Correlation of shoulder and elbow injuries with muscle tightness, core stability, and balance by longitudinal measurements in junior high school baseball players

Relationship of Forearm-Hand Inertia With Throwing Motion Patterns and Elbow Valgus Load in Adolescent Baseball Players

Background

Growth-specific physical characteristics in adolescence may mediate throwing-related loads and movement patterns associated with elbow injuries. In a previous study, the authors calculated the forearm-hand inertia, which is the moment of inertia centered at the elbow joint.

Purpose

To determine the relationship of forearm-hand inertia values with throwing motion patterns and elbow valgus load in adolescent baseball players.

Study Design

Descriptive laboratory study.

Methods

A total of 35 adolescent baseball players underwent measurements by dual-energy x-ray absorptiometry (DXA) scans and a throwing trial. Forearm-hand inertia was determined as the joint moment around the elbow using the subregion analysis mode of DXA. Elbow valgus torque and ball speed during throwing were measured using a dedicated sensor and speed gun, and throwing efficiency was calculated by dividing the elbow valgus load by the ball speed. Players were divided according to the throwing motion pattern in which maximum acceleration occurred: pelvis-upper arm-forearm (proximal-to-distal sequencing [PDS] group; n = 19) or pelvis-forearm-upper arm (proximal upper extremity [PUE] group; n = 16). The groups were compared in terms of ball speed, elbow valgus torque, throwing efficiency, and forearm-hand inertia using t tests and analysis of covariance, with forearm-hand inertia as covariates. The chi-square test was used to examine the relationship between throwing motion patterns and forearm-hand inertia.

Results

The PUE group had a higher elbow valgus load (effect size [ES] = 0.65; P = .03), throwing efficiency (ES = 0.63; P = .02), and forearm-hand inertia values (ES = 0.64; P = .04) than the PDS group. In addition, a significant relationship was observed with throwing patterns when forearm-hand inertia values were 350 kg·m2 (OR, 2.36; 95% CI, 1.09-5.12; P = .012) and 400 kg·m2 (OR, 1.68; 95% CI, 0.99-2.85; P = .037).

Conclusion

Study results indicated that growth-specific physical characteristics in adolescent baseball players exhibited in forearm-hand inertia mediated the relationship between high elbow valgus and poor throwing efficiency caused by poor throwing motion patterns.

Clinical Relevance

A better understanding of the details in muscle function with throwing mechanics may prevent future injuries.

Effects of 60 versus 30 Minutes of Pilates Exercise on Cervicothoracic Alignment, Muscle Strength, and Endurance in University Students with Upper Crossed Syndrome

Background/Objectives: This study determined the effects of 60 min or 30 min Pilates program on cervicothoracic alignment, muscular strength, and endurance in university students with upper-crossed syndrome (UCS). Methods: Twenty-six university students with UCS were randomly allocated into 60 min Pilates (60 PG, n = 9), 30 min Pilates (30 PG, n = 9), and control (CG, n = 8) groups. The 60 and 30 PG students participated in the Pilates program, focusing on relaxation, stability, mobility, and strengthening of the cervical, thoracic, and scapular muscles for 60 or 30 min per session, twice a week, for 12 weeks. Cervicothoracic alignment was measured using BodyStyle to determine craniovertebral angle (CVA), forward shoulder angle (FSA), head position angle (HPA), head tilt angle (HTA), and kyphosis angle (KA). We measured the muscular strength and endurance of the shoulder on the dominant side. Results: After the intervention, CVA, HPA, HTA, and KA significantly improved in the 60 and 30 PG (all p < 0.01) but not in the CG (p > 0.05). There were no significant differences between the 60 and 30 PG at 4, 8, and 12 weeks. Shoulder strength differed between shoulder flexion and horizontal abduction (p < 0.01). Shoulder endurance differed between extension, flexion, and horizontal abduction (p < 0.05, p < 0.01, and p < 0.001, respectively). Conclusions: This study confirmed the effectiveness of the Pilates program in improving cervicothoracic sagittal alignment and shoulder muscular function in university students with UCS. Additionally, the effects of participating in 60 and 30 min Pilates programs were found to be equivalent. Therefore, encouraging busy university students to participate in at least 30 min of the Pilates program is important.

Association between core strength and dynamic balance of throwing hand in professional healthy cricket fast bowlers: A cross sectional study

BACKGROUND

The core musculature gets activated by feed forward fashion during the movement of upper extremity, as in kinetic chain of throwing, shoulder muscle contributes larger dynamic balance and also in reversed manner. Aim of the current study was to associate the strength of core and the dynamic balance of throwing hand in cricket fast bowlers.

METHODS

72 subjects were initially screened for eligibility, and ultimately, 55 male participants from various cricket coaching academies, aged 19.1 ± 2.6 on average, were included. The mean BMI of the participants was 20.9. The assessments included the Modified Upper Quarter Y Balance Test (mUQYBT)- Medial (M), Supero-Lateral reach (SL), Infero-Lateral reach(IL) along with Core measures- 600 Abdominal flexion test (600 AFT), right side plank test (RSP), Left side plank test (LSP), Beiring Sorenson test (BST), all of which were successfully completed.

RESULTS

Based on our findings, we observed a mild positive correlation between the values of mUQYBT and core measures. We employed Pearson's coefficient to evaluate the association, and the R2 values were utilized to quantify the amount of variability. The resulting scores were RSP to SL (r = 0.38, R2 = 0.14), LSP to SL (r = 0.43, R2 = 0.19), LSP to RSP (r = 0.790, R2 = 0.62), BSP to Composite score (r = 0.29, R2 = 0.08), SL to 600 AFT* (r = 0.231, R2 = 0.05) and BMI to IL* (r = -0.107, R2 = 0.01).

CONCLUSION

In conclusion, a positive correlation was exhibited between dynamic balance and core strength in healthy cricket fast bowlers. Educating bowlers on proper movement techniques and prescribing targeted exercises can enhance dynamic balance, reducing the risk of injuries.

Impact of low back pain experience on future occurrence of shoulder pain in adolescent baseball players: A 1-year prospective cohort study

BACKGROUND

Low back pain can affect musculoskeletal problems of the upper limb in adolescent overhead athletes. However, few epidemiological studies have examined this causal relationship. This prospective cohort study aimed to investigate the relationship between baseline low back pain experience and the occurrence of future shoulder and elbow pain among high school baseball players.

METHODS

Participants comprised 383 high school baseball players from 43 high school baseball teams who had undergone baseline medical evaluations (a self-completed questionnaire and physical examination). The occurrence of shoulder and elbow pain during a 1-year follow-up and associations with baseline low back pain (positive subjective symptom during the last year at baseline) adjusted for flexibility of the scapulo-thoracic region, shoulder, and lower extremities, such as straight-leg raise angle (hamstring tightness), Thomas test (iliopsoas tightness), heel-buttock-distance (quadriceps tightness) and passive range of motion of the hip were investigated using multivariable analysis.

RESULTS

A total of 307 players (80.2%) participated in the 1-year follow-up survey, with shoulder and elbow pain reported in 75 players (24.4%) and 119 players (38.8%), respectively, during follow-up. After adjusting for factors associated with shoulder pain using logistic regression modeling, significant associations between LBP experienced during the last year at baseline (odds ratio, 2.18; 95% confidence interval, 1.23-3.87; P = 0.0078) and new-onset of shoulder pain were noted.

CONCLUSIONS

Baseline low back pain impacted future shoulder pain in high school baseball players during the 1-year follow-up. Management of shoulder pain warrants careful attention to low back pain.

Fastpitch Softball Injuries: Epidemiology, Biomechanics, and Injury Prevention

PURPOSE OF REVIEW

Fastpitch softball is one of the most popular sports among youth and high school female athletes. Despite some similarities to baseball, key differences between the two sports result in different injury patterns, and there is comparatively less literature describing injury epidemiology in fastpitch softball. The purpose of this review is to describe the epidemiology, biomechanics, and injury prevention efforts in regards to fastpitch softball injury with a particular focus on underhand pitching.

RECENT FINDINGS

The injury rate in softball is relatively low and extended time loss injuries in particular are uncommon. Lower extremity injuries are more common overall in softball, but pitchers more often suffer upper extremity injury. Pitchers account for a relatively small proportion of all injuries recorded, but represent a similarly small subset of team rosters, with most teams carrying only a few pitchers in total. The underhand pitching motion exerts significant glenohumeral distractive forces and high stress across the biceps-labrum complex. Core and lower extremity strengthening play an important role in injury prevention for softball pitchers and position players. Fatigue and number of games pitched are tied to increased strength deficiencies and pain in fastpitch softball pitchers, yet pitch count limits are not employed in any major fastpitch softball leagues. While overall injury incidence is low in fastpitch softball players, the potential for overuse injury in pitchers in particular is noteworthy and not nearly as scrutinized as within the baseball community. Critical longitudinal tracking of softball injuries at varying levels of play would be helpful to better understand the sport's injury risk. There are currently no formal pitch count limits enforced in a majority of fastpitch softball leagues. Core and lower extremity strengthening, pre-season conditioning, and monitoring of pitchers for signs of fatigue may be helpful in injury prevention.

Evaluation of Hip Characteristics in Baseball and Softball Athletes with and Without Throwing Arm Pain

During throwing, the lower extremity assists in the generation and transfer of momentum. Lower extremity stability assists in this transfer by providing a base for distal mobility of the arm segments. This study aimed to determine differences between hip rotational range of motion and strength based on the presence of throwing-arm pain (yes/no) and throwing sport (baseball/softball). We hypothesized those experiencing pain would display decreases in hip range of motion and strength, and that softball players would display greater range of motion than baseball, but less strength based on sex-specific characteristics. Forty-four baseball (13±2 years, 165.2±13.0 cm, 58.5±13.4 kg) and 50 softball players (13±2 years, 160.9±11.2 cm, 62.7±17.9 kg) participated. Multivariate analysis of variance tests (2×2) determined differences in bilateral hip range of motion, total arc of motion, and strength between pain status and sport. There were no significant interactions (>0.05) for pain status and sport on hip range of motion, total arc of motion, and strength. Furthermore, no significant main effects (>0.05) were found for pain status or sport alone on range of motion or strength. Future work should be directed at explaining the effects of hip characteristics on the throwing motion and how it equates to throwing-arm health.

Shoulder and Neck Pain in Swimmers: Front Crawl Stroke Analysis, Correlation with the Symptomatology in 61 Masters Athletes and Short Literature Review

Background: Swimming and, specifically, front crawl, can be included among the "overhead" sports. Overhead sports are a risk factor for some problems of the musculoskeletal system, especially the shoulder. The aim of this study was to assess the incidence of shoulder and neck pain in a Masters Swimming Team and its correlation with the crawl stroke. Methods: This is an observational study through video-analysis of the stroke and a questionnaire. The participants selected for the present study were 61 athletes of a Masters team, whose prevailing training stroke was the front crawl. Their stroke was analyzed during training using a go-pro camera mounted on a sliding trolley on a track, evaluating their technical defects with their trainer. A questionnaire about frequency of shoulder and neck pain during the last five years was administered to all the participants at the study. Results: From the questionnaire, 45 and 55 out of 61 athletes had suffered from shoulder pain and cervical pain, respectively. Both types of pain were correlated with the weekly swimming volume. The swimmers with hyperflexion of the wrist and prolonged internal rotation in the pulling phase had shoulder problems. Those who suffered from current shoulder pain reduced the underwater time. The four swimmers with an excessive body roll during breathing and those who kept their heads extended, reported cervical pain. Conclusions: Shoulder and neck pain could be prevented with the correction of specific technical errors in crawl stroke.

Characteristics of upper limb mass, muscle CSA and stiffness in adolescent baseball players with and without elbow injury

Since elbow injuries are common in adolescent baseball players, this study aimed to determine the relationship between musculoskeletal status and elbow injuries in 47 baseball players aged 12-14 years. Participants answered a questionnaire and had their general body measurements taken. Magnetic resonance imaging was used to evaluate muscle cross sectional areas (CSA) of the upper arm flexor and extensor muscles, and x-ray absorptiometry was used to determine the mass of the upper arm and the total mass of the forearm and hand. Shear wave elastography was used to determine muscle stiffness of the biceps brachii, brachialis, pronator teres, and brachioradialis. An orthopedic surgeon performed a clinical assessment and elbow ultrasonography for each participant to diagnose elbow injuries. The measured values were compared between the elbow injury and control groups using two-sample t-tests. The elbow injury group had significantly higher muscle stiffness in the brachialis (p < 0.001) and brachioradialis (p = 0.004) muscles and greater elbow flexor CSA of the distal upper arm (p = 0.004) than the control group. The total mass of the forearm and hand and the mass ratio of the forearm and hand to the upper arm were significantly greater in the elbow injury group than in the control group (p = 0.002 and p < 0.001). Thus, it may be necessary to increase flexibility of the brachialis and brachioradialis flexible by stretching and massaging in addition to evaluating the mass distal to the elbow and the elbow flexor muscle size of the distal upper arm to manage elbow injury in youth baseball players. Characteristics of Upper Limb Mass, Muscle Cross-Sectional Area and Stiffness in Adolescent Baseball Players with and without Elbow Injury.

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.

Age-Related Differences in the Limited Range of Motion of the Lower Extremity and Their Relation to Low Back Pain in Young Baseball Players: A Cross-Sectional Study of 1215 Players

BACKGROUND

Age-related differences in the limited range of motion of the lower extremities and their relationship with low back pain in juvenile athletes have not been well assessed. This study investigated the relationship between low back pain and limited range of motion of the hip and knee in young baseball players during the baseball season.

RESULTS

Participants comprised 1215 baseball players (216 pitchers, 999 fielders) aged 6-16 years who underwent medical checkups (self-completed questionnaire and physical examination). Of the 1215 players, 255 (21.0%) experienced seasonal low back pain requiring rest during the previous year. The prevalence of low back pain and a positive Thomas test, straight-leg-raising test, and heel-to-buttock test increased with age. Univariate analysis revealed that a positive heel-to-buttock test in both the throwing and non-throwing arm sides in the 11-12 age group and a positive Thomas test in the throwing arm side in the 13-14 age group were associated with seasonal low back pain (P = 0.0051, P = 0.021, and P = 0.048, respectively). Multivariate analysis, adjusted for factors associated with low back pain, showed significant associations between the positive heel-to-buttock test (odds ratio 1.75, 95% confidence interval 1.11-2.79; P = 0.016) and low back pain in players aged 11-14 years.

CONCLUSIONS

A positive heel-to-buttock test is potentially associated with low back pain among juvenile baseball players. Particular attention should be paid to the limited range of motion of the knee joint and tightness of the quadriceps femoris muscle among baseball players with low back pain aged 11-14 years.

Association of trunk and lower limb factors with shoulder complaints and sport performance in overhead athletes: A systematic review including GRADE recommendations and meta-analysis

OBJECTIVE

To identify the association of trunk and lower limb factors with shoulder complaints and sport performance in overhead athletes.

METHODS

Search performed at PubMed/Medline, Embase, CINAHL, LILACS, Cochrane, Web of Science and SPORTDiscus for observational studies. Methodological quality and strength of the evidence was assessed with the Newcastle-Ottawa Scale and GRADE. Meta-analysis and effects sizes analysis were calculated when possible.

RESULTS

Sixty-five studies were included. Low to very-low evidence suggests no association of trunk/lower limb strength, endurance, power, jump or balance with shoulder complaints and/or throwing performance. Athletes with shoulder complaints performed worse in trunk stability and endurance tests (mean difference: -6.83 (95%CI: -8.78, -4.88)). Athletes with high throwing performance presented better results in CMJ, horizontal jump, power measures and knee extension strength. For swimmers, there was no association of trunk/lower limb endurance with shoulder complaints (moderate evidence) and no association of balance and swimming performance (low evidence). Better trunk/lower limb strength, power and vertical jumps measures were associated with better swimming performance.

CONCLUSIONS

In methodologically similar studies, some trunk/lower limb outcomes are associated with shoulder complaint or sport/swimming performance. Results should be considered with caution and future studies should use better methodologies.

Evaluating Pelvis Rotation Style at Foot Contact: A Propensity Scored Biomechanical Analysis in High School and Professional Pitchers

BACKGROUND

Early pelvis rotation has been associated with decreased throwing arm kinetics and conventionally was considered a component of proper pitching form in baseball throwers. However, previous assessments of pelvis rotation style have not accounted for confounders such as playing level, anthropometric characteristics, or ball velocity and have not evaluated sufficient sample sizes.

PURPOSE

To compare kinetic and kinematic parameters based on pelvis rotation style in high school and professional pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

High school and professional baseball pitchers threw 8 to 12 fastball pitches while being evaluated using 3-dimensional motion capture (480 Hz). These pitchers were 1:1 propensity score matched by age, height, weight, handedness, and ball velocity based on early (<60°) versus late (≥60°) pelvis rotation style at foot contact. A total of 26 kinematic and 10 kinetic parameters were compared between groups. The kinematic parameters were used to conduct a linear regression between early and late pelvis rotation at foot contact.

RESULTS

Pelvis rotation at foot contact was not significantly associated with ball velocity for either high school (P = .243) or professional pitchers (P = .075). No difference was found in elbow varus torque between high school early rotators (57.5 ± 14.9 N·m) and late rotators (51.3 ± 14.7 N·m; P = .036) and between professional early rotators (80.1 ± 11.8 N·m) and late rotators (79.0 ± 11.2 N·m; P = .663). At foot contact in high school pitchers, stride length increased by 2.1% of body height (B = -0.205; β = -0.470; P < .001), trunk rotation increased by 4.2° (B = -0.417; β = -0.488; P < .001), and trunk flexion at foot contact decreased by 4.4° (B = 0.442; β = 0.476; P < .001) with every 10° increase in pelvis rotation. At foot contact in professional pitchers, stride length increased by 2.3% of body height (B = -0.229; β = -0.478; P < .001), trunk rotation increased by 4.3° (B = -0.431; β = -0.515; P < .001), and trunk flexion decreased by 4.0° (B = 0.404; β = 0.373; P < .001) with every 10° increase in pelvis rotation.

CONCLUSION

Pelvis rotation at foot contact was associated with several kinematic parameters in both groups and may influence mechanics further along the kinetic chain. Landing open or closed was not significantly associated with throwing arm kinetics or ball velocity for both high school and professional baseball pitchers, contrary to previous thought.

CLINICAL RELEVANCE

Coaches and players may better focus their efforts on refining other kinematic parameters for enhanced performance outcomes and safe pitching mechanics.

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.

Relationship between Standing Trunk Extension Angle and Medial Elbow Injuries in Young Baseball Pitchers

Purpose: The purpose of this study was to investigate the relationship between the standing trunk extension angle and medial elbow injuries. Subjects and methods: The study participants were 90 male baseball pitchers (10−12 years) belonging to youth baseball teams. Pitching elbow injuries were evaluated by an orthopedic surgeon using ultrasound scans and physical examination findings. A single optical three-dimensional motion analysis system was used for the trunk extension measurements, with three-dimensional coordinates captured. The overall, upper, and lower trunk angles were then analyzed. Results: Trunk extension angle during standing trunk extension was significantly smaller among participants who were positive for medial elbow injuries on ultrasound scans (positive: 71.4° ± 10.3°; negative: 75.7° ± 9.2°; t = 2.05, p < 0.05). The upper trunk extension angle was significantly smaller than the lower trunk extension angle among participants who were positive for medial elbow injuries on physical examination (upper: 33.0° ± 6.9°; lower: 41.2° ± 8.2°; t = −2.42, p < 0.05). Conclusions: Trunk extension angle during standing trunk extension is associated with medial elbow injuries. Evaluating the trunk extension angle as multiple segments rather than a single rigid body is valuable.

Hip Abductor Strength Asymmetry: Relationship to Upper Extremity Injury in Professional Baseball Players

BACKGROUND

Hip strength is an important factor for control of the lumbo-pelvic-hip complex. Deficits in hip strength may affect throwing performance and contribute to upper extremity injuries.

HYPOTHESIS

Deficits in hip abduction isometric strength would be greater in those who sustained an upper extremity injury and hip strength would predict injury incidence.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Minor League baseball players (n = 188, age = 21.5 ± 2.2 years; n = 98 pitchers; n = 90 position players) volunteered. Hip abduction isometric strength was assessed bilaterally with a handheld dynamometer in side-lying position, expressed as torque using leg length (N·m). Hip abduction strength asymmetry was represented by [(trail leg/lead leg) × 100]. Overuse or nontraumatic throwing arm injuries were prospectively tracked. Poisson regression models were used to estimate relative risk ratios associated with hip asymmetry; confounders, including history of prior overuse injury in the past year, were included.

RESULTS

Hip abduction asymmetry ranged from 0.05% to 57.5%. During the first 2 months of the season, 18 players (n = 12 pitchers) sustained an upper extremity injury. In pitchers, for every 5% increase in hip abduction asymmetry, there was a 1.24 increased risk of sustaining a shoulder or elbow injury. No relationship between hip abduction strength and injury was observed for position players.

CONCLUSION

Hip abduction asymmetry in pitchers was related to subsequent upper extremity injuries. The observed risk ratio indicates that hip abduction asymmetry may contribute a significant but small increased risk of injury.

CLINICAL RELEVANCE

Hip abduction muscle deficits may affect pitching mechanics and increase arm stress. Addressing hip asymmetry deficits that exceed 5% may be beneficial in reducing upper extremity injury rates in pitchers.

Comparison of Core Muscle Asymmetry Using Spine Balance 3D in Patients with Arthroscopic Shoulder Surgery: A STROBE-Compliant Cross-Sectional Study

Background and Objectives: Joint immobilization after shoulder surgery can cause an imbalance in the periscapular muscles and affect the kinetic chain throughout the body. There is a difference in core muscle stability because of the asymmetry of the lower extremity muscles. However, the difference due to the asymmetry of the upper-extremity muscles has not been studied extensively. The purpose of this study is to investigate the effect of joint immobilization on the symmetry of the core muscles involved in proximal stability for distal mobility. Materials and Methods: Fifty-five patients who underwent arthroscopic shoulder surgery participated in this study. Core muscle asymmetry (CMA) was measured using a body tilt device. The evaluation variables were analyzed according to the surgical site based on the direction of the core muscle ratio and core muscle state ratio. Results: No differences in CMA were found based on the surgical site (p > 0.05). As a result of the additional subanalysis, significant differences in sex and postoperative day were established (p < 0.05). CMA was low during the intensive postoperative rehabilitation period. However, sex-related differences were greater in males than in females. Conclusions: The clinical results suggest that core muscle training is necessary to reduce CMA during rehabilitation after the immobilization period has elapsed.

The Reliability and Validity of a Clinical Measurement Proposed to Quantify Humeral Torsion

BACKGROUND

Range of motion (ROM) impairments of the overhead athletes' shoulder are commonly addressed through mobility-based treatments, however, adaptations from humeral torsion (HT) are not amenable to such interventions. A clinical measurement to quantify HT has been proposed, however, the validity is not conclusive.

PURPOSE

The primary aim of this study is to determine the intrarater reliability and standard error of measurement (SEM) of the biceps forearm angle (BFA) measurement. The secondary aim of this study is to investigate the convergent validity of the BFA compared to diagnostic ultrasound.

STUDY DESIGN

Cross Sectional Reliability and Validity Study.

METHODS

HT measurements, utilizing diagnostic ultrasound, were compared to BFA in 74 shoulders (37 subjects) over two sessions. Each measurement was performed three times and a third investigator recorded measures to ensure blinding. Reliability was investigated using utilizing an intraclass correlation coefficient (ICC 3,k).

RESULTS

Intrarater reliability values were 0.923 and 0.849 for diagnostic ultrasound and BFA methods respectively. Convergent validity was r = 0.566. The standard error of measurement for diagnostic ultrasound and BFA was 3° and 5°, respectively. The 95% limits of agreement between the two measurement methods were -24.80° and 19.80° with a mean difference of -2.50° indicating that on average the diagnostic ultrasound measurement was lower than that of the BFA method.

CONCLUSION

The BFA is a reliable clinical method for quantifying HT, however, demonstrates moderate to poor convergent validity when compared to diagnostic ultrasound.

LEVEL OF EVIDENCE

2b.

Effects of posture and lower limb muscle strength on the results of the Star Excursion Balance Test

[Purpose] This study aimed to clarify the relationship between the distance measurements in the Star Excursion Balance Test and participants’ posture and lower limb muscle strength. [Participants and Methods] Nine healthy male college students participated in this study. Star Excursion Balance Test distance was measured in both lower limbs by performing anterior, posterolateral, and posteromedial trials; measuring the maximum reach; and performing three-dimensional motion analysis to determine the posture at maximum reach. Isokinetic muscle strength for knee flexion/extension, hip flexion/extension, and hip adduction/abduction were measured using an isokinetic machine. [Results] The hip extension strength, reach side ankle dorsiflexion angles, stance side knee flexion, reach side knee flexion, and knee flexion strength were selected as significant explanatory variables in the anterior direction. For the posteromedial direction, hip adduction and hip extension strength, reach side hip flexion angle, and stance side hip flexion angle were selected. For the posterolateral direction, reach side knee flexion angle and stance side ankle dorsiflexion, knee flexion strength and reach side hip flexion angle were selected. [Conclusion] The related factors differed between the dominant and non-dominant legs even in the same reach direction.

The FIFA 11+ Shoulder Injury Prevention Program Was Effective in Reducing Upper Extremity Injuries Among Soccer Goalkeepers: A Randomized Controlled Trial

BACKGROUND

Soccer is one of the most popular sports worldwide. Goalkeepers are more likely to injure their upper limbs, particularly their shoulders, than outfield players. To reduce upper extremity injuries, the FIFA 11+ Shoulder Injury Prevention Program (FIFA 11+S) was developed.

PURPOSE

The purpose of this study was to assess the effectiveness of the FIFA 11+S program in reducing the incidence of upper extremity injuries among amateur soccer goalkeepers.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 726 goalkeepers, who were blinded to study intent, were randomly assigned to the experimental group (n = 360) or control group (n = 366). The experimental group was instructed to perform the FIFA 11+S program before all training sessions for 1 season (6 months). The control group was instructed to continue performing their usual routine warm-up program before training sessions for 1 season. Primary outcomes included the incidence of upper extremity injury and incidence of mechanism, type, and severity of injury measured using injury risk ratios (IRR); compliance with the experimental and control interventions was also recorded.

RESULTS

A total of 50 injuries (0.62 injuries per 1000 exposure-hours) were reported in the experimental group, and 122 injuries (1.94 injuries/1000 hours) were reported in the control group. The FIFA 11+S program reduced the total number of upper extremity injuries by 68% (IRR = 0.32 [95% CI, 0.27-0.34]) compared with the usual warm-up. The FIFA 11+S program reduced the incidence of contact injury (IRR = 0.30 [95% CI, 0.25-0.31]), noncontact injury (IRR = 0.40 [95% CI, 0.35-0.43]), initial injury (IRR = 0.34 [95% CI, 0.29-0.36]), recurrent injury (IRR = 0.20 [95% CI, 0.17-0.21]), and overuse injury (IRR = 0.40 [95% CI, 0.35-0.43]). Participants in the experimental group demonstrated a significant decrease in injuries of minor (IRR = 0.32 [95% CI, 0.27-0.34]) and moderate severity (IRR = 0.33 [95% CI, 0.29-0.35]) compared with the control group. We noted no difference in compliance between the experimental and control groups (80% vs 73%, respectively; P = .92).

CONCLUSION

The FIFA 11+S program resulted in 50% fewer upper extremity injuries among soccer goalkeepers, compared with a regular warm-up.

REGISTRATION

ACTRN12618001080213 (Australian New Zealand Clinical Trials Registry).

Relationships between balance and physical fitness variables in firefighter recruits

BACKGROUND

Research has suggested that balance ability contributes to musculoskeletal injury (MSKI) rates in firefighters. Though the Y-Balance Test (YBT) can predict injury, it is unclear what physical measures inform YBT performance in firefighters. Thus, there is a lack of knowledge regarding best practice for improving balance in firefighters.

OBJECTIVE

To evaluate the relationship between the YBT and fitness measures, including body composition, aerobic capacity, functional total-body power, upper and lower-body strength, and movement efficiency, among firefighters.

METHODS

Dynamic balance (YBT), body mass index (BMI), body-fat percentage (BF%), fat free mass (FFM), aerobic capacity (VO2max), stair climb (SC), upper (1RMbench) and lower-body (1RMsquat) strength, and Fusionetics™ Movement Efficiency Screen (ME) measures were collected among 35 firefighter recruits. Pearson correlation coefficients were used to examine relationships between YBT and the performance measures.

RESULTS

Dynamic balance ability in firefighter recruits is significantly (p < 0.05) related to BMI, lower-body strength, and movement quality, but not with aerobic capacity, stair climb performance, and upper body strength.

CONCLUSIONS

Greater YBT performance in firefighter recruits is associated with lower BMI, greater functional movement, and greater lower-body strength. Future research is warranted to incorporate these elements into balance training programs for firefighter recruits.

The Relationship Between Dynamic Balance Ability and Shoulder Pain in High School Baseball Pitchers

BACKGROUND

Dynamic balance is essential for pitching motion because pitching kinematics requires whole body coordination. The Star Excursion Balance Test (SEBT) and the Y balance test (YBT) evaluate dynamic balance quantitatively. There are some reports that investigated the relationship between SEBT/YBT and pain in upper and lower extremities, but there is no study among high school baseball pitchers.

HYPOTHESIS

Dynamic balance deficiency is associated with shoulder pain among high school baseball pitchers.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 259 male high school pitchers who participated in the preseason medical checkups were included in the study. YBT was used to measure their dynamic balance. The participants completed a questionnaire which asked if they were currently experiencing shoulder pain.

RESULTS

Twenty-two pitchers had shoulder pain during the preseason medical checkups. In the YBT, the posterolateral balance while standing with the axis leg as well as the posteromedial and posterolateral balance while standing with the step leg were significantly lower in the pain group than in the nonpain group (P = 0.05, 0.04, and 0.001, respectively). A logistic regression analysis showed that posterolateral balance when standing with the step leg was an independent risk factor for current shoulder pain (P = 0.04, odds ratio 0.942, 95% CI 0.892-0.996).

CONCLUSION

The dynamic balance of high school baseball pitchers with shoulder pain was lower than that of participants without shoulder pain. In particular, posterolateral direction with the step leg standing was significantly related to shoulder pain.

CLINICAL RELEVANCE

Among high school baseball pitchers, decreased dynamic balance was related to current shoulder pain. YBT maybe recommended in preseason medical checkups for high school baseball pitchers.

Validation of the Muscle Tightness Measurement Tool

BACKGROUND AND PURPOSE

For nurses, muscle tightness is an important aspect of patient care, but no bedside tool is available that allows them to measure it. Therefore, a standardized tool that measures muscle tightness is needed. The purpose of this study was to validate a tool to measure muscle tightness.

METHODS

Using Delphi technique and quantitative design, the tool was validated in two phases. The phase 1 included 20 expert clinicians who established content validity with Lawshe's rating. In phase 2, divergent validity was established by administering the tool to one group that had muscle tightness (n = 26) and one group that did not (n = 20).

RESULTS

Findings indicate that the muscle tightness measurement tool has content and divergent validity.

CONCLUSIONS

Further tool refinement with validity and reliability studies are recommended for clinical practice.

Epidemiology and pain in elementary school-aged players: a survey of Japanese badminton players participating in the national tournament

Pain is common in athletes which should be well managed. To identify risk factors for shoulder pain, and the association between shoulder pain, lower back pain and knee pain among elementary school-aged badminton players, we conducted a cross-sectional study to collect data of the past year among 611 elementary school age (7-12 years old) badminton players belonging to the Japan Schoolchildren Badminton Federation using a questionnaire. Odds ratio (OR) and 95% confidence interval (CI) were estimated by multivariate logistic regression analysis. The overall incidence rate of shoulder injuries, lower back injuries and knee injuries was 0.38 injuries per 1000 h of badminton training. Players with training time per day > 2.5 h were 2.64 times (95% CI 1.03-6.78, p = 0.043) more likely to sustain shoulder pain than those with training time per day ≤ 2.5 h. A significant association was revealed between shoulder pain and knee pain as well as between lower back pain and knee pain as training hours per day > 2.5 h. Moreover, lower back pain was significantly associated with shoulder pain independent of training hours per day (≤ 2.5 h: p = 0.001; > 2.5 h: p < 0.001). These findings indicate that training time per day is risk factor, and shoulder pain, lower back pain and knee pain were associated with each other in elementary school-aged badminton players.

Ankle dorsiflexion deficit in the back leg is a risk factor for shoulder and elbow injuries in young baseball players

The relationship between ankle joint function and throwing-related injuries has not been demonstrated. We hypothesized that limited ankle joint range of motion (ROM) was related to risk factors for shoulder and elbow injuries in young baseball players. This 12-month prospective cohort study evaluated the age, height, weight, playing position, shoulder, elbow, and ankle function of 228 enrolled baseball players. Shoulder and elbow injuries were tracked during the season. Univariate and multivariate analyses were performed to identify risk factors for shoulder and elbow injuries among participants divided into non-injured and injured groups. Univariate analysis showed that age, height, weight, ROM of elbow flexion in the dominant arm, muscle strength ratio of shoulder abduction, and the likelihood of being a pitcher or a catcher were significantly greater in the injured group than in the non-injured group. ROM of shoulder abduction-external/internal rotation, shoulder total arc on the dominant arm, ankle joint dorsiflexion, and plantar flexion on the back (non-lead) and front (lead) legs were significantly less in the injured group than in the non-injured group. In conclusion, ROM dorsiflexion deficits in the back leg, shoulder abduction-external rotation in the dominant arm, ROM increase in elbow flexion on the dominant side, older age, and being a pitcher were significant independent risk factors for injury.

Relationship Between Upper Limb Injuries and Hip Range of Motion in Elementary and Junior High School Baseball Players

Background:

Shoulder and elbow injuries are major problems in baseball players. Tightness of the upper extremities has been reported as a risk factor for shoulder and elbow injuries in elementary and junior high school baseball players. However, few studies have been conducted on the relationship between decreased hip range of motion (ROM) and shoulder and elbow injuries.

Purpose/Hypothesis:

This study aimed to prospectively examine the relationship between hip ROM and throwing-related shoulder and elbow injuries in elementary and junior high school baseball players. The hypothesis was that players with unrestricted ROM in the hip would have a reduced risk of upper extremity injuries.

Methods:

The study included 263 baseball players (mean ± SD age, 10.5 ± 1.3 years; range, 7-14 years). The following physical parameters were assessed: (1) hip flexion ROM measured in the supine position and (2) hip internal and external rotation in the prone position. After the season, players completed questionnaires regarding shoulder and/or elbow injuries. For comparison, the players were classified as injured (not able to play for ≥8 days because of shoulder and/or elbow problems) or noninjured.

Results:

During the season, 52 players had shoulder and/or elbow injuries. When the injured and noninjured groups were compared, hip flexion on the dominant side (121.5° ± 12.0° vs 126.7° ± 9.8°, respectively; P < .01), hip flexion on the nondominant side (119.6° ± 11.7° vs 126.0° ± 9.9°, respectively; P < .01), and internal rotation on the dominant side (52.5° ± 11.3° vs 56.8° ± 10.8°, respectively; P = .01) were significantly reduced in the injured group.

Conclusion:

We identified preseason decreases in flexion bilaterally and internal rotation on the dominant side as risk factors for shoulder and elbow injuries in elementary and junior high school baseball players. Further studies are required to prevent disabilities in elementary and junior high school baseball players through development of prevention and intervention programs.

Injury prevention effects of stretching exercise intervention by physical therapists in male high school soccer players

We aimed to examine the prevalence of injury after physical therapy intervention for muscle tightness and injury prevention in male high school soccer players. A randomized controlled trial was conducted. Participants comprised 124 players from two high schools who competed in national tournament soccer games held from April 2018 to March 2019. Players were randomly divided into intervention (with a 12-week stretching intervention by physical therapists) and control groups (without the intervention). Players and coaches provided written information regarding injuries and daily training and match times; physical therapists visited each team weekly to collect data and review documentation. Muscle tightness and injury incidence, number, type, location, circumstances, situations, severity, and contents during the 12-week intervention period and a subsequent 40-week observation period were compared between groups. Injuries were significantly lower with intervention during the 40-week observation period (P < .01) but not during the 12-week intervention period (P = .44). Injury types mainly included disorder, non-contact, lower-limb/trunk, and muscle/tendon injuries. Significant interactions were observed for all tightness-test measurement items. The intervention group showed significant improvements in heel-buttock distance, and straight leg-raise and hip rotation angles (pre-intervention < 12 weeks < 52 weeks), as well as significant improvements in ankle dorsiflexion angles at 12 and 52 weeks (relative to pre-intervention values). Instructed stretching exercises, personally designed by physical therapists to address muscle tightness, improved the range of motion and trunk flexibility, with a positive effect on the injury rate in male high school soccer players, especially for non-contact disorder injuries during training.

Assessment of the Relationship between Y-Balance Test and Stabilometric Parameters in Youth Footballers

Objectives

The purpose of the study was to evaluate the correlation between dynamic test results obtained on a stabilometric platform and the results achieved on the Y-balance test (Y-BT).

Method

The study group consisted of 52 adolescent athletes, aged 14 to 17 years. Each participant was evaluated in the scope of their ability to maintain dynamic balance using the Y-BT as well as via dynamic tests on the ‘Alfa' stabilometric platform. The following parameters were analysed: (a) from the Y-BT—relative reach of the right and left lower limbs in the anterior, posterolateral, and posteromedial directions, as well as the side-to side difference in relative reach for each direction and (b) from the ‘Alfa' platform—path length and time to reach the target using right and left lower limbs in the anterior and posterior directions.

Results

A correlation between the results obtained on the stabilometric platform and the Y-BT was found only for the posteromedial direction. Statistical analysis demonstrated that the increased difference between the right and left lower limbs in the posteromedial test is related to an increase in time taken to reach the points located forward and to the left, and backwards and to the right, as well as an increase in the overall time required to complete the task on the stabilometric platform.

Conclusions

The results from the Y-BT and stabilometric platform are weakly related in adolescents. These findings indicate that the Y-BT and stabilometric platform analyse different kinds of dynamic balance in adolescents. Thus, these tools should not be used interchangeably in clinical practice or scientific research.

Regional Interdependence and the Role of the Lower Body in Elbow Injury in Baseball Players: A Systematic Review

BACKGROUND

Elbow injuries are exceedingly common in baseball players. Previous studies have identified that upper extremity strength and range of motion deficits pose a risk for these injuries, but few studies have examined the effect of lower extremity deficits. Given the role of the lower extremity in the kinetic chain of the baseball throwing motion, lower body deficits may affect the kinematics of the upper extremity and play a role in the elbow injury of baseball players.

PURPOSE

To systematically review the current literature investigating the association of trunk and lower extremity deficits with elbow pain or injury in baseball players.

STUDY DESIGN

Systematic review.

METHODS

A systematic review of the literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines to identify and analyze all previous studies focused on the association of elbow pain and/or injury with functional deficits of the trunk and lower extremities.

RESULTS

A total of 14 studies met inclusion criteria, examining a range of baseball players extending from youth to professional athletes. One of the 14 studies examined other types of overhead throwing athletes alongside baseball players. Lower extremity-related risk factors for elbow pain and injury in these athletes were found and stratified per level of play. Factors included specific hip range of motion, lower extremity injury or pain, balance, and foot arch posture. Associations were also found with lower extremity injury and noncompliance with primary prevention programs.

CONCLUSION

Specific lower extremity deficits were found to be independent risk factors for elbow pain and injury in throwing athletes at certain levels of play. Additionally, prevention programs designed to correct deficits in identified risk factors were effective in reducing the incidence of elbow injury in youth athletes. These results highlight the potential of screening and subsequent intervention to reduce the incidence of elbow injury in certain subsets of baseball players.

Longitudinal Change of Forearm-Hand Inertia Value and Shoulder Musculature Using Dual X-ray Absorptiometry in Youth Japanese Baseball Players: Implications for Elbow Injury

It is important to understand the timing of the maximum increase of forearm-hand inertia value and lean body mass (LBM) of the shoulder girdle musculature when elbow injury frequently occurs. This study aimed to clarify the discrepancies of those in youth baseball players. Forty-three male baseball players (8- to 14-years-old) participated in this study. The forearm-hand inertia value and LBM of the shoulder girdle musculature were calculated using dual-energy X-ray absorptiometry (DXA). A cubic spline fit was applied to the annual increase forearm-hand inertia value and LBM of the shoulder girdle musculature for each chronological age and years from peak height velocity (PHV) age. As a result of cubic splines fitting, the peak timing for forearm-hand inertia value and LBM of the shoulder girdle musculature was 12.42 and 12.75 years in chronological age, −0.66 and −0.11 years in PHV age. Therefore, the peak timing of forearm-hand inertia value was about 4 months earlier in chronological age and half a year earlier in PHV age than LBM of the shoulder girdle musculature. Acquiring sufficient shoulder girdle musculature during the period when the growth of the shoulder girdle musculature cannot catch up with forearm-hand inertial value is necessary to reduce the elbow load while throwing.

Dynamic Balance Evaluation: Reliability and Validity of a Computerized Wobble Board

Fusco, A, Giancotti, GF, Fuchs, PX, Wagner, H, Varalda, C, Capranica, L, and Cortis, C. Dynamic balance evaluation: reliability and validity of a computerized wobble board. J Strength Cond Res 34(6): 1709-1715, 2020-Computerized wobble boards (WBs) are inexpensive, transportable, and user-friendly devices to objectively quantify the dynamic balance performances out of laboratory settings, although it has not been established if they are reliable and valid tools. Therefore, the purpose of this study was to determine the reliability and validity of a computerized WB. Thirty-nine (18 females and 21 males) young adults (age: 23.3 ± 2.1 years; body mass: 65.9 ± 1.8 kg; height: 168.2 ± 8.8 cm; leg length: 78.8 ± 5.7 cm; and body mass index: 23.2 ± 2.1 kg·m) participated in the study. Subjects were assessed during 3 separate sessions on different days with a 48-hour rest in between. A total number of 2 WB single limb tests and 1 Y Balance Test (YBT) were performed. The WB performance was registered using the proprietary software and represented by the time spent in the target zone, which represented the 0° tilt angle measured by the triaxial accelerometer in the WB. YBT normalized reach distances were recorded for the anterior, posteromedial, and posterolateral directions. Intraclass correlation coefficient, 95% confidence interval, SEM, minimal detectable change, and Bland-Altman plots were used to evaluate intrasession and intersession reliability, whereas Pearson product moment correlation was used to determine concurrent validity. Reliability ranged from fair to excellent, showing acceptable levels of error and low minimal detectable change. However, all correlation coefficients between WB and YBT outcomes were poor. Despite the 2 methods addressing different aspects of balance performance, WB seems to validly serve its purpose and showed good reliability. Therefore, computerized WBs have the potential to become essential devices for dynamic balance assessment.

THE USE OF POSTURAL RESTORATION FOR TREATMENT OF CHRONIC ROTATOR CUFF PATHOLOGY: A CASE REPORT

Background and Purpose

Postural Restoration Institute® (PRI) theories and rehabilitation techniques focus on restoring balance to anatomical systems. Common postural asymmetries can present in athletes as dysfunctions and limitations. The purpose of this case report was to examine the use of PRI exercises and theories to address pelvic alignment, along with core stabilization, during treatment of shoulder dysfunction in a collegiate volleyball player.

Case Description

A 22-year-old female volleyball athlete reported unresolved right rotator cuff tendinopathy. She presented with bilateral rib cage flare, anterior pelvic tilt, and bilateral ROM differences in hip and shoulder internal and external rotation. PRI® special test findings included a positive left and right Adduction Drop Test (ADT), positive left Extension Drop, and Hruska Adduction Lift test (left=2, right=3) indicating posterior exterior chain (PEC) pattern of dysfunction. The traditional shoulder rehabilitation program from the previous season was eliminated and a PRI based intervention was performed. Intervention exercises included the 90/90 dead bug diaphragmatic breathing, 90/90 hamstring hip lift, and right sidelying respiratory left adductor pull back. Exercises were performed as three sets of ten diaphragmatic breathing repetitions, a minimum of three times weekly prior to activity.

Outcomes

Likert scale ratings of pain decreased from a six pre-intervention to two. The left hip gained 10° of internal rotation and the right hip gained 14° of external rotation. Right shoulder internal rotation increased 15°. Hruska Adduction Lift improved to a four bilaterally (right by day 24, and left by day 31). Left extension drop test was negative following day 17.

Discussion

PRI® exercises focusing on core and pelvic stability translated to improved hip and shoulder ROM, and decreased shoulder pain associated with rotator cuff tendinopathy. By treating pelvic alignment with the PRI® exercises, the ROM imbalance and pain at the shoulder joint were addressed.

Conclusion

Incorporating PRI exercises and theories into the rehabilitation program of a volleyball player was useful in addressing underlying imbalances throughout the kinetic chain.

Level of Evidence

3b.

Preseason Neck Mobility Is Associated With Throwing-Related Shoulder and Elbow Injuries, Pain, and Disability in College Baseball Pitchers

Background

Shoulder and elbow injuries in baseball pitchers, which can lead to significant pain and disability, have been on the rise at all levels of play for 3 decades. Despite anatomic and neurophysiological relationships, neck mobility has not been explored as a contributor to shoulder and elbow injuries in baseball pitchers.

Hypothesis

Impaired neck mobility will increase the risk of shoulder and elbow injuries in college baseball pitchers.

Study Design

Cohort study; Level of evidence, 2.

Methods

Posture, neck mobility, and shoulder passive range of motion were measured in healthy college baseball pitchers during the 2018 preseason. Time loss (days lost because of shoulder or elbow injuries) and patient-reported disability via Functional Arm Scale for Throwers (FAST) scores were used to dichotomize pitchers into injured and uninjured groups. Receiver operating characteristic curves were generated, and accuracy values and risk ratios (RRs) were calculated to assess the diagnostic utility of the physical measures. Time-to-injury analysis was conducted to assess the timing of injuries.

Results

A total of 49 pitchers (mean age, 19.92 ± 1.48 years; mean height, 187.04 ± 6.02 cm; mean weight, 89.14 ± 12.08 kg) completed the study. There were 10 pitchers (20.4%) who sustained a time-loss injury >7 days because of a shoulder or elbow injury. A Cervical Flexion-Rotation Test (CFRT) finding on the dominant side of ≤39° resulted in over 9 times the increased risk of time-loss injuries (RR, 9.38 [95% CI, 1.28-68.49]). Time-to-injury analysis demonstrated differences between the 2 groups (χ² = 7.667; P = .01). Pitchers with a >39.25° finding on the CFRT played a mean 109.4 of 112 days (95% CI, 105-114) before the injury, while pitchers with ≤39.25° only played 83.6 of 112 days (95% CI, 68-99). A CFRT finding of ≤38° (RR, 3.91 [95% CI, 1.23-12.39]), cervical flexion range of motion of ≤64° (RR, 10.56 [95% CI, 1.50-74.34]), and weight of >86.9 kg (RR, 10.42 [95% CI, 1.14-213.70]) were also associated with an increased risk of patient-reported pain and disability on the FAST pitcher module.

Conclusion

College baseball pitchers with less neck mobility during the preseason had an increased risk of time loss and shoulder and elbow disability during the season. The predictive value of these measures as part of a risk screening profile should be further explored.

Role of the kinetic chain in shoulder rehabilitation: does incorporating the trunk and lower limb into shoulder exercise regimes influence shoulder muscle recruitment patterns? Systematic review of electromyography studies

OBJECTIVE

To investigate the influence of trunk and lower limb motion on electromyography (EMG) muscle activity and recruitment patterns around the shoulder.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE, CINAHL, PEDro, AMED, PubMed, Cochrane Central Register of Controlled trials, Cochrane Database of Systematic reviews, SportsDiscuss and PROSPERO.

ELIGIBILITY CRITERIA

Studies investigating both multiregional kinetic chain (KC) shoulder exercises and localised non-kinetic chain (nKC) shoulder exercises in healthy subjects under the same experimental conditions were included in this review.

RESULTS

KC exercises produced greater EMG activation levels in 5 of 11 studies for the lower trapezius. Of the remaining studies, five found no difference between the exercise types and one favoured nKC exercises. KC exercises produced greater EMG activation levels in 5 of 11 studies for the serratus anterior. Of the remaining studies, three reported the opposite and three found no significant difference between the exercise types. nKC exercises produced greater EMG activation in infraspinatus in three of four studies. KC exercises produced the lowest trapezius muscle ratios in all studies. Studies investigating the upper trapezius, middle trapezius, supraspinatus, subscapularis, biceps brachii, latifissimus dorsi, pectoralis major, deltoid, and trapezius and serratus anterior ratios showed inconsistency.

CONCLUSION

This review found evidence that integrating the KC during shoulder rehabilitation may increase axioscapular muscle recruitment, produce lower trapezius muscle ratios and reduce the demands on the rotator cuff. Stepping appears preferable to squatting.

PROSPERO REGISTRATION NUMBER

CRD42015032557, 2015.

Influence of different jaw positions on dynamic balance using Y-balance test

BACKGROUND

Jaw sensory-motor system has been shown to affect static balance of the body. It would be interesting to know whether it can influence dynamic balance as well. The objective of this study is to examine the influence of different jaw positions on dynamic balance using the Y-balance test.

METHODS

Eighty healthy male participants aged 20-35 years were invited to participate in this study. Dynamic balance was measured by the Y-balance test in three directions (anterior, posteromedial, and posterolateral) for each leg separately in three jaw positions: resting jaw (control), open-jaw, and clenched jaw.

RESULTS

There were no significant differences in reach distances between the different jaw positions except in the posterolateral direction. In comparison with resting jaw position, reach distance was significantly higher in open-jaw position for the right leg and in clenched and open-jaw positions for the left leg in the posterolateral direction.

CONCLUSIONS

Although various studies have shown direct or indirect influence of jaw sensory-motor system on static postural control, results of this study point to limited relation with dynamic postural control among healthy subjects. However, it supports the potential of the jaw sensory-motor system to affect motor control during functional tasks in patients with postural instability or similar disorders.

Restriction in the hip internal rotation of the stride leg is associated with elbow and shoulder pain in elite young baseball players

BACKGROUND

Evidence is scarce concerning the relationship of physical dysfunction of the trunk and lower extremities with elbow and shoulder pain in young baseball players. This study aimed to examine the association of joint flexibility of the trunk and lower extremities and dynamic postural control with elbow and shoulder pain among elite young baseball players.

METHODS

We analyzed baseball players (aged 9-12 years) who participated in the National Junior Sports Clubs Baseball Festival. Range of motion in external rotation and internal rotation (IR) of the hip, as well as the finger-to-floor distance and heel-to-buttock distance, was measured. The straight-leg-raise test was also conducted. Dynamic postural control was evaluated using the Star Excursion Balance Test. Multivariable logistic regression analyses were conducted to examine the association of physical function with the elbow or shoulder pain incidence.

RESULTS

Of 210 players surveyed, 177 without elbow or shoulder pain were included in the analysis. Of the participants, 16 (9.0%) reported having elbow or shoulder pain during the tournament. Participants with the incidence of elbow or shoulder pain had a significant restriction in hip IR of the stride leg compared with those without pain (35.8° vs. 43.7°, P = .022). There were no significant associations of other joint flexibilities and the Star Excursion Balance Test with elbow or shoulder pain.

CONCLUSION

Decreased hip IR range of motion of the stride leg was significantly associated with the elbow or shoulder pain incidence. Players, coaches, and clinicians should consider the physical function of the trunk and lower extremities for the prevention of elbow and shoulder pain.

Analysis of lower extremity side-reaching motion in junior high school baseball players

[Purpose] The aim of this study was to clarify the movement pattern of the pelvis and trunk of junior high school baseball players based on the lateral reach motion of the lower limb, which is related to poor pitching movement. [Participants and Methods] Twenty-five male students belonging to a baseball club participated in this study. Each participant performed the lower limb side reach movement in the standing position, during which the movements of the knee joint, hip joint, pelvis, and trunk were analyzed. [Results] A significant correlation was found between reach distance and reach leg hip abduction, supporting leg hip abduction, trunk side bending, and trunk tilt. We found a significant correlation between reach leg hip abduction and pelvic tilt and trunk side bending and between supporting leg hip abduction and pelvic tilt, knee valgus, and trunk side bending. Furthermore, we found a significant correlation between knee valgus and lower leg tilt and trunk tilt and between trunk side bending and pelvic tilt. [Conclusion] This study suggests that in the standing position movement at this age, the hip and trunk movements are related to and affect performance.

Upper Extremity Musculoskeletal Characteristics and the Kerlan-Jobe Orthopaedic Clinic Questionnaire Score in Collegiate Baseball Athletes

CONTEXT

Upper extremity (UE) musculoskeletal injuries are common in baseball athletes due to the increased demand placed on the UE. The link between risk factors for UE musculoskeletal injuries and baseball athletes' perceived UE function and pain, as measured by the Kerlan-Jobe Orthopaedic Clinic (KJOC) questionnaire, is unclear.

OBJECTIVE

To (1) describe the musculoskeletal characteristics of the UE (posture, range of motion, flexibility, and isometric strength) in a population of baseball athletes and (2) determine the predictive capability of UE musculoskeletal characteristics for the KJOC score in these athletes.

DESIGN

Cohort study.

SETTING

Athletic training room.

PATIENTS OR OTHER PARTICIPANTS

A total of 37 male National Collegiate Athletic Association Division I baseball athletes (age = 20.10 ± 1.27 years, height = 186.96 ± 7.64 cm, mass = 90.60 ± 10.69 kg).

INTERVENTION(S)

Athletes self-reported all shoulder musculoskeletal injuries and completed the KJOC questionnaire. Postural assessment consisted of forward head and shoulder posture. Flexibility tests characterized glenohumeral internal and external rotation, posterior shoulder tightness, and pectoralis minor length. Strength tests involved the lower and middle trapezius, rhomboid, glenohumeral internal and external rotation, pectoralis major, serratus anterior, supraspinatus, and upper trapezius.

MAIN OUTCOME MEASURE(S)

All 10 KJOC questions were summed for an overall score out of 100. Questions 1 through 5 were summed for a pain score; questions 6 through 10 were summed for a function score. All data were assessed for normality. A stepwise multiple regression model was fit to determine if the predictor variables assessed could predict the KJOC score. We set the α level a priori at .05.

RESULTS

For the KJOC total score, a 1-year history of shoulder injury accounted for 7.80% of the variance in the KJOC total score (P = .07). For KJOC questions 1 through 5, a history of UE injury in the year before testing and posterior shoulder tightness accounted for 14.40% of the variance in the KJOC total score (P = .047).

CONCLUSIONS

The link between a history of UE musculoskeletal injuries and the KJOC score highlights the need for continued focus on self-perceived pain and function after UE musculoskeletal injury.

THE IMPACT OF LUMBOPELVIC CONTROL ON OVERHEAD PERFORMANCE AND SHOULDER INJURY IN OVERHEAD ATHLETES: A SYSTEMATIC REVIEW

BACKGROUND

The lumbopelvic region is utilized in almost all functional tasks and has been proposed to provide dynamic stability to distal extremities.

PURPOSE

To systematically evaluate the current literature that examined the effect of lumbopelvic control on overhead performance and shoulder injury in overhead athletes.

STUDY DESIGN

Systematic Review.

METHODS

A comprehensive systematic electronic search was conducted using PubMed, CINAHL, ProQuest, Scopus, and SPORTDiscus. Articles were considered for inclusion if they included a measure of lumbopelvic control and assessed shoulder pain, disability, injury, or overhead performance outcome. Cohen's d effect size was calculated when necessary statistical data were available to determine the impact of lumbopelvic control.

RESULTS

The search revealed 3,312 total articles and 2,883 articles were screened after duplicates were removed. After titles and abstracts were screened, 45 full text articles were reviewed. Fifteen full-text articles ultimately met inclusion criteria. Effect sizes ranged from trivial (0.10) to large (0.86), indicating a varying degree of positive effects on performance and shoulder injuries. The majority of included articles concluded individuals with greater lumbopelvic control demonstrated improved performance and decreased occurrence of injury.

CONCLUSION

Results suggest that improved lumbopelvic control relates to improved athletic performance and decreased shoulder injury. Additional higher quality research is needed to further support these findings, establish a standard measure for lumbopelvic control, and determine preventative factors for injury, pain, and disability.

LEVEL OF EVIDENCE

2a.

Shoulder and elbow pain in junior high school baseball players: Results of a nationwide survey

BACKGROUND

Despite proposals and guidelines to prevent baseball injuries in young players by societies and organizations, many shoulder and elbow injuries continue to occur among junior high school baseball players. In order to investigate the training conditions of junior high school baseball players and the risk factors for shoulder and elbow pain in the players, we conducted a questionnaire survey among junior high school baseball players throughout the country.

METHODS

The questionnaire survey was conducted among junior high school baseball players in September 2016.

RESULTS

A total of 11,134 junior high school baseball players belonging to 495 teams responded to the survey. Among these, 4004 players trained every day of the week and 1151 players played baseball games every month with no off-season. Among 9752 players who did not have shoulder and/or elbow pain in the spring and summer of 2015, 19.2% of players experienced elbow pain over the course of one year, 13.6% of players experienced shoulder pain, and 28.0% complained of shoulder and/or elbow pain. The frequency of elbow pain was more than that of shoulder pain. At risk for shoulder pain were pitchers and catchers and second-year students, while risk factors for elbow pain were playing pitcher and catcher positions, pitching or throwing ≥300 balls per week, playing ≥10 games on average per month and being left-handed.

CONCLUSION

Risk factors for shoulder pain were different from those for elbow pain. To prevent elbow pain, coaches should pay attention to pitchers and catchers and left-handed players and not allow players to pitch or throw ≥300 full-power balls per week or participate in ≥10 games per month. They should also pay attention to pitchers and catchers and second-year students to prevent shoulder pain. It is important for coaches to train multiple pitchers and catchers.

Risk Factors for Elbow and Shoulder Injuries in Adolescent Baseball Players: A Systematic Review

BACKGROUND

The incidence of shoulder and elbow injuries among adolescent baseball players is on the rise. These injuries may lead to surgery or retirement at a young age.

PURPOSE

To identify independent risk factors for elbow and shoulder injuries in adolescent baseball players. A secondary aim was to determine whether the literature supports the Major League Baseball and USA Baseball Pitch Smart guidelines.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines utilizing MEDLINE, SPORTDiscus, and Web of Science. Because of study heterogeneity, a quantitative synthesis was not performed. A qualitative review was performed on 19 independent risk factors for elbow and shoulder injuries in adolescent baseball players. Level of evidence was assigned per the Oxford Centre for Evidence-Based Medicine Working Group, and risk of bias was graded per the Newcastle-Ottawa Scale.

RESULTS

Twenty-two articles met criteria for inclusion. Of the 19 independent variables that were analyzed, age, height, playing for multiple teams, pitch velocity, and arm fatigue were found to be independent risk factors for throwing arm injuries. Pitches per game appears to be a risk factor for shoulder injuries. Seven independent variables (innings pitched per game, showcase participation, games per year, training days per week, pitch type, shoulder external rotation, and shoulder total range of motion) do not appear to be significant risk factors. The data were inconclusive for the remaining 6 variables (weight, months of pitching per year, innings or pitches per year, catching, shoulder horizontal adduction, and glenohumeral internal rotation deficit).

CONCLUSION

The results from this study demonstrate that age, height, playing for multiple teams, pitch velocity, and arm fatigue are clear risk factors for throwing arm injuries in adolescent baseball players. Pitches per game appears to be a risk factor for shoulder injuries. Other variables are either inconclusive or do not appear to be specific risk factors for injuries.

Understanding Symptoms of Muscle Tightness, Weakness, and Rigidity From a Nursing Perspective

PURPOSE

This study examined the nature of muscle tightness from nurses' perspectives and explored how the symptoms of muscle tightness are communicated, managed, and differentiated from other conditions, such as muscle rigidity and muscle weakness.

DESIGN

An exploratory, descriptive qualitative design was used.

METHODS

Eight rehabilitation nurses described lexicons, care strategies, and communication for muscle tightness, weakness, and rigidity.

FINDINGS

Nurses used conflicting terms to describe muscle tightness, weakness, and rigidity. They identified medications and range of motion as the best strategies to manage muscle conditions. Nurses approach care holistically and do not differentiate care strategies that are based only on a symptoms lens.

CONCLUSIONS

Nurses were unable to clearly differentiate between muscle tightness and rigidity.

CLINICAL RELEVANCE

Nurses influence patients' choice of vocabulary; therefore, they must use simple but precise terminologies to educate their patients. Miscommunication between nurses and patients can lead to errors, which can have negative consequences.

Coexistence of Trunk or Lower Extremity Pain with Elbow and/or Shoulder Pain among Young Overhead Athletes: A Cross-Sectional Study

Elbow or shoulder injuries are common in overhead sports. Because energy derived from the lower extremity passes through the trunk to the upper extremity in overhead motion, a break in such a kinetic chain could lead to arm injuries. However, there is only limited information about the role of the trunk and lower extremity support in preventing elbow or shoulder injuries. This study aimed to explore the association of trunk and lower extremity pain with elbow/shoulder pain among young overhead athletes. We conducted a cross-sectional study using self-reported questionnaires mailed to young athletes belonging to the Miyagi Amateur Sports Association. The final study population comprised 2,215 young athletes playing baseball (n = 1,422), volleyball (n = 546), softball (n = 14), handball (n = 28), tennis (n = 110), or badminton (n = 95). The median age of the participants was 11 years (range: 6 to 15 years). Multiple logistic regression analysis revealed the higher prevalence of elbow and/or shoulder pain in athletes with back pain (OR = 5.52, 95% CI = 3.51-8.69), hip pain (OR = 6.13, 95% CI = 3.35-11.22), knee pain (OR = 2.28, 95% CI = 1.48-3.51), and foot pain (OR = 3.03, 95% CI = 1.95-4.72), compared with those without pain. We propose that trunk or lower extremity pain is significantly associated with elbow or shoulder pain among young overhead athletes. Assessing for pain in trunk or lower extremity, as well as elbow and/or shoulder pain, may help prevent serious injuries in young overhead athletes.

Analysis of the kinetic chain in asymptomatic individuals with and without scapular dyskinesis

BACKGROUND

This study measured strength of the trunk and hip, and compared Y Balance Test and Upper Quarter Y Balance Test in individuals without and with scapular dyskinesis. Strength and endurance of the scapulothoracic muscles were also assessed.

METHODS

Forty-four individuals without shoulder pain were divided in 2 groups: without scapular dyskinesis (age 26.00, SD 4.10 years) and scapular dyskinesis (age 23.68, SD 4.20 years). Scapular dyskinesis was assessed by clinical observation of the scapular motion during arm elevation, and was classified as present or absent. A handheld dynamometer was used to measure the isometric strength of the trunk flexors and lateral flexors, hip extensors and abductors, lower trapezius, serratus anterior, and latissimus dorsi. Y and Upper Quarter Y Balance Tests were performed with the individual in single-limb and 3-point plank position, respectively. Endurance of the scapulothoracic muscles was assessed with the individuals in prone with the arm at 135° abduction. Independent t-test and Mann-Witney test were used for comparison between groups. A P < 0.05 was considered significant. Effect sizes between groups were also calculated.

FINDINGS

No differences (P > 0.05) were demonstrated between groups for all variables. Moderate effect size (d ~ 0.40) was found for the trunk flexors and hip extensors, and endurance of the scapulothoracic muscles, whereas the scapular dyskinesis group showed less strength and endurance in relation to the group without dyskinesis.

INTERPRETATION

Strength of the trunk flexors and hip extensors, and endurance of the scapulothoracic muscles seem to have influence in scapular dyskinesis in non-athletes without shoulder pain.

Injury Prevention in Baseball: from Youth to the Pros

PURPOSE OF REVIEW

This review examines recent literature on injury epidemiology and prevention in the sport of baseball from youth to professional levels.

RECENT FINDINGS

Overuse is the predominant mechanism of injury in youth baseball players. Newer stretching and exercise protocols may help prevent these injuries. At the professional level, however, overuse has not been proven to correlate with increased injury incidence, but pitch counts are still monitored. There continues to be a rise in operations performed for baseball-related injuries, including ulnar collateral ligament (UCL) reconstruction, particularly in younger athletes. As the level of play increases, there is significant loss of participation due to injuries, such as the UCL in the upper extremity and the hamstrings in the lower extremity. Baseball is a widely popular sport, which has led to a focus on injury epidemiology and prevention. While the majority of research regarding baseball injuries focuses on pitchers, fielders and catchers are also at risk. In an attempt to decrease non-contact injuries in the upper and lower extremities, stretching and strengthening exercises are vitally important. Because injury profiles demonstrate significant variability from youth to professional baseball, unique prevention strategies are likely necessary at each level. More research is needed to develop and validate appropriately targeted injury prevention programs.

Side-to-side difference in dynamic unilateral balance ability and pitching performance in Japanese collegiate baseball pitchers

[Purpose] To evaluate the side-to-side difference in dynamic unilateral balance ability and to determine the correlation of the balance ability with pitching performance in collegiate baseball pitchers. [Subjects and Methods] Twenty-five Japanese collegiate baseball pitchers participated in this study. Dynamic balance ability during a unilateral stance was bilaterally evaluated using the star excursion balance test (SEBT). The pitchers threw 20 fastballs at an official pitching distance; the maximal ball velocity and pitching accuracy (the number of strike/20 pitches × 100) were assessed. Side-to-side difference in scores of SEBT was assessed using a paired t-test. Correlations between SEBT scores and pitching performance were evaluated for both legs using a Pearson’s correlation analysis. [Results] The pivot side showed significantly higher score of the SEBT in the anteromedial direction than the stride side. On the other hand, the SEBT scores in the pivot and stride legs did not have significant correlations with maximal ball velocity and pitching accuracy. [Conclusion] These findings suggest that marked side-to-side difference does not exist in the dynamic unilateral balance ability of collegiate baseball pitchers and that the dynamic unilateral balance ability of each leg is not directly related to maximal ball velocity and pitching accuracy.

Efficacy of a Prevention Program for Medial Elbow Injuries in Youth Baseball Players

BACKGROUND

Youth baseball players are at high risk for elbow injuries, which can lead to future functional disability.

PURPOSE

To evaluate the effectiveness of a prevention program to lower the risk of medial elbow injury in these athletes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Youth baseball players, 8 to 11 years old, without a history of elbow and shoulder pain, were allocated to either the intervention (n = 136) or control (n = 169) group. The intervention consisted of 9 strengthening and 9 stretching exercises, performed during warm-up or at home, with high compliance defined as completion of the program 1 or more times per week. The following outcome variables were measured: clinical assessment of the elbow and shoulder joint, ultrasonography assessment of the elbow, and assessment of physical function (passive range of motion of the elbow, shoulder, and hip; strength of the shoulder and scapular muscles; and measurement of the thoracic kyphosis angle). The clinical and ultrasonography assessments were measured at baseline and at 3-month intervals over the 1-year follow-up. Physical function outcomes were measured at baseline and at the endpoint of the follow-up. The primary endpoint of effectiveness was the incidence of medial elbow injury. Secondary endpoints were absolute measures of physical function and change in these measures over the 1-year follow-up.

RESULTS

The incidence rate of medial elbow injury was significantly lower in the intervention group (0.8/1000 athlete-exposures) than the control group (1.7/1000 athlete-exposures) (hazard ratio, 50.8%; 95% CI, 0.292-0.882; P = .016). The program improved total range of shoulder rotation (dominant side), hip internal rotation (nondominant side), shoulder internal rotation deficit (bilaterally), lower trapezius muscle strength (dominant side), and the thoracic kyphosis angle. Improvements in the following variables of physical function were predictive of a lower rate of medial elbow injury: increased total shoulder total rotation (odds ratio [OR], 0.973; 95% CI, 0.950-0.997), increased hip internal rotation of the nondominant side (OR, 0.962; 95% CI, 0.936-0.989), and decreased thoracic kyphosis angle (OR, 1.058; 95% CI, 1.015-1.103).

CONCLUSION

A prevention program aiming to improve physical function can prevent medial elbow injury in youth baseball players.

Upper Extremity Range of Motion and Pitching Profile of Baseball Pitchers in Japan

BACKGROUND

Shoulder range of motion and pitch count in baseball pitchers have been linked to pitching-related upper extremity injury.

PURPOSE

To investigate upper extremity range of motion and pitching profiles in baseball pitchers in Japan as well as to make a comparison between injured and noninjured pitchers.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Forty-one Little League to college-level baseball pitchers were measured for bilateral shoulder and elbow range of motion, including shoulder internal rotation (IR), external rotation (ER), shoulder horizontal adduction (HAD), and elbow extension (EXT). They were also asked to answer a simple questionnaire regarding their past pitching-related medical history and pitching profile. Additionally, 28 participants with baseball-related upper extremity injuries (injury group) were compared with 13 participants without injury (no-injury group) for the same parameters. Collected data were analyzed using analysis of variance.

RESULTS

Significant limb differences (dominant vs nondominant side) were noted for ER (117.2° vs 109.8°, P = .02), IR (53.5° vs 61.9°, P = .007), HAD (28.3° vs 32.8°, P = .03), and EXT (1.0° vs 4.6°, P = .01). A significant between-group difference (injury vs no-injury group) was observed for IR in both the dominant (55.4° vs 45.6°, P = .03) and nondominant shoulder (65.3° vs 55.0°, P = .01). Participants in the injury group pitched more games in a season and more innings per game started.

CONCLUSION

Japanese baseball pitchers displayed adaptive changes in upper extremity range of motion similar to American pitchers when compared bilaterally. Injured pitchers exhibited greater IR range of motion in their pitching arm compared with noninjured pitchers.

Physical Risk Factors for a Medial Elbow Injury in Junior Baseball Players: A Prospective Cohort Study of 353 Players

BACKGROUND

The physical risk factors for a medial elbow injury in junior baseball players are unknown.

PURPOSE

To identify the risk factors for an initial medial elbow injury in junior baseball players.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Junior baseball players (aged 6-12 years) without a history of elbow pain underwent a clinical assessment, ultrasonography, and physical function measurements before the baseball season started. Bilateral passive range of motion (ROM) of elbow extension and flexion, external rotation (ER) and internal rotation (IR) of the shoulder, and ER and IR of the hip were measured. IR and ER strength of the shoulder and scapular muscles were measured on both sides. The thoracic kyphosis angle was measured with participants in a relaxed standing position. Before these examinations, every participant completed a questionnaire regarding his or her age, sex, total years of baseball played, position in baseball, number of balls thrown, and episodes of pain during throwing. After the initial test session, each participant was followed up for 12 months to assess for the occurrence of a new injury. Multiple regression analysis was used to identify the risk factors for a medial elbow injury.

RESULTS

Seventy-eight players (22.1%) sustained a medial elbow injury. Age ≥9 years (odds ratio [OR], 2.708; 95% CI, 1.224-5.990), pitcher position (OR, 2.620; 95% CI, 1.389-4.941), >100 throws per day (OR, 1.936; 95% CI, 1.072-3.497), thoracic kyphosis angle ≥30° (OR, 2.501; 95% CI, 1.381-4.531), and elbow extension deficit ≥5° (OR, 1.973; 95% CI, 1.022-3.809) were significantly associated with a medial elbow injury.

CONCLUSION

The incidence of an initial medial elbow injury was 22.1%. Age, number of throws per day, thoracic kyphosis angle, and elbow extension deficit are newly discovered risk factors related to physical function. Improvement of the posture and early detection of a silent elbow extension deficit may prevent a medial elbow injury.

Differences in hip range of motion among collegiate pitchers when compared to youth and professional baseball pitcher data

The purpose of this study was to measure passive hip internal (IR) and external rotation (ER) range of motion (ROM) in collegiate baseball pitchers and compare to published youth and professional values. Measures were taken on the bilateral hips of 29 participants (mean age 20.0±1.4, range 18-22 years). Results identified no significant differences between the stance and stride hip in collegiate right handed pitchers for IR (p= 0.22, ES 0.23) and ER (p=.08, ES= 0.25). There was no significant difference in left handed pitchers for IR (p= 0.80, ES= 0.11) and ER (p= 0.56, ES= 0.15). When comparing youth to collegiate, IR increased in the stance (2º) and stride (5º) hip and an increase in the stance (5º) and stride (5º) hip were present for ER as well. From collegiate to professional, IR increased in the stance (4º) and stride (3º) hip whereas a decrease in the stance (9º) and stride (12º) hip was present for ER. The data suggests an increase in passive ROM from youth to collegiate and a decrease from collegiate to professional. Understanding passive hip ROM values among the different levels of pitchers may assist clinicians in developing time dependent interventions to prevent future injury and enhance performance.