Current concepts in the evaluation and treatment of the shoulder in overhead-throwing athletes, part 1: physical characteristics and clinical examination

Damage for gain: The useful damage of the Pitcher's paradox

Introduction

Sport-specific adaptations of the glenohumeral joint may arise in adolescent overhead athletes who begin high-performance sports early in life. Research mainly addresses overuse injuries, leaving gaps in prevention, with adults studied more than youths.

Objective

This study aims to investigate sport-adaptations of the glenohumeral joint in asymptomatic adolescent volleyball players to identify potential shoulder injury risk factors.

Design

Observational study.

Setting

Clinical screening campaign conducted at the Physical Medicine and Rehabilitation Unit of Policlinic Hospital in Catania, Italy.

Participants

Forty asymptomatic under-16 athletes were evaluated.

Interventions

Shoulder internal rotation (IR) and external rotation (ER), range of motion (ROM), total-rotation ROM, glenohumeral IR deficit (GIRD), general joint laxity using Beighton score, apprehension, relocation, O'Brian tests, and ultrasound (US) glenohumeral distance were tested bilaterally. Variables such as the player's position, the age they began the sport, limb dominance, weight, and height were also considered.

Results

The median US glenohumeral distance was at 0.42 ± 0.26 cm, which is consistent with the range found in non-dislocated shoulders of a healthy non-athletic population. The ER ROM was significantly greater in the dominant shoulder than the contralateral one (P = 0.0001), and there was a significant correlation between the ER ROM of attackers and their US glenohumeral distance (P = 0.0413). Furthermore, shoulder IR ROM and US glenohumeral distance were not significantly different between the dominant and contralateral limbs (P = 0.05). None of the athletes presented GIRD. Other tests, including the Beighton score, apprehension, and relocation tests, yielded no significant differences between the dominant and contralateral limbs.

Conclusions

Despite an increased shoulder ER in the dominant limb, the glenohumeral joint remains stable, suggesting that greater ROM in ER does not equate to instability in overhead athletes without hyperlaxity. Nevertheless, increased ER impacts glenohumeral distance in attacker volleyball players. This finding suggests that the shoulder morphological adaptation process starts early in attackers.

Effect of Clubbell Training on Glenohumeral Internal and External Rotation, Muscle Function, and Ball Velocity in Baseball Pitchers

OBJECTIVES This study examined the effects of clubbell exercises in a pitcher training program on the range of motion (ROM), muscle function, and its subsequent influence on pitching velocity. Additionally, this study aimed to develop an optimal training program to prevent injury while improving pitcher performance.METHODS Eighteen pitchers were included and equally divided into clubbell exercise and control groups. Clubbell training was conducted through 60-minute sessions twice a week for 12 weeks. Internal/external rotational (IR/ER) ROM, IR/ER muscle strength, muscle endurance, muscle power, and pitching velocity were measured before and after the intervention.RESULTS The IR (<i>p</i> = 0.051) and total ROM (TROM; <i>p</i> = 0.05) of the throwing arm decreased in the control group but increased in the clubbell exercise group, with an observed tendency of interaction. In the non-throwing arm, the ER ROM was significantly different between the two groups (<i>p</i> <0 .05), also with an observed tendency of interaction (<i>p</i> = 0.055). IR peak torque per body weight at 60°/sec significantly increased in both groups over the exercise period (<i>p</i> < 0.01). Total work per body weight and average power of IR at 180°/sec increased in both groups over the exercise period (<i>p</i> < 0.01). The pitching velocity decreased in both groups throughout the exercise period (<i>p</i> < 0.05).CONCLUSIONS Although 12 weeks of clubbell training had limited effects on ROM, the findings revealed that this exercise could be effective in improving pitching performance, preventing injuries, and maintaining long-term performance. Further studies are recommended for a more detailed assessment.

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

Background

Humeral torsion is an important osseous adaptation in throwing athletes that can contribute to arm injuries. Currently there are no cheap and easy to use clinical tools to measure humeral torsion, inhibiting clinical assessment. Models with low error and "good" calibration slope may be helpful for prediction.

Hypothesis/Purpose

To develop prediction models using a range of machine learning methods to predict humeral torsion in professional baseball pitchers and compare these models to a previously developed regression-based prediction model.

Study Design

Prospective cohort.

Methods

An eleven-year professional baseball cohort was recruited from 2009-2019. Age, arm dominance, injury history, and continent of origin were collected as well as preseason shoulder external and internal rotation, horizontal adduction passive range of motion, and humeral torsion were collected each season. Regression and machine learning models were developed to predict humeral torsion followed by internal validation with 10-fold cross validation. Root mean square error (RMSE), which is reported in degrees (°) and calibration slope (agreement of predicted and actual outcome; best = 1.00) were assessed.

Results

Four hundred and seven pitchers (Age: 23.2 +/-2.4 years, body mass index: 25.1 +/-2.3 km/m2, Left-Handed: 17%) participated. Regression model RMSE was 12° and calibration was 1.00 (95% CI: 0.94, 1.06). Random Forest RMSE was 9° and calibration was 1.33 (95% CI: 1.29, 1.37). Gradient boosting machine RMSE was 9° and calibration was 1.09 (95% CI: 1.04, 1.14). Support vector machine RMSE was 10° and calibration was 1.13 (95% CI: 1.08, 1.18). Artificial neural network RMSE was 15° and calibration was 1.03 (95% CI: 0.97, 1.09).

Conclusion

This is the first study to show that machine learning models do not improve baseball humeral torsion prediction compared to a traditional regression model. While machine learning models demonstrated improved RMSE compared to the regression, the machine learning models displayed poorer calibration compared to regression. Based on these results it is recommended to use a simple equation from a statistical model which can be quickly and efficiently integrated within a clinical setting.

Levels of Evidence

2.

More Elevated Fastballs Associated With Placement on the Injured List due to Shoulder Injury

Purpose

To evaluate whether impending shoulder injury was associated with changes in pitch location or velocity immediately preceding injury.

Methods

Pitchers placed on the injured list (IL) due to a shoulder injury between 2015 and 2020 were identified in the Major League Baseball transactions database. Four-seam fastball velocity and frequency of pitch location for each pitch type was collected for each player in the season before placement on the IL and within 1 month of placement on the IL with a minimum of 55 pitches thrown of 1 type. Pitch locations were collected as identified by Baseball Savant’s Game-Day Zones. Game-Day Zones were consolidated into high (above the strike zone midpoint) versus low, arm side (closer to the pitcher’s arm side of the plate) versus opposite side, and within the strike zone versus out of zone. Repeated measures analysis of variance determined differences in four-seam velocity and the location distribution of 4-seam fastballs, change-ups, and breaking balls among each group.

Results

In total, 267 pitchers were placed on the IL for a shoulder injury with the majority diagnosed with inflammation (89/267) followed by strain or sprain (69/267). Four-seam fastball locations significantly increased above the mid-point of the zone (45.9% vs 42.4%, P = .008) and out of the strike zone (48.5% vs 46.5%, P = .011) within a month before IL placement. There was no significant change in 4-seam fastball velocity immediately before IL placement.

Conclusions

Pitchers threw more elevated 4-seam fastballs and out-of-zone 4-seam fastballs in the month before IL placement for shoulder injury. These findings suggest that a loss of 4-seam fastball command decreases with impending shoulder injury.

Level of Evidence

IV, prognostic case series.

Development and internal validation of a humeral torsion prediction model in professional baseball pitchers

BACKGROUND

Humeral torsion (HT) has been linked to pitching arm injury risk after controlling for shoulder range of motion. Currently measuring HT uses expensive equipment, which inhibits clinical assessment. Developing an HT predictive model can aid clinical baseball arm injury risk examination. Therefore, the purpose of this study was to develop and internally validate an HT prediction model using standard clinical tests and measures in professional baseball pitchers.

METHODS

An 11-year (2009-2019) prospective professional baseball cohort was used for this study. Participants were included if they were able to participate in all practices and competitions and were under a Minor League Baseball contract. Preseason shoulder range of motion (external rotation [ER], internal rotation [IR], horizontal adduction [HA]) and HT were collected each season. Player age, arm dominance, arm injury history, and continent of origin were also collected. Examiners were blinded to arm dominance. An a priori power analysis determined that 244 players were needed for accurate prediction models. Missing data was low (<3%); thus, a complete case analysis was performed. Model development followed the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) recommendations. Regression models with restricted cubic splines were performed. Following primary model development, bootstrapping with 2000 iterations were performed to reduce overfitting and assess optimism shrinkage. Prediction model performance was assessed through root mean square error (RMSE), R², and calibration slope with 95% confidence intervals (CIs). Sensitivity analyses included dominant and nondominant HT.

RESULTS

A total of 407 professional pitchers (age: 23.2 [standard deviation 2.4] years, left-handed: 17%; arm history prevalence: 21%) participated. Predictors with the highest influence within the model include IR (0.4, 95% CI 0.3, 0.5; P < .001), ER (-0.3, 95% CI -0.4, -0.2; P < .001), HA (0.3, 95% CI 0.2, 0.4; P < .001), and arm dominance (right-handed: -1.9, 95% CI -3.6, -0.1; P = .034). Final model RMSE was 12, R² was 0.41, and calibration was 1.00 (95% CI 0.94, 1.06). Sensitivity analyses demonstrated similar model performance.

CONCLUSIONS

Every 3° of IR explained 1° of HT. Every 3° of ER explained 1° less of HT, and every 7° of HA explained 1° of HT. Right-handers had 2° less HT. Models demonstrated good predictive performance. This predictive model can be used by clinicians to infer HT using standard clinical test and measures. These data can be used to enhance professional baseball arm injury examination.

Mirror Cross-Exercise on a Kinetic Chain Approach Improves Throwing Performance in Professional Volleyball Athletes With Scapular Dyskinesis

CONTEXT

Volleyball players have shown to be at an increased risk of developing scapular dyskinesis. The kinetic chain exercise approach has gained a lot of attention because of its claims to provide an improved motor control and scapular kinematics. A form of cross exercise, known as mirror therapy, may enhance the effects of a kinetic chain exercise approach in throwing performance.

OBJECTIVE

To examine the effects of mirror cross exercise (MCE), based on a kinetic chain exercise approach in the throwing performance of volleyball athletes with scapular dyskinesis.

DESIGN

Randomized controlled trial.

SETTING

Biomechanics laboratory.

METHODS

39 volleyball players with scapular dyskinesis were randomly allocated into 3 groups. The first group completed a 6-week kinetic chain approach (KCA group), the second group completed a kinetic chain exercise approach program in addition to MCE group, and the control group followed only their regular training program. Before and after delivering both interventions, throwing accuracy, speed, and force were determined while measuring the ground reaction forces of the drive leg during throwing. Two-way mixed analysis of variance investigated the effects of intervention and time and their interaction.

RESULTS

The results showed intervention × time statistically significant interactions for throwing accuracy, speed, and force for the MCE and the KCA groups. Over the 6-week training period, the MCE and the KCA groups showed significant improvements in throwing accuracy (P < .01) and speed (P < .01), while the ground reaction forces did not change (P > .05). Throwing force increased significantly in the MCE group (P = .01). Between-group comparison showed statistically significant improvements in the throwing accuracy for the MCE and KCA groups against the control group (P < .01) at posttesting. The MCE demonstrated superior results over the KCA in the aforementioned measures.

CONCLUSIONS

This study suggests that the addition of MCE in a KCA program enhances energy transfer throughout the distal and proximal segments, thus improving kinetic chain recruitment and potentially preventing shoulder pathology.

Interval Return to Play Programs for the Tennis Athlete

PURPOSE OF REVIEW

General guidelines exist for return to sport after injury. The goal of these guidelines is to outline phases of recovery that will minimize the risk of reinjury and promote an optimal return to function for the athlete. This paper analyzes the current research pertaining to interval return to play programs with a special focus on the tennis athlete. The authors examine the different components of an interval tennis program and work to develop what they feel are the necessary elements of the optimal return to sport guidelines for tennis athletes. These criteria are based on the available literature, research, and preliminary data collection as well as the personal experiences and clinical observations of the authors.

RECENT FINDINGS

Interval sports programs are typically designed to guide the athlete back to competition after an injury. The current research reveals the obstacles present in implementing an appropriate interval sports program including a lack of consensus on which criteria is actually necessary and relevant. Limited research is present for interval tennis programs. Return to sport competition and sports science is continuously evolving. The authors highlight the necessary components in rehabilitation and performance principles for establishing a comprehensive interval tennis program. In addition, the role of technology in sports rehabilitation is assessed as it pertains to return to play. The authors proposed that interval sports program can help guide and direct future clinicians in their rehabilitation of the tennis athlete.

AN ASSESSMENT OF THE CONTRACTILE PROPERTIES OF THE SHOULDER MUSCULATURE IN ELITE VOLLEYBALL PLAYERS USING TENSIOMYOGRAPHY

Background

In volleyball, offensive (Hitters) and defensive players (Non-Hitters) perform differing actions that vary both kinematically and in terms of intensity. This may impose contrasting demands on the musculature involved in performing these actions. Previous research has identified differences in the muscle activation and contractile properties of the lower-body musculature between positions. Additionally, asymmetries between dominant and non-dominant limbs of the upper-body musculature has been observed in athletes performing overhead movements.

Purpose

The aim of this study was to use Tensiomyography (TMG) to examine the contractile properties of the shoulder musculature in elite volleyball players.

Study Design

Cross-sectional study.

Methods

Thirty-one elite volleyball players participated in this study (Age: 23 ± 2 yrs, Body Mass: 76.5 ± 9.8 kg, Stature: 181 ± 9.3 cm), 26 of which displayed right-limb dominance and five displayed left-limb dominance. Contractile properties of the shoulder musculature including the anterior deltoid (AD), biceps brachii (BB), posterior deltoid (PD), and the upper trapezius (UT) were assessed bilaterally using TMG measures on one occasion prior to any training or exercise. The contractile measures provided by TMG included the maximal displacement (Dm), contraction time (Tc), delay time (Td), sustain time (Ts), and the relaxation time (Tr).

Results

No statistically significant differences were observed between positions or limbs, except that Hitters displayed a significantly lower Ts of the left AD compared to Non-hitters (p = 0.01, ES = 1.02), and significant differences between dominant and non-dominant sides in the Td of the UT in Non-hitters were present (p = 0.05, ES = 0.8).

Conclusion

These data suggest that irrespective of playing position and limb dominance, contractile properties of the shoulder musculature in elite volleyball players, as measured using TMG, display few significant differences.

Levels of Evidence

3b.

Glenohumeral internal rotation deficit in non-pitcher overhead athletic athletes: case series analysis of ten athletes

BACKGROUND

The glenohumeral internal rotation deficit (GIRD) is diagnosed when there is a loss of 20° of internal rotation compared to the contralateral shoulder. This condition has already been well described in a group of throwing athletes, i.e. baseball pitchers. However, athletic athletes such as javelin throwers, discus throwers, hammer throwers, shot putters may also be susceptible to this condition. Reports are lacking to recognize these symptoms as GIRD for these group of athletes. We aim to evaluate these subgroups of athletes for the possibility of GIRD.

MATERIALS AND METHODS

We examined ten athletes (javelin, hammer throwers, and shot putters) for signs of GIRD. Signs of loss of internal rotation were assessed by measuring shoulder range of motion (internal rotation and external rotation) in supine position and posterior shoulder tightness test. Complaints of shoulder pain, evidence of scapular malposition, inferior medial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement (SICK) scapula, posterior shoulder flexibility test were examined.

RESULTS

The athletes had a mean training period of 3.8 years. One athlete had complaints of mild pain on their dominant shoulder. Two athletes had GIRD (20° and 25°) with no posterior shoulder tightness. Three athletes had posterior shoulder tightness, but normal total shoulder ROM (195°, 180°, and 185°). Three athletes had increased external rotation (105°, 100°, 125°). No subjects had scapular dyskinesia nor SICK scapula syndrome. All athletes had normal total shoulder ROM.

CONCLUSION

Glenohumeral internal rotation deficit could be present in non-pitcher overhead athletics athletes.

Risk Factors of Overuse Shoulder Injuries in Overhead Athletes: A Systematic Review

CONTEXT

Shoulder injuries are highly prevalent in sports involving the upper extremity. Some risk factors have been identified in the literature, but consensus is still lacking.

OBJECTIVES

To identify risk factors of overuse shoulder injury in overhead athletes, as described in the literature.

DATA SOURCES

A systematic review of the literature from the years 1970 to 2018 was performed using 2 electronic databases: PubMed and Scopus.

STUDY SELECTION

Prospective studies, written in English, that described at least 1 risk factor associated with overuse shoulder injuries in overhead sports (volleyball, handball, basketball, swimming, water polo, badminton, baseball, and tennis) were considered for analysis.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Data were extracted from 25 studies. Study methodology quality was evaluated using the Modified Coleman Methodology Score.

RESULTS

Intrinsic factors, previous injury, range of motion (lack or excess), and rotator cuff weakness (isometric and isokinetic) highly increase the risk of future injuries. Additionally, years of athletic practice, body mass index, sex, age, and level of play seem to have modest influence. As for the effect of scapular dysfunction on shoulder injuries, it is still controversial, though these are typically linked. Extrinsic factors, field position, condition of practice (match/training), time of season, and training load also have influence on the occurrence of shoulder injuries.

CONCLUSION

Range of motion, rotator cuff muscle weakness, and training load are important modifiable factors associated with shoulder injuries. Scapular dysfunction may also have influence. The preventive approach for shoulder injury should focus on these factors.

Isokinetic Performance of Shoulder External and Internal Rotators of Professional Volleyball Athletes by Different Positions

This study aimed to exam the isokinetic shoulder rotator strength of professional volleyball athletes, by playing positions. This cross-sectional study included a total of 49 healthy male professional volleyball players. We measured the isokinetic strength of the external rotator (ER) and internal rotator (IR) muscles and compared the dominant and non-dominant shoulders at angular speeds of 60°/s and 180°/s. In ER, all positions of players had similar strength between the dominant shoulder and non-dominant shoulders. Conversely, all playing positions except libero had stronger strength in dominant shoulder than that in the non-dominant shoulder. The ER/IR ratio in the dominant shoulder was significantly lower only for the attacker (outside hitter and opposite) at 60°/s and 180°/s (P < 0.0001; P = 0.0028 respectively) and blocker at 60°/s (P = 0.0273) when compared with non-dominant shoulder. Furthermore, the attacker had a lower ER/IR ratio in the dominant shoulder than setter and libero at 60°/s and 180°/s. For elite volleyball players without injury, the dominant shoulder had a higher strength of internal rotation, causing the relative muscle imbalance than the non-dominant shoulder, especially for the attacker and blocker positions. Training program should be individualized for each playing position to improve the imbalanced shoulder.

Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass

BACKGROUND

Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand.

METHODS

Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p ≤ 0.05; Bonferroni adjusted α = 0.008).

RESULTS

PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles.

CONCLUSION

Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.

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.

Analysis of the presence and influence of Glenohumeral Internal Rotation Deficit on posterior stiffness and isometric shoulder rotators strength ratio in recreational and amateur handball players

OBJECTIVE

To determine whether recreational and amateur handball players exhibit Glenohumeral Internal Rotation Deficit (GIRD), and if it is accompanied by posterior stiffness and changes in shoulder rotators strength.

DESIGN

Cross-Sectional Study; SETTING: Research laboratory.

PARTICIPANTS

Indoor and beach handball players, members of handball teams or engaged in some handball recreational group.

MAIN OUTCOME MEASURES

Range of motion (ROM) of internal rotation (IR) and horizontal adduction (HA), and isometric internal and external rotators strength. Based on the ROM of internal rotation, they were allocated to groups with and without GIRD.

RESULTS

The dominant shoulder of GIRD group obtained a lower ROM of IR compared to the non-dominant shoulder of the same group (p < 0.01) and to the dominant (p = 0.02) and non-dominant (p = 0.01) shoulders of the group without GIRD. Less horizontal adduction was observed in both groups (p = 0.01), as well as greater external rotator strength (p = 0.01) and external/internal rotators strength ratio (p < 0.04) in the dominant shoulder. The rotators strength ratio was greater in GIRD group (p < 0.01).

CONCLUSIONS

The present study showed the dominant shoulder had greater posterior stiffness and external rotator strength, regardless of GIRD. Also the group with GIRD showed higher rotators strength ratio.

Effect of neuromuscular training on functional throwing performance and speed in asymptomatic cricket players

OBJECTIVE

To determine the effect of neuromuscular training on functional throwing performance and speed among asymptomatic cricket players.

DESIGN

Single-subject A-B-A design.

METHOD

Forty-three male asymptomatic sub-elite cricket players were recruited from Karnataka Institute of Cricket, Bangalore, India, with a mean age of 20.4 ± 2.03 years. Throwing accuracy and throwing speed were measured using Functional Throwing Performance Index (FTPI) and radar gun respectively, at zero, 12, 24 and 30 weeks in accordance with the A-B-A single-subject design. The neuromuscular training of the throwing arm was performed for 12 weeks, two days a week of supervised training including rhythmic stabilization drills were performed. A non-supervised training session including shoulder strengthening programme was conducted three days a week.

RESULT

Participants demonstrated significant improvement in throwing accuracy (p < 0.001) and speed (p < 0.001) after 12 weeks of neuromuscular training. Six weeks post-withdrawal of the neuromuscular training on throwing accuracy was not significant (p = 0.117), However, speed was sustained (p = 0.013).

CONCLUSION

Neuromuscular training showed an improved efficiency in throwing performance following 12 weeks of training in sub-elite cricket players. The sustained effect was not observed following 6 weeks of withdrawal of training.

Test-retest reliability of the ASES-p shoulder scale

INTRODUCTION

Shoulder disorders are common musculoskeletal problems. The self-assessed ASES questionnaire (ASES-p) is one of the most widely used tools for evaluating shoulder function. Its 11 items are divided in a function (10 items) and pain (1 item) dimension, assigned between 0 and 50 points each. Their sum is the scale's total score, with higher values indicating better health status. The current work explores the test-retest reliability of the Spanish version of the ASES-p score values.

MATERIALS AND METHODS

The scale was administered twice to a sample of subjects with various shoulder pathologies, via telephone interviews performed at 3-7 days apart. Exact agreement was calculated on an item and score basis. Score variability was assessed with the 95% limits of agreement method (LoA).

RESULTS

N = 161 subjects were initially contacted, and a total of 82 stable health status subjects provided valid test-retest replies. "Do usual sport" was the only item with missing data. Exact agreement oscillated between 67 and 89% per item. The 95% LoA ranged between -5.9 and 6.9 points for function; -13.2 to 11.9 for pain and -10.3 to 10.1 for the total ASES-p score.

CONCLUSIONS

Test-retest reliability in stable patients was considered acceptable for the function and total scores, but not for pain. This may reflect usual pain behaviour, but it also implies that the pain evaluation should be further studied. The ASES-p pain subscore should not be used as the single measure for monitoring shoulder pain. Revisiting the "do usual sports" item may increase the scale's applicability.

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.

Effect of a 6-Week Weighted Baseball Throwing Program on Pitch Velocity, Pitching Arm Biomechanics, Passive Range of Motion, and Injury Rates

BACKGROUND

Emphasis on enhancing baseball pitch velocity has become popular, especially through weighted-ball throwing. However, little is known about the physical effects or safety of these programs. The purpose of this study was to examine the effects of training with weighted baseballs on pitch velocity, passive range of motion (PROM), muscle strength, elbow torque, and injury rates.

HYPOTHESIS

A 6-week weighted ball training program would result in a change in pitching biomechanical and physical characteristics.

STUDY DESIGN

Randomized controlled trial.

LEVEL OF EVIDENCE

Level 1.

METHODS

During the baseball offseason, 38 healthy baseball pitchers were randomized into a control group and an experimental group. Pitch velocity, shoulder and elbow PROM, shoulder strength, elbow varus torque, and shoulder internal rotation velocity were measured in both groups. The experimental group then performed a 6-week weighted ball throwing program 3 times per week using balls ranging from 2 to 32 ounces while the control group only used a 5-ounce regulation baseball. Both groups performed a strength training program. Measurements were then repeated after the 6-week period. Injuries were tracked over the 6-week training program and the subsequent baseball season. The effect of training with a weighted ball program was assessed using 2-way repeated-measures analysis of variance at an a priori significance level of P < 0.05.

RESULTS

Mean age, height, mass, and pretesting throwing velocity were 15.3 ± 1.2 years (range, 13-18 years), 1.73 ± 0.28 m, 68.3 ± 11 kg, and 30.3 ± 0.7 m/s, respectively. Pitch velocity showed a statistically significant increase (3.3%) in the experimental group ( P < 0.001). There was a statistically significant increase of 4.3° of shoulder external rotation in the experimental group. The overall injury rate was 24% in the experimental group. Four participants in the experimental group suffered elbow injuries, 2 during the training program and 2 in the season after training. No pitchers in the control group were injured at any time during the study.

CONCLUSION

Performing a 6-week weighted ball throwing program increased pitch velocity. However, the program resulted in increased shoulder external rotation PROM and increased injury rate.

CLINICAL RELEVANCE

Although weighted-ball training may increase pitch velocity, caution is warranted because of the notable increase in injuries and physical changes observed in this cohort.

Passive accessory joint mobilization in the multimodal management of chronic dysesthesia following thalamic stroke

Study design: Case Report. Purpose: Stroke is the most common cause of long-term disability. Dysesthesia, an unpleasant sensory disturbance, is common following thalamic stroke and evidence-based interventions for this impairment are limited. The purpose of this case report was to describe a decrease in dysesthesia following manual therapy intervention in a patient with history of right lacunar thalamic stroke. Case description: A 66-year-old female presented with tingling and dysesthesia in left hemisensory distribution including left trunk and upper/lower extremities, limiting function. Decreased left shoulder active range of motion, positive sensory symptoms but no sensory loss in light touch was found. She denied pain and moderate shoulder muscular weakness was demonstrated. Laterality testing revealed right/left limb discrimination deficits and neglect-like symptoms were reported. Passive accessory joint motion assessment of glenohumeral and thoracic spine revealed hypomobility and provoked dysesthesia. Interventions included passive oscillatory joint mobilization of glenohumeral joint, thoracic spine, ribs and shoulder strengthening. Results: After six sessions, shoulder function, active range of motion, strength improved and dysesthesia decreased. Global Rating of Change Scale was +5 and QuickDASH score decreased from 45% to 22% disability. Laterality testing was unchanged. Conclusion: Manual therapy may be a beneficial intervention in management of thalamic stroke-related dysesthesia. Implications for Rehabilitation While pain is common following thalamic stroke, patients may present with chronic paresthesia or dysesthesia, often in a hemisensory distribution. Passive movement may promote inhibition of hyperexcitable cortical pathways, which may diminish aberrant sensations. Passive oscillatory manual therapy may be an effective way to treat sensory disturbances such as paresthesias or dysesthesia.

Patient self-report section of the ASES questionnaire: a Spanish validation study using classical test theory and the Rasch model

Background

The aim of the current study was to validate the self-report section of the American Shoulder and Elbow Surgeons questionnaire (ASES-p) into Spanish.

Methods

Shoulder pathology patients were recruited and followed up to 6 months post treatment. The ASES-p, Constant, SF-36 and Barthel scales were filled-in pre and post treatment. Reliability was tested with Cronbach’s alpha, convergent validity with Spearman’s correlations coefficients. Confirmatory factor analysis (CFA) and the Rasch model were implemented for assessing structural validity and unidimensionality of the scale. Models with and without the pain item were considered. Responsiveness to change was explored via standardised effect sizes.

Results

Results were acceptable for both tested models. Cronbach’s alpha was 0.91, total scale correlations with Constant and physical SF-36 dimensions were >0.50. Factor loadings for CFA were >0.40. The Rasch model confirmed unidimensionality of the scale, even though item 10 “do usual sport” was suggested as non-informative. Finally, patients with improved post treatment shoulder function and those receiving surgery had higher standardised effect sizes.

Conclusions

The adapted Spanish ASES-p version is a valid and reliable tool for shoulder evaluation and its unidimensionality is supported by the data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-016-0552-1) contains supplementary material, which is available to authorized users.

The volleyball athlete's shoulder: biomechanical adaptations and injury associations

In volleyball, the dominant shoulder of the athlete undergoes biomechanical and morphological adaptations; however, definitive conclusions about their exact nature, aetiology, purpose and associations with shoulder injury have not been reached. We present a systematic review of the existing literature describing biomechanical adaptations in the dominant shoulders of volleyball players and factors that may predispose to shoulder pain/injury. A thorough literature search via Medline, EMBASE and SCOPUS was conducted for original studies of volleyball players and 15 eligible articles were identified. Assessment of study quality was performed using the STROBE statement. The reviewed literature supports the existence of a glenohumeral internal rotation deficit (GIRD) and a possible (and less pronounced) external rotation gain in the dominant vs. the non-dominant shoulder of volleyball athletes. Unlike other overhead sports, the GIRD in volleyball athletes appears to be anatomical as a response to the repetitive overhead movements and not to be associated with shoulder pain/injury. Additionally, the dominant shoulder exhibits muscular imbalance, which appears to be a significant risk factor for shoulder pain. Strengthening of the external rotators should be used alongside shoulder stretching and joint mobilisations, core strengthening and optimisation of spike technique as part of injury management and prevention programmes.

Biomechanical effects of anterior capsular plication and rotator interval closure in simulated anterior shoulder instability

PURPOSE

The purpose of this study was to determine the effect of a stepwise arthroscopic anterior plication and arthroscopic-equivalent rotator interval (RI) closure on glenohumeral range of motion, kinematics, and translation in the setting of anterior instability.

METHODS

Six cadaveric shoulders were stretched to 10 % beyond maximum external rotation (ER) to create an anterior shoulder instability model. Range of motion, kinematics, and glenohumeral translations were recorded for the following conditions: (1) intact, (2) stretched, (3) after anterior capsular plication, and (4) after RI closure.

RESULTS

The total range of motion after capsular stretching increased significantly in the 60° abduction position (p = 0.037). Average ER and total rotation were significantly decreased from the intact and stretched conditions by both repair conditions at 60° and 0° of glenohumeral abduction (p < 0.05), with no significant difference between plication and additional RI closure. At 0° abduction and 0° ER, glenohumeral translation decreased significantly from the stretched condition after RI closure with 10 and 15 N anterior and 10 N posterior loads (p < 0.05). At 30° ER, translation after RI closure was significantly less than both the intact and stretched conditions with 10 N anterior loads (p = 0.009; p = 0.004). These changes in translational stability were not seen with plication alone.

CONCLUSIONS

Anterior capsular plication reduced glenohumeral range of motion back to the intact state, and often tighter. RI closure did not contribute significantly to the reduction in the range of motion, but had implications regarding glenohumeral translation. Caution should be taken when performing anterior plication and combined repairs to avoid overtightening. Intraoperative translations could be useful when debating RI closure in patients with unidirectional anterior glenohumeral instability.

COMPARISON OF SCAPULAR MUSCLE ACTIVATIONS DURING THREE OVERHEAD THROWING EXERCISES

BACKGROUND

With shoulder pain and injury on the rise in overhead athletes, clinicians are often examining preventative exercises to address functional abnormalities. Because shoulder impingement is prevalent in overhead athletes, much focus is on scapular stability and the function of the stabilizing force couple of the upper and lower trapezius and serratus anterior.

HYPOTHESIS/PURPOSE

The purpose of this study was to examine scapular muscle activation during a series of throws and holds (throwing without releasing) with two different ball weights (7oz and 12oz). It was hypothesized that the holds exercises would elicit greater activation of the scapular musculature than the throw, irrespective of ball weight.

STUDY DESIGN

Case control laboratory study.

METHODS

Twenty-two NCAA Division I, right hand dominant, softball players (19.91 + 1.04 years; 169.24 + 7.36 cm; 72.09 + 10.61 kg) volunteered to participate. Surface EMG was utilized to measure muscle activity in the upper, middle and lower trapezius and serratus anterior muscles during three different throwing activities.

RESULTS

MANOVA results revealed no significant differences in muscle activity between throwing conditions, F(16,82) = 1.02, p = 0.446, Wilks' Λ = 0.696, Cohen's d = 0.44 (7oz holds), 0.24 (12oz holds), power = 0.625.

CONCLUSION/CLINICAL RELEVANCE

The results may provide some clinical insight in advocating the use of holds with different ball weights. The holds throw may be an effective step in shoulder strengthening that can more closely mimic the functional movement of throwing without the element of ball release.

LEVELS OF EVIDENCE

Level 3.

Periodization and physical therapy: Bridging the gap between training and rehabilitation

BACKGROUND

Exercise prescription and training progression for competitive athletes has evolved considerably in recent decades, as strength and conditioning coaches increasingly use periodization models to inform the development and implementation of training programs for their athletes. Similarly, exercise prescription and progression is a fundamental skill for sport physical therapists, and is necessary for balancing the physiological stresses of injury with an athlete's capacity for recovery.

OBJECTIVE

This article will provide the sport physical therapist with an overview of periodization models and their application to rehabilitation.

SUMMARY

In recent decades models for exercise prescription and progression also have evolved in theory and scope, contributing to improved rehabilitation for countless athletes, when compared to care offered to athletes of previous generations. Nonetheless, despite such advances, such models typically fail to fully bridge the gap between such rehabilitation schemes and the corresponding training models that coaches use to help athletes peak for competition. Greater knowledge of periodization models can help sport physical therapists in their evaluation, clinical reasoning skills, exercise progression, and goal setting for the sustained return of athletes to high level competition.

Range of motion and isometric strength of shoulder joints of team handball athletes during the playing season, Part II: changes after midseason

OBJECTIVE

Our objective was to investigate the influence of workload and consecutive changes on active range of motion and isometric strength of team handball athletes' throwing shoulders (TSs) because the available data are insufficient.

METHODS

In a longitudinal investigation, 31 professional male handball athletes underwent a clinical shoulder examination. Athletes were examined at the beginning (week 0), at the end (week 6) of the preseasonal training, and at the end of the half-season (week 22) on both shoulders to determine isometric rotational strength (hand held dynamometer) and active range of motion (goniometer).

RESULTS

This analysis demonstrates the results subsequently from week 6 to week 22 and from week 0 to week 22. The glenohumeral internal rotation (IR) deficit (GIRD), external rotation (ER) gain, and ER at the TS increased significantly (P < .05, η(2) > 0.10, d > 0.30) in the first sequence (week 6 to week 22) but not significantly from week 0 to week 22. The total range of motion remained stable, and IR changed but not significantly. There was no influence on IR, ER, and total range of motion at the non-TS. The isometric strength of the TS and non-TS IR did not change. The isometric strength in ER significantly increased bilaterally during the investigation period.

CONCLUSIONS

Our data verify changes and influences, such as an increasing GIRD, at the overhead TS joint in accordance with the workload during team handball season. ER gain did improve after the half-season period but did not fully compensate the GIRD at the TS.

Strength asymmetry of the shoulders in elite volleyball players

CONTEXT

Volleyball players are reported to have shoulder strength imbalances. Previous authors have primarily investigated small samples of male players at a single skill level, without considering playing position, and with inconsistent findings.

OBJECTIVE

To evaluate shoulder strength asymmetry and a history of shoulder injury in a large sample of professional volleyball players of both sexes across different playing positions and skill levels.

DESIGN

Descriptive laboratory study.

PATIENTS OR OTHER PARTICIPANTS

A sample of 183 volleyball players (99 men, 84 women).

MAIN OUTCOME MEASURE(S)

We assessed shoulder internal-rotator and external-rotator concentric strength at 60°/s using an isokinetic dynamometer and dominant-nondominant differences in shoulder strength and strength ratios using repeated-measures analyses of variance. Peak torque was normalized for body mass and external-rotation/internal-rotation concentric strength.

RESULTS

Internal-rotation strength was asymmetric in favor of the dominant side in both sexes, regardless of previous shoulder injury status. Male volleyball players had a lower shoulder strength ratio on the dominant side, regardless of previous shoulder injury status. However, this finding was valid only when hand dominance was taken into account. Female volleyball players playing at a higher level (ie, first versus second division) were 3.43 times more likely to have an abnormal strength ratio. Playing position was not associated with an abnormal shoulder strength ratio or strength asymmetry.

CONCLUSIONS

In male volleyball players, the external-rotation/internal-rotation strength ratio of the dominant shoulder was lower, regardless of playing position, skill level, or a previous shoulder injury. In female players, the ratio was less only in those at a higher skill level. Although speculative, these findings generally suggest that female volleyball players could have a lower risk of developing shoulder-related problems than male volleyball players. Isokinetic shoulder testing may reveal important information about the possible risk factors for shoulder injuries, so we recommend including it in the functional screening of volleyball players.

Throwing injuries in the adolescent athlete

INTRODUCTION

Adolescents ranging in age from 11-15 (early-mid adolescence) comprise the largest percentage of baseball and softball athletes in the United States. Shoulder and elbow injuries are commonly experienced by these athletes with baseball pitchers and softball position players most likely to be injured.

COMMON INJURIES

Physeal injury often termed "Little League" shoulder or elbow is common and should be differentiated from soft tissue injuries such as biceps, rotator cuff, or UCL injuries. Regardless of diagnosis, rehabilitation of these athletes' shoulder and elbow injuries provide a unique challenge given their rapidly changing physical status.

TREATMENT

Common impairments include alterations in shoulder range of motion, decreased muscle performance, and poor neuromuscular control of the scapula, core, and lower extremity. A criterion based, progressive rehabilitation program is presented. Discharge from formal rehabilitation should occur only when the athlete has demonstrated a resolution of symptoms, acceptable ROM, muscle performance, and neuromuscular control while progressing through a symptom free return to sport.

PREVENTION OF REINJURY

Reintegration into the desired level of sport participation should be guided by the sports medicine professional with a focus on long-term durability in sport performance as well as injury prevention. A prevention program which includes parent, coach, and athlete education, regular screening to identify those athletes at the highest risk, and monitoring athletes for the development of risk factors or warning signs of injury over the course of participation is indicated.

LEVEL OF EVIDENCE

5.

Diagnostic imaging of the throwing athlete's shoulder

The diagnostic capabilities of advanced imaging have increasingly enabled clinicians to delineate between structural alterations and injuries more efficiently than ever before. These impressive gains have unfortunately begun to provide a reliance on imaging at the loss of quality in the clinical examination. Ideally, imaging of the shoulder complex is performed to confirm the provisional diagnosis developed from the history and clinical exam rather than to create such. This clinical commentary will provide the framework for both basic and advanced uses of imaging as well as discussion of evolving modalities.

LEVEL OF EVIDENCE

5.

Microinstability of the shoulder in the overhead athlete

The overhead throwing athlete is an extremely challenging patient in sports medicine. The repetitive microtraumatic stresses and extreme ranges of motion observed within the athlete's shoulder joint complex during the throwing motion constantly place the athlete at risk for injury. While gross instability of the shoulder is possible, microinstability is seen far more frequently and is associated with a variety of different pathologies, including rotator cuff tendonitis, internal impingement, and labral lesions. Treatment of the overhead athlete requires the understanding of several principles based on the unique physical characteristics of this type of athlete and the demands placed upon the static stabilizing structures during the act of throwing. The purpose of this paper is to describe these principles and incorporate them into in a multi-phase progressive rehabilitation program designed to prevent injuries and rehabilitate the injured athlete, both non-operatively and postoperatively.

Analyzing shoulder translation with navigation technology

PURPOSE

Asymmetric stress imposed on the shoulder can lead to anterior shoulder instability in young athletes who perform repetitive overhead motions. A common treatment, surgical anterior capsule tightening, assumes that the instability is caused by abnormal anterior laxity. This study investigated the possibility that one element of overall imbalance, posterior capsular tightness, could be an underlying reason for shoulder instability. Surgical navigation technology, which is more accurate than whole-body motion-capture systems, was used to study anterior translational motions.

METHOD

The study was used four cadaver shoulders, with the scapula and rotator cuff muscles intact. Opto-electronic surgical navigation localization devices were mounted on the scapula and humerus to accurately capture positions and orientations. The shoulders were passively moved through 7 motions, 5 of simple angulation and 2 combinations of clinical interest. Each motion was repeated in 4 different soft-tissue states: rotator cuff intact, capsule intact, and surgically induced capsular tightnesses of 5 and 10mm.

RESULTS

The shoulders had significantly greater anterior translation when the posterior capsule was artificially tightened (p < 0.05); this was particularly in movements that combined abduction with internal or external rotation, which are typical overhead sports motions. Overall translation was indifferent to whether the shoulders were intact or dissected down to the capsule, as was translation during flexion was indifferent to dissection state (p > 0.95).

CONCLUSION

Surgical navigation technology can easily be used to analyze cadaveric shoulder motion, with opportunities for adaptation to anesthetized patients. Results suggest that the inverse of artificial tightening, such as surgical release of the posterior capsule, may be an effective minimally invasive treatment of chronic shoulder dislocation subsequent to sports motions.

Current concepts in the evaluation and treatment of the shoulder in overhead throwing athletes, part 2: injury prevention and treatment

The overhead throwing athlete is an extremely challenging patient in sports medicine. The repetitive microtraumatic stresses imposed on the athlete's shoulder joint complex during the throwing motion constantly place the athlete at risk for injury. Treatment of the overhead athlete requires the understanding of several principles based on the unique physical characteristics of the overhead athlete and the demands endured during the act of throwing. These principles are described and incorporated in a multiphase progressive rehabilitation program designed to prevent injuries and rehabilitate the injured athlete, both nonoperatively and postoperatively.