Relationships Between Lower Extremity Power and Fastball Spin Rate and Ball Velocity in Professional Baseball Pitchers.

ABSTRACT: Wong, R, Laudner, K, Amonette, W, Vazquez, J, Evans, D, and Meister, K. Relationships between lower extremity power and fastball spin rate and ball velocity in professional baseball pitchers. J Strength Cond Res 37(4): 823-828, 2023-Lower extremity power has been hypothesized to increase ball spin and velocity during pitching in baseball. Therefore, the purpose of this study was to determine the relationship between lower extremity power and fastball spin rate in professional baseball pitchers. A secondary purpose was to determine the relationship between lower extremity power and ball velocity. Fifty-three asymptomatic professional pitchers participated (24.5 ± 3.6 years; 189.9 ± 6.1 cm; 92.6 ± 10.3 kg). Each athlete performed 3 separate bilateral jump tests on force plates: countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). The average fastball spin rate and ball velocity for each pitcher was calculated using a 3-dimensional Doppler radar and video system over the course of a competitive season. Standard multiple regression analyses ( p ≤ 0.05) revealed significant relationship between ball spin and summation of variables for the CMJ (peak force, peak power, rate of power development, and jump height) ( R2 = 0.20, F = 3.1, p = 0.03). However, no individual variable was significantly associated ( p > 0.09). There was also a significant amount of variance in ball spin explained by summation of variables for the SJ (peak force, peak power, rate of power development, and jump height) ( R2 = 0.19, F = 2.8, p = 0.04); rate of power development was the only variable that significantly predicted ball spin within this model ( B = 0.27; 95% confidence interval [CI]: 0.003-0.75, p = 0.05). Ball spin was not associated with summation of DJ variables (peak power, rate of power development, jump height, reactive strength index, and total peak power in watts) ( R2 = 0.18, F = 2.0, p = 0.09). For ball velocity, there were no significant relationships for the summation of either the CMJ variables ( R2 = 0.10, p = 0.28) or the SJ variables ( R2 = 0.07, p = 0.44). However, there was a significant amount of variance in ball velocity explained by summation of variables for the DJ ( R2 = 0.30, F = 3.93, p = 0.005). The reactive strength index was the sole unique contribution to this model ( B = 1.18; 95% CI: -10.34 to 2.36, p = 0.002). These findings highlight the relevance of increased lower extremity power on increasing fastball spin rate and ball velocity.

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

BACKGROUND: Decreased glenohumeral (GH) horizontal adduction range of motion (ROM) among baseball pitchers has been associated with the development of various shoulder and elbow pathologies. No research has examined how this tightness may affect the forces placed on the shoulder and elbow during the pitching motion. METHODS: Fifty-five asymptomatic National Collegiate Athletic Association Division I baseball pitchers participated. Twenty-five participants had -10° or less horizontal adduction ROM in their throwing shoulder. The remaining 30 participants had greater than -10° of horizontal adduction. A digital inclinometer was used to measure GH horizontal adduction, internal rotation, and external rotation ROM while in 90° of shoulder abduction. Forces produced in the throwing shoulder and elbow were assessed with a 3-dimension, high-speed video capture system and based on the sum of angular momenta of the kinetic chain segments around the center of gravity. Separate 2-tailed t tests were run to determine significant differences between groups (P < .05). RESULTS: Both groups presented with significant bilateral differences in their total arcs of motion (P < .04). This suggests that the loss of horizontal adduction in these groups was at least partially due to soft tissue tightness. There were no significant between-group differences for shoulder external rotation torque or shoulder and elbow distraction (P > .10). The restricted ROM group had significantly more shoulder abduction torque (P = .04), shoulder horizontal abduction torque (P = .004), elbow flexion torque (P = .002), and elbow valgus torque (P = .02) compared with the control group. CONCLUSIONS: These results demonstrate that collegiate pitchers with -10° or less of horizontal adduction ROM in their throwing shoulder create significantly more shoulder abduction and horizontal abduction torque, as well as more elbow flexion and valgus torque, during the pitching motion than those with more ROM.

Relationships Between Clinically Measured Upper-Extremity Physical Characteristics and Ball Spin Rate in Professional Baseball Pitchers.

ABSTRACT: Wong, R, Laudner, K, Evans, D, Miller, L, Blank, T, and Meister, K. Relationships between clinically measured upper-extremity physical characteristics and ball spin rate in professional baseball pitchers. J Strength Cond Res 35(5): 1331-1337, 2021-During baseball pitching, physical characteristics of the shoulder, elbow, wrist, hand, and fingers have been hypothesized to be critical to creating ball spin. The purpose of this study was to determine if pitchers with greater shoulder, elbow, wrist, and finger range of motion (ROM), arm and hand length, wrist strength, or grip and finger strength would produce greater ball spin than those with less physical characteristics. Ninety, asymptomatic, professional baseball pitchers participated (age = 24.5 ± 3.9 years; height = 189.9 ± 6.1 cm; body mass = 92.6 ± 10.6 kg). Goniometers and a digital level were used to measure shoulder, elbow, wrist, and finger ROM, a tape measure was used to assess arm and hand lengths, and handheld dynamometers were used to measure wrist, grip, and finger strength. Ball spin was measured using a 3-dimensional Doppler radar and video system. Standard multiple regression analyses showed no significant relationships existed between ball spin and any of the upper-extremity ROM or limb length variables (R2 = 0.01-0.03; p = 0.40-0.94). However, there was a significant relationship for the summation of wrist strength (R2 = 0.24, p = 0.03). Both time to wrist extension strength {B = 0.50 (95% confidence interval [CI]: 0.23-0.76), p = 0.001} and radial deviation strength (B = 0.41 [95% CI: 0.15-0.66], p = 0.002) were significant predictors within this model. These results demonstrate that the rate of ball spin during a pitch may be partially altered by increasing wrist extension acceleration and radial deviation strength. However, the subsequent clinical measurements of shoulder, elbow, wrist, and finger ROM, arm and hand length, and grip and finger strength were not associated with ball spin.

The influence of lumbopelvic control on shoulder and elbow kinetics in elite baseball pitchers.

BACKGROUND: Research has shown that diminished lumbopelvic control has a negative effect on pitching performance and can lead to more days on the disabled list. Despite the identified correlation between lumbopelvic control and injury, there is no research that has shown whether insufficient lumbopelvic control increases the force placed on the throwing arm. METHODS: Forty-three asymptomatic, National Collegiate Athletic Association Division I and professional minor league baseball pitchers participated. We measured the bilateral amount of anterior-posterior lumbopelvic tilt during a single-leg stance trunk stability test. We measured the shoulder and elbow kinetics of the throwing arm during the pitching motion using a 3-dimensional, high-speed video capture system. We used 2-tailed Pearson product-moment correlation coefficients (r) to determine the strength of the relationships between variables (P < .05). RESULTS: There were no significant relationships between the stride leg and any of the pitching kinetic variables (r < 0.23, P > .14). Similarly, there were no significant relationships between the drive leg and maximum shoulder distraction force, shoulder external rotation torque, or elbow distraction force (r <-0.24, P > .13). However, the drive leg did have significant relationships with both maximum shoulder horizontal torque (r = 0.44, P = .003) and elbow valgus torque (r = 0.46, P = .002). CONCLUSIONS: Our results show that a relationship exists between lumbopelvic control of the drive leg and both shoulder horizontal torque and elbow valgus torque during the throwing motion. Because of these relationships, clinicians should consider incorporating lumbopelvic control training exercises to minimize the kinetic force placed on the throwing shoulder and elbow during the pitching motion.

Descriptive Profile of Lumbopelvic Control in Collegiate Baseball Pitchers.

Laudner, K, Wong, R, Latal, J, and Meister, K. Descriptive profile of lumbopelvic control in collegiate baseball pitchers. J Strength Cond Res 32(4): 1150-1154, 2018-Throwing a baseball requires the transmission of forces generated in the lower extremity, through the trunk, then to the upper extremity, and ultimately out through the ball. Disruptions in this kinetic chain, specifically in lumbopelvic control, have been associated with decreased pitching performance and increased risk of injury. The purpose of this study was to establish normative data of lumbopelvic control among collegiate baseball pitchers. Data were compared bilaterally and with a group of nonthrowing physically active individuals. Eighteen asymptomatic pitchers and 30 nonthrowing subjects participated in this study. Each subject performed 6 separate tests bilaterally: single-leg balance, single-leg mini-squat, and static single-leg bridge. An iPod-based tilt sensor was placed around the waist of each subject and used to determine the amount of anterior-posterior lumbopelvic tilt during each test. Independent t tests showed that neither group had any bilateral differences in lumbopelvic control (p > 0.10). The groups had similar lumbopelvic tilt values during the single-leg balance (p > 0.08) and mini-squat tests (p > 0.72), but a significant difference during the bridge maneuver. For this test, the pitchers had less lumbopelvic control than the control group for both the lead leg (p = 0.003) and trail leg (p = 0.01). The descriptive values of this study may assist in designing lumbopelvic conditioning programs with the intent of enhancing pitching performance, as well as in the prevention, evaluation, and treatment of various injuries associated with lumbopelvic control deviations.

Strong Correlation of Upper-Extremity Blood-Flow Volume With Grip Strength While in a Provocative Shoulder Position in Baseball Pitchers.

CONTEXT: Baseball players, specifically pitchers, with symptomatic neurovascular occlusion often initially complain of arm fatigue and loss of ball control and velocity. As the compression continues complaints may manifest in dull pain, paresthesia, and decreased grip strength. OBJECTIVE: To determine the correlation between upper-extremity blood-flow volume and grip strength among baseball pitchers. DESIGN: Cross-sectional. SETTING: Athletic training room. PARTICIPANTS: 66 professional baseball pitchers (age 21.6 ± 2.0 y, height 186.9 ± 5.7 cm, mass 91.3 ± 10.9 kg) before the start of spring training. MAIN OUTCOME MEASURES: Diagnostic ultrasound was used to measure upper-extremity blood-flow volume with the throwing shoulder in a resting position and in a provocative position. Grip strength was measured with participants seated and their throwing-arm elbow flexed to 90°. Pearson product-moment correlation coefficients were used to determine the strength of the relationships between blood-flow volume in the 2 arm positions and grip strength (P < .05). RESULTS: No significant relationship was found between blood-flow volume in the resting position and grip strength (r = .03, P = .81); however, a strong positive correlation was found in the 2nd provocative position (r = .67, P = .001). This relationship indicates that as blood-flow volume tested in a provocative shoulder position decreases, so does grip strength. CONCLUSION: A strong positive relationship was found in pitchers, demonstrating that as upper-extremity blood-flow volume while in the provocative shoulder position decreases, so does grip strength.

Upper extremity blood flow changes in professional baseball pitchers between two consecutive seasons.

BACKGROUND: Because of the tremendous forces produced and the repetitive nature of baseball, players have shown various shoulder adaptations in strength and range of motion. However, no research has identified whether alterations occur in the blood flow to the dominant arm among competitive baseball players. METHODS: Twenty professional baseball pitchers and 16 position players participated. Measurements were taken on day 1 of 2 consecutive spring training seasons. Diagnostic ultrasound was used to measure blood flow of the throwing arm brachial artery. These measurements were taken in a standing position with the test arm resting at the participant's side and again with the test arm in a provocative shoulder position. Separate 1-way analyses of variance were conducted to compare blood flow between seasons (P < .05). RESULTS: In a resting position, the blood flow of the pitchers did not change from 1 year to the next (P = .48). However, blood flow of the pitchers in the provocative position significantly decreased after the first year (P = .009). The position players did not have any significant changes in blood flow for either arm position (P > .11). CONCLUSIONS: In a provocative shoulder position, the blood flow of pitchers significantly decreased after 1 competitive baseball season. These results indicate that after a competitive season, the blood flow to the upper extremity of pitchers may be compromised.

Decreased blood flow in the throwing arm of professional baseball pitchers.

BACKGROUND: As a consequence of the repetitive forces placed on the throwing arm of a baseball player, various bony, capsuloligamentous, and muscular adaptations occur and have been identified. However, no research has identified whether adaptations also exist in the vasculature of the upper extremity in the competitive baseball player. METHODS: Fifty-one professional baseball pitchers and 34 position players participated. Diagnostic ultrasound was used to measure bilateral blood flow of the brachial artery. These measurements were taken with the participant standing with the test arm resting at the participant's side and again with the test arm in a provocative shoulder position. RESULTS: The throwing arm of the pitchers had significantly less blood flow volume when in the provocative shoulder position compared with their nonthrowing arm (P = .01). Pitchers did not have any bilateral difference while in the resting position (P = .19). There were no bilateral differences among the position players while in the resting (P = .64) or provocative positions (P = .63). Pitchers had significantly less blood flow of the throwing shoulder while in the provocative position compared with position players (P = .02). There were no other between-group differences. CONCLUSIONS: While in a provocative shoulder position, pitchers have significantly less blood flow in their throwing arm compared with their nonthrowing arm and with the throwing arm of position players. These results provide a descriptive profile of blood flow volume among baseball players, which may be used in the evaluation and treatment of such athletes with vascular disorders.

Shoulder adaptations among pitchers and position players over the course of a competitive baseball season.

OBJECTIVE: To determine if throwing arm shoulder range of motion (ROM) and scapular kinematic differences exist between baseball pitchers and position players over the course of a baseball season. DESIGN: Prospective cohort. SETTING: Professional baseball athletic training room. PARTICIPANTS: Sixteen asymptomatic professional baseball pitchers and 16 position players. INDEPENDENT VARIABLES: Preseason glenohumeral (GH) posterior tightness and scapular position. MAIN OUTCOME MEASURES: Throwing arm GH horizontal adduction ROM and GH internal rotation bilateral asymmetry ROM, as well as bilateral differences in forward scapular posture and throwing arm scapular upward rotation at rest, 60, 90, and 120 degrees of humeral elevation were measured. These measurements were taken before and at the conclusion of a 140-game baseball season. RESULTS: Analyses of covariances showed no significant differences in GH horizontal adduction or internal rotation asymmetry ROM between groups over the course of the season. However, the pitchers developed significantly less scapular upward rotation at 60 degrees (P = 0.007) and 90 degrees (P = 0.006) of humeral elevation compared with the position players during the season. Forward scapular posture (P = 0.23) and scapular upward rotation at 0 degrees (P = 0.93) and 120 degrees (P = 0.29) of humeral elevation were not significantly different between groups. CONCLUSIONS: These results suggest that baseball position players develop more scapular upward rotation over the course of a competitive season than pitchers. This discrepancy may increase the pitchers' risk of injury and may partially explain their higher incidence of shoulder injury compared with position players. Therefore, pitchers may benefit from strengthening exercises and stretches aimed at increasing scapular upward rotation throughout the competitive baseball season.

The relationship between anterior glenohumeral laxity and proprioception in collegiate baseball players.

OBJECTIVE: To determine if a relationship exists between anterior glenohumeral (GH) laxity and proprioception. DESIGN: Cross-sectional study. SETTING: University biomechanics laboratory. PARTICIPANTS: Thirty asymptomatic collegiate baseball players. INDEPENDENT VARIABLES: Anterior GH laxity. MAIN OUTCOME MEASURES: Proprioception (active joint position sense) at positions of 75 degrees of external rotation, 30 degrees of external rotation, and 30 degrees of internal rotation were measured using an isokinetic dynomometer. Anterior GH laxity was measured using an instrumented arthrometer. RESULTS: Linear regression analyses showed that there were no relationships between anterior GH laxity and active joint position sense at 30 degrees of GH internal rotation and 30 degrees of GH external rotation (r = 0.21, P = 0.13). However, there was a moderate positive relationship between anterior GH laxity and joint position sense at 75 degrees of shoulder external rotation (r = 0.56, P = 0.001). CONCLUSIONS: These results suggest that shoulder proprioception in 75 degrees of external rotation decreases as anterior GH laxity increases. These results may prove beneficial in the prevention, evaluation, and treatment of various shoulder injuries associated with GH laxity.

Lack of a relationship between glenohumeral external-rotation strength and posterior shoulder tightness in baseball players.

CONTEXT: Posterior shoulder tightness has been associated with altered shoulder range of motion (ROM) and several pathologic entities in baseball players. This tightness is hypothesized to be the result of the cumulative stress placed on the posterior shoulder during the deceleration phase of the throwing motion. The role of the posterior shoulder static restraints is to absorb this load while the glenohumeral (GH) external rotators eccentrically decelerate the arm after ball release and therefore also help dissipate this force. As such, the authors hypothesized that if the GH external rotators are weak, an excessive amount of this deceleration force is placed on the static restraints, which may lead to subsequent tightness. OBJECTIVE: To compare the relationship between GH external-rotation strength and posterior shoulder tightness as measured by GH horizontal-adduction and internal-rotation ROM. DESIGN: Descriptive study. SETTING: Laboratory. PARTICIPANTS: 45 professional baseball players. MAIN OUTCOME MEASURES: GH external-rotation strength and GH horizontal-adduction and internal-rotation ROM. RESULTS: GH external-rotation strength showed no relationship with either GH horizontal-adduction ROM (r2 = .02, P = .40) or GH internal-rotation ROM (r2 = .002, P = .77). CONCLUSION: There is little to no relationship between GH external-rotation strength and posterior shoulder tightness in professional baseball players. The posterior static restraints of the shoulder may absorb a large majority of the deceleration forces during the throwing motion. Although strengthening of the posterior shoulder dynamic restraints should not be overlooked, routine stretching of the static restraints may be more beneficial for decreasing posterior shoulder tightness and the subsequent risks associated with this tightness, although future research is warranted.

Lumbopelvic Control and the Development of Upper Extremity Injury in Professional Baseball Pitchers.

BACKGROUND: The baseball-throwing motion requires a sequential order of motions and forces initiating in the lower limbs and transferring through the trunk and ultimately to the upper extremity. Any disruption in this sequence can increase the forces placed on subsequent segments. No research has examined if baseball pitchers with less lumbopelvic control are more likely to develop upper extremity injury than pitchers with more control. PURPOSE: To determine if baseball pitchers who sustain a chronic upper extremity injury have less lumbopelvic control before their injury compared with a group of pitchers who do not sustain an injury. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 49 asymptomatic, professional baseball pitchers from a single Major League Baseball organization participated. Lumbopelvic control was measured using an iPod-based digital level secured to a Velcro belt around each player's waist to measure anteroposterior (AP) and mediolateral (ML) deviations (degrees) during single-leg balance with movement and static bridge maneuvers. During a competitive season, 22 of these pitchers developed upper extremity injuries, while the remaining 27 sustained no injuries. Separate 2-tailed t-tests were run to determine if there were significant differences in lumbopelvic control between groups (P < .05). RESULTS: There were no significant between-group differences for the stride leg (nondominant) during the bridge test in either the AP (P = .79) or the ML (P = .42) directions, or either direction during the drive leg bridge test (P > .68). However, the injured group had significantly less lumbopelvic control than the noninjured group during stride leg balance in both the AP (P = .03) and the ML (P = .001) directions and for drive leg balance in both the AP (P = .01) and the ML (P = .04) directions. CONCLUSION: These results demonstrate that baseball pitchers with diminished lumbopelvic control, particularly during stride leg and drive leg single-leg balance with movement, had more upper extremity injuries than those with more control. Clinicians should consider evaluating lumbopelvic control in injury prevention protocols and provide appropriate exercises for restoring lumbopelvic control before returning athletes to competition after injury. Specific attention should be given to testing and exercises that mimic a single-limb balance task.

POSTERIOR SHOULDER TIGHTNESS AND SUBACROMIAL IMPINGEMENT CHARACTERISTICS IN BASEBALL PITCHERS: A BLINDED, MATCHED CONTROL STUDY.

BACKGROUND: Baseball pitchers frequently develop varying levels of posterior shoulder tightness (PST) and often present with characteristics associated with subacromial impingement. PURPOSE: To determine if a group of baseball pitchers with excessive PST (bilateral internal rotation ROM difference >18 ° and bilateral total arc of motion difference >5 °) have differences in subacromial joint space, forward scapular posture, or glenohumeral elevation range of motion (ROM) when compared to a control group. STUDY DESIGN: Descriptive, cross-sectional study. METHODS: Thirty-five asymptomatic professional baseball pitchers with excessive PST were matched with 35 pitchers with acceptable levels of PST. The investigators measured subacromial space using diagnostic ultrasound, glenohumeral elevation ROM using a digital goniometer, and scapular posture using a double square, and were blinded to the group of each participant. Separate t-tests were used to determine significant differences between groups (p < 0.05). RESULTS: The excessive PST group presented with significantly less subacromial space (p = .0007) and glenohumeral elevation ROM (p = .03) compared to the acceptable level PST group. The excessive PST group also had significantly more forward scapular posture than the control group (p = .03). CONCLUSION: The baseball pitchers with excessive PST had less subacromial space and glenohumeral elevation ROM, as well as more forward scapular posture in their throwing arms compared to pitchers with acceptable levels of PST. LEVEL OF EVIDENCE: 3.

Lower-extremity ground reaction forces in youth windmill softball pitchers.

Ground reaction forces are important in pitching given that the only external contact a pitcher has is between the foot and the ground. Windmill softball pitchers are routinely seen clinically for injuries to the lower extremities, and lower-extremity kinetics have not been well studied. The purpose of this study was to investigate the relationships between ground reaction forces and throwing mechanics in youth windmill pitchers and to provide a scientific basis for the improvement of preventive and rehabilitative protocols. Fifty-three youth softball pitchers were tested in an indoor facility. High-speed video and force plate data were collected for fastballs from each pitcher. Average ball speed was 25 m/sec. Peak vertical ground reaction force averaged 139 % body weight (BW), peak anterior force averaged 24 %BW, and the medially directed component of the ground reaction force averaged 42 %BW. Loading rates to peak force in all 3 directions were high. Preventive and rehabilitative protocols for windmill softball pitchers can begin to be improved on the basis of knowledge of the magnitudes and times to peak forces under the stride foot.

Relationships between ball velocity and throwing mechanics in collegiate baseball pitchers.

Although ball speed is considered a measure of success in baseball pitching, little is known about the relationship between ball velocity and pitching mechanics. Investigation of this relationship has been limited, and the studies carried out have varied in methodology. Three-dimensional, high-speed (240 Hz) video data were collected on fastballs from 54 collegiate baseball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing shoulder and elbow were calculated. Multiple linear regression analysis was used to relate ball velocity and pitching mechanics. Ball velocity averaged 35 m/sec (79 mph) for the 54 college pitchers. Nearly 70% of the variability in ball speed can be explained by a combination of 10 parameters related to pitching mechanics. Body mass and 9 temporal and kinematic parameters related to pitching mechanics combine to account for 68% of the variance in ball velocity for a collegiate population of athletes. These variables can be manipulated via mechanical changes and sport-specific training to affect ball velocity. The results of the study can be used to increase ball velocity while at the same time minimizing stresses on the throwing arm elbow and shoulder. Improved training programs can begin to be developed based on these data.

Assessing posterior shoulder contracture: the reliability and validity of measuring glenohumeral joint horizontal adduction.

CONTEXT: Increased contracture of the dominant posterior shoulder in throwing athletes has been associated with the development of altered shoulder rotational motion as well as several shoulder conditions. Clinicians must be able to accurately and reliably measure posterior shoulder contractures during the evaluation of such athletes in order to provide appropriate treatment. OBJECTIVE: To evaluate the reliability and validity of assessing posterior shoulder contracture by measuring supine glenohumeral (GH) horizontal adduction. DESIGN: Descriptive with repeated measures. SETTING: The biomechanics laboratory at Illinois State University (Normal, IL) and the athletic training room in Surprise, AZ. PATIENTS OR OTHER PARTICIPANTS: Twenty-four shoulders were tested in 12 subjects (age = 21.9 +/- 4.3 years, height = 175.0 +/- 10.0 cm, mass = 82.4 +/- 19.1 kg) for determination of reliability, and 46 shoulders were tested in 23 professional baseball pitchers (age = 21.25 +/- 1.66 years, height = 190.0 +/- 5.0 cm, mass = 88.45 +/- 6.99 kg) for determination of validity. MAIN OUTCOME MEASURE(S): We examined intratester and intertester reliability over 3 testing sessions by having 2 examiners measure GH horizontal adduction with the subject in a supine position with the scapula stabilized. To determine the validity and clinical usefulness of this measurement, we examined the relationship between GH horizontal adduction motion and internal shoulder rotational motion among a group of baseball pitchers. RESULTS: Intraclass correlation coefficients were high for intratester (0.93, SEM = 1.64 degrees ) and intertester (0.91, SEM = 1.71 degrees ) measurements. This measurement was also shown to have a moderate to good relationship with lost internal shoulder rotational motion ( r = .72, P = .001) of the dominant arm among the baseball pitchers. CONCLUSIONS: Based on the results of this study, we found that measuring GH horizontal adduction with the subject supine and the scapula stabilized is a reliable and valid technique for assessing posterior shoulder contracture.

Epidemiology and Impact of Knee Injuries in Major and Minor League Baseball Players.

Few studies have explored the frequency and impact of lower extremity injuries, such as those to the knee, among professional baseball players. The purpose of this study was to detail the epidemiology of knee injuries in Major League Baseball (MLB) and Minor League Baseball (MiLB) players during the 2011-2014 seasons. It was hypothesized that knee injuries are a common occurrence in these athletes, and represent a significant source of time away from play. The MLB Health and Injury Tracking System database was searched to identify all patients diagnosed with knee injuries during the 2011-2014 seasons. All injuries that occurred during the preseason, regular season, and postseason that resulted in time away from play were included. Injury data analyzed included total number of knee injuries, specific diagnoses, injury mechanisms, locations, player positions, and time lost. Descriptive statistics were conducted and injury rates per athlete-exposures were calculated. During the 2011-2014 seasons, a total of 2171 knee injuries occurred in MLB and MiLB players, representing 6.5% of all injuries in professional baseball. The knee injury rate across both the MLB and MiLB was 1.2 per 1000 athlete-exposures. The mean number of days missed per injury across both leagues was 16.2 with a total of 30,449 days of missed play amongst all athletes over the 4 seasons. Injuries to the knee were the fifth most common cause of missed time in all of baseball, and the fourth most common reason for missed games in the MLB alone. Approximately 12% of all injuries required surgical intervention. The most common mechanism of injury was noncontact (44%), and base runners were injured more frequently than any other position (24%). The infield (30%) and home plate (23%) were the most common locations in which injuries occurred. These data can be utilized for targeted injury prevention initiatives.

Sonographic stress measurement of glenohumeral joint laxity in collegiate swimmers and age-matched controls.

BACKGROUND: Glenohumeral laxity that is greater than normal has been implicated as a causal factor in the development of shoulder pain and dysfunction in elite swimmers; however, quantitative evidence demonstrating greater-than-normal glenohumeral joint laxity in swimmers is lacking. OBJECTIVE: To quantify glenohumeral joint laxity in elite swimmers and nonswimming controls using stress sonography. STUDY DESIGN: Controlled laboratory study. METHODS: Force-displacement measures were performed bilaterally in 42 National Collegiate Athletic Association Division I swimmers and 44 age-matched controls. Of the 42 swimmers, 27 (64%) reported a history of unilateral or bilateral shoulder pain resulting from swimming. Ultrasound imaging was used to measure glenohumeral joint displacement under stressed and non-stressed conditions. RESULTS: An analysis of variance revealed no significant difference in glenohumeral joint displacement between swimmers (anterior, 2.82 +/- 1.7 mm; posterior, 5.30 +/- 2.4 mm) and age-matched controls (anterior, 2.74 +/- 1.7 mm; posterior, 4.90 +/- 2.7 mm). No significant difference in glenohumeral joint displacement was found between swimmers with a history of shoulder pain (anterior, 2.90 +/- 1.6 mm; posterior, 5.42 +/- 2.3 mm) versus swimmers without a history of shoulder pain (anterior, 2.74 +/- 1.8 mm; posterior, 5.14 +/- 2.6 mm). Shoulders displayed significantly more glenohumeral joint displacement in the posterior direction compared to the anterior direction (P < .001). CONCLUSIONS: Our instrumented technique was unable to identify significantly greater glenohumeral joint displacement in elite swimmers compared to nonswimming controls, and elite swimmers with a history of shoulder pain were not found to have significantly more glenohumeral joint displacement compared to swimmers without a history of shoulder pain. CLINICAL RELEVANCE: Objective assessment of glenohumeral joint displacement in athletes participating in overhead-motion sports may be important for injury prevention and management.