anterior and middle scalene muscles were visualized in the short-axis view using ultrasound. In this view, the elastic moduli of the anterior and middle scalene muscles were measured using shear wave elastography in the following arm and neck positions: (1) adduction and neutral rotation of the shoulder (neutral), (2) 90° of abduction and external rotation of the shoulder (ABER), and (3) ABER with neck rotation toward the nonthrowing side (ABER+NR). Repeated-measures analysis of variance and a paired t test were used to compare the elastic modulus values among the 3 positions and between the 2 muscles, respectively.

Results:

Overall, 30 baseball players were included. In both scalene muscles, the elastic moduli were significantly greater in the ABER versus neutral position (anterior scalene: 14.4 ± 3.8 vs 9.4 ± 2.0 kPa, respectively [P < .001]; middle scalene: 15.8 ± 5.0 vs 10.9 ± 3.4 kPa, respectively [P < .001]). In the neutral position, the elastic modulus was significantly greater in the middle scalene than the anterior scalene (10.9 ± 3.4 vs 9.4 ± 2.0 kPa, respectively; P = .03). In the ABER+NR position, the elastic modulus was significantly greater in the anterior scalene than the middle scalene (18.1 ± 4.6 vs 15.8 ± 2.6 kPa, respectively; P = .03).

Conclusion:

Because the ABER position was a simulation of the throwing position, these results indicate that this position could be associated with high elastic moduli of the scalene muscles, and both the anterior and middle scalene muscles may be involved.

GIRD syndrome in male handball and volleyball players: Is the decrease of total range of motion the turning point to pathology?

BACKGROUND

Adaptations in glenohumeral range of motion may affect overhead athletes and lead to shoulder pathologies.

OBJECTIVE

The purpose of this study was to evaluate glenohumeral internal rotation deficit (GIRD) and postero-superior impingement among male handball and volleyball players and the relationship between these pathologies and training level (amateur vs. professional), position (attack vs. no attack), experience (> 5 years vs. < 5 years) and sports.

METHODS

Sixty-seven handball players and 67 volleyball players with a mean age of 25 [± 5] years were included. The range of motion including external and internal rotation in 90∘ abduction of the dominant and non-dominant shoulder was measured of each examined athlete. Visual analogue scale, disabilities of the shoulder and hand score, constant score and subjective shoulder value were recorded. The athletes were examined for postero-superior impingement and abduction force was measured with an isokinetic dynamometer.

RESULTS

Internal rotation was significantly lower and external rotation was significantly greater in the dominant arm for both sports. 72% presented with GIRD. GIRD was more prevalent in athletes active for > 5 years (odds ratio (OR) 3), in those training > 3 times per week (OR 1.4) and in handball players (OR 2.7). 24% presented with postero-superior impingement. Players active for > 5 years (OR 1.22), professionals (OR 1.14), volleyball players (OR 1.19), offensive players (OR 2.2) and athletes with GIRD > 10∘ (OR 1.5) showed a higher prevalence of postero-superior impingement.

CONCLUSION

GIRD is a common phenomenon in handball and volleyball players. Offensive players are frequently suffering from postero-superior impingement. GIRD > 10∘ leads in nearly 75% of the athletes to a decrease of total range of motion and a high rate of postero-superior impingement. Thus, a decreased range of motion seems to be the turning point from adaptation to pathology. Therefore, regular controls of range of motion and countermeasures by means of stretching the posterior shoulder joint should be integrated in the training content.

Posterior shoulder capsule of the dominant arm is stiffer in baseball players than that in nonthrowing population

BACKGROUND

Posterior shoulder capsule tightness is one of the factors for shoulder injuries in overhead athletes. Recent studies have shown the posterior capsule of the dominant arm to be stiffer than that of the nondominant arm in baseball players. However, whether posterior capsule tightness in the dominant arm is exclusive to overhead athletes remains unknown. This study aimed to investigate whether the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

METHODS

Fifteen male collegiate asymptomatic baseball players (baseball-player group) and fifteen male college students who did not partake in overhead sports (nonthrowing group) participated in this study. We measured the shear moduli of the middle and inferior posterior capsules, superior infraspinatus, inferior infraspinatus, teres minor, and posterior deltoid in the dominant arm by ultrasound shear wave elastography. We compared shear moduli between the two groups using an independent samples t-test and Mann-Whitney test. In addition, we investigated the correlation between the range of glenohumeral internal rotation and each shear modulus in each group using the Pearson correlation coefficient.

RESULTS

The shear moduli in the baseball-player group were significantly higher than those in the nonthrowing group in both the middle posterior capsule (baseball-player group: 36.1 ± 5.6 kPa vs. nonthrowing group: 29.0 ± 8.6 kPa; P = .018) and inferior posterior capsule (37.1 ± 9.6 kPa vs. 27.9 ± 6.8 kPa; P = .002). However, no difference in the shear moduli of individual muscle groups was identified. The glenohumeral internal rotation range exhibited a statistically significant negative correlation with the shear modulus of the inferior posterior capsule in the baseball-player group (Pearson correlation coefficient = -0.586, P = .022).

CONCLUSION

Our findings suggest that the posterior shoulder capsule of the dominant arm in baseball players is stiffer than that in nonthrowing population.

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.

The Effects of Sleeper and Superman Stretches on Time-Zero Shoulder Range of Motion in Collegiate Athletes

Purpose

This study aimed to determine whether prone cross-body adduction (superman stretch) improves range of motion (ROM) more than the sleeper stretch.

Methods

Collegiate overhead athletes were randomized to either a sleeper group or a superman stretch group. ROM measurements were collected before and after stretches by three orthopedic surgeons.

Results

We assessed a total of 212 shoulders. Both stretches demonstrated significant improvements in ROM, except horizontal adduction, which only improved in the superman stretch group.

Conclusions

The superman stretch may be superior in producing immediate improvements in horizontal adduction when compared to the traditional sleeper stretch.

Reliability of visual inspection and palpation to assess relative flexibility of the shoulder

INTRODUCTION

Movement compensations during internal rotation of the shoulder can provoke pain. Reliably observing and measuring compensations in the shoulder using visual and palpatory methods can result in more efficacious treatments of shoulder pathology. Despite this, the reliability of these measures and the relationship between them is unknown.

METHODS

Bilateral shoulders of 33 Doctor of Physical Therapy (DPT) students were measured. Two third-year DPT student examiners used visual inspection and physical palpation to identify the first signs of internal rotation (IR) passive stiffness. Measurements were taken and recorded by a third examiner using the GetMyROM (Version 1.1) iPhone application.

RESULTS

Good intra-rater reliability for both examiners was identified for physical palpation (ICC = 0.896, 95% CI = 0.830, 0.936, ICC = 0.901, 95% CI = 0.839, 0.939) and visual inspection (ICC = 0.813, 95% CI = 0.699, 0.884, ICC = 0.782, 95% CI = 0.667, 0.880). Moderate interrater reliability was found between the examiners for physical palpation (ICC = 0.681, 95% CI = 0.479, 0.797) while poor interrater reliability was found between examiners for visual inspection (ICC = 0.481, 95% CI = 0.234, 0.648). The correlation between physical palpation and visual inspection indicated moderate reliability for both examiners (r = 0.815, p = 0.01, r = 0.832, p = 0.01).

CONCLUSION

The findings of this research study indicate that both physical palpation and visual inspection are reliable methods for measuring relative flexibility of shoulder IR when performed by the same examiner. However, the reliability for both methods decreases when performed by different examiners. Additionally, a strong correlation was found between both measures.

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.

Age-related change in shear elastic modulus of the thoracolumbar multifidus muscle in healthy Beagle dogs using ultrasound shear wave elastography

Background

Multifidus muscle stiffness decreases in patients with lumbar intervertebral disk herniation; however, age-related changes in humans have not been reported.

Objectives

The reliability of ultrasound shear wave elastography in dogs, and changes in the shear elastic modulus of the thoracolumbar multifidus muscle with aging in dogs, were investigated.

Methods

Twelve beagle dogs were divided into 2 groups based on the age of onset of intervertebral disk herniation: young (aged not exceeding 2 years; 1.3 ± 0.6 years old, n = 5) and adult (4.9 ± 1.2 years old, n = 7). The shear elastic modulus of the multifidus muscle, from the thirteenth thoracic spine to the fourth lumbar spine, was measured using ultrasound shear wave elastography. The length, cross-sectional area and muscle to fat ratio of the multifidus muscle, and the grade of intervertebral disk degeneration, were assessed using radiographic and magnetic resonance imaging examinations.

Results

The length and cross-sectional area of the multifidus muscle increased caudally. In the young group, the shear elastic modulus of the multifidus muscle of the thirteenth thoracic spine was less than that of the third lumbar spine. In the adult group, the shear elastic modulus of the multifidus muscle of first and third lumbar spine was lower than that of the same site in the young group.

Conclusions

Ultrasound can be used to measure shear wave elastography of the thoracolumbar multifidus in dogs. If the multifidus muscle stiffness decreases, we should consider age-related change.

Stiffness of the infraspinatus and the teres minor muscles during shoulder external rotation: An in-vitro and in-vivo shear wave elastography study

BACKGROUND

A better understanding of the morphological and functional differences in the anatomical sub-regions of the rotator cuff muscles is critical so that appropriate surgical and rehabilitation methodologies can be implemented in patients with shoulder-related injuries. The purpose of the current study was to develop a comprehensive imaging protocol using shear-wave elastography for the infraspinatus and teres minor muscles, and investigate differences in elastic properties of three distinct infraspinatus muscle sub-regions and of the teres minor muscle.

METHODS

First, we developed a protocol for probe positioning for both muscles using three cadaveric shoulders. Second, we evaluated in-vivo elastic properties [passive and active stiffness (kPa)] and excursion (mm) outcomes from these muscles during shoulder external rotation.

FINDINGS

Elastic properties were significantly different among the infraspinatus muscle sub-regions and teres minor muscle. Passive stiffness decreased with increasing rotation angles except for the middle sub-region of the infraspinatus muscle which showed a decreased up to mid-range followed by an increment towards the end-range. Overall, active stiffness of the infraspinatus muscle and teres minor muscle decreased with increasing rotation angles, while that of the middle sub-region increased up to mid-range, and decreased at the end-range.

INTERPRETATION

Distinct characteristics of the infraspinatus and teres minor muscles, and more importantly, of the individual sub-regions within the infraspinatus muscle call for an in-depth analysis of their morphological and functional differences. Special attention should be put into these sub-regions when performing surgical and rehabilitation procedures for patients with shoulder-related injuries.

Effective stretching positions for the posterior shoulder capsule as determined by shear wave elastography

BACKGROUND

Stretching is often used to prevent and treat posterior shoulder capsule tightness; however, the most effective stretching positions are not clearly defined. The purpose of this study was to identify the stretching positions that specifically applied the greatest passive tension on the posterior shoulder capsule by evaluating the elastic characteristics of posterior capsules and muscles in various stretching positions using ultrasound shear wave elastography (SWE).

METHODS

We evaluated 9 fresh-frozen shoulders (mean age 86.6 ± 7.7 years) without osteoarthritis or rotator cuff tears. All posterior shoulder tissues were preserved intact. Shear moduli of the middle and inferior posterior shoulder capsules and the posterior shoulder muscles were evaluated using SWE. We obtained shear modulus measurements in 9 stretching positions using a combination of glenohumeral elevation planes and angles (frontal, sagittal, scapular; -30°, 0°, 30°, 60°, respectively). A 4-Nm torque for shoulder internal rotation or horizontal adduction was applied in each position. We also measured shear moduli in the resting position (0° elevation with neutral shoulder internal/external rotation). We compared the shear moduli of all stretching and resting positions using 1-way repeated measures analysis of variance (P < .05). In addition, we compared the shear modulus in 2 positions (ie, resting and each stretching) among tissues (ie, capsules and muscles) with repeated measures using 2-way analysis of variance (P < .05).

RESULTS

Shear modulus values for the middle posterior capsules in "internal rotation at 30° in scapular plane elevation" (28.7 ± 14.3 kPa, P = .01) and in "horizontal adduction at 60° of elevation" (31.1 ± 13.1 kPa, P < .001) were significantly higher than that of the resting position (11.0 ± 7.3 kPa). The shear modulus value for the inferior posterior capsule in "internal rotation at 30° of flexion" was significantly higher than that of the resting position (39.0 ± 17.3 vs. 15.4 ± 13.9 kPa, respectively; P = .004). Additionally, the shear modulus values for the posterior capsules in "internal rotation at 30° in scapular plane elevation and flexion" were significantly higher than that of the posterior shoulder muscles.

CONCLUSION

Effective middle posterior shoulder capsule stretching positions were shoulder "internal rotation at 30° of scapular plane elevation" and "horizontal adduction at 60° of elevation." Shoulder "internal rotation at 30° of flexion" was the most effective position for the inferior posterior shoulder capsule. Stretching in these positions could relieve posterior shoulder capsule tightness and contribute to the prevention and treatment of throwing injuries of the shoulder.

Epimuscular myofascial force transmission from biarticular rectus femoris elongation increases shear modulus of monoarticular quadriceps muscles

This study aimed to examine the effect of rectus femoris (RF) elongation with passive hip angle change on the shear moduli of the vastus lateralis (VL) and medialis (VM) to verify whether Epimuscular myofascial force transmission (EMFT) occurs in the human quadriceps. Fourteen healthy men participated in this study. The shear moduli of the RF, VL, and VM were measured in four hip positions: flexion (Flex), extension and abduction (Ext-Abd), extension (Ext), and extension and adduction (Ext-Add). As the behavior of shear moduli may differ depending on the parts of the vasti muscles, we measured the medial and lateral parts of the VL (Medial-VL and Lateral-VL) and VM (Medial-VM and Lateral-VM). The shear moduli at the Ext and Ext-Add positions were higher than at the Flex position in the RF, VL, and VM. The shear moduli during Ext and Ext-Add were higher than at the Ext-Abd in the RF, VL, and Lateral-VM. Moreover, the shear modulus of the Lateral-VM was higher than of the Medial-VM (Flex: 8.5% higher; Ext-Abd: 15.6%; Ext: 30.2%; Ext-Add: 32.6%). The shear moduli of the VL and VM, which are monoarticular muscles of the knee, increased with passive hip extension or adduction with extension, even when the knee angle was kept constant. The results suggest that EMFT occurs in the quadriceps, and EMFT had a great impact in the Lateral-VM, which is anatomically adjacent to the RF, but it had little effect in the Medial-VM, which is further away from the RF.

Chronic Adaptations of the Posterior Rotator Cuff in Professional Pitchers

BACKGROUND

Because of the large forces and high frequency of throwing, the upper extremity experiences repetitive stresses that lead to acute and chronic adaptations. While the importance of pennation angle and muscle thickness as predictors of muscle force production has been shown in other populations and other joints, there has been little research done that examines these variables in the shoulders of baseball players.

PURPOSE

(1) To examine the chronic effect pitching has on the rotator cuff muscle architecture (pennation angle and muscle thickness) in healthy professional baseball pitchers, and (2) to examine the correlation between muscle architecture and clinical measures of strength and range of motion (ROM).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Twenty-eight healthy professional pitchers were recruited during the 2019 spring training. Internal rotation (IR) and external rotation (ER) strength were measured with a handheld dynamometer and IR and ER ROM were measured with an inclinometer. A diagnostic ultrasound machine was utilized to capture images of humeral retroversion, as well as the pennation angle and muscle thickness of the infraspinatus and teres minor muscles. ImageJ software was used to quantify the pennation angle and muscle thickness.

RESULTS

There were no significant differences between the dominant and nondominant arms for ER or IR strength. Also, no pennation angle and muscle thickness differences were found between the dominant and nondominant arms. A weak positive relationship between infraspinatus muscle thickness (superficial and total) and ER strength (P = .016, R = 0.287 and P = .009, R = 0.316) and a moderate negative relationship between soft tissue glenohumeral internal rotation deficit (GIRD) and the bilateral difference of the teres minor deep pennation angle (R = -0.477, P = .008) were observed. No other significant relationships were noted.

CONCLUSION

Our results are contrary to current literature as we expected to see a stronger dominant arm, with a larger pennation angle and greater muscle thickness. Interestingly, we found that ER strength was positively related to only the thickness of the infraspinatus muscle, and that soft tissue GIRD was positively related to only the side-to-side adaptation of the pennation angle within the deep portion of the teres minor. This suggests that when posterior shoulder tightness occurs, specifically the architecture of the teres minor muscle is involved. However, the organization to which these players belonged has a very extensive training protocol throughout the year that emphasizes bilateral training during a large majority of the exercises. Therefore, the results may not be generalizable to all professional players.

The Effect of Straight-Line Long-Toss Versus Ultra-Long-Toss Throwing on Passive Glenohumeral Range of Motion Recovery After Pitching

BACKGROUND

Repetitive throwing in baseball pitchers can lead to pathologic changes in shoulder anatomy, range of motion (notably glenohumeral internal rotation deficit), and subsequent injury; however, the ideal strengthening, recovery, and maintenance protocol of the throwing shoulder in baseball remains unclear. Two strategies for throwing shoulder recovery from pitching are straight-line long-toss (SLT) throwing and ultra-long-toss (ULT) throwing, although neither is preferentially supported by empirical data.

HYPOTHESIS

ULT will be more effective in returning baseline internal rotation as compared with SLT in collegiate pitchers after a pitching session.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 24 National Collegiate Athletic Association Division I baseball pitchers with mean age 20.0 ± 1.1 years were randomized to either the ULT group (n = 13; 9 right-hand dominant, 4 left-hand dominant) or SLT group (n = 11; 10 right-hand dominant, 1 left-hand dominant). Measurements (dominant and nondominant, 90° abducted external rotation [ER], internal rotation [IR], and total range of motion [TROM]) were taken at 5 time points across 3 days: before and immediately after a standardized bullpen session on day 1; before and immediately after a randomized standardized ULT or SLT session on day 2; and before practice on Day 3.

RESULTS

ULT demonstrated significantly greater final ER compared with baseline (+10°; P = 0.05), but did not demonstrate significant IR changes. Similarly, SLT demonstrated significantly greater post-SLT ER (+12°; P = 0.02) and TROM (+12°;P = 0.01) compared with baseline, but no significant IR changes. Final ER measurements were similar between ULT (135° ± 14°) and SLT (138° ± 10°) (P = 0.59). There was also no statistically significant difference in final IR between ULT (51° ± 14°) and SLT (56° ± 8°) (P = 0.27).

CONCLUSION

The routine use of postperformance, ULT throwing to recover from range of motion alterations, specifically IR loss, after a pitching session is not superior to standard, SLT throwing. Based on these findings, the choice of postpitching recovery throwing could be player specific based on experience and comfort.

CLINICAL RELEVANCE

The most effective throwing regimens for enhancing performance and reducing residual impairment are unclear, and ideal recovery and maintenance protocols are frequently debated with little supporting data. Two strategies for throwing shoulder recovery from pitching are SLT and ULT throwing. These are employed to help maintain range of motion and limit IR loss in pitchers. The routine use of ULT throwing for recovery and to limit range of motion alterations after a pitching session is not superior to SLT throwing.

Soft Tissue Mobilization and Stretching for Shoulder in CrossFitters: A Randomized Pilot Study

Background. The shoulder in CrossFit should have a balance between mobility and stability. Glenohumeral internal rotation deficit and posterior shoulder stiffness are risk factors for overhead shoulder injury. Objective. To determine the effectiveness of instrument-assisted soft tissue mobilization and horizontal adduction stretch in CrossFit practitioners’ shoulders. Methods: Twenty-one regular CrossFitters were allocated to experimental (stretching with isometric contraction and instrument-assisted soft tissue mobilization) or control groups (instrument-assisted soft tissue mobilization). Each session lasted 5 min, 2 days a week, over a period of 4 weeks. Shoulder internal rotation and horizontal adduction (digital inclinometer), as well as posterior shoulder stretch perception (Park scale), were evaluated. Shapiro–Wilk test was used to analyze the distribution of the sample. Parametric Student’s t-test was used to obtain the intragroup differences. The inter- and intra-rater differences were calculated using a repeated measures analysis of variance (ANOVA). Results. Average age was 30.81 years (SD: 5.35), with an average height of 178 (SD: 7.93) cm and average weight of 82.69 (SD: 10.82) kg. Changes were found in the experimental group following intervention (p < 0.05), and when comparing baseline and follow-up assessments (p < 0.05) in all variables. Significant differences were found in the control group following intervention (p < 0.05), in right horizontal adduction and left internal rotation. When comparing the perception of internal rotation and horizontal adduction in both groups, significant differences were found. Conclusions. Instrument-assisted soft tissue mobilization can improve shoulder horizontal adduction and internal rotation. An instrument-assisted soft tissue mobilization technique yields the same results alone as those achieved in combination with post-isometric stretch with shoulder adduction.

Mapping of Back Muscle Stiffness along Spine during Standing and Lying in Young Adults: A Pilot Study on Spinal Stiffness Quantification with Ultrasound Imaging

Muscle stiffness in the spinal region is essential for maintaining spinal function, and might be related to multiple spinal musculoskeletal disorders. However, information on the distribution of muscle stiffness along the spine in different postures in large subject samples has been lacking, which merits further investigation. This study introduced a new protocol of measuring bilateral back muscle stiffness along the thoracic and lumbar spine (at T3, T7, T11, L1 & L4 levels) with both ultrasound shear-wave elastography (SWE) and tissue ultrasound palpation system (TUPS) in the lying and standing postures of 64 healthy adults. Good inter-/intra-reliability existed in the SWE and TUPS back muscle stiffness measurements (ICC ≥ 0.731, p < 0.05). Back muscle stiffness at the L4 level was found to be the largest in the thoracic and lumbar regions (p < 0.05). The back muscle stiffness of males was significantly larger than that of females in both lying and standing postures (p < 0.03). SWE stiffness was found to be significantly larger in standing posture than lying among subjects (p < 0.001). It is reliable to apply SWE and TUPS to measure back muscle stiffness. The reported data on healthy young adults in this study may also serve as normative reference data for future studies on patients with scoliosis, low back pain, etc.

Glenohumeral Internal Rotation Deficit: Prime Suspect or Innocent Bystander?

PURPOSE OF REVIEW

Glenohumeral internal rotation deficit (GIRD) is a term used in the literature to describe the physiological adaptation that occurs in the dominant arm of the overhead-throwing athlete. The meaning of this term and the clinical significance and the rationale for its treatment have all been described with some ambiguity within the literature. GIRD as a measurement is multivariate. There is an adaptive bony component in humeral retroversion (HR) and muscular contributions in the form of thixotropy which can confound the capsular component of GIRD. Emerging diagnostic tools such as ultrasound can help differentiate between the bony and soft tissue contributions as well as provide a dynamic assessment in the throwing shoulder. The purpose of this review is to describe and differentiate between anatomical GIRD (aGIRD) and pathological GIRD (pGIRD), discuss the clinical significance of pGIRD and values reported within the literature, and describe its measurement and clinical treatment.

RECENT FINDINGS

Recent literature has demonstrated that GIRD alone is not associated with injury risk of the upper extremity in the overhead athlete. Although past literature has demonstrated pGIRD as increasing injury risk, other variables such as external rotation (ER) deficit, horizontal adduction deficit, and shoulder flexion deficit have been associated with injury of the upper extremity while GIRD did not. Further, an appreciation for the difference between adaptive GIRD and pathologic GIRD has recently been emphasized to ensure optimal treatment addresses the pathologic portion of GIRD. The recent focus on early treatment approaches to pGIRD may play a role in its diminished risk association. This review offers the term humeral retroversion (HR) Corrected GIRD as a more clinically sensitive value that may provide the clinician a more precise rationale for the treatment of pGIRD. Currently, diagnostic ultrasound is a reliable and valid method for measuring HR in the overhead-throwing athlete. Future research that validates clinical methods for assessing HR could provide utility for clinical decision-making in the absence of diagnostic ultrasound.

Effects of self-stretching with mobilization on shoulder range of motion in individuals with glenohumeral internal rotation deficits: a randomized controlled trial

BACKGROUND

The combined effects of cross-body stretching and dorsal glide mobilization have not been examined previously, although both stretching and mobilization maneuvers are effective for improving shoulder range of motion (ROM). Thus, the aim of this study was to demonstrate the effects of stretching with mobilization (SWM) on glenohumeral (GH) internal rotation (IR) and horizontal adduction (HA) ROM.

METHODS

Forty individuals with GH IR deficits were randomized to perform simultaneous combined cross-body stretching and dorsal glide mobilization (SWM group, comprising 10 male and 10 female patients) or cross-body stretching alone (stretching group, comprising 10 male and 10 female patients). GH IR ROM, HA ROM, and shoulder mobility were assessed before and immediately following interventions. Group and time differences were analyzed using 2-way repeated-measures analysis of variance.

RESULTS

Greater changes in GH IR ROM (6°, P < .001), HA ROM (10°, P < .001), and shoulder mobility (-2 cm, P = .018) were observed in the SWM group than in the stretching group, although significant increases were observed in GH IR ROM (SWM group, P < .001; stretching group, P < .001), HA ROM (SWM group, P < .001; stretching group, P = .042), and shoulder mobility (SWM group, P < .001; stretching group, P < .001) after both interventions.

CONCLUSION

This study shows that SWM could be a useful exercise for shoulder ROM recovery in individuals with GH IR deficits.

Assessment of the Passive Tension of the First Dorsal Interosseous and First Lumbrical Muscles Using Shear Wave Elastography

PURPOSE

Quantitative evaluation of passive tension of the intrinsic muscles of the hand is necessary to assess contracture of the intrinsic muscles accurately. The aim of this study was to evaluate the shear modulus, which is related to passive muscle tension, of the first dorsal interosseous (FDI) and first lumbrical (FL) muscles using shear wave elastography.

METHODS

Subjects were 18 healthy males. The shear modulus of the FDI and FL muscles was assessed at several proximal interphalangeal (PIP), distal interphalangeal (DIP), metacarpophalangeal (MCP), and wrist joint positions. The position in which the MCP joint was flexed 60° past 0° with PIP-DIP joint extension and that in which the MCP joint was extended 30° past 0° with PIP-DIP joint flexion were respectively defined as the slack and stretched positions. We analyzed whether the shear modulus was affected by finger position (slack or stretched), wrist position (30° flexion past 0° and 30° extension past 0°), and muscle (FDI or FL).

RESULTS

Shear modulus in the stretched position was significantly higher than that in the slack position. The shear modulus of the FL muscle at 30° wrist extension was significantly higher than that at 30° flexion. The shear modulus of the FL muscle was significantly higher than that of the FDI muscle in the stretched position with the wrist at 30° flexion and extension, and in the slack position with the wrist at 30° extension.

CONCLUSIONS

The shear modulus of the FDI and FL muscles increased with MCP joint extension and PIP-DIP joint flexion. The difference in the muscle characteristics between the FDI and FL muscles should be considered when evaluating or treating contractures of the intrinsic muscles.

CLINICAL RELEVANCE

Shear wave elastography can evaluate the condition of the intrinsic muscles of the hand quantitatively.

Sacroiliac Stretching Improves Glenohumeral Internal Rotation Deficit of the Opposite Shoulder in Baseball Players in a Randomized Control Trial

Introduction:

Glenohumeral internal rotation deficit (GIRD) is a well-documented finding in throwing athletes.

Purpose:

To investigate whether stretching the contralateral sacroiliac (SI) joint can improve GIRD in baseball players.

Method:

After internal shoulder rotation was measured in 23 minor league baseball players, the players randomly were assigned to either a control (ie, sleeper stretch of the dominant shoulder) or experimental (ie, SI joint stretch contralateral to the dominant shoulder) group. Afterward, internal rotation (IR) of their dominant shoulders was remeasured.

Results:

The mean initial end-range IR was 68.6° (SD = 7.9°) in the sleeper stretch group (n = 8) and 64.5° (SD = 5.1°) in the SI joint stretch group (n = 15). After stretching, the sleeper stretch group's mean end-range IR was 72.1° (SD = 7.2°), a 3.5° improvement (P = 0.1058), whereas the contralateral SI joint stretch group's mean end-range IR was 71.9° (SD = 6.6°), a 7.4° improvement (P = 0.0041).

Conclusions:

Stretching the contralateral SI joint improved GIRD more than the sleeper's stretch.

Scapular kinematic alterations during arm elevation with decrease in pectoralis minor stiffness after stretching in healthy individuals

BACKGROUND

Pectoralis minor tightness may be seen in individuals with scapular dyskinesis, and stretching is used for the treatment of altered scapular motion in sports and clinical fields. However, few researchers have reported on the effects of pectoralis minor stiffness on scapular motion during arm elevation. This study investigated whether an acute decrease of pectoralis minor stiffness after stretching changes the scapular motion during arm elevation.

METHODS

The study allocated 15 dominant and 15 nondominant upper limbs in healthy men as control and interventional limbs, respectively. In the intervention limb group, the shoulder was passively and horizontally abducted at 150° of elevation for 5 minutes to stretch the pectoralis minor muscle. Before and after stretching, an electromagnetic sensor was used to examine 3-dimensional scapular motion during abduction and scaption. Ultrasonic shear wave elastography was used to measure pectoralis minor stiffness before and immediately after stretching and after arm elevation.

RESULTS

In the interventional limb, pectoralis minor stiffness decreased by 3.2 kPa immediately after stretching and by 2.5 kPa after arm elevation. The maximal changes in scapular kinematics after stretching were 4.8° of external rotation and 3.3° of posterior tilt in abduction, and 4.5° of external rotation and 3.7° of posterior tilt in scaption. Upward rotation in abduction or scaption did not change.

CONCLUSIONS

Stretching for the pectoralis minor muscle increases external rotation and posterior tilt of the scapula during arm elevation.

Evidence of Generalized Muscle Stiffness in the Presence of Latent Trigger Points Within Infraspinatus

OBJECTIVE

To evaluate stiffness of infraspinatus muscle tissue, both with and without latent trigger points, using ultrasound shear wave elastography (SWE). The primary hypothesis is that muscle with a latent trigger point will demonstrate a discrete region of increased shear wave speed. The secondary hypothesis is that shear wave speed (SWS) in the region with the trigger point will be higher in patients compared with controls, and will be similar between the two groups in the uninvolved regions.

DESIGN

Case-control.

SETTING

Hospital-based outpatient physical therapy center.

PARTICIPANTS

Convenience sample (N=18) of patients (6 female, 3 male, mean age=44) (range=31-61y) diagnosed with latent trigger points in infraspinatus and matched controls without trigger points.

MAIN OUTCOME MEASURES

Shear wave speed (m/s).

RESULTS

SWS of the latent trigger point (mean=4.09±SD1.4 m/s) did not differ from the adjacent muscle tissue (3.92±1.6 m/s, P>.05), but was elevated compared to corresponding tissue in controls (2.8±0.75 m/s, P=.02). SWS was generally greater in patients' uninvolved tissue (3.83±1.6 m/s) when compared to corresponding tissue in controls (2.62±0.2 m/s, P=.05).

CONCLUSION

Although discrete regions of increased SWS corresponding to the trigger point were not observed in patients, evidence of generally increased muscle stiffness in infraspinatus was exhibited compared to healthy controls. Further study of additional muscles with SWE is warranted.

Shear wave sonoelastography of skeletal muscle: basic principles, biomechanical concepts, clinical applications, and future perspectives

Imaging plays an important role in the diagnosis and therapeutic response evaluation of muscular diseases. However, one important limitation is its incapacity to assess the in vivo biomechanical properties of the muscles. The emerging shear wave sonoelastography technique offers a quantifiable spatial representation of the viscoelastic characteristics of skeletal muscle. Elastography is a non-invasive tool used to analyze the physiologic and biomechanical properties of muscles in healthy and pathologic conditions. However, radiologists need to familiarize themselves with the muscular biomechanical concepts and technical challenges of shear wave elastography. This review introduces the basic principles of muscle shear wave elastography, analyzes the factors that can influence measurements and provides an overview of its potential clinical applications in the field of muscular diseases.

Management of Rotator Cuff Injuries in the Elite Athlete

PURPOSE OF REVIEW

Rotator cuff injuries are a common cause of pain and dysfunction for the elite athlete and can result in time loss from participation. This review highlights the current management of these injuries.

RECENT FINDINGS

Conservative management of rotator cuff injuries continues to be the "gold standard" in the elite athlete. This includes a comprehensive rehabilitation program, anti-inflammatories, and corticosteroid injections. Newer treatment techniques such as intramuscular dry needling and the use of biologics such as platelet-rich plasma and stem cells demonstrate early promising results; however, these modalities require further investigation to determine their effectiveness. Rotator cuff injuries can range from contusions and tendinopathy to full-thickness tears. A comprehensive evaluation is needed to determine the extent of injury and appropriate plan of care. Management strategies can range from rehabilitation to operative intervention and are guided by the size of the tear, time of season, sport, performance limitations, and presence of concomitant pathology.

The application of ultrasound elastography in the shoulder

Ultrasound elastography (EUS) is a recently developed method for the assessment of tissue elasticity by applying mechanical stress and subsequently analyzing tissue displacement with ultrasound. To date, mainly two different techniques are used in clinical practice: strain (compression) EUS and shear wave EUS. However, shear wave EUS has been shown to be more examiner independent and more reliable as this technique allows a quantitative measurement of tissue elasticity. There is increasing evidence that EUS can be used to evaluate mechanical properties of musculoskeletal tissue. Thus, it might be a powerful tool to detect and to monitor pathologic processes affecting the shoulder girdle. As ultrasound is an essential clinical tool for the examination of the shoulder, this review describes the two most important EUS techniques available for clinical use, presenting the published evidence on the applications of EUS for the evaluation of pathologic processes affecting the shoulder joint. In addition, technical issues, limitations, and future perspectives of these methods for the assessment of the shoulder are outlined.

Acute effect and time course of extension and internal rotation stretching of the shoulder on infraspinatus muscle hardness

BACKGROUND

A decrease in flexibility of the infraspinatus muscle causes limitations in the range of shoulder motion. Static stretching (SS) is a useful method to improve muscle flexibility and joint mobility. Previous researchers investigated effective stretching methods for the infraspinatus. However, few researchers investigated the acute effect of SS on the infraspinatus muscle's flexibility. In addition, the minimum SS time required to increase the infraspinatus muscle's flexibility remains unclear. The aims of this study included investigating the acute effect of SS on the infraspinatus muscle's hardness (an index of muscle flexibility) by measuring shear elastic modulus and determining minimum SS time to decrease the infraspinatus muscle's hardness.

METHODS

This included measuring the effect of SS with extension and internal rotation of the shoulder on the infraspinatus muscle's hardness in 20 healthy men. Hence, shear elastic modulus of the infraspinatus was measured by ultrasonic shear wave elastography before and after every 10 seconds up to 120 seconds of SS.

RESULTS

Two-way analysis of variance indicated a significant main effect of SS duration on shear elastic modulus. The post hoc test indicated no significant difference between shear elastic modulus after 10 seconds of SS and that before SS. However, shear elastic modulus immediately after a period ranging from 20 seconds to 120 seconds of SS was significantly lower than that before SS.

CONCLUSION

The results suggested that shoulder extension and internal rotation SS effectively decreased the infraspinatus muscle's hardness. In addition, the results indicated that a period exceeding 20 seconds of SS decreased the infraspinatus muscle's hardness.