Pitcher Research Articles

大学野球投手の投球課題前後での肩関節内旋時の受動トルク比較

Previous study reported that baseball pitchers had a decreased shoulder internal rotation (IR) range of motion after pitching. However, whether the decreased range of motion associated with pitching is caused by tightness of the posterior shoulder has not been clarified yet. The joint stiffness in the passive torque can be compared with posterior shoulder tightness before and after pitching. Hence, this study aimed to compare shoulder IR stiffness based on passive torque before and after pitching in baseball pitcher. Eleven health male collage baseball pitchers were recruited. Passive torque during IR (max IR, peak torque and stiffness) of dominant and non-dominant arms was measured using an isokinetic dynamometer. Measurements were taken before, after, and post 24 hours after pitching (105 pitches). It was observed that after pitching, max IR and peak torque were significantly decreased compared to those before pitching. However, there was no difference in the stiffness of passive torque among three measurements. In conclusion, healthy college baseball pitchers have a decreased IR range of motion after pitching. However, this result is not due to posterior shoulder tissue tightness, but because of altered stretch tolerance.

Comparison of Peak Shoulder Distraction Forces Between Pain and Pain-Free Youth Baseball Pitchers.

Increased shoulder distraction force during a baseball pitch may make a pitcher susceptible to rotator cuff or glenohumeral labral injuries. A precursor to a pitching injury may be pain experienced in the throwing arm. To (1) compare peak shoulder distraction (PSD) forces in youth baseball pitchers with and without upper extremity pain when throwing a fastball and (2) assess if PSD forces across trials differ between pain and pain-free groups. Controlled laboratory study. A total of 38 male baseball pitchers aged 11 to 18 years were separated into a pain-free group (n = 19; mean age, 13.2 ± 1.7 years; mean height, 163.9 ± 13.5 cm; mean weight, 57.4 ± 13.5 kg) and a pain group (n = 19; mean age, 13.3 ± 1.8 years; mean height, 164.9 ± 12.5 cm; mean weight, 56.7 ± 14.0 kg). Pitchers in the pain group indicated that they experienced pain in their upper extremity while throwing a baseball. Pitching mechanical data from 3 fastballs per pitcher were recorded with an electromagnetic tracking system and motion capture software. The mean PSD (mPSD) was calculated as the mean PSD of 3 pitches per pitcher, the trial with the highest recorded PSD was determined as the maximum-effort PSD (PSDmax), and the PSD range (rPSD) was defined as the difference of the PSD force of the trial with the highest PSD and the lowest PSD for each pitcher. The PSD force was normalized to the pitcher's body weight (%BW). Pitch velocity was also recorded. The mPSD force was 114%BW ± 36%BW for the pain group and 89%BW ± 21%BW for the pain-free group. Pitchers in the pain group exhibited a significantly higher PSDmax force (t30.548 = 2.894; P = .007) and mPSD force (t29.231 = 2.709; P = .009) compared with those in the pain-free group. There were no significant between-group differences in the rPSD force or pitch velocity. The normalized PSDmax force was higher in pitchers who experienced pain while throwing fastballs compared with pitchers who were pain-free while throwing. Baseball pitchers who experience pain in their throwing arm are likely to have higher shoulder distraction forces. Improvement in pitching biomechanics and corrective exercises may assist in the mitigation of pain while pitching.

Measuring the Average Peak Timing of Kinematic Variables in Youth and Adolescent Baseball Pitchers.

Previous studies have examined the timing of peak kinematic variables during the pitching cycle in high school, collegiate, and professional pitchers. These same variables have been studied less in younger populations. To determine whether youth and adolescent baseball pitchers will experience peaks in certain kinematic variables at different times throughout the pitching cycle compared to professional/collegiate pitchers. Cross-sectional, descriptive study. Twenty-four participants were recruited for testing consisting of five recorded pitches using 3-Dimensional VICON® motion analysis system. The maximum values and timing of the peak kinematic variables were averaged across all trials using VICON Polygon® data analysis software. These values were recorded as percentages of the pitching cycle, defined from foot contact (0%) to ball release (100%). The following variables were examined: shoulder external rotation range of motion, shoulder internal rotation velocity, trunk rotation range of motion, trunk rotation velocity, pelvic rotation velocity, and stride length. Descriptive outcomes were calculated and results were compared to previous studies examining the same variables in collegiate and professional pitchers. Twenty-four male participants (mean age 12.75 years, SD ± 2.02) were included in the study. Mean and standard deviations were identified for peak kinematic variables of shoulder external rotation ROM (158.71°, ±9.32), shoulder internal rotation velocity (92.26 rad/sec, ±19.29), trunk rotation velocity (15.94 rad/sec, ±1.68), trunk rotation ROM (23.57°, ±8.14), and average stride length (81.97% height ±4.57). Additionally, mean and standard deviations of peak kinematic variables were expressed as percentages to reflect when they occurred in the pitching cycle and included trunk rotation ROM (8.45%, ±12.72), pelvic rotation velocity (33.26%, ±16.42), trunk rotation velocity (41.59%, ±9.27), shoulder external rotation ROM (71.34%, ±6.61), and shoulder internal rotation velocity (86.93%, ±6.45). The sequential order of each variable was similar in youth and adolescents in comparison to collegiate and professional pitchers. However, the timing of each variable within the pitching cycle occurred approximately 10% earlier in the younger pitchers. The findings suggest differences in pitching mechanics exist between younger and more experienced populations. Level 3.

Effect of number of college baseball pitching on movement, performance, physical strength, physiological, and psychological functions of pitchers

This study aimed to examine the effects of college baseball pitching on movement, performance, physical strength, and physiological and psychological functions of pitchers. The participants were 10 right-handed male pitchers from the University baseball team. The number of pitches were 15 per inning and 135 per nine innings. Ball speed and accuracy were measured for each pitching. The grip strength, back muscle strength, and standing long jump were measured before and after all pitches. Blood lactate levels were measured before pitching, at the end of the 5th and 7th innings, and at 3rd, 6th, and 9th minutes after pitching. The participant’s heart rate and subjective exercise intensity were measured at the beginning and end of each inning using the Borg scale measurement. Five high-speed cameras were used to capture the pitching motions. The displacement of the center of gravity, lower and upper limb joint angles, and the speed of each segment were calculated. The baseball speed and accuracy did not change with the increased number of pitches. However, the grip strength decreased. Although blood lactate and heart rate were not altered, subjective exercise intensity was increased. The lower limb kinematics remained unchanged; however, elbow height was reduced in the upper limb. These results suggest that highly competitive pitchers experience subjective fatigue with the increased number of pitches, however, they maintain pitch performance, speed, and accuracy without altering whole-body physiology and lower-body function and form.

A Baseball Injury and Performance Initiative to Combat Health Risks Associated With Early Sport Specialization

ABSTRACT Ulnar collateral ligament (UCL) injuries have been increasing steadily for the past decade, especially among youth and adolescent amateurs. USA Baseball's Pitch Smart guidelines have been introduced to combat UCL and other throwing arm injuries because overuse is the paramount cause. Fatigue is also a major contributor to injuries. Other factors include inadequate strength, recovery methods, and parental and caregiver education. Significant misconceptions exist among parents and caregivers about UCL injury, surgical repair, strength and conditioning, and injury prevention that can directly influence their children's health and safety in sport. Therefore, parents' and caregivers' education is imperative to reduce injuries in youth baseball. This article presents an educational opportunity by providing an evidence-based training program designed to prevent injuries and maximize performance called the Baseball Injury and Performance Initiative 10 (BIPI 10). The BIPI 10 program conditions baseball players through whole-bodied movement, varying contraction tempos, and plyometrics that are sport specific. BIPI 10 is believed to offer high compliance because training can be completed daily in less than 10 minutes and initiated anywhere across competitive levels on a worldwide scale in a similar fashion to the Fédération Internationale de Football Association (FIFA) program FIFA 11+ for soccer.

Repetitive pitching decreases the elbow valgus stability provided by the flexor-pronator mass: the effects of repetitive pitching on elbow valgus stability

Baseball pitching induces a large elbow valgus load, stressing the ulnar collateral ligament. Flexor-pronator mass contraction contributes to valgus stability; however, repetitive baseball pitching may weaken the flexor-pronator mass contractile function. The present study investigated the effects of repetitive baseball pitching on the medial valgus stability measured using ultrasonography. We hypothesized that repetitive pitching would decrease elbow valgus stability. This was a controlled laboratory study. Fifteen young male baseball players at the collegiate level (age: 23.0 ± 1.4 years) were enrolled. The medial elbow joint space was measured using ultrasonography (B-mode, 12-MHz linear array transducer) in the following three conditions: at rest (unloaded), under 3 kg valgus load (loaded), and under valgus load with maximal grip contraction to activate flexor-pronator mass (loaded-contracted). All measurements were performed before and after the pitching tasks, which comprised five sets of 20 pitches. Two-way repeated-measures analysis of variance was applied to determine changes in the medial elbow joint space. The post-hoc test with Bonferroni adjustment was applied to assess the changes within the time and condition. The medial elbow joint space was significantly greater under the loaded than the unloaded and loaded-contracted conditions both before- and after- pitching (p < 0.001). In the loaded-contracted condition, the medial elbow joint space significantly increased after repetitive baseball pitching (p < 0.001). The results of the present study indicated that repetitive baseball pitching reduced the elbow valgus stability. This reduction could be attributed to the decreased flexor-pronator mass contractile function. Insufficient contraction may increase the tensile load on the ulnar collateral ligament with pitching. Flexor-pronator mass contraction plays a role in narrowing the medial elbow joint space; however, repetitive baseball pitching reduced the elbow valgus stability. It has been suggested that sufficient rest and recovery of the flexor-pronator mass function are required to reduce the ulnar collateral ligament injury risk.

Comparison of the "Tall and Fall" Versus "Drop and Drive" Pitching Styles: Analysis of Major League Baseball Pitchers During a Single Season.

Previous research has documented the proportion of "tall and fall" (TF) and "drop and drive" (DD) pitching styles among Major League Baseball (MLB) pitchers who underwent ulnar collateral ligament reconstruction (UCLR). The proportion of these 2 styles among all MLB pitchers remains unknown. To determine the proportion of the TF and DD pitching styles in all rostered MLB pitchers during a single season as well as the proportion of TF and DD pitchers who sustained an upper extremity (UE) injury and those who underwent UCLR. Cross-sectional study; Level of evidence, 3. Pitcher demographic characteristics from the 2019 MLB season and pitching information were obtained via open-access sources. Two-dimensional video analysis was used to categorize the included pitchers into TF and DD groups. Statistical comparisons and contrasts were made using 2-tailed t tests, chi-square tests, and Pearson correlation analyses as appropriate. Of the 660 MLB rostered pitchers in 2019 (age, 27.39 ± 3.51 years; body mass index, 26.34 ± 2.47 kg/m2; fastball velocity, 150.49 ± 3.99 kph [93.51 ± 2.48 mph]), 412 (62.4%) pitchers used the TF style and 248 (37.6%) pitchers used the DD style. Significantly more UE injuries were seen in the TF group compared with the DD group (112 vs 38 injuries, respectively; P < .001). Twelve pitchers underwent UCLR (TF, 10; DD, 2), representing a 1.8% UCLR rate among all pitchers. This was a second surgery for 2 pitchers, both of whom used the TF pitching style. Significantly more pitchers in the TF group than the DD group had undergone UCLR before 2019 (135 vs 56 pitchers, respectively; P = .005). The results of the present study demonstrated a higher prevalence of both UE injury and prior UCLR in TF pitchers. Further research is needed to explore the potential association between pitching style and UE injury.

Collegiate baseball pitchers demonstrate a relationship between ball velocity and elbow varus torque, both within and across pitchers

ABSTRACT High elbow varus torque during baseball pitching has been identified as a potential cause of ulnar collateral ligament injury in baseball pitchers. In general, elbow varus torque increases as ball velocity increases across pitchers. However, studies incorporating within-subject analyses report that not all professional pitchers have a positive relationship between elbow varus torque and ball velocity (T-V relationship). It remains unknown whether collegiate pitchers show the same trend as professionals in their T-V relationships. The current study investigated the T-V relationship of collegiate pitchers focusing on both across and within pitchers. Division 1 collegiate pitchers (n = 81) were assessed for elbow torque and ball velocity during pitching. Both across- and within-pitcher T-V relationships were significant (p < 0.05) using linear regression. However, more variance in elbow varus torque was explained using the within-pitcher relationship (R2 = 0.29) than the across-pitcher relationship (R2 = 0.05). Of the 81 pitchers, nearly half (n = 39) had significant T-V relationships, while the other half (n = 42) did not. Our findings indicate that the T-V relationship should be assessed on an individual basis as T-V is pitcher-specific.

Mechanism for control of ball spin rate by the upper limb in baseball pitching based on singular value decomposition

This study aims to examine the mechanism by which the ball spin rate during fastball pitching is controlled by synergistic joint torque. The participants were seven baseball players. The kinematics and kinetics of the fingers, wrist, elbow, and shoulder were calculated using the inverse dynamics method. The synergistic relationship between the joint torques was calculated using singular value decomposition. The similarity of the spatial pattern of the joint torque in each participant was evaluated using cosine similarity. The results indicated that there were three types of synergistic torque control: (1) two pitchers had a synergistic torque control that was primarily based on shoulder internal rotation torque, (2) two pitchers had a synergistic torque control that was primarily based on elbow extension torque, and (3) three pitchers had a synergistic torque control that was primarily based on shoulder horizontal adduction torque. In particular, pitchers with a high spin rate relative to the ball velocity (SPV) had a torque control of the shoulder internal rotation type. In contrast, pitchers with a low SPV had a torque control of the shoulder horizontal adduction type. It is considered that pitchers with a high SPV execute shoulder internal rotation torque, which has the same direction as that of ball spin, based on hierarchical control to increase the ball spin rate. These results suggest that pitchers with high and low SPVs exhibit different motor patterns. Pitchers and coach need to focus on the shoulder joint as well as the fingers when they throw fastball.

The relationship between pitching parameters and release points of different pitch types in major league baseball players.

The purpose of this study was to deepen our understanding of pitches and to obtain basic knowledge about pitches by comparing 4-seam and other pitches in Major League Baseball (MLB). We analyzed big data for 1,820 professional baseball pitchers of MLB on release speed, spin rate, release point 3D coordinates (X, Y, and Z axes), amount of change for 4-seam, and seven changing ball types (sinker, slider, changeup, cutter, curve, split finger, and knuckle curve), using PITCHf/x and TrackMan. We also evaluated three relationships: (1) between the release points and the ball types of pitch; (2) between the amount of change in the ball and the release speed; and (3) between the release speed and the spin rate. The release speed was significantly slower in seven changing ball types than in the 4-seam (p < 0.01, respectively). The spin rate and the amount of change (ΔX and ΔZ) were significantly different between 4-seam and seven changing ball types (p < 0.01, respectively). Release point 3D coordinates (X, Y, and Z axes) were significantly different between 4-seam and slider, cutter, and curve (p < 0.01, respectively). Based on these findings, the eight pitch types were mainly divided into three groups: 4-seam, curve, and off-speed pitch types. Seven changing ball types included specific characteristics for each parameter. The correspondence among the release speed, ΔX, and ΔZ at the 3D coordinates is an arch with 4-seam as the apex. Our results suggest an effective strategy for changing the release point and displacement of a ball's trajectory to improve the performance of baseball pitchers.

Proximal to distal sequencing impacts on maximum shoulder joint angles and the risk of impingement in baseball pitching involving a scapular independent thoracohumeral model.

Hyperangulation of the scapulohumeral joint due to poor coordination of the scapula during throwing motion is claimed to be a major cause of internal impingement in baseball pitchers. However, evidence of injurious scapular kinematics is lacking, particularly regarding how hyperangularion actually occurs in full-effort pitching. The purpose of this study was to describe sequential scapular motions involved in attaining maximum joint angles during pitching and the implications for internal impingement in elite baseball pitchers. An electromagnetic goniometer system computed kinematics for pelvis, thorax, scapulae, arms, and forearms during baseball pitching in 72 pitchers. Internal impingement risk was assessed based on kinematic characteristics of internal impingement quantified in a cadaveric study. The pelvis, thorax, and scapula rotated in the proximal-to-distal sequence. Large forearm layback observed near the end of the cocking phase (182 ± 27°) was achieved with a submaximal scapulohumeral external rotation (98 ± 14°). In the next 0.027 ± 0.007 s, forward thoracic rotation and then scapular rotation caused increased scapulohumeral external rotation to a maximum of 113 ± 14°. Here, humeral horizontal adduction and scapula protraction occurred simultaneously preventing the humerus from lagging further behind the scapula. Only one participant reached critical hyperangulation beyond which internal impingement was reported to occur. Most elite pitchers safely attained the fully cocked position, yet off-timed recoiling of scapular protraction caused hyperangulation in full-effort pitching. Therefore, proximal-distal sequencing between the scapula and humerus should be evaluated to lessen the risk of internal impingement in baseball pitchers.

Kinematic and kinetic comparison between preprofessional pitchers from the Dominican Republic and the United States.

Pitching biomechanical efficiency is defined as the association between pitch velocity and arm kinetics. Pitching mechanics inefficiency, an increase in arm kinetics without the resultant increase in pitch velocity, can lead to increased arm strain, increasing arm injury risk. The purpose of this study was to compare arm kinetics, elbow varus torque and shoulder force, in preprofessional United States (US) and Dominican Republic (DR) pitchers. Kinematics that are known to influence elbow varus torque and shoulder force as well as a representative of pitch velocity (hand velocity) were also compared. A retrospective review was performed on baseball pitchers from the DR and US who participated in biomechanical evaluations conducted by the University biomechanics laboratory personnel. Three-dimensional biomechanical analyses were performed on US (n = 37) and DR (n = 37) baseball pitchers. Potential differences between US and DR pitchers were assessed through analysis of covariance with 95% confidence intervals [95% confidence Interval (CI)]. Preprofessional DR pitchers experienced increased elbow varus torque compared with their US counterparts [DR: 7.5 (1.1); US: 5.9 (1.1) %BWxH; Beta: -2.0 (95% CI: -2.7, -1.2) %BWxH], despite throwing fastballs with slower hand velocity [DR: 3,967.1 (939.4); US: 5,109.1 (613.8) °/s; Beta: 1,129.5 (95% CI: 677.5, 1,581.4) °/s]. DR and US pitchers demonstrated similar shoulder force [DR: 136.8 (23.8); US: 155.0 (25.7); Beta: 0.4 (95% CI: -1.2, 19.7) %BW]. Increased elbow varus torque although decreased hand velocity suggests inefficient pitching mechanics among DR pitchers. Inefficient pitching mechanics and increased elbow torque should be considered when developing training programs and pitching plans for professional pitchers from the Dominican Republic.

Are 4D Motion Sensors Valid and Reliable for Studying Baseball Pitching?

Background: Baseball pitching injuries are on the rise. Inertial measurement units (IMUs) provide immediate feedback to players and coaches, allowing for collection outside of the traditional laboratory setting with real-world application. The 4D Motion system provides kinematics throughout the pitching motion and may be beneficial for individualized programs in the throwing athlete. A systematic analysis of these sensors has not been completed. Purpose: To evaluate the validity of the 4D Motion IMU system for analyzing the baseball pitching motion compared with marker-based motion capture, and evaluate the internal reliability and consistency of the device. Study Design: Controlled laboratory study. Methods: Ten high school pitchers participated in this study (10 male; 9 right-hand dominant; mean age, 16.6 ± 1.3 years; mean body mass index, 24.1 ± 3.9). Participants were simultaneously outfitted with six 4D Motion IMU sensors and retroreflective markers. The pitchers threw fastballs at maximum effort off a mound at the standard height and distance. A comparison was made between the IMUs and corresponding motion capture values for shoulder external rotation, elbow flexion, chest extension, pelvis and chest rotation velocity, and rotation acceleration. Results: Significant differences were found for 5 of 7 metrics analyzed. The IMU overreported most metrics, except for elbow flexion and pelvis rotation angular acceleration, where both positive and negative errors were observed. The root mean square error and percentage errors indicated smaller discrepancies for chest extension (4°± 5°) and pelvis (38 ± 19 deg/s) and chest (96 ± 42 deg/s) rotation velocity, with elbow flexion having the largest variance (21°± 9°). Conclusion: The values of the 4D Motion IMU system should not be considered equivalent when compared with marker-based motion capture studies. The system lacked internal consistency and reliability, with angular velocities being the most consistent. Caution should be used when using the metrics provided by an IMU-based system for individualized monitoring. Clinical Relevance: If found valid and reliable, IMUs could be used for longitudinal workload monitoring, individualized throwing and rehabilitation programs, and ultimately injury prevention. This study demonstrates that the data obtained from a 4D Motion system using Gen 3 sensors are not equivalent to the data obtained from a marker-based motion capture system.

An Exploratory Investigation Evaluating the Impact of Fatigue-Induced Stride Length Compensations on Ankle Biomechanics among Skilled Baseball Pitchers.

Altered propulsive and bracing ground reaction forces from lower-body fatigue significantly impact stride length to increase weakness in dynamic elbow stabilizers and risk of medial elbow injury in baseball pitchers. This work investigated altered stride length on three-dimensional ankle joint dynamics to illustrate fatigue-induced changes in ankle motion that can also be impacted by coaching errors. Nineteen pitchers (15 collegiate and 4 high school) were randomized in a crossover design study that encouraged fatigue by throwing two simulated 80-pitch games at ±25% of their desired stride length. An integrated motion-capture system with two force plates and radar gun tracked each throw. Retrospective analysis using pairwise comparisons, including effect size calculations, were undertaken to identify differences in ankle dynamics between stride length conditions for both the drive and stride leg. Longer strides were found to be more effective in drive ankle propulsion and stride-bracing mechanics. Conversely, shorter strides delayed bracing dynamics by demonstrating continued drive ankle plantar flexion moments after stride-foot contact to extend pitchers' time in propulsion (p < 0.001, d > 0.8). Additionally, heightened braking effects were seen during the acceleration phase of throwing with greater stride knee extension power when pitching with shorter strides (p < 0.001, d > 0.8). The knowledge gained from this work offers new insight into compensatory stride length adaptation that impacts systemic and throwing arm-specific fatigue to maintain ball velocity, as bilateral ankle joint dynamics can be significantly affected in response to cumulative workload.

"Ankle Dorsiflexion does not Significantly Correlate with Varus Torque at the Elbow in Collegiate Baseball Pitchers"

"Ankle Dorsiflexion does not Significantly Correlate with Varus Torque at the Elbow in Collegiate Baseball Pitchers"

Does Prehabilitation Before Surgery Affect Return to Sport in Baseball Pitchers With Partial Ulnar Collateral Ligament Tears?

Purposeful rehabilitation before surgery (prehabilitation) has been researched and implemented in the treatment of anterior cruciate ligament tears. However, it is unclear whether prehabilitation would affect outcomes for baseball pitchers with partial ulnar collateral ligament (UCL) tears. The purpose of this study was to determine whether baseball pitchers with partial UCL tears who completed ≥4 weeks of prehabilitation (prehab group) have different return to play (RTP) outcomes than pitchers with 0 to 3 weeks of preoperative physical therapy (no prehab group). We hypothesized that pitchers in the prehab group would have similar RTP rates compared with pitchers in the no prehab group. Cohort study; Level of evidence, 3. Baseball pitchers of all competitive levels who underwent primary UCL reconstruction (UCLR) or UCL repair between 2010 and 2019 were included. Physician chart notes, magnetic resonance images, and operative notes were screened to confirm primary UCLR or UCL repair of a partial UCL tear and to identify whether the nonoperative treatment had been attempted. Patients were contacted via RedCap for postoperative complications, reoperations, RTP, and patient-reported outcomes (Kerlan-Jobe Orthopaedic Clinic score, Andrews-Timmerman score, Conway-Jobe score, and satisfaction). Overall, 105 baseball pitchers (n = 55 prehab group; n = 50 no prehab group) were included and evaluated at 3.4 ± 2.5 years postoperatively. Six pitchers underwent UCL repair, and 99 pitchers underwent UCLR. All demographic characteristics were similar between groups except the prehab group received a gracilis graft more frequently (76.5% vs 51.2%; P = .038). The RTP rate (prehab [88.1%] vs no prehab [93.8%]; P = .465) was similar between groups. All other postoperative outcomes were also similar between groups, including revision rates and patient-reported outcomes. Postoperative and patient-reported outcomes did not differ significantly between pitchers with partial UCL tears who performed rehabilitation before UCL surgery and pitchers who did not attempt a significant period of rehabilitation before UCL surgery. Clinicians should feel comfortable recommending rehabilitation for patients with partial UCL tears who wish to attempt a period of nonoperative treatment, as postoperative outcomes are not affected if UCL surgery is later needed.

Forearm Pronation at Foot Contact: A Biomechanical Motion-Capture Analysis in High School and Professional Pitchers.

It has previously been speculated that baseball pitchers who display excessive forearm pronation at foot contact (FC) have a higher propensity toward ulnar collateral ligament injury and subsequent surgery. To evaluate the association between degree of forearm pronation/supination at FC and throwing arm kinetics in high school and professional pitchers, at both the individual (intrapitcher) and the group (interpitcher) level. Descriptive laboratory study. High school (n = 41) and professional (n = 196) pitchers threw 8 to 12 fastballs while being assessed with a 3-dimensional motion-capture system (480 Hz). Pitchers at each playing level were divided into a supination or pronation subgroup depending on degree of forearm pronation at FC. Regression models were built to observe the relationship between forearm pronation at FC and kinetic and kinematic parameters of interest. At both the individual and the group level of high school and professional pitchers, there was no significant correlation between forearm pronation at FC and elbow varus torque (P min = .21). For every 10° increase in forearm pronation at FC in the individual high school pitcher, elbow flexion at FC decreased by 5°, whereas maximum elbow extension velocity was achieved 0.6% later in the pitch. In addition, elbow medial force increased by 4.1 N and elbow varus torque increased by 0.8 N·m for every 10° increase in forearm supination at FC. For every 10° increase in forearm supination in the individual professional pitcher, ball velocity increased by 0.5 m/s, shoulder external rotation at FC decreased by 11°, and elbow medial force decreased by 5.5 N. Supination- or pronation-predominant forearm motion during the pitch did not significantly differ between playing levels. Excessive forearm pronation at FC was not a significant risk factor for increased throwing arm kinetics for high school or professional pitchers. There was a weak positive association between forearm supination at FC and elbow varus torque in the individual high school pitcher. Ultimately, coaches and pitchers may be better served by redirecting their focus to other mechanical aspects of the pitch that may have stronger associations with injury risk implications as well as performance.

기계학습을 이용한 한국 프로야구 신인 투수들의 유형화 및 잠재력 평가

본 연구는 한국 프로야구(Korea Baseball Organization; KBO) 투수의 유형별 잠재력 평가를 통해 신인 드래프트 전략의 방향성을 제시하는 데 목적이 있다. 연구의 대상은 2015년부터 2020년까지 지명된 한국 프로야구 투수 중 데뷔 시즌 속구 평균 구속 데이터 확보가 가능한 37명으로 선정하였다. 연구 대상의 키, 체중, 데뷔 시즌 속구 평균 구속, WAR(Wins Above Replacement) 최종학력, 우완 좌완여부, 최근 시즌 속구 평균 구속에 대한 데이터는 한국 프로야구 공식 사이트와 스탯티즈 사이트를 통해 수집하였다. 이렇게 확보한 데이터는 MinMaxscaler를 통해 전처리 후, K-평균 군집분석 알고리즘을 통해 투수들의 유형을 분류하였다. K-평균 군집분석 결과 빠른 공을 던지는 투수, 체격이 좋은 투수, 구속과 체격이 보통인 투수로 유형이 나누어졌다. 이후 유형별로 WAR을 통해 경기력 수준을 확인하였고, 대졸 투수 비율, 좌완 투수 비율, 속구 평균 구속 증가 정도를 유형별로 비교하였다. 그뿐만 아니라, 피어슨 상관계수를 이용한 상관관계 분석을 통해 키, 체중, 데뷔 시즌 속구 평균 구속, WAR 간의 연관성을 파악하였다. 그 결과 투수 유형 중 빠른 공을 던지는 투수 유형이 체격이 좋은 투수 유형과 구속과 체격이 보통인 투수 유형에 비해 팀 승리에 가장 큰 기여를 하였다. 속구 평균 구속과 WAR은 양의 상관관계가 있다는 것을 확인했다. 그러므로 본 연구의 결과는 한국 프로야구에서 신인 투수의 선발 시에 구속이 가장 중요한 지표가 된다는 것을 암시한다.

Roles of each leg in impulse generation in professional baseball pitchers: preliminary findings uncover the contribution of the back leg towards whole-body rotation

ABSTRACT This study examined the roles of each leg in generating linear and angular impulses during baseball pitching. Professional pitchers (n = 4) pitched from a force plate instrumented mound, and 6–11 successful fastball pitches were used for analyses. We compared linear and angular impulses across the back and front legs. Linear and angular impulses were calculated from ground reaction force (GRF) and moment about each global axis passing through the centre of mass (COM), respectively. Additionally, we analysed measures that control the moment: (1) GRF magnitude, (2) magnitude of the position vector from COM to the centre of pressure and (3) the angle between (1) and (2). We found that the back leg generated forward linear impulse and the front leg generated backward linear impulse for all pitchers. Surprisingly, we found that the back leg generated significantly greater positive angular impulse about a global leftward axis (from the mound towards first base) than did the front leg in all four pitchers. Furthermore, the back leg’s moment about the leftward axis became positive after the magnitude of forward GRF decreased from its maximum, suggesting that the back leg’s role transitioned from generating forward linear momentum to angular momentum.

Paper 23: Outcomes Following Arthroscopic Removal of A Posteromedial Osteophyte and Risk of Future Ulnar Collateral Ligament Reconstruction

Objectives: Despite successful return to sport (RTS) outcomes after posteromedial osteophyte resection, one possible consequence of removing this osteophyte is increased stress on the ulnar collateral ligament (UCL), leading to a UCL injury. It is currently unknown how often overhead athletes who have an isolated posteromedial osteophyte resection progress to require UCL reconstruction (UCLR). Therefore, the purpose of this study was to report outcomes following arthroscopic resection of posteromedial osteophyte in overhead athletes and determine if baseball pitchers who underwent arthroscopic posteromedial osteophyte resection for posteromedial impingement went on to require UCL surgery. Methods: All patients who underwent elbow arthroscopy from 2010-2020 were reviewed. Patients were included if they underwent isolated arthroscopic posteromedial osteophyte resection without concomitant UCL surgery, were overhead athletes at the onset of posteromedial impingement symptoms and had no history of prior elbow surgery. Primary outcomes included RTS rate, complications, subsequent shoulder and elbow injury/surgery and several patient-reported outcome measures (Kerlan-Jobe Orthopaedic Clinic score, Timmerman-Andrews Elbow score, Conway-Jobe score). Results: Overall, 36 overhead athletes were evaluated at 5.1 years post-operatively, including 28 baseball pitchers, 3 baseball catchers, 3 softball players, 1 tennis player, and 1 volleyball player. 77% of overhead athletes RTS and had a mean KJOC score of 70, with 89% of athletes having either an excellent (73%) or good (16%) Conway-Jobe score at long-term follow-up. Subsequent UCLR was required in 18% (n=5) of baseball pitchers at a median of 13 months post-op. Three of the five UCLR were performed shortly after posteromedial osteophyte resection (6, 7, and 13 months post-op), while the other two UCLRs were performed at 6.2 and 7.5 years post-op. Conclusions: Following arthroscopic posteromedial osteophyte resection, 77% of athletes were able to RTS. Baseball pitchers who undergo arthroscopic posteromedial osteophyte resection have an 18% risk of subsequent UCLR.