scholarly journals Adaptations of the Shoulder to Overhead Throwing in Youth Athletes

2015 ◽  
Vol 50 (7) ◽  
pp. 726-732 ◽  
Author(s):  
Matthew Michael Astolfi ◽  
Aaron H. Struminger ◽  
Todd D. Royer ◽  
Thomas W. Kaminski ◽  
Charles B. Swanik,
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Mixed Model ◽  
External Rotation ◽  
Posterior Capsule ◽  
Shoulder Injuries ◽  
Cross Sectional ◽  
Youth Baseball ◽  
Capsule Thickness ◽  
Overhead Throwing

Context The high number of repetitions and high forces associated with overhead throwing lead to anatomical adaptations, such as humeral retrotorsion and posterior-capsule thickness, in elite and professional baseball athletes. However, little is known about the origin and progression of these changes that may account for the increasing trend of chronic shoulder injuries in youth baseball and precipitate subsequent pathologic conditions throughout a young athlete's lifetime. Objective To investigate the relationship of age and upper extremity dominance on humeral retrotorsion, posterior-capsule thickness, and glenohumeral range of motion. Design Cross-sectional study. Setting Research laboratory, local baseball fields, and training facilities. Patients or Other Participants Thirty-six boys (mean age = 10.94 ± 1.34 years, height = 151.31 ± 12.17 cm, mass = 42.51 ± 10.32 kg) ranging in age from 8 to 12 years and involved in organized youth baseball. Main Outcome Measure(s) Diagnostic ultrasound was used to determine humeral retrotorsion and posterior-capsule thickness. Glenohumeral internal rotation and external rotation were measured using a handheld inclinometer. We used 2 × 2 mixed-model analyses of variance to compare the influence of limb dominance and age on the dependent variables of humeral retrotorsion, posterior-capsule thickness, internal rotation, and external rotation. Results The dominant shoulders of youth throwers exhibited less glenohumeral internal rotation but greater humeral retrotorsion, posterior-capsule thickness, and glenohumeral external rotation than the nondominant shoulders. Dominant internal rotation was greater in the 8- to 10-year-old group than in the 11- to 12-year-old group, and results trended toward a difference (F1,33 = 4.12, P = .05). Correlations existed between humeral retrotorsion and range of motion (P < .05). Conclusions The structural adaptations in the dominant shoulders of younger baseball players were similar to adaptations observed in older baseball athletes, indicating that more examination is needed in younger athletes. We are the first to demonstrate greater posterior-capsule thickness in the dominant shoulders of youth baseball athletes.

scholarly journals Glenohumeral and Hip Range-of-Motion and Strength Measures in Youth Baseball Athletes

2016 ◽  
Vol 51 (6) ◽  
pp. 466-473 ◽  
Author(s):  
Kelsey J. Picha ◽  
Josie L. Harding ◽  
Kellie C. Huxel Bliven
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
External Rotation ◽  
Gluteus Medius ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Hip Strength ◽  
Older Athletes ◽  
Youth Baseball ◽  
Hip Internal Rotation

Context: The repetitive demands of throwing affect glenohumeral (GH) range of motion (ROM) and strength. Less is known about hip alterations in skeletally immature athletes. Objective: To compare GH and hip ROM and strength between age, position, and side of youth baseball athletes. Design: Cross-sectional study. Setting: Multicenter testing. Patients or Other Participants: Seventy-two healthy baseball athletes. Participants' self-reported characteristics were age group (7−11 years [n = 28] or 12−18 years [n = 44]), position (pitcher [n = 22], position player [n = 47], unreported [n = 3]), and side (throwing or nonthrowing arm, lead or stance leg). Main Outcome Measure(s): Bilateral GH and hip internal- and external-rotation ROM were measured passively and summed for total arc of motion (TAM). Glenohumeral and hip rotation and gluteus medius strength were measured. Analyses included linear mixed models. Results: Glenohumeral internal rotation was less in throwing than in nonthrowing arms (P < .05) except in younger pitchers (P = .86). Compared with older athletes, younger athletes had more GH external rotation (103.3° ± 7.7° versus 97.5° ± 9.4°; P = .002), TAM (156.4° ± 8.7° versus 147.9° ± 10.9°; P = .04), and external rotation in throwing compared with nonthrowing arms (101.9° ± 1.2° versus 97.9° ± 1.1°; P < .001). Glenohumeral TAM was less in throwing than in nonthrowing arms (150.5° ± 2.1° versus 154.9° ± 1.3°; P = .01). Younger athletes had more hip internal rotation (38.9° ± 6.8° versus 31.2° ± 7.5°; P < .001) and TAM (68.4° ± 10.0° versus 60.7° ± 9.8°; P = .001) than older athletes. Lead-leg hip internal-rotation ROM was greater than in the stance leg (34.8° ± 8.9° versus 32.8° ± 7.7°; P = .01). Overall, older players were stronger than younger players (P < .05), and the throwing arm was stronger in internal rotation than the nonthrowing arm (10.12 ± 3.72 lb [4.59 ± 1.69 kg] versus 9.43 ± 3.18 lb [4.28 ± 1.44 kg]; P = .047). Conclusions: Youth baseball athletes had typical GH ROM adaptations of less internal rotation and more external rotation in the throwing versus the nonthrowing arm. Greater ROM in younger athletes may be explained by prepubertal characteristics. We obtained hip-strength values in youth baseball athletes, and as expected, older athletes were stronger.

Shoulder Rotation Function following the Sup-ER Protocol in Children with Brachial Plexus Injuries

Hand ◽  
2020 ◽  
pp. 155894472093736
Author(s):  
Leeor S. Yefet ◽  
Doria Bellows ◽  
Marija Bucevska ◽  
Rebecca Courtemanche ◽  
Kim Durlacher ◽  
...  
Keyword(s):  
Cohort Study ◽  
Brachial Plexus ◽  
Range Of Motion ◽  
Internal Rotation ◽  
External Rotation ◽  
Cross Sectional ◽  
Elbow Function ◽  
Rotation Strength ◽  
Rotation Function

Background: Our group previously developed an upper extremity repositioning (Sup-ER) protocol for brachial plexus birth injuries (BPBIs) that may improve supination and external rotation (ER) at 2 years of age. Questions were raised about the potential for the protocol to cause internal rotation (IR) deficits. The goal of this study was to explore the longer-term outcomes of the Sup-ER protocol and investigate IR/ER function. Methods: This prospective cross-sectional cohort study examined 16 children older than 4 years of age with significant enough BPBI to be treated with the Sup-ER protocol. Total shoulder and elbow function were assessed, including passive and active ranges of motion and strength of IR and ER. Results: Range of motion (ROM) for most active movements was decreased in the affected compared to unaffected arm. Notably, IR passive ROM was similar in the affected (78.7°) and unaffected arm (82.8°). External rotation strength of the affected arm was weaker (42.8 N) compared to the unaffected arm (57.9 N). IR strength had a greater deficit in the affected (43.2 N) arm compared to the unaffected arm (72.2 N), but both ER and IR showed less deficit than described in the literature. Conclusions: Despite differences in ranges of motion between the affected and unaffected arms, ROMs for the affected arm were comparable to the functional limits as reported in the literature. The Sup-ER protocol shows potential to optimize long-term shoulder rotation function in children with BPBI without compromising IR.

scholarly journals Shoulder-Rotator Strength, Range of Motion, and Acromiohumeral Distance in Asymptomatic Adolescent Volleyball Attackers

2016 ◽  
Vol 51 (9) ◽  
pp. 733-738 ◽  
Author(s):  
Gulcan Harput ◽  
Hande Guney ◽  
Ugur Toprak ◽  
Tunca Kaya ◽  
Fatma Filiz Colakoglu ◽  
...  
Keyword(s):  
Range Of Motion ◽  
High Performance ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Cross Sectional Study ◽  
Shoulder Injuries ◽  
Adolescent Athletes ◽  
Cross Sectional ◽  
Acromiohumeral Distance ◽  
External Rotator

Context: Sport-specific adaptations at the glenohumeral joint could occur in adolescent athletes because they start participating in high-performance sports in early childhood. Objective: To investigate shoulder-rotator strength, internal-rotation (IR) and external-rotation (ER) range of motion (ROM), and acromiohumeral distance (AHD) in asymptomatic adolescent volleyball attackers to determine if they have risk factors for injury. Design: Cross-sectional study. Setting: University laboratory. Participants: Thirty-nine adolescent high school-aged volleyball attackers (22 boys, 17 girls; age = 16.0 ± 1.4 years, height = 179.2 ± 9.0 cm, mass = 67.1 ± 10.9 kg, body mass index = 20.7 ± 2.6 kg/m2). Main Outcome Measure(s): Shoulder IR and ER ROM, total-rotation ROM, glenohumeral IR deficit, AHD, and concentric and eccentric strength of the shoulder internal and external rotators were tested bilaterally. Results: External-rotation ROM was greater (t38 = 4.92, P < .001), but IR ROM (t38 = −8.61, P < .001) and total ROM (t38 = −3.55, P = .01) were less in the dominant shoulder, and 15 athletes had a glenohumeral IR deficit (IR ROM loss > 18°). We observed greater concentric internal-rotator (t38 = 2.89, P = .006) and eccentric external-rotator (t38 = 2.65, P = .01) strength in the dominant than in the nondominant shoulder. The AHD was less in the dominant shoulder (t38 = −3.60, P < .001). Conclusions: Adolescent volleyball attackers demonstrated decreased IR ROM, total ROM, and AHD and increased ER ROM in their dominant shoulder. Therefore, routine screening of adolescent athletes and designing training programs for hazardous adaptive changes could be important in preventing shoulder injuries.

scholarly journals Glenohumeral Rotational Range of Motion in Collegiate Overhead-Throwing Athletes During an Athletic Season

2009 ◽  
Vol 44 (6) ◽  
pp. 611-616 ◽  
Author(s):  
Priscilla M. Dwelly ◽  
Brady L. Tripp ◽  
Patricia A. Tripp ◽  
Lindsey E. Eberman ◽  
Steven Gorin
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Ncaa Division I ◽  
Mean Difference ◽  
Division I ◽  
Shoulder Injuries ◽  
The Mean ◽  
Overhead Throwing ◽  
Division Ii ◽  
Over Time

Abstract Context: Repetitive throwing at high velocities leads to altered range of motion (ROM) in the dominant shoulder compared with the nondominant shoulder in overhead-throwing athletes. Loss of glenohumeral internal rotation (IR), or glenohumeral internal-rotation deficit (GIRD), is associated with shoulder injuries. Therefore, GIRD should be evaluated during the clinical examination of the thrower's shoulder. Objective: To assess glenohumeral ROM in competitive baseball and softball athletes at 3 intervals over the course of an athletic season in order to (1) examine changes in ROM over time and (2) monitor the prevalence of GIRD. Design: Observational, repeated-measures study. Setting: Collegiate athletic training room. Patients or Other Participants: Forty-eight healthy National Collegiate Athletic Association (NCAA) Division I or Division II athletes (age  =  19 ± 1 years, height  =  174 ± 14 cm, mass  =  77.8 ± 18.1 kg; 19 softball, 29 baseball players). Main Outcome Measure(s): We measured glenohumeral IR, external rotation (ER), total arc (ER + IR), and GIRD at 3 times: prefall, prespring, and postspring. We calculated GIRD in 2 ways: as the difference in IR between dominant and nondominant shoulders and as the percentage of the total arc. Results: In the dominant shoulder, ER increased during the season (F2,96  =  17.433, P < .001), but IR remained the same (F2,96  =  1.839, P  =  .17). The total arc in the dominant shoulder increased between time intervals (F2,96  =  14.030, P < .001); the mean difference between prefall and postspring measurements was 9.694° (P < .001), and the mean difference between prefall and postspring measurements was 10.990° (P < .001). In the nondominant shoulder, ER increased over the season (F2,96  =  23.395, P < .001), but IR did not change over the season (F2,96  =  0.087, P  =  .90). The total arc in the nondominant shoulder increased between prefall and prespring measurements and between prefall and postspring measurements (F2,96  =  18.552, P < .001). No changes were noted in GIRD over time. However, more athletes with GIRD were identified with the GIRD (IR difference) calculation in prefall (n  =  6) than in prespring (n  =  1) and postspring (n  =  4) (Cochran Q  =  5.2, P  =  .07). In addition, more athletes with GIRD were identified with the GIRD (% total arc) calculation in postspring (n  =  6) than in prefall (n  =  5) or prespring (n  =  4) (Cochran Q  =  2.6, P  =  .27). Conclusions: Healthy NCAA Division I and Division II athletes did not display changes in glenohumeral IR over an athletic season. However, they gained in ER and total arc during the season in both shoulders. Future researchers should investigate changes over multiple seasons. The 2 methods of calculating GIRD identified different athletes as having GIRD, indicating that additional investigation is warranted to determine the clinical benefits of each method.

Effect of Posterior Capsule Tightness and Humeral Retroversion on 5 Glenohumeral Joint Range of Motion Measurements: A Cadaveric Study

2019 ◽  
Vol 47 (6) ◽  
pp. 1434-1440 ◽  
Author(s):  
Dayana P. Rosa ◽  
Paula R. Camargo ◽  
John D. Borstad
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Posterior Capsule ◽  
Joint Range Of Motion ◽  
Motion Measurements ◽  
Humeral Retroversion ◽  
Clinical Measurements ◽  
Joint Range

Background: Altered glenohumeral joint range of motion can be caused by increased humeral retroversion (HR) and/or posterior capsule tightness (PCT). To make informed clinical decisions, it is vital to understand how HR and PCT alterations, individually and in combination, affect joint range of motion measurements. Purpose: To evaluate the effect of experimental tissue alterations on clinical range of motion measures. Study Design: Controlled laboratory study. Methods: Five clinical measurements were quantified in 8 fresh-frozen cadavers under 4 experimentally created conditions: baseline (no alterations), HR condition (20° increase in HR by transecting the bone), PCT condition (20% decrease in length via thermal energy), and PCT + HR combined. Clinical measurements included bicipital forearm angle, low flexion, glenohumeral internal and external rotation, and horizontal adduction. All measurements were taken by the same blinded tester. Separate 1-factor repeated measures analyses of variance were used to evaluate the effect of the alterations on each clinical measurement. Results: There was a significant main effect of condition for bicipital forearm angle ( P = .02, F = 4.03), low flexion ( P = .02, F = 3.86), internal rotation ( P = .03, F = 3.65), and external rotation ( P < .001, F = 15.15) but not for horizontal adduction ( P = .29, F = 1.33). The HR condition resulted in a decreased bicipital forearm angle of 16.1° and 15.8° as compared with the PCT and PCT + HR conditions, respectively. When compared with baseline, the PCT + HR condition decreased the low flexion test by 13.5°, and the HR condition decreased internal rotation range of motion by 14.2°. All conditions increased external rotation when compared with baseline. Conclusion: Greater measurement changes were noted in both HR conditions, suggesting that bony alterations influence motion to a greater extent than posterior capsule alterations. Clinical Relevance: Clinicians should be aware that humeral retroversion will influence the measurement of posterior shoulder tightness.

scholarly journals Dominant-Limb Range-of-Motion and Humeral-Retrotorsion Adaptation in Collegiate Baseball and Softball Position Players

2014 ◽  
Vol 49 (4) ◽  
pp. 507-513 ◽  
Author(s):  
Elizabeth E. Hibberd ◽  
Sakiko Oyama ◽  
Justin Tatman ◽  
Joseph B. Myers
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Athletic Training ◽  
External Rotation ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Baseball Players ◽  
Glenohumeral Internal Rotation Deficit ◽  
Total Range ◽  
Collegiate Baseball

Context: Biomechanically, the motions used by baseball and softball pitchers differ greatly; however, the throwing motions of position players in both sports are strikingly similar. Although the adaptations to the dominant limb from overhead throwing have been well documented in baseball athletes, these adaptations have not been clearly identified in softball players. This information is important in order to develop and implement injury-prevention programs specific to decreasing the risk of upper extremity injury in softball athletes. Objective: To compare range-of-motion and humeral-retrotorsion characteristics of collegiate baseball and softball position players and of baseball and softball players to sex-matched controls. Design: Cross-sectional study. Setting: Research laboratories and athletic training rooms at the University of North Carolina at Chapel Hill. Patients or Other Participants: Fifty-three collegiate baseball players, 35 collegiate softball players, 25 male controls (nonoverhead athletes), and 19 female controls (nonoverhead athletes). Intervention(s): Range of motion and humeral retrotorsion were measured using a digital inclinometer and diagnostic ultrasound. Main Outcome Measure(s): Glenohumeral internal-rotation deficit, external-rotation gain, total glenohumeral range of motion, and humeral retrotorsion. Results: Baseball players had greater glenohumeral internal-rotation deficit, total–range-of-motion, and humeral-retrotorsion difference than softball players and male controls. There were no differences between glenohumeral internal-rotation deficit, total–range-of-motion, and humeral-retrotorsion difference in softball players and female controls. Conclusions: Few differences were evident between softball players and female control participants, although range-of-motion and humeral-retrotorsion adaptations were significantly different than baseball players. The throwing motions are similar between softball and baseball, but the athletes adapt to the demands of the sport differently; thus, stretching/strengthening programs designed for baseball may not be the most effective programs for softball athletes.

Rotational Motion Changes in the Glenohumeral Joint of the Adolescent/Little League Baseball Player

2005 ◽  
Vol 33 (5) ◽  
pp. 693-698 ◽  
Author(s):  
Keith Meister ◽  
Timothy Day ◽  
Marybeth Horodyski ◽  
Thomas W. Kaminski ◽  
Michael P. Wasik ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Rotational Motion ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Age Groups ◽  
Baseball Player ◽  
Cross Sectional ◽  
Little League ◽  
Total Range

Background Differences in range of motion and rotational motion between the dominant and nondominant shoulders in throwing athletes are well documented, although the age at which these changes begin to occur is not known. Hypothesis Changes in glenohumeral rotational motion in the shoulder of the Little League/adolescent baseball player occur during the most formative years of physical development. Study Design Cross-sectional study. Methods Elevation, internal rotation at 90° of abduction, and external rotation at 90° of abduction were measured in the dominant and nondominant shoulders of 294 baseball players, aged 8 to 16 years. Results Analysis of variance revealed 2-way interactions between arm dominance by age for elevation (P =. 005) and internal rotation (P =. 001). Significant differences were noted between dominant and nondominant arms for internal rotation at 90° (P =.001) and external rotation at 90° (P =. 001). Elevation, internal rotation at 90°, external rotation at 90°, and total range of motion varied significantly (P =. 001) among age groups. Elevation in the dominant arms of 16-year-olds was on average 5.3° less than in 8-year-olds (179.6° vs 174.3°). In the nondominant arms, mean elevation for 16-year-olds was 5.6° less than in 8-year-olds (179.7° vs 174.1°). Internal rotation at 90° for the dominant arms averaged 39.0° at age 8 and only 21.3° at age 16. In the non-dominant arms, internal rotation for 8-year-olds averaged 42.2° and only 33.1° for 16-year-olds. Conclusions Elevation and total range of motion decreased as age increased. These changes may be consequences of both bone and soft tissue adaptation. The most dramatic decline in total range of motion was seen between the 13-year-olds and 14-year-olds, in the year before peak incidence of Little Leaguer's shoulder. This decrease in rotational motion may cause increased stress at the physis during throwing.

Shoulder Range of Motion Deficits in Youth Throwers Presenting With Elbow Pain

2021 ◽  
pp. 194173812110363
Author(s):  
Michael Rosen ◽  
Karim Meijer ◽  
Scott Tucker ◽  
C. Luke Wilcox ◽  
Hillary A. Plummer ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
External Rotation ◽  
Group Versus ◽  
Control Group ◽  
Pain Group ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Elbow Pain ◽  
Shoulder Range Of Motion

Background: Glenohumeral internal rotation deficit (GIRD) and total arc of motion difference (TAMD) have been associated with elbow injuries in throwing athletes. Hypothesis: Youth pitchers with elbow pain will have greater GIRD and TAMD compared with youth pitchers without elbow pain. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: Glenohumeral range of motion of 25 consecutive throwing athletes presenting with elbow pain and that of a matched control group of 18 asymptomatic throwing athletes were compared. Bilateral glenohumeral internal rotation, external rotation, and horizontal adduction at 90° were measured and GIRD and TAMD were then calculated. An analysis of variance was performed to compare range of motion between throwers with and without elbow pain. Results: The average GIRD of the elbow pain group was 32.7° compared with 14.5° in the control group ( P < 0.05). The average TAMD in the elbow pain group was 28.3° compared with 6.7° in the control group ( P < 0.05). GIRD and TAMD were present in 88% (22 of 25) and 96% (24 of 25) of the elbow pain group versus 33.3% (6 of 18) and 55.6% (10 of 18) of the control group, respectively. Conclusion: Compared with asymptomatic youth pitchers, those presenting with elbow pain have a statistically significant GIRD and TAMD. Clinical Relevance: This study suggests that a GIRD and TAMD may predispose youth pitchers to present with symptomatic elbow pain.

Range of motion and muscle function on shoulder joints of young handball athletes

2021 ◽  
pp. 1-7
Author(s):  
Luis Ceballos-Laita ◽  
Alberto Pérez-Manzano ◽  
Teresa Mingo-Gómez ◽  
Ignacio Hernando-Garijo ◽  
Ricardo Medrano-De-La-Fuente ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Muscle Function ◽  
External Rotation ◽  
Posterior Part ◽  
Cross Sectional Study ◽  
Control Group ◽  
Cross Sectional ◽  
Shoulder Range Of Motion ◽  
Rotation Strength

BACKGROUND: The detection of primary risk factors through the assessment of shoulder range of motion (ROM) and muscle function could prevent injuries in the initial stages of the handball (HB) practice. OBJECTIVE: To compare shoulder ROM, muscle strength and muscle extensibility between throwing and non-throwing shoulders in young HB athletes and between non-HB athletes. METHODS: A cross-sectional study was designed. Participants aged between 14–16 years that practice physical activity regularly were included and divided in two groups. The HB group included volunteers who practiced HB, the control group included volunteers who practiced other activities. The variables measured were internal rotation and external rotation ROM, maximum isometric strength, and extensibility of the tissues of the posterior part of the throwing and non-throwing shoulder. RESULTS: Thirty-seven subjects were included. The HB group (n= 19) showed greater ROM in both shoulders compared to the control group (n= 18) (p< 0.05). The throwing shoulder of the HB group showed less internal rotation ROM, greater external rotation ROM and greater internal rotation strength when compared to the non-throwing shoulder (p< 0.05). CONCLUSIONS: The results of the study suggest that young HB athletes present differences in shoulder ROM compared to non-HB athletes. Also, HB athletes showed differences in ROM and strength between the TS and non-TS. Hence, the assessment of the shoulder ROM and muscle function should be taken into consideration to avoid injuries in this population.

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

2021 ◽  
Author(s):  
Tomonobu Ishigaki ◽  
Motoki Hirokawa ◽  
Yuya Ezawa ◽  
Masanori Yamanaka
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
External Rotation ◽  
Pearson Correlation ◽  
Supraspinatus Tendon ◽  
Shoulder Injuries ◽  
Baseball Players ◽  
Collegiate Baseball ◽  
Tendon Thickness ◽  
College Baseball

AbstractBaseball 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.

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