Shoulder Range of Motion and Baseball Arm Injuries: A Systematic Review and Meta-Analysis

Upper Extremity Musculoskeletal Profiles in Tennis Players: A Systematic Review

CONTEXT

Tennis-specific musculoskeletal (MSK) screening can assess range of motion (ROM) and muscular imbalances. Identifying normative values before implementing a MSK screen is essential in contributing to athlete performance and injury risk profiles.

OBJECTIVE

To review upper extremity MSK data in healthy tennis players across age, sex, and level of play.

DATA SOURCE

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed for this review. A search was conducted in MEDLINE, SPORTDiscus, Embase, and CINAHL.

STUDY SELECTION

This review included shoulder, elbow, and wrist ROM, isometric strength, or isokinetic strength in a tennis population. Each article was critically appraised to help identify the internal and external validity of each study.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

A total of 41 studies met the search criteria. Each contributor organized the data elements of interest into data tables, with a second contributor assigned for review. Data elements of interest included player and study characteristics: ROM, isometric dynamometry, and isokinetic strength.

RESULTS

A total of 3174 players were included in the final studies. Most of the players included were competitive adolescents and young adults; 15 studies included ROM data. Male tennis players consistently had more external rotation (ER) gain (range, 1.8º to 8.8º) and internal rotation (IR) loss (range, -15.3º to -3.0º) when compared with their female counterparts (ER range, -2.5º to 5.8º; IR range, -10.4º to -3º). Shoulder IR and ER strength were measured in the majority of all the strength studies, with the external rotators generating at least two-thirds the strength of the internal rotators.

CONCLUSION

Overall MSK data of tennis players indicate that shoulder strength values are often larger than nontennis players, but equal to or slightly lower than comparable athletes in other overhead sports. Adaptive changes of the glenohumeral joint and subsequent rotational motion are similar to those of other overhead athletes.

Limited Total Arc Glenohumeral Rotation and Shoulder Biomechanics During Baseball Pitching

CONTEXT

Upper extremity injuries in baseball pitchers cause significant time loss from competing and decreased quality of life. Although shoulder range of motion (ROM) is reported as a key factor to prevent potential injury, it remains unclear how limited glenohumeral ROM affects pitching biomechanics which may contribute to upper extremity injuries.

OBJECTIVE

To investigate how pitchers with decreased total arc glenohumeral ROM of the throwing arm differed in upper extremity pitching kinematics and kinetics as well as ball velocity compared with pitchers with greater levels of glenohumeral ROM.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifty-seven baseball pitchers (ages 18-24) were divided into either control (≥160° total arc) or lower ROM (<160° total arc) groups.

MAIN OUTCOME MEASURE(S)

The mean glenohumeral ROM deficits, pitching kinematic and kinetic outcomes, and ball velocity were compared between groups.

RESULTS

The control group demonstrated significantly less deficit in total arc ROM between arms than the lower ROM (control: -1.5° ± 10.0°; lower ROM: -12.4° ± 13.9°; P < .001). While the lower ROM group displayed less maximal shoulder external rotation (ER) while pitching, the control group had significantly less difference in ROM between maximal shoulder ER while pitching and clinically measured ER (lower ROM: 64.4° ± 12.1°; control: 55.8° ± 16.6°; P = .025). The control group had significantly faster ball velocity than the lower ROM group (control: 85.0 ± 4.3 mph; lower ROM: 82.4 ± 4.8 mph; P = .024).

CONCLUSION

Pitchers with decreased total arc glenohumeral ROM (<160° total arc) may undergo overstretching toward ER in the shoulder during the late cocking phase. Pitchers with higher total arc ROM can pitch the same or faster ball without increasing loading in the upper extremity. Total arc glenohumeral ROM measurement can be a clinical screening tool to monitor shoulder condition over the time, and pitchers with limited total arc ROM might be at higher risk of shoulder injury.

Shoulder Injury Incidence and Epidemiology in Youth, High School, and Collegiate Fastpitch Softball Players: A Systematic Review and Future Research Perspectives

CONTEXT

Fastpitch softball is one of the most popular sports in the United States among young female athletes. Softball players regularly subject their shoulders to extreme range of motion and high velocity movements. To date, no systematic review has reported on the epidemiology and incidence of shoulder injuries in softball players.

OBJECTIVE

To describe the incidence and epidemiology of softball-related shoulder injuries in youth, high school, and collegiate female softball players.

DATA SOURCES

PubMed, Web of Science, and Embase were searched for relevant English language articles from 1980 to 2023.

STUDY SELECTION

Studies selected based on predefined inclusion criteria. Studies were required to be available full text, in English.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

A preliminary screening was performed based on study title and abstract. In the subsequent screening, the full text versions of the remaining articles were evaluated by 2 reviewers for the fulfillment of the inclusion criteria.

RESULTS

A total of 7 articles met criteria for inclusion. All studies evaluated injuries among softball players for at least 1 season. In total, there were 1107 softball-related shoulder injuries reported in the 7 studies included in this systematic review. Of the 3 studies that included a shoulder injury rate, a mean rate of 4.01 shoulder injuries per 10,000 athlete-exposures was calculated. The 2 most common shoulder injuries were shoulder muscle-tendon strains (297) and shoulder/biceps tendinitis (220).

CONCLUSION

High-level prospective studies reporting injury incidence and risk factors among female softball players are extremely limited. Only 2 studies eligible for inclusion in this systematic review were prospective in nature, with neither of these reporting the specific injury rate for shoulder injuries among softball players.

Limitations of Separating Athletes into High or Low-Risk Groups based on a Cut-Off. A Clinical Commentary

Background

Athlete injury risk assessment and management is an important, yet challenging task for sport and exercise medicine professionals. A common approach to injury risk screening is to stratify athletes into risk groups based on their performance on a test relative to a cut-off threshold. However, one potential reason for ineffective injury prevention efforts is the over-reliance on identifying these 'at-risk' groups using arbitrary cut-offs for these tests and measures. The purpose of this commentary is to discuss the conceptual and technical issues related to the use of a cut-off in both research and clinical practice.

Clinical Question

How can we better assess and interpret clinical tests or measures to enable a more effective injury risk assessment in athletes?

Key Results

Cut-offs typically lack strong biologic plausibility to support them; and are typically derived in a data-driven manner and thus not generalizable to other samples. When a cut-off is used in analyses, information is lost, leading to potentially misleading results and less accurate injury risk prediction. Dichotomizing a continuous variable using a cut-off should be avoided. Using continuous variables on its original scale is advantageous because information is not discarded, outcome prediction accuracy is not lost, and personalized medicine can be facilitated.

Clinical Application

Researchers and clinicians are encouraged to analyze and interpret the results of tests and measures using continuous variables and avoid relying on singular cut-offs to guide decisions. Injury risk can be predicted more accurately when using continuous variables in their natural form. A more accurate risk prediction will facilitate personalized approaches to injury risk mitigation and may lead to a decline in injury rates.

Level of Evidence

5.

Effects of Stretching or Strengthening Exercise on Spinal and Lumbopelvic Posture: A Systematic Review with Meta-Analysis

BACKGROUND

Abnormal posture (e.g. loss of lordosis) has been associated with the occurrence of musculoskeletal pain. Stretching tight muscles while strengthening the antagonists represents the most common method to treat the assumed muscle imbalance. However, despite its high popularity, there is no quantitative synthesis of the available evidence examining the effectiveness of the stretch-and-strengthen approach.

METHODS

A systematic review with meta-analysis was conducted, searching PubMed, Web of Science and Google Scholar. We included controlled clinical trials investigating the effects of stretching or strengthening on spinal and lumbopelvic posture (e.g., pelvic tilt, lumbar lordosis, thoracic kyphosis, head tilt) in healthy individuals. Effect sizes were pooled using robust variance estimation. To rate the certainty about the evidence, the GRADE approach was applied.

RESULTS

A total of 23 studies with 969 participants were identified. Neither acute (d = 0.01, p = 0.97) nor chronic stretching (d=-0.19, p = 0.16) had an impact on posture. Chronic strengthening was associated with large improvements (d=-0.83, p = 0.01), but no study examined acute effects. Strengthening was superior (d = 0.81, p = 0.004) to stretching. Sub-analyses found strengthening to be effective in the thoracic and cervical spine (d=-1.04, p = 0.005) but not in the lumbar and lumbopelvic region (d=-0.23, p = 0.25). Stretching was ineffective in all locations (p > 0.05).

CONCLUSION

Moderate-certainty evidence does not support the use of stretching as a treatment of muscle imbalance. In contrast, therapists should focus on strengthening programs targeting weakened muscles.

Periscapular Strength Profile Changes in Collegiate Baseball Pitchers Over the Course of a Season

Background

Repetitive application of high forces to the shoulder and scapular musculature during the pitching motion over the course of a collegiate baseball season may lead to changes in strength and increased fatigue, potentially predisposing pitching athletes to injury. The purpose of this study was to investigate periscapular strength profiles of Division I collegiate baseball players over the course of a season.

Methods

This study was a retrospective data analysis of 18 Division I baseball pitchers. Isometric scapular plane abduction (scaption), external rotator, internal rotator, middle trapezius, and lower trapezius isometric strength was measured on throwing arm of each subject using a MicroFET 2 handheld dynamometer. Data were collected in a single session at the preseason, midseason, and postseason of the college baseball season, which spanned a five-month period. A repeated measures ANOVA was utilized to determine if there was a significant change in periscapular strength across the baseball season.

Results

Over the three time-points, all strength values decreased for each muscle group, with decreases ranging from 3-14%. Changes in scaption strength values were statistically significant (p=0.018, partial eta squared =0.284) with an 8% reduction over the entire season, specifically with a 5% decline from mid-season to post-season. While external rotator, internal rotator, middle trapezius, and lower trapezius strength values all decreased over the course of the season (range 0.02kg to 1.8kg), these differences were not statistically significant. However, the middle trapezius strength value change (1.3kg loss) exceeded the minimal detectible change.

Conclusion

Periscapular muscles in baseball pitchers diminish in strength over the course of a collegiate baseball season. Understanding strength changes over the course of a season may influence training and therapeutic interventions.

Level of Evidence

3b.

Return to Play in the Professional Athlete

The management of any injury in elite athletes poses unique challenges distinct from the general population because the goal is rapid recovery and return to play (RTP) while simultaneously managing residual symptoms and minimizing risk of reinjury. The time required for treatment, recovery, and return to peak performance can have consequences for both the athlete and his or her team: financial implications, psychological stressors, team dynamics, and future performance. RTP after an injury in the professional athlete requires a complex decision-making process with many stakeholders. Several factors influence this decision, not the least of which is the type and mechanism of injury. This article provides an overview of the RTP process including nonmedical factors that may influence this decision, common injuries seen in professional athletes, injury patterns particular to certain popular sports, and imaging guidelines for such injuries.

The COVID-19 lockdown as a model of detraining in division 1 college softball players

BACKGROUND

The COVID-19 pandemic interrupted the organized training of softball players, similar to the abrupt cessation of sports participation that can happen after an injury. Thus, the COVID-19 pandemic offers a unique model to study how sudden detraining influences softball players.

METHODS

We recruited a sample of convenience of National Collegiate Athletic Association Division 1 softball players. They participated in three data collections: pre-lockdown (Jan 2020, T1), post-lockdown (Sept 2020, T2), and before the 2021 season (Jan 2021, T3). Between T1 and T2, players received an at-home conditioning and throwing program, but compliance was not strictly monitored. Between T2-T3, players resumed formal fall training (team-organized workouts, on-field practice, and within-team scrimmage games). At each time point, we collected bilaterally: 1) shoulder internal rotation (IR) and external rotation (ER) range of motion (ROM); 2) shoulder IR and ER strength; 3) hip IR and ER ROM; and 4) hip abduction and extension strength. We used four independent (2 Sides × 3 Timepoints) MANOVA with repeated measures; we followed up significant MANOVA main effect of time with Sidak posthoc tests for pairwise comparisons between time points.

RESULTS

Fifteen players participated in this study. We found a significant MANOVA main effect of time for shoulder and hip ROM (p < 0.01). Between T1-T2, dominant shoulder ER ROM decreased 6.5°, dominant shoulder IR ROM increased 4.3°, and lead hip IR ROM increased 4.4°. Between T2-T3, dominant shoulder ER ROM increased 6.3° and trail hip ER ROM increased 5.9°. We found a significant MANOVA main effect of time for shoulder strength (p = 0.03) but not for hip strength (p = 0.18). Between T2-T3, non-dominant shoulder IR and ER increased 1.8 kg and 1.5 kg, respectively.

CONCLUSION

A sudden and prolonged cessation of organized training generated changes in shoulder and hip ROM but affected strength to a lesser extent. The loss of shoulder ER and increased lead hip IR ROM are maladaptive as they are associated with injury in overhead athletes. Resuming team-organized training and scrimmage reversed some (shoulder ER), but not all of these changes. Practitioners should monitor clinical variables regularly and be aware of potential changes due to unexpected and prolonged interruptions in training, such as when players suffer sports-related injuries.

Adaptive pathology: new insights into the physical examination and imaging of the thrower's shoulder and elbow

Throwing with high velocity requires extremes of glenohumeral external rotation of the abducted arm where particularly high forces in the shoulder and elbow are endured. Repeated throwing leads to dominant-arm bony remodeling of the humerus, glenoid, and elbow, and multiple soft tissue changes that would be considered abnormal. Many of these features are thought to be adaptive and protective. The purpose of this work is to (1) define the concept of adaptive pathology; (2) review the mechanics of the throwing motion; (3) review pertinent physical examination and imaging findings seen in asymptomatic throwers' shoulders and elbows and describe how these changes develop and may be adaptive-allowing the thrower to perform at high levels; and then (4) review the principles of surgical treatment in the throwing athletes, which should focus on reducing symptoms, but not necessarily restoring the thrower's anatomy to normal.

Validity and Reliability of POM-Checker for Measuring Shoulder Range of Motion in Healthy Participants: A Pilot Single-Center Comparative Study

BACKGROUND

The aim of this study was to compare shoulder movement measurements between a Kinect-based markerless ROM assessment device (POM-Checker) and a 3D motion capture analysis system (BTS SMART DX-400).

METHODS

This was a single-visit clinical trial designed to evaluate the validity and reliability of the POM-Checker. The primary outcome was to assess the equivalence between two measurement devices within the same set of participants, aiming to evaluate the validity of the POM-Checker compared to the gold standard device (3D Motion Analysis System). As this was a pilot study, six participants were included.

RESULTS

The intraclass correlation coefficient (ICC) and the corresponding 95% confidence intervals (CIs) were used to assess the reproducibility of the measurements. Among the 18 movements analyzed, 16 exhibited ICC values of >0.75, indicating excellent reproducibility.

CONCLUSION

The results showed that the POM-checker is reliable and validated to measure the range of motion of the shoulder joint.

Return to Sport and Clinical Outcomes Following Osteochondral Autograft Transplantation in Baseball Players and Gymnasts With Unstable Osteochondritis Dissecans: A Critically Appraised Topic

CLINICAL SCENARIO

Osteochondritis dissecans (OCD) of the capitellum is a condition occurring at the elbow and often seen in both baseball players and gymnasts due to the repetitive loading of the radiocapitellar joint. Treatment options for OCD vary and are dependent on lesion presentation, elbow motion, and growth plate maturity. OCD lesions categorized as unstable can be treated with an osteochondral autograft transplantation surgery (OATS).

FOCUSED CLINICAL QUESTION

In an adolescent population, what are the return to sport rates and clinical outcomes following OATS in baseball players and gymnasts with unstable OCD lesions?

SUMMARY OF KEY FINDINGS

Three articles met the inclusion criteria for this appraisal, and all indicate an OATS procedure should be considered in the management of unstable OCD lesions. Return to play outcomes were favorable for both baseball players and gymnasts. Self-reported patient function and elbow extension all improved following an OATS.

CLINICAL BOTTOM LINE

An OATS procedure is a favorable option for the management of OCD lesions of the elbow in baseball players and gymnasts.

STRENGTH OF RECOMMENDATION

There is level B evidence to support return to sport and clinical outcomes in baseball players and gymnasts following an OATS procedure. This score is directly related to the quality of evidence that currently exists on the topic.

A Field-expedient Arm Care Screening Tool Can Identify Musculoskeletal Risk Factors in Baseball Players

BACKGROUND

Preseason movement screening can identify modifiable risk factors, deterioration of function, and potential for injury in baseball players. Limited resources and time prevent high school baseball coaches from performing movement screens on their players.

HYPOTHESIS

The arm care screen (ACS) will be highly sensitive to detecting musculoskeletal risk factors.

STUDY DESIGN

Cross-sectional.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 150 baseball players were independently scored on the ACS electronically by reviewing a video recording of each player's screening performance. Discriminability of the ACS was determined with a 2 × 2 contingency table dichotomizing musculoskeletal risk factors as present or absent based on a predetermined cutoff value and those who passed or failed the corresponding ACS subtest.

RESULTS

High sensitivity was observed on the reciprocal shoulder mobility (0.89; 95% CI 0.81-0.94), 90/90 total body rotation (0.86; 95% CI 0.79-0.92), and lower body diagonal reach (0.85; 95% CI 0.78-0.91) tests of the ACS suggesting sufficient ability to identify musculoskeletal impairments and risk factors.

CONCLUSION

The ACS is a simplistic screening tool that the coach can administer to discriminate between youth, high school, and college-level baseball players who possess musculoskeletal risk factors. The ACS subtests demonstrated high sensitivity for correctly identifying musculoskeletal risk factors common in baseball players and can be useful as a screening tool for baseball coaches developing arm care exercise programs.

CLINICAL RELEVANCE

A field-expedient screen could provide coaches the ability to identify musculoskeletal risk factors that need to be addressed to minimize injury risk factors in a time-efficient manner.

Organizational risk profiling and education associated with reduction in professional pitching arm injuries: a natural experiment

Background

Risk profiling and education are strategies implemented to help reduce injury risk; however, currently. there is little evidence on the effect of these interventions on injury incidence. The purpose of this study was to evaluate the influence of risk profiling and education on upper extremity injury incidence in minor league (MiLB) pitchers and to stratify by injury severity.

Methods

A prospective natural experiment study was conducted from 2013 to 2019 on MiLB pitchers. Beginning in the 2015 season, pitchers were examined and risk profiled for upper extremity injury. Shoulder external, internal, total range of motion, horizontal adduction, and humeral torsion were measured. Organizational risk profiling and education was implemented starting in 2015, based on preseason assessments. Chi-squared test was performed to investigate potential differences between shoulder range of motion risk categories between 2013-2014 (pre) and 2015-2019 (post) seasons. Interrupted time series analyses were performed to assess the association between organizational risk profiling and education on arm injury in MiLB pitchers and were repeated for 7-27 and 28+ day injury severity.

Results

297 pitchers were included (pre: 119, post: 178). Upper extremity injury incidence was 1.5 injuries per 1000 athletic exposures. Pitchers in the 2015-2019 seasons demonstrated increased preseason shoulder injury risk for internal (P = .003) and external (P = .007), while the 2013-2014 seasons demonstrated greater horizontal adduction risk (P = .04). There were no differences between seasons for total range of motion risk (P =.76). Risk profiling and education resulted in an adjusted time loss upper extremity injury reduction for the 2015-2019 seasons (0.68 (95% CI: 0.47, 0.99)), which impacted 7-27 days (0.62 (95% CI: 0.42, 0.93)) but not for 28+ days (0.71 (95% CI: 0.47, 1.06)) time loss. There was no reduction in combined trunk and lower extremity injuries for the 2015-2019 seasons (1.55 (95% CI: 0.79, 3.01)).

Conclusions

Organizational risk profiling and education appear to reduce professional pitching overall and 7-27-day upper extremity injury risk by 33%-38%. There was no difference in trunk and lower extremity injuries over the period, strengthening the reduction in upper extremity injury risk results. This suggests that while injury risk increased over time, organizational risk profiling mitigated the expected increase in upper extremity injury rates. Risk profiling and education can be used as a clinical screening and intervention tool to help decrease upper extremity injuries in professional baseball populations.

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

CONTEXT

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

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Shoulder Range of Motion Measurements and Baseball Elbow Injuries: Ambiguity in Scientific Models, Approach, and Execution is Hurting Overhead Athlete Health

Elbow injuries are a significant and increasing issue in baseball. Elbow injuries account for 16% of all injuries sustained at the professional level and collegiate level. Because of the continued rise in injury rates, loss of performance value, and medical burden, sports medicine clinicians have attempted to research the causes underlying this injury epidemic in an attempt to help mitigate baseball elbow injuries. Shoulder range of motion (ROM) is the most researched clinical metric related to elbow injuries in baseball and has the greatest consensus as a viable prognostic factor specifically for medial elbow injury. Shoulder ROM is easy to measure, can be modified through stretching and manual therapy interventions, and can be easily assessed during preseason screening throughout all baseball levels. Despite a large number of studies and the widespread use of shoulder ROM in injury risk screening, current findings are unclear as to whether there is a true cause-effect relation with baseball elbow injuries. We argue that the conflicting findings revolving around the value of shoulder ROM measurements associated with baseball elbow injuries are the result of 4 gaps in the research approaches implemented to date: ambiguous research questions, mixed study populations, statistical models used, and shoulder ROM methodology. Specifically, there is a mismatch of methods, statistical models, and conclusions such as (1) investigating the association (i.e., correlation) between shoulder ROM measurements and injury and (2) investigating the cause-effect relation of shoulder ROM to baseball injuries. The purpose of this article is to detail the required scientific steps to evaluate whether preseason shoulder ROM is a potential causal factor for pitching elbow injury. We also provide recommendations to allow for future causal inferences to be made between shoulder ROM and elbow injury. This information will ultimately assist in informing clinical models of care and decision making for baseball throwers.

Assessing the validity of inertial measurement units for shoulder kinematics using a commercial sensor-software system: A validation study

Background and  Aims

Wearable inertial sensors may offer additional kinematic parameters of the shoulder compared to traditional instruments such as goniometers when elaborate and time-consuming data processing procedures are undertaken. However, in clinical practice simple-real time motion analysis is required to improve clinical reasoning. Therefore, the aim was to assess the criterion validity between a portable "off-the-shelf" sensor-software system (IMU) and optical motion (Mocap) for measuring kinematic parameters during active shoulder movements.

Methods

24 healthy participants (9 female, 15 male, age 29 ± 4 years, height 177 ± 11 cm, weight 73 ± 14 kg) were included. Range of motion (ROM), total range of motion (TROM), peak and mean angular velocity of both systems were assessed during simple (abduction/adduction, horizontal flexion/horizontal extension, vertical flexion/extension, and external/internal rotation) and complex shoulder movements. Criterion validity was determined using intraclass-correlation coefficients (ICC), root mean square error (RMSE) and Bland and Altmann analysis (bias; upper and lower limits of agreement).

Results

ROM and TROM analysis revealed inconsistent validity during simple (ICC: 0.040-0.733, RMSE: 9.7°-20.3°, bias: 1.2°-50.7°) and insufficient agreement during complex shoulder movements (ICC: 0.104-0.453, RMSE: 10.1°-23.3°, bias: 1.0°-55.9°). Peak angular velocity (ICC: 0.202-0.865, RMSE: 14.6°/s-26.7°/s, bias: 10.2°/s-29.9°/s) and mean angular velocity (ICC: 0.019-0.786, RMSE:6.1°/s-34.2°/s, bias: 1.6°/s-27.8°/s) were inconsistent.

Conclusions

The "off-the-shelf" sensor-software system showed overall insufficient agreement with the gold standard. Further development of commercial IMU-software-solutions may increase measurement accuracy and permit their integration into everyday clinical practice.

Clinical Measures of Adolescent Softball Players With and Without Upper-Extremity Pain: A Preliminary Study

CONTEXT

Upper-extremity (UE) pain is a concern among softball adolescent athletes. However, research on preseason screening of demographic characteristics and clinical measures among those with and without UE pain among adolescent softball athletes is underreported. This study sought to present functional outcomes and clinical measures of shoulder and hip complex flexibility, range of motion (ROM), and strength in adolescent softball athletes with and without UE pain.

DESIGN

Cross-sectional study.

METHODS

Sixty-seven athletes were assessed at the start of the spring season. The Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire was administered to determine UE function. UE measurements included shoulder ROM, flexibility, and strength; lower-extremity measurements included hip ROM and strength. These variables were reported for players with and without UE pain as mean and SD. Independent samples t tests were performed to analyze differences between the groups.

RESULTS

Thirteen (19.4%) athletes reported UE pain during preseason screening. Mean Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire score among athletes with UE pain was 58.0 (17.6) compared with 97.1 (6.9) for athletes reporting no UE pain (P < .001). Athletes with UE pain presented with significantly less dominant side external rotation ROM (UE pain: 106.5 [10.4], no UE pain: 114.6 [11.3]) and total ROM (UE pain: 163.7 [14.5], no UE Pain: 174.8 [14.3]).

CONCLUSION

These findings inform clinicians on function and preseason clinical measures in adolescent softball athletes who present with or without UE pain. Athletes with UE pain demonstrated lower outcome scores indicating likely impact on overall UE function. These athletes also appeared to demonstrate UE ROM differences compared with athletes without UE pain. Further research is needed to investigate larger sample sizes and positional differences at baseline and throughout the season to determine if clinical measures used in the current study are risk factors for pain and injury.

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

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

Effectiveness of a Shoulder Exercise Program in Division I Collegiate Baseball Players During the Fall Season

BACKGROUND

Deficits in shoulder range of motion (ROM) and strength are associated with risk of arm injury in baseball players.

PURPOSE

The purpose of this study was to assess the effectiveness of a standardized exercise program, during the fall season, on shoulder ROM and rotational strength in collegiate baseball players.

STUDY DESIGN

Prospective cohort study.

METHODS

Passive shoulder internal rotation (IR), external rotation (ER), and horizontal adduction ROM were measured with an inclinometer. Shoulder IR and ER strength was assessed using a hand-held dynamometer and normalized to body weight. Players performed a program of shoulder stretching and strengthening exercises, three times/week for one month and then one time/week for two months. Paired sample t-tests compared pre-intervention to post-intervention outcome measures.

RESULTS

Division I baseball players (n=43; 19.6±1.2years, 185.8±5.5cm, 90.5±7.0kg) volunteered. From pre- to post-intervention, there were increases in horizontal adduction ROM in the throwing (Mean Difference (MD)=6.1°, 95%CI=3.7,8.5; p<0.001) and non-throwing arm (MD=8.0°, 95%CI=5.6,10.3; p<0.001), and a decrease in non-throwing arm ER ROM (MD=2.8°, 95%CI= 0.2,5.5; p=0.039). The ER ROM surplus (throwing - non-throwing) increased (MD=5.6°, 95%CI= 1.1,10.2; p=0.016). Throwing arm (MD=1.3%BW, 95%CI=0.5-2.1, p=0.003) and non-throwing arm (MD=1.2%BW, 95%CI=0.4,2.0; p=0.004) ER strength decreased. A notable, but non-significant increase in IR strength on the throwing arm (MD=1.6%BW, 95%CI=0.1,3.0; p=0.055) and decrease on the non-throwing arm (MD=1.2%BW, 95%CI=0.0,2.4; p=0.055) occurred. Additionally, throwing arm ER:IR strength ratio (MD=0.16, 95%CI=0.08,0.25; p<0.001) also decreased.

CONCLUSION

Changes in shoulder horizontal adduction ROM, IR strength and relative ER surplus on the throwing arm were noted at the end of the season. The lack of change in IR and ER ROM and may be related to the lack of deficits at the start of the fall season.

LEVEL OF EVIDENCE

2.

Risk Factors of Shoulder and Elbow Injuries in Baseball: A Scoping Review of 3 Types of Evidence

Background

Shoulder and elbow overuse injuries are the most common problems in baseball players. No scoping review has compared the findings from different types of evidence.

Purpose

To map the broad evidence from 3 types of evidence (epidemiological, biomechanical, and narrative) on potential risk factors for shoulder and elbow injuries in baseball and identify gaps in the existing literature to guide future research.

Study Design

Scoping review.

Methods

Eight electronic databases were searched from inception to May 14, 2020. Any peer-reviewed papers that investigated or discussed potential risk factors for shoulder and elbow injuries in baseball were included.

Results

A total of 302 studies (107 epidemiological studies, 85 biomechanical studies, and 110 narrative reviews) were included. Risk factors were categorized into 9 domains: sports profiles, physical characteristics/functions, pitching mechanics, performance, behavioral, psychosocial, biological and developmental, injury/sports profiles, and environmental factors. Studies were consistent in supporting limited shoulder range of motion (ROM) and player positions (pitchers or catchers) as risk factors for shoulder injuries. For elbow injuries, the majority of the included studies suggested that being pitchers or catchers and working with higher ball velocity can be risk factors.

Conclusion

Findings were consistent in some risk factors, such as limited shoulder ROM and positions. However, findings were inconsistent or limited for most factors, and substantial research gaps were identified. Research assessing those factors with inconsistent or limited evidence in the current literature were recognized to be priorities for future studies.

Biomechanical Analysis of the Throwing Athlete and Its Impact on Return to Sport

Throwing sports remain a popular pastime and frequent source of musculoskeletal injuries, particularly those involving the shoulder and elbow. Biomechanical analyses of throwing athletes have identified pathomechanic factors that predispose throwers to injury or poor performance. These factors, or key performance indicators, are an ongoing topic of research, with the goals of improved injury prediction, prevention, and rehabilitation. Important key performance indicators in the literature to date include shoulder and elbow torque, shoulder rotation, kinetic chain function (as measured by trunk rotation timing and hip-shoulder separation), and lower-extremity mechanics (including stride characteristics). The current gold standard for biomechanical analysis of the throwing athlete involves marker-based 3-dimensional) video motion capture. Emerging technologies such as marker-less motion capture, wearable technology, and machine learning have the potential to further refine our understanding. This review will discuss the biomechanics of throwing, with particular attention to baseball pitching, while also delineating methods of modern throwing analysis, implications for clinical orthopaedic practice, and future areas of research interest.

Level of Evidence

V, expert opinion.

2022 Bern Consensus Statement on Shoulder Injury Prevention, Rehabilitation, and Return to Sport for Athletes at All Participation Levels

There is an absence of high-quality evidence to support rehabilitation and return-to-sport decisions following shoulder injuries in athletes. The Athlete Shoulder Consensus Group was convened to lead a consensus process that aimed to produce best-practice guidance for clinicians, athletes, and coaches for managing shoulder injuries in sport. We developed the consensus via a 2-round Delphi process (involving more than 40 content and methods experts) and an in-person meeting. This consensus statement provides guidance with respect to load and risk management, supporting athlete shoulder rehabilitation, and decision making during the return-to-sport process. This statement is designed to offer clinicians the flexibility to apply principle-based approaches to managing the return-to-sport process within a variety of sporting backgrounds. The principles and consensus of experts working across multiple sports may provide a template for developing additional sport-specific guidance in the future. J Orthop Sports Phys Ther 2022;52(1):11-28. doi:10.2519/jospt.2022.10952.

The Intra- and Inter-rater Reliability of an Arm Care Screening Tool in High School Baseball Coaches

BACKGROUND

Preseason movement screening can identify modifiable risk factors, deterioration of function, and potential for injury in baseball players. Limited resources and time intensive testing procedures prevent high school coaches from accurately performing frequent movement screens on their players.

PURPOSE

To establish the intra-rater and inter-rater reliability of a novel arm care screening tool based on the concepts of the Functional Movement Screen (FMS™) and Selective Functional Movement Assessment (SFMA™) in high school coaches.

STUDY DESIGN

Methodological intra- and inter-rater reliability study.

METHODS

Thirty-one male high school baseball players (15.9 years ± 1.06) were independently scored on the Arm Care Screen (ACS) by three examiners (two coaches, one physical therapist) in real-time and again seven days later by reviewing video recordings of each players' initial screening performance. Results from each examiner were compared within and between raters using Cohen's kappa and percent absolute agreement.

RESULTS

Substantial to excellent intra-rater and inter-rater reliability were established among all raters for each component of the ACS. The mean Cohen's kappa coefficient for intra-rater reliability was 0.76 (95% confidence interval, 0.54-0.95) and percent absolute agreement ranged from 0.82-0.94 among all raters. Inter-rater reliability demonstrated a mean Cohen's kappa value of 0.89 (95% confidence interval, 0.77-0.99) while percent absolute agreement between raters ranged from 0.81-1.00. Intra- and inter-rater reliability did not differ between raters with various movement screening experience (p>0.05).

CONCLUSIONS

High school baseball coaches with limited experience screening movement can reliably score all three components of the ACS in less than three minutes with minimal training.

LEVEL OF EVIDENCE

Level 3, Reliability study.

Shoulder External Rotational Properties During Physical Examination Are Associated With Injury That Requires Surgery and Shoulder Joint Loading During Baseball Pitching

BACKGROUND

Throwing arm injuries are common because of the demand on the shoulder. The shoulder is qualitatively checked regularly by team physicians. Excessive instability and joint loading in baseball pitching are risk factors for throwing arm injuries. Knowledge of shoulder flexibility, range of motion, and joint loading may provide new insights for treatments to reduce the likelihood of injury incidence.

PURPOSE

To investigate the relationship among injuries, shoulder external rotational properties, and shoulder joint loading in baseball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Pitching kinetics, shoulder rotational tests, and self-reported injury questionnaires were used to study 177 collegiate baseball pitchers. Pitching motion data were collected at 240 Hz using a motion capture system. A custom program calculated the shoulder joint loading. The shoulder rotational test quantitatively records shoulder range of motion and flexibility using a custom-made wireless device. Self-reported injury questionnaires were filled out during tests and yearly follow-ups. The total length of the study was 5 years. Analysis of variance, chi-square, and regression tests were performed to compare differences among groups and detect correlations with surgery and shoulder joint loadings.

RESULTS

There were significant differences in shoulder flexibility among surgery groups. Shoulder external rotational properties during physical examination were significantly associated with shoulder joint loading in baseball pitching. High shoulder external rotation was associated with 14% to 36% lower shoulder posterior force and adduction, internal rotation, and horizontal adduction torque (P < .05). High shoulder flexibility was associated with 13% higher anterior force (P < .05). High shoulder external rotation before external rotation torque was applied was associated with 13% to 33% lower shoulder inferior force and adduction, internal rotation, and horizontal adduction torque (P < .05). There were no significant differences in shoulder joint loading among the surgery groups.

CONCLUSION

Shoulder injuries that require surgery were associated with shoulder external rotation flexibility. High shoulder external rotation may be advantageous because it lowers the force and torque on the shoulder joint.

CLINICAL RELEVANCE

The ability to understand shoulder external rotational properties, joint loading, and injury during baseball pitching helps further our understanding of injury mechanisms. The shoulder rotational test should be used as a screening tool to identify players at risk.

Professional Baseball Player Type and Geographic Region of Origin Impacts Shoulder External and Internal Rotation Strength

BACKGROUND

Shoulder strength deficits are implicated in arm injuries and performance deficits in baseball players.

PURPOSE

To characterize shoulder external (ER) and internal (IR) rotation strength in professional baseball players, and compare strength across player type (pitchers, position players) and geographic origin (North America, Latin America).

STUDY DESIGN

Cross-sectional.

METHODS

Minor league professional baseball players from North America and Latin America (n=242; age=22.4±2.3 years; n=135 pitchers and n=107 position players; n=162 North American and n=80 Latin American players) volunteered at spring training. Bilateral shoulder IR and ER isometric strength was measured in sitting with the arm at the side using a handheld dynamometer stabilized on a wall via a specialized jig. Strength was normalized to body weight, and compared using t-tests between player type and geographic area of origin (p < 0.05).

RESULTS

Position players had greater strength in ER, IR and ER:IR (ER:0.7-2.7N/kg; IR:1.3-3.8N/kg; ER:IR ratio 0.36-1.22) compared to pitchers (ER:0.5-2.5N/kg; IR:0.6- 4.2N/kg; ER:IR ratio 0.44-1.16) on the throwing arm. North American pitchers had lower ER [MD= -0.4 (95%CI:-0.7,-0.2);p=0.002] and IR [MD= -0.2 (95%CI:-0.4,-0.1);p=0.006] than Latin American pitchers on the throwing arm. There were no differences between geographic groups for position players.

DISCUSSION/CONCLUSIONS

Player position and geographic origin influence shoulder rotational strength values in professional baseball players. Position players have 14 - 20% higher ER and IR isometric strength than pitchers. Moreover, Latin American pitchers exhibited 11.8% greater ER strength and 16.7% greater IR strength as compared to North American pitchers. Normative values can be used to determine player deficits, declines in performance, and targets for return to play after injury.

LEVEL OF EVIDENCE

Level II.

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

BACKGROUND

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

HYPOTHESIS

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

STUDY DESIGN

Cross-sectional.

LEVEL OF EVIDENCE

Level 3.

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

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

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

The effects of restricted glenohumeral horizontal adduction motion on shoulder and elbow forces in collegiate baseball pitchers

BACKGROUND

Decreased glenohumeral (GH) horizontal adduction range of motion (ROM) among baseball pitchers has been associated with the development of various shoulder and elbow pathologies. No research has examined how this tightness may affect the forces placed on the shoulder and elbow during the pitching motion.

METHODS

Fifty-five asymptomatic National Collegiate Athletic Association Division I baseball pitchers participated. Twenty-five participants had -10° or less horizontal adduction ROM in their throwing shoulder. The remaining 30 participants had greater than -10° of horizontal adduction. A digital inclinometer was used to measure GH horizontal adduction, internal rotation, and external rotation ROM while in 90° of shoulder abduction. Forces produced in the throwing shoulder and elbow were assessed with a 3-dimension, high-speed video capture system and based on the sum of angular momenta of the kinetic chain segments around the center of gravity. Separate 2-tailed t tests were run to determine significant differences between groups (P < .05).

RESULTS

Both groups presented with significant bilateral differences in their total arcs of motion (P < .04). This suggests that the loss of horizontal adduction in these groups was at least partially due to soft tissue tightness. There were no significant between-group differences for shoulder external rotation torque or shoulder and elbow distraction (P > .10). The restricted ROM group had significantly more shoulder abduction torque (P = .04), shoulder horizontal abduction torque (P = .004), elbow flexion torque (P = .002), and elbow valgus torque (P = .02) compared with the control group.

CONCLUSIONS

These results demonstrate that collegiate pitchers with -10° or less of horizontal adduction ROM in their throwing shoulder create significantly more shoulder abduction and horizontal abduction torque, as well as more elbow flexion and valgus torque, during the pitching motion than those with more ROM.

Current Concepts in Arm Care Exercise Programs and Injury Risk Reduction in Adolescent Baseball Players: A Clinical Review

CONTEXT

Awareness of important injury risk factors associated with excessive pitching volume has been highlighted in the literature, but injury rates remain high. Shoulder pain in baseball players is associated with various changes in musculoskeletal movements, which presents as measurable impairments throughout the kinetic chain. Baseball coaches and rehabilitation professionals have utilized exercise programs targeting strength and flexibility of the throwing arm to prevent injuries. The purpose of this review is to summarize the current evidence regarding the effectiveness of arm care exercise programs in reducing upper extremity injury rates in adolescent baseball players.

EVIDENCE ACQUISITION

A search of electronic databases, including CINAHL with full text, MEDLINE, and SPORTDiscus was conducted to retrieve available articles in English from the years 2010 through 2020. The search terms injury prevention, exercise, and adolescent baseball were used.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Improving shoulder internal rotation range of motion by stretching the posterior shoulder muscles daily was associated with a 36% risk reduction of shoulder and elbow injuries. Group-based arm care exercise programs that target multiple musculoskeletal impairments demonstrated an approximately 50% reduced risk of elbow injury.

CONCLUSION

For adolescent baseball players, arm care injury prevention programs focusing on important musculoskeletal impairments are effective at reducing injury incidence rates. Multimodal injury prevention programs that improve multiple musculoskeletal impairments are more comprehensive and may result in better injury reduction than programs focusing on a singular impairment.

Preseason Upper Extremity Range of Motion and Strength in Relation to In-Season Injuries in NCAA Division I Gymnasts

Background

Gymnastics is a demanding sport that places unique forces on the upper extremity. The repetitive nature of the sport and the high-impact forces involved may predispose the gymnast to overuse injuries. Risk factors for injuries in gymnastics are not well understood.

Purpose/Hypothesis

The purpose of this study was to ascertain whether preseason upper extremity range of motion (ROM) and strength differ between National Collegiate Athletic Association (NCAA) Division I collegiate gymnasts who sustain an in-season upper extremity injury and those who do not. We hypothesized that gymnasts who sustain an upper extremity injury would demonstrate reduced ROM and strength compared with noninjured gymnasts.

Study Design

Cohort study; Level of evidence, 3.

Methods

Over 4 seasons, from 2014 to 2018, a total of 15 female NCAA Division I collegiate gymnasts underwent preseason upper extremity ROM (shoulder: flexion, internal and external rotation; elbow: extension; wrist: extension) and strength (shoulder: internal and external rotation, and middle and lower trapezius) testing. Overuse upper extremity injuries were tracked in each subsequent season. Gymnasts were dichotomized into injured and noninjured groups, and a 2 × 2 analysis of variance was used to measure differences in preseason measures between the groups as well as within arms (injured vs noninjured arm for the injured group; dominant vs nondominant arm for the noninjured group).

Results

A total of 12 overuse upper extremity injuries (10 shoulders; 2 wrist/forearm) occurred during 31 gymnast-seasons. There were no significant interactions for preseason ROM and strength measurements between groups (injured vs noninjured) or within arms (injured and noninjured arm for the injured group; dominant and nondominant arm for the noninjured group; P = .07).

Conclusion

Preseason upper extremity ROM and strength were not different between gymnasts who sustained an in-season upper extremity overuse injury and those who did not. It is possible that ROM and strength measures used to screen other overhead athletes may not capture the unique features and requirements of gymnastics. Further, it may be challenging to discern differences in clinical measures of ROM and strength in gymnastics populations owing to the bilateral nature of the sport.

Influence of a Pre-throwing Protocol on Range of Motion and Strength in Baseball Athletes

Though chronic overhand throwing is known to result in range of motion and strength adaptations, there is limited research regarding interventions for maintenance of these characteristics. Therefore, the purposes of this study were to explore the use of a pre-throwing protocol focusing on lumbopelvic-hip complex musculature in high school baseball players and examine its effects on shoulder and hip range of motion and isometric strength over the course of a season. Four exercises were added to the intervention team's warm-up routine. The control and intervention teams' passive bilateral hip and shoulder range of motion and isometric strength were assessed pre/post-season. A multivariate analysis of variance revealed significant differences in delta scores between the teams for multiple shoulder and hip range of motion and isometric strength variables. Key results were the intervention team lost significantly more stride hip external rotation but gained more isometric strength than the control team. The intervention team was also able to better maintain shoulder range of motion than the control team. Practitioners should use the results of this study and consider incorporating exercises that target lumbopelvic-hip complex musculature into their current training program.

The Relationship Between Humeral Torsion and Arm Injury in Baseball Players: A Systematic Review and Meta-analysis

CONTEXT

Humeral torsion (HT) has been linked to various injuries and benefits. However, the exact interplay between HT, shoulder range of motion (ROM), competition level differences, and injury risk is unclear.

OBJECTIVE

To determine the relationship between HT, ROM, and injury risk in baseball players. Secondarily, to determine HT based on competition level.

DATA SOURCES

PubMed, Embase, Web of Science, CINAHL, and Cochrane databases were searched from inception until November 4, 2018.

STUDY SELECTION

Inclusion criteria consisted of (1) HT measurements and (2) arm injury or shoulder ROM.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

Two reviewers recorded patient demographics, competition level, HT, shoulder ROM, and injury data.

RESULTS

A total of 32 studies were included. There was no difference between baseball players with shoulder and elbow injuries and noninjured players (side-to-side HT difference: mean difference [MD], 1.75 [95% CI, -1.83 to 2.18]; dominant arm: MD, 0.17 [95% CI, -1.83 to 2.18]). Meta-regression determined that for every 1° increase in shoulder internal rotation (IR), there was a subsequent increase of 0.65° in HT (95% CI, 0.28 to 1.02). HT did not explain external rotation (ER ROM: 0.19 [95% CI, -0.24 to 0.61]) or horizontal adduction (HA ROM: 0.18 [95% CI, -0.46 to 0.82]). There were no differences between HT at the high school, college, or professional levels.

CONCLUSION

No relationship was found between HT and injury risk. However, HT explained 65% of IR ROM but did not explain ER ROM or HA ROM. There were no differences in HT pertaining to competition level. The majority of IR may be nonmodifiable. Treatment to restore and maintain clinical IR may be important, especially in players with naturally greater torsion. HT adaptation may occur prior to high school, which can assist in decisions regarding adolescent baseball participation.

Preseason shoulder range of motion screening and in-season risk of shoulder and elbow injuries in overhead athletes: systematic review and meta-analysis

Objective

To characterise whether preseason screening of shoulder range of motion (ROM) is associated with the risk of shoulder and elbow injuries in overhead athletes.

Design

Systematic review and meta-analysis.

Data sources

Six electronic databases up to 22 September 2018.

Eligibility criteria

Inclusion criteria were (1) overhead athletes from Olympic or college sports, (2) preseason measures of shoulder ROM, (3) tracked in-season injuries at the shoulder and elbow, and (4) prospective cohort design. Exclusion criteria were (1) included contact injuries, (2) lower extremity, spine and hand injuries, and (3) full report not published in English.

Results

Fifteen studies were identified, and they included 3314 overhead athletes (baseball (74.6%), softball (3.1%), handball (16.1%), tennis (2.0%), volleyball (2.0%) and swimming (2.2%)). Female athletes are unrepresented (12% of the overall sample). Study quality ranged from 11 to 18 points on a modified Downs and Black checklist (maximum score 21, better quality). In one study, swimmers with low (<93°) or high (>100°) shoulder external rotation were at higher risk of injuries. Using data pooled from three studies of professional baseball pitchers, we showed in the meta-analysis that shoulder external rotation insufficiency (throwing arm <5° greater than the non-throwing arm) was associated with injury (odds ratio=1.90, 95% confidence interval 1.24 to 2.92, p<0.01).

Conclusion

Preseason screening of shoulder external rotation ROM may identify professional baseball pitchers and swimmers at risk of injury. Shoulder ROM screening may not be effective to identify handball, softball, volleyball and tennis players at risk of injuries. The results of this systematic review and meta-analysis should be interpreted with caution due to the limited number of studies and their high degree of heterogeneity.

PROSPERO registration number

CRD42017072895.