Effect of a 6-Week Weighted Baseball Throwing Program on Pitch Velocity, Pitching Arm Biomechanics, Passive Range of Motion, and Injury Rates

Countermovement Jump and Momentum Generation Associations to Fastball Velocity Performance Among Division I Collegiate Pitchers

ABSTRACT

Sakurai, M, Qiao, M, Szymanski, DJ, and Crotin, RL. Countermovement jump and momentum generation associations to fastball velocity performance among Division I collegiate pitchers. J Strength Cond Res 38(7): 1288-1294, 2024-The current study explored the relationships between countermovement jump (CMJ) profiles and baseball pitching performance. Nineteen Division I collegiate pitchers performed in-laboratory pitching and bilateral CMJs. Whole-body kinematics and ground reaction force were collected during both pitching and CMJ evaluations. Statistically significant correlations of concentric impulse and peak power in the CMJ test with fastball velocity were observed (r = 0.71 and 0.68). Concentric impulse in CMJ also showed a statistically significant correlation with linear momentum in the anterior-posterior direction during pitching (r = 0.68). Lean body mass and body mass showed statistically significant correlations with both of the 2 linear momentums during pitching (r = 0.71∼0.83), and concentric impulse in CMJ (r = 0.71 and 0.81). Pelvis and trunk pitching mechanics did not correlate with any of the CMJ variables at the statistically significant level, whereas the direction of the correlations varied (|r| < 0.45). Assessment of a baseball pitcher's CMJ should focus on concentric impulse and peak power because only these showed meaningful relationships with fastball velocity or momentum generation during pitching. An increase in lean body mass is also suggested to be able to generate more impulse and momentum. Baseball coaches, strength coaches, and clinicians are encouraged to include lower-body explosive training to enhance the force and power output capacity of baseball pitchers.

Arm Health in Elite Collegiate Summer League Baseball Players Assessed by the Kerlan-Jobe Orthopaedic Clinic Score

CONTEXT

Collegiate baseball players with professional aspirations often participate in summer leagues; foremost among them is the Cape Cod Baseball League (CCBL). Injuries acquired during the collegiate baseball season can be carried into the CCBL season and vice versa.

OBJECTIVE

To assess the history of throwing arm injury and current functionality in midseason CCBL players.

DESIGN

Cross-sectional study.

SETTING

Online questionnaire.

PATIENTS OR OTHER PARTICIPANTS

A total of 123 CCBL players participated. Qualifying athletes were ≥18 years old and were rostered CCBL players with remaining collegiate eligibility.

MAIN OUTCOME MEASURE(S)

After collecting background information, we used the Kerlan-Jobe Orthopaedic Clinic (KJOC) Shoulder and Elbow questionnaire to assess the history of throwing arm injury and current functionality. The maximum KJOC score is 100.0; higher scores correspond with greater functionality.

RESULTS

The mean KJOC score was 86.6 ± 14.5 (n = 92); 24.5% (23/94) of players reported a prior diagnosis of throwing arm injury other than a strain or sprain. A total of 49 (49/96, 51.0%) players had undergone rehabilitation for a throwing arm injury, and 7 (7/96, 7.3%) had experienced a medical procedure. Players with no previous treatment (n = 41, mean KJOC score = 88.9 ± 19.0) more frequently demonstrated KJOC scores of ≥90 than players with such treatment (n = 55, 80.9 ± 17.1; P < .001). The 18 players with time-loss arm injury in the last year had lower mean KJOC scores (71.3 ± 20.0) than players with no injury or time loss (90.3 ± 9.8; P < .001). Similarly, players who reported current arm trouble (n = 15) had lower KJOC scores (71.6 ± 17.5) than players with healthy arms (89.5 ± 11.9; P < .001).

CONCLUSIONS

The average KJOC score of the CCBL players was <90, with particularly low scores in athletes with prior arm injury and treatment.

An Interval Throwing Program for Baseball Pitchers Based upon Workload Data

Background

Interval throwing programs (ITP) have been used for decades to enable baseball pitchers to return to competition after injury or surgery by gradually applying load to the throwing arm. Past programs have been based on personal experience; however, advances in our understanding of the biomechanics and workloads of throwing allow for a more modern data-based program to be developed.

Hypothesis/Purpose

To 1) develop a updated ITP for rehabilitation of modern baseball pitchers based upon biomechanical and throwing workload data, and 2) compare the updated program with a past program to determine differences in chronic workload and acute:chronic workload ratios (ACWR).

Study Design

Cross-sectional study.

Methods

Workloads (i.e. daily, acute, chronic, and ACWR) for the original ITP were built from the prescribed throwing schedule. Elbow varus torque per throw was calculated based upon a relationship between elbow varus torque and throwing distance. Throw counts, daily/chronic/acute workloads, and ACWR were calculated and plotted over time. A new ITP was built to model current pitcher's throwing schedules and gradually increased ACWR over time.

Results

The original ITP had a throwing schedule of 136 days, final chronic workload 15.0, and the ACWR above or below the "safe" range (i.e. 0.7 - 1.3) for 18% of the program with a peak of 1.61. The updated ITP was built to consist of a 217-day schedule, final chronic workload of 10.8, and deviated from the safe range for 9% of the program, with a peak of 1.33.

Conclusion

The newly created ITP is more familiar to modern baseball pitchers while exhibiting a more gradual buildup of chronic workload than traditional ITP programs. This ITP may be used to return baseball pitchers back to competition as safely and efficiently as possible, and potentially with less risk of setbacks or reinjury. The ITP may be used following common injuries or surgeries to the throwing shoulder and elbow, such as Tommy John surgery, while also serving as a basis for future development of shorter duration ITPs.

Level of Evidence

2c.

A systematic review of techniques for step cut osteotomy in cubitus varus: A comprehensive analysis

Background

Cubitus varus, a common post-traumatic deformity of the elbow in children, poses challenges for both patients and surgeons. Step cut osteotomy has emerged as a reasonable surgical technique to address this condition, offering multiple approaches and modifications.

Methods

We present a comprehensive systematic review of techniques for step cut osteotomy in cubitus varus, analyzing 13 studies that meet our inclusion criteria. These studies encompass diverse patient populations, including pediatric and adult cases, and span different geographical regions.

Results

Our systematic review explores three primary osteotomy techniques-Classic Step-Cut Osteotomy, Reverse V Osteotomy, and Modified Step Cut Osteotomy-along with their modifications, providing surgeons with valuable options for individualized correction. Functional outcomes showcase improvements in range of motion, functional scores, and carrying angle, highlighting the technique's efficacy in restoring elbow function and enhancing quality of life. Radiological evaluations demonstrate successful corrections of various angles and achievement of bony union, reinforcing the stability and anatomical improvements achieved through step cut osteotomy.

Conclusions

Complication rates are notably low, with transient nerve palsies being the most commonly encountered, often resolving within months. Implant failure and other complications are infrequent, underlining the safety and reliability of step cut osteotomy as a surgical intervention for cubitus varus.While the predominance of retrospective studies and heterogeneity across included studies warrant caution, our systematic review provides a robust and diverse synthesis of evidence. It underscores the significance of step cut osteotomy in managing cubitus varus deformity, emphasizing its versatility, favourable outcomes, and safety profile. Further research with rigorous designs and longer follow-up periods will enhance our understanding of step cut osteotomy's role in cubitus varus correction.

Rehabilitation of the painful elbow

Although lateral elbow pain and medial ulnar collateral ligament injury are common musculoskeletal pathologies in overhead athletes, the evidence supporting specific interventions for managing these conditions is scarce. Management of these conditions has been guided mostly by expert opinion rather than empirical evidence, yet the lack of comparative data in the literature has not negatively affected return-to-play rates following surgery. However, an understanding of what is known regarding unimodal and multimodal treatments for lateral elbow pain and medial ulnar collateral ligament injury is needed for clinicians to select evidence-based treatment pathways and highlight what is not known to develop future high-quality investigations.

Rehabilitation of the painful shoulder

Managing the painful shoulder in overhead athletes can be difficult because of a lack of time-loss injuries in overhead sports and focusing primarily on either pathoanatomic causes or movement impairments. Although managing the painful shoulder can be challenging, the combination of identifying pathoanatomic causes with movement impairments can provide a more focused rehabilitation approach directed at the causes of shoulder pain. Understanding the potential influence of scapular positioning as well as mobility and/or strength impairments on shoulder pain can help clinicians develop more directed rehabilitation programs. Furthermore, sports-specific methods such as long toss or the use of weighted balls for achieving physiological or performance-based gains have limited empirical evidence regarding their clinical and performance-based benefits, which may impede the rehabilitation process. Applying a comprehensive evaluation approach prior to and throughout the treatment process can assist clinicians with selecting the most appropriate treatment based on patient need. Reconsidering traditional treatments based on existing evidence may help refine the treatment process for overhead athletes with shoulder pain.

Effects of Ball Size and Weight on Throwing Kinematics and Kinetics in Youth Baseball Athletes

BACKGROUND

In baseball, youth athletes play on smaller fields with shorter distances between bases, shorter pitching distances, and smaller mounds. Despite this, youth athletes use baseballs weighing the same amount as those used at the professional level, possibly predisposing youth baseball players to injuries.

PURPOSE

(1) To determine the effects of throwing a smaller, lighter, and both smaller and lighter baseball on throwing arm stress in youth athletes and (2) to also investigate how changing the ball size and weight would affect elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity during the throwing motion.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This cross-sectional cohort study analyzed the kinematics and kinetics of 38 youth baseball players (mean age, 8.3 ± 0.8 years) throwing a baseball modified in size and weight. Three-dimensional motion data were collected using a retroreflective marker set and a 12-camera motion analysis system. Full-body kinematics and kinetics were calculated using commercial software. Participants threw 5 different types of baseballs 3 times each, in random order, with full effort from a pitching mound to a target 14 m away. The balls used were a 5-oz regular baseball, 5-oz (0.142-kg) baseball with a 5% reduced circumference, 4-oz (0.113-kg) baseball, 4-oz baseball with a 5% reduced circumference, and 3-oz (0.085-kg) baseball. Analysis of variance was used to determine statistical differences in elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity among baseball types. The Tukey post hoc test was used to further investigate differences between the ball groups, considering P < .05 to be significant.

RESULTS

Analysis of variance detected a significant difference in elbow varus torque among ball groups (P = .024). The Tukey post hoc test revealed a moderate difference in elbow varus torque between the 5-oz baseball (4.73 ± 1.06 percentage body weight × height [%BW × H]) and 3-oz baseball (4.06 ± 0.83 %BW × H) (P = .017; d = 0.677 [95% CI, 0.08-1.27]). No significant differences were found in shoulder distraction force or throwing arm internal rotation velocity among ball groups.

CONCLUSION

Compared with a 5-oz baseball, throwing a 3-oz baseball resulted in decreased elbow varus torque with a moderate effect size.

Understanding Shoulder and Elbow Injuries in the Windmill Softball Pitcher

Although pitching-related injuries in the overhead athlete have been studied extensively, injuries associated with windmill pitching are not as clearly elucidated. Windmill pitching produces high forces and torques in the upper extremity, and studies have shown it creates similar shoulder and elbow joint loads to those reported in baseball pitchers. Studies have shown that the windmill pitching motion generates high levels of biceps activation with an eccentric load, placing the biceps at increased risk for overuse injuries. Although the American Orthopaedic Society for Sports Medicine published prevention guidelines including recommendations for maximum pitch counts in softball, these recommendations have not been adopted by most United States softball governing bodies. The repetitive windmill motion in conjunction with high pitch count demands in competitive softball creates notable challenges for the sports medicine physician. As with overhead throwing athletes, identifying and preventing overuse is crucial in preventing injuries in the windmill pitcher, and prevention and rehabilitation should focus on optimizing mechanics and kinematics, core, hip, and lower body strength, and recognition of muscle fatigue. With more than two million fastpitch softball participants in the United States, it is essential to better understand the etiology, evaluation, and prevention of injuries in the windmill pitching athlete.

The impact of resistance-based training programs on throwing performance and throwing-related injuries in baseball players: A systematic review

The aim of this systematic review is to assess the effects of structured resistance training programs on the throwing performance and injury risk of baseball players, irrespective of their age or sex. The literature search was carried out on 18/10/2023, utilizing databases that include PubMed, Scopus, and the Web of Science. Our inclusion criteria encompassed research involving baseball players of all ages and sex who had undergone resistance-based training interventions. For comparison, we considered active control groups, irrespective of their exposure to additional training programs. The outcomes under investigation were related to throwing performance (i.e., throwing velocity and accuracy) and injuries associated with throwing. In our review, we exclusively included studies with a two- or multi-arm design. We evaluated the risk of bias using the PEDro scale. Out of the initial pool of 509 studies, we carefully examined 27 full-text articles and ultimately selected and analyzed 16 studies for inclusion in our review. Out of the 12 studies that compared and presented the inferential statistics for the post-training effects of the experimental versus control groups, it was observed that 8 of these studies demonstrated a significantly more favorable impact of the experimental group on enhancing throwing velocity when compared to the control group. Out of the three studies that compared the experimental and control groups in terms of throwing accuracy, only one study showed a significant improvement in the experimental group compared to the control group after the intervention. In conclusion, this systematic review indicates that resistance-based training interventions appear to be effective in enhancing throwing velocity. However, the evidence regarding the efficacy of these interventions in improving throwing accuracy is less robust. It is worth noting that while some experimental conditions may lead to an increase in injury rates, there is limited data available on this aspect, with only a few studies reporting on this variable.

Early single sport specialization does not improve pitching velocity, motion, strength, or utilization in high school baseball pitchers

Background

The impact of single-sport specialization on performance and injury risk in youth and adolescent athletes remains debated. The purpose of this study was to determine the incidence of single-sport specialization and its association with pitch velocity, pitcher utilization, range of motion, strength, and injury history.

Methods

High school pitchers in the Northeastern, Southeastern, Midwestern, and Western Regions of the United States were prospectively recruited. Prior to the season, pitchers were surveyed about their basic demographics, sport participation history, and injury history. At this timepoint, a standardized physical examination was performed and max pitch velocity was measured. They were then prospectively followed over the ensuing high school season, where pitch utilization and counts were followed and injuries were tracked.

Results

Across the study, 115 pitchers were recruited, of whom 53% played baseball as their only sport and 47% played other sports. Single- position specialization within baseball was uncommon as 90% of athletes played positions other than pitcher. There were no differences in range of motion, strength, or pitch velocity between multisport athletes and single-sport specialists. Within the multisport group, 26% reported a history of injury, while 38% of the single-sport specialists reported a history of injury (P = .179). There were no significant differences in pitcher utilization between multisport athletes and single-sport specialists. Only a single prospective injury occurred in the 115 players.

Conclusion

Although single-sport specialization is common, nearly half of all high school pitchers in this study were multisport athletes. While injury history was generally similar between the two groups, single-sport baseball players did not have the following: improved motion, increased strength, higher ball velocity, or greater pitching volumes during the high school baseball season compared to multisport athletes. Accordingly, single-sport specialization did not have a competitive advantage for these high school pitchers based on the performance factors studied. Further prospective studies are necessary to understand the association between single-sport specialization and injury risk in high school baseball players.

Biomechanical Basis of Interval Throwing Programs for Baseball Pitchers: A Systematic Review

Background

Interval throwing programs are used in rehabilitation of throwing injuries, especially ulnar collateral ligament injuries. Athletes who are rehabilitating begin by throwing on flat ground progressing through increasing distances, number of throws, and intensity of throwing. If the athlete is a baseball pitcher, the flat-ground throwing phase is followed by pitching on a mound at progressively increased effort. The goal is to build back arm strength and capacity with an emphasis on proper mechanics.

Purpose

To determine whether interval throwing progressively builds joint kinetics (specifically, elbow varus torque) to the level required during full-effort baseball pitching. A secondary purpose was to examine the kinematics produced during interval throwing compared to those seen during baseball pitching.

Study Design

Systematic Review.

Methods

Following PRISMA guidelines, PubMed, Embase, Web of Science, SPORTDiscus, and Google Scholar were systematically searched for biomechanical studies of flat-ground throwing and partial-effort pitching in baseball between 1987 and 2023. Studies that reported the biomechanics of either flat-ground throwing, or partial-effort pitching were included in this review. The AXIS tool was used to assess study quality.

Results

Thirteen articles met the inclusion criteria. Ten studies were determined to be of moderate quality, while three studies were deemed high quality. Elbow varus torque during partial-effort pitching was less than during full-effort pitching. Elbow varus torque for most flat-ground throws did not exceed full-effort pitching torque. While most studies showed increased elbow varus torque with increased flat-ground throwing distance, the distance at which elbow varus torque matched or exceeded full-effort pitching elbow varus torque was not consistent.As flat-ground throwing distance increased, shoulder external rotation angle and shoulder internal rotation velocity increased. Arm slot (forearm angle above horizontal) decreased as flat-ground throwing distance increased. For varied effort pitching, shoulder external rotation angle, shoulder internal rotation velocity, elbow extension velocity, and ball velocity increased as effort increased. While the front knee extended slightly from foot contact to ball release in full-effort pitching, the front knee flexed slightly during partial-effort pitching.

Conclusions

An interval throwing program progressively builds elbow varus torque up to levels produced in full-effort baseball pitching. While differences exist between interval throwing kinematics and pitching kinematics, the patterns are similar in general.

Level of Evidence

2.

Characteristics Associated With Noncompliance of Current Pitch Smart Guidelines in High School Baseball Pitchers Throughout the United States

Background

Although pitch count and rest guidelines have been promoted for youth and adolescent baseball players for nearly 2 decades, compliance with guidelines remains poorly understood.

Purpose/Hypothesis

The purpose of this study was to determine the frequency of compliance with Major League Baseball (MLB) Pitch Smart guidelines as well as the association between compliance and range of motion (ROM), strength, velocity, injury, and pitcher utilization. It was hypothesized that pitchers in violation of current recommendations would have increased strength, velocity, and injury.

Study Design

Case-control study; Level of evidence, 3.

Methods

This was a prospective, multicenter study of 115 high school pitchers throughout the United States. Pitchers were surveyed about their compliance with current off-season, rest-related guidelines, and history of injury. During the preseason, pitchers underwent standardized physical examinations, and pitch velocity was measured. Pitch counts were collected during the baseball season that followed. Dynamometer strength testing of shoulder forward flexion, and external rotation as well as grip strength was recorded. We compared pitchers who were compliant with recommendations with those who were noncompliant using Student t and Mann-Whitney U tests.

Results

Based on preseason data, 84% of pitchers had violated current Pitch Smart guidelines. During the season, 14% had at least 1 violation of the Pitch Smart guidelines. Across both the preseason survey and in-season pitch counts, 89% of players had at least 1 violation of the Pitch Smart guidelines. While there were no significant differences in ROM or strength, the noncompliant group had higher maximum pitch velocity than the compliant group (74 ± 8 vs 69 ± 5 mph [119 ± 13 vs 111 ± 8 kph], respectively; P = .009). Players' self-reported velocity differed significantly from the direct measurement, for both peak velocity (80 ± 6 vs 73 ± 8 mph [129 ± 9 vs 117 ± 13 kph], respectively; P < .001) and mean velocity (73 ± 8 vs 53 ± 27 mph [117 ± 13 vs 85 ± 43 kph], respectively; P < .001).

Conclusion

Most high school pitchers were not fully compliant with current Pitch Smart guidelines, and they tended to overestimate their peak velocity by 7 mph (11 kph). Pitchers who threw with greater velocity were at higher risk for violating Pitch Smart recommendations.

Does High Medial Elbow Stress During Pitching Compromise the Dynamic Stabilizers of The Elbow?

Background

The flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS) are thought to provide dynamic stability to the medial elbow, with a lesser contribution from the pronator teres (PT).

Hypothesis/Purpose

The purpose of this study was to determine if baseball pitchers with higher valgus elbow torque experience greater FCU and FDS strength loss.

Study Design

Controlled Laboratory Study.

Methods

A pilot study was performed to determine if middle and ring finger flexion strength tests preferentially activated the FCU and FDS versus the PT (10 men age 36±12 yr). EMG amplitudes, expressed as percent of maximal voluntary contraction (MVC) were compared between tests and muscles. In a field study of college baseball pitchers, middle finger, ring finger and grip strength were tested prior to, immediately after, and one day after 14 pitching performances in 10 pitchers (21±2 yr). Elbow valgus torque was measured from an inertial measurement unit, housed in a compression sleeve and pitchers were categorized as having high or low valgus torque.

Results

For the pilot study EMG activations were 74% FDS, 66% FCU and 35% PT for the middle finger test (muscle effect p=0.032) and 93% FCU, 61% FDS and 23% PT for the ring finger test (muscle effect p=0.005). In the field study, pitchers with high valgus torque showed marked post-game middle finger fatigue (88% of baseline) and incomplete recovery the following day (95%), while pitchers with low valgus torque showed no strength loss (107% post game, 106% a day later; group x time p=0.022). Results were similar for ring finger strength (high torque: 94% post game 96% a day later; low torque: 114% post game 107% a day later; group x time p=0.048). By contrast, grip strength was not different between pitchers with high versus low valgus torque (p=0.143).

Conclusion

High medial elbow stress during pitching fatigues the dynamic stabilizers of the medial elbow.

Level of Evidence

Level 3©The Author(s).

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

Background

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

Methods

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

Results

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

Conclusions

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

A systematic review of the evidence for effectiveness of interventions to address transport and other unintentional injuries among adolescents

INTRODUCTION

Globally, injuries are a leading cause of mortality and morbidity for adolescents, which disproportionately affect the disadvantaged. To build an investment case for adolescent injury prevention, evidence is needed as to effective interventions.

METHODS

A systematic review of peer-reviewed original research published between 2010-2022 was conducted. CINAHL, Cochrane Central, Embase, Medline and PsycINFO databases were searched for studies reporting the effectiveness of unintentional injury prevention interventions for adolescents (10-24 years), with assessment of study quality and equity (e.g., age, gender, ethnicity, socio-economic status).

RESULTS

Sixty-two studies were included; 59 (95.2%) from high-income countries (HIC). Thirty-eight studies (61.3%) reported no aspect of equity. Thirty-six studies (58.1%) reported prevention of sports injuries (commonly neuromuscular training often focused on soccer-related injuries, rule changes and protective equipment). Twenty-one studies (33.9%) reported prevention of road traffic injury, with legislative approaches, commonly graduated driver licensing schemes, found to be effective in reducing fatal and nonfatal road traffic injury. Seven studies reported interventions for other unintentional injuries (e.g., falls).

DISCUSSION

Interventions were strongly biased towards HIC, which does not reflect the global distribution of adolescent injury burden. Low consideration of equity in included studies indicates current evidence largely excludes adolescent populations at increased risk of injury. A large proportion of studies evaluated interventions to prevent sports injury, a prevalent yet low severity injury mechanism. Findings highlight the importance of education and enforcement alongside legislative approaches for preventing adolescent transport injuries. Despite drowning being a leading cause of injury-related harm among adolescents, no interventions were identified.

CONCLUSION

This review provides evidence to support investment in effective adolescent injury prevention interventions. Further evidence of effectiveness is needed, especially for low- and middle-income countries, populations at increased risk of injury who would benefit from greater consideration of equity and for high lethality injury mechanisms like drowning.

Role of Pelvis and Trunk Biomechanics in Generating Ball Velocity in Baseball Pitching

ABSTRACT

Orishimo, KF, Kremenic, IJ, Mullaney, MJ, Fukunaga, T, Serio, N, and McHugh, MP. Role of pelvis and trunk biomechanics in generating ball velocity in baseball pitching. J Strength Cond Res 37(3): 623-628, 2023-The purpose of this study was to determine the impact of pelvis rotation velocity, trunk rotation velocity, and hip-shoulder separation on ball velocity during baseball pitching. Fastball pitching kinematics were recorded in 29 male pitchers (age 17 ± 2 years, 23 high school, 6 college). Pelvis and trunk angular velocities and hip-shoulder separation were calculated and averaged for the 3 fastest pitches. Associations between peak pelvis velocity, peak trunk velocity, hip-shoulder separation at foot contact, and ball velocity were assessed using Pearson correlation coefficients and multiple regression. The average ball velocity was 33.5 ± 2.8 m·s -1 . The average hip-shoulder separation at foot contact was 50 ± 12°. The peak pelvis velocity (596 ± 88°·s -1 ) occurred at 12 ± 11% of the time from stride foot contact to ball release, with the peak trunk velocity (959 ± 120°·s -1 ) occurring at 36 ± 11%. Peak trunk velocity was predictive of ball velocity ( p = 0.002), with 25% of the variability in ball velocity explained. No combination of factors further explained ball velocity. Hip-shoulder separation at foot contact (17%, p = 0.027), peak pelvis velocity (23%, p = 0.008), and the timing of peak pelvis velocity (16%, p = 0.031) individually predicted peak trunk velocity. The combination of peak pelvis velocity, hip-shoulder separation at foot contact, and the timing of peak trunk velocity explained 55% of the variability in trunk rotation velocity ( p < 0.001). These data highlight the importance of interactions between pelvis and trunk for maximizing velocity in pitching. Training to improve pelvis-trunk axial dissociation may increase maximal trunk rotation velocity and thereby increase ball velocity without increasing training load on the shoulder and elbow.

Resistance Training Induces Improvements in Range of Motion: A Systematic Review and Meta-Analysis

BACKGROUND

Although it is known that resistance training can be as effective as stretch training to increase joint range of motion, to date no comprehensive meta-analysis has investigated the effects of resistance training on range of motion with all its potential affecting variables.

OBJECTIVE

The objective of this systematic review with meta-analysis was to evaluate the effect of chronic resistance training on range of motion compared either to a control condition or stretch training or to a combination of resistance training and stretch training to stretch training, while assessing moderating variables.

DESIGN

For the main analysis, a random-effect meta-analysis was used and for the subgroup analysis a mixed-effect model was implemented. Whilst subgroup analyses included sex and participants' activity levels, meta-regression included age, frequency, and duration of resistance training.

DATA SOURCES

Following the systematic search in four databases (PubMed, Scopus, SPORTDiscus, and Web of Science) and reference lists, 55 studies were found to be eligible.

ELIGIBILITY CRITERIA

Controlled or randomized controlled trials that separately compared the training effects of resistance training exercises with either a control group, stretching group, or combined stretch and resistance training group on range of motion in healthy participants.

RESULTS

Resistance training increased range of motion (effect size [ES] = 0.73; p < 0.001) with the exception of no significant range of motion improvement with resistance training using only body mass. There were no significant differences between resistance training versus stretch training (ES = 0.08; p = 0.79) or between resistance training and stretch training versus stretch training alone (ES = - 0.001; p = 0.99). Although "trained or active people" increased range of motion (ES = 0.43; p < 0.001) "untrained and sedentary" individuals had significantly (p = 0.005) higher magnitude range of motion changes (ES = 1.042; p < 0.001). There were no detected differences between sex and contraction type. Meta-regression showed no effect of age, training duration, or frequency.

CONCLUSIONS

As resistance training with external loads can improve range of motion, stretching prior to or after resistance training may not be necessary to enhance flexibility.

Sensor Location Matters When Estimating Player Workload for Baseball Pitching

Estimating external workload in baseball pitchers is important for training and rehabilitation. Since current methods of estimating workload through pitch counts and rest days have only been marginally successful, clubs are looking for more sophisticated methods to quantify the mechanical loads experienced by pitchers. Among these are the use of wearable systems. While wearables offer a promising solution, there remains a lack of standards or guidelines for how best to employ these devices. As a result, sensor location and workload calculation methods vary from system to system. This can influence workload estimates and blur their interpretation and utility when making decisions about training or returning to sport. The primary purpose of this study was to determine the extent to which sensor location influences workload estimate. A secondary purpose was to compare estimates using different workload calculations. Acceleration data from three sensor locations-trunk, throwing upper arm, and throwing forearm-were collected from ten collegiate pitchers as they threw a series of pitches during a single bullpen session. The effect of sensor location and pitch type was assessed in relation to four different workload estimates. Sensor location significantly influenced workload estimates. Workload estimates calculated from the forearm sensor were significantly different across pitch types. Whole-body workload measured from a trunk-mounted sensor may not adequately reflect the mechanical loads experienced at throwing arm segments. A sensor on the forearm was the most sensitive to differences in workloads across pitch types, regardless of the calculation method.

Using Sensors for Player Development: Assessing Biomechanical Factors Related to Pitch Command and Velocity

Pitching biomechanical research is highly focused on injury prevention with little attention to how biomechanical data can facilitate skill development. The overall purpose of this study was to explore how sensor-derived segment kinematics and timing relate to command and ball velocity during baseball pitching. We used a cross-sectional design to analyze a series of pitches thrown from 10 collegiate baseball pitchers. We collected biomechanical data from six inertial sensors, subjective command from the pitchers, and ball velocity from a radar device. Stepwise regression analyses were used to explore biomechanical variables associated with command for all pitches and ball velocity for fastballs only. We found that only peak forearm linear acceleration was significantly associated with command, whereas several segment kinematic measures were significantly associated with ball velocity. Our results suggest that different biomechanical variables are linked to specific pithing skills. Our findings suggest that end-effector (forearm) movement is more important for pitch command, whereas proximal-to-distal (pelvis, trunk, upper arm, forearm) segmental movement is important for ball velocity.

Determinants of Biomechanical Efficiency in Collegiate and Professional Baseball Pitchers

BACKGROUND

Biomechanical efficiency, defined as fastball velocity per unit of normalized elbow varus torque, is a relatively new metric applied to improving the performance and health of baseball pitching.

PURPOSE/HYPOTHESIS

The purpose of this work was to evaluate kinematic parameters influencing biomechanical efficiency among professional and collegiate pitchers. Kinematic differences were compared between pitchers of high and low biomechanical efficiency. We hypothesized that professional pitchers would have greater biomechanical efficiency than collegiate pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A deidentified biomechanical database of 545 pitchers (447 professional, 98 collegiate) was analyzed. A multivariate linear regression model was used to evaluate significant findings a priori with α = .05. Additionally, biomechanical differences were identified between competition levels and between high and low biomechanical efficiency groups using Mann-Whitney U test (α = .05).

RESULTS

Competition level and 11 (of 21) kinematic variables explained 27% of the variance in biomechanical efficiency, with most of the predictors being throwing arm kinematics (elbow flexion at stride foot contact [SFC]: β, -1.47; SE, 0.26; shoulder abduction at SFC: β, -1.78; SE, 0.39; shoulder external rotation at SFC: β, 0.60; SE, 0.22; maximum external rotation [MER] angle: β, 1.82; SE, 0.42; shoulder horizontal adduction at MER: β, -3.42; SE, 0.71) (all P≤ .05). Professional pitchers had greater biomechanical efficiency than collegiate pitchers (711.0 ± 101.0 vs 657.0 ± 99.3, respectively; P < .001; d = 0.53). Compared with the low-efficiency group, the high-efficiency group had significantly lower normalized elbow varus torque with greater weight and height (high: 0.047 ± 0.004 %wt*ht vs. low: 0.063 ± 0.006 %wt*ht, P <.001; d = 3.20). At the instant of SFC, the high-efficiency group demonstrated greater shoulder external rotation and less elbow flexion, shoulder abduction, and pelvic rotation. The high-efficiency group also had greater MER and less shoulder horizontal adduction at MER, trunk side tilt at ball release, and knee excursion from foot contact to ball release.

CONCLUSION

Professional pitchers had greater biomechanical efficiency than collegiate pitchers. Biomechanical efficiency was also affected by 11 kinematic variables identified in this study. Pitchers with higher efficiency had distinct differences in arm position, trunk side tilt, and lead-knee extension range of motion in the delivery. Thus, pitchers and baseball organizations should focus on these factors to lower normalized elbow varus torque relative to ball velocity.

Athletes Perceive Weighted Baseballs to Carry a Notable Injury Risk, yet Still Use Them Frequently: A Multicenter Survey Study

Weighted baseball use in throwing programs is widespread; however, their use remains controversial. Prior research shows that weighted baseball programs can increase ball velocity but potentially increase throwing arm injuries. This study aims to ascertain perceptions of weighted baseballs among elite baseball players.

Weighted Baseball Training Affects Arm Speed Without Increasing Elbow and Shoulder Joint Kinetics

Long-term training effects of weighted ball throwing programs have been well documented. However, the mechanisms that facilitate these effects are poorly understood. The purpose of this study is to investigate within-session effects of throwing overload and underload baseballs to provide mechanistic evidence for weighted baseball training methods. Twenty-six collegiate- and professional-level baseball pitchers aged 20-30 years (mean age 23.5 [2.7] y) participated in a biomechanical evaluation while pitching a series of leather weighted baseballs. A 1-way repeated-measures analysis of variance was used to evaluate the intrasubject effect of ball weight on a total of 15 kinematic, kinetic, and performance parameters. Ball weight significantly affected pitch velocity, maximum elbow flexion, maximum pelvis rotation velocity, maximum shoulder internal rotation velocity, maximum elbow extension velocity, and anterior trunk tilt at ball release. None of the measured arm joint kinetics were significantly affected by ball weight. Training with 3- to 7-ounce (85- to 198-g) baseballs can be used to work on increasing pitching velocity without increasing throwing arm joint kinetics.

A Comparison of Pitching Biomechanics and Sport Specialization in High School Pitchers

Background

The prevalence of sport specialization in high school athletes continues to rise, particularly among baseball players. Previous research has focused on the incidence of injury among specialized and non-specialized athletes but has yet to examine the level of sport specialization and pitching biomechanics.

Hypotheses/Purpose

The purpose of this study was to investigate differences in pitching volume and biomechanics between low-, moderate-, and high-level specialized baseball pitchers. It was hypothesized that high-level specialized pitchers would have the most pitching volume within the current and previous years while low-level specialized pitchers would exhibit the least amount. The second hypothesis states that kinematics and kinetics commonly associated with performance and injury risk would differ between low-, moderate-, and high-level specialized pitchers.

Study Design

Case-Control Study.

Methods

Thirty-six high school baseball pitchers completed a custom sport specialization questionnaire before participating in a three-dimensional pitching motion analysis. Sport specialization was based off current guidelines and categorized as low-, moderate-, and high-level specialized based upon self-reported outcomes. Pitchers then threw ≈10 fastballs from a mound engineered to professional specifications. Data averaged across fastballs was used for biomechanics variables. Key pitching biomechanical and pitching volume variables were compared between low-, moderate-, and high-level specialized pitchers.

Results

High-level specialized pitchers were older (p = 0.003), had larger body mass (p = 0.05) and BMI (p = 0.045), and threw faster (p = 0.01) compared to low-level specialized pitchers. Pitching volume and pitching biomechanics were similar across groups.

Conclusions

Pitching biomechanics were similar across groups, although high-level specialized pitchers threw with significantly higher throwing velocity compared to low-level pitchers. The low amount of pitching volume throughout the season may be responsible for the lack of additional observed differences. Further research should examine the relationship between pitching biomechanics, upper extremity strength and flexibility, and sport specialization.

Level of Evidence

Level III.

Disabled Throwing Shoulder: 2021 Update: Part 2-Pathomechanics and Treatment

The purpose of this paper is to provide updated information for sports healthcare specialists regarding the disabled throwing shoulder (DTS). A panel of experts, recognized for their experience and expertise in this field, was assembled to address and provide updated information on several topics that have been identified as key areas in creating the DTS spectrum. Each panel member submitted a concise presentation on one of the topics within these areas, each of which were then edited and sent back to the group for their comments and consensus agreement in each area. Part two presents the following consensus conclusions and summary findings regarding pathomechanics and treatment, including (1) internal impingement results from a combination of scapular protraction and humeral head translation; (2) the clinically significant labral injury that represents pathoanatomy can occur at any position around the glenoid, with posterior injuries most common; (3) meticulous history and physical examination, with a thorough kinetic chain assessment, is necessary to comprehensively identify all the factors in the DTS and clinically significant labral injury; (4) surgical treatment should be carefully performed, with specific indications and techniques incorporating low profile implants posterior to the biceps that avoid capsular constraint; (5) rehabilitation should correct all kinetic chain deficits while also developing high-functioning, throwing-specific motor patterns and proper distribution of loads and forces across all joints during throwing; and (6) injury risk modification must focus on individualized athlete workload to avoid overuse. LEVEL OF EVIDENCE: V, expert opinion.

The Clinician's Guide to Baseball Pitching Biomechanics

CONTEXT

Improper baseball pitching biomechanics are associated with increased stresses on the throwing elbow and shoulder as well as an increased risk of injury.

EVIDENCE ACQUISITION

Previous studies quantifying pitching kinematics and kinetics were reviewed.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

At the instant of lead foot contact, the elbow should be flexed approximately 90° with the shoulder at about 90° abduction, 20° horizontal abduction, and 45° external rotation. The stride length should be about 85% of the pitcher's height with the lead foot in a slightly closed position. The pelvis should be rotated slightly open toward home plate with the upper torso in line with the pitching direction. Improper shoulder external rotation at foot contact is associated with increased elbow and shoulder torques and forces and may be corrected by changing the stride length and/or arm path. From foot contact to maximum shoulder external rotation to ball release, the pitcher should demonstrate a kinematic chain of lead knee extension, pelvis rotation, upper trunk rotation, elbow extension, and shoulder internal rotation. The lead knee should be flexed about 45° at foot contact and 30° at ball release. Corrective strategies for insufficient knee extension may involve technical issues (stride length, lead foot position, lead foot orientation) and/or strength and conditioning of the lower body. Improper pelvis and upper trunk rotation often indicate the need for core strength and flexibility. Maximum shoulder external rotation should be about 170°. Insufficient external rotation leads to low shoulder internal rotation velocity and low ball velocity. Deviation from 90° abduction decreases the ability to achieve maximum external rotation, increases elbow torque, and decreases the dynamic stability in the glenohumeral joint.

CONCLUSION

Improved pitching biomechanics can increase performance and reduce risk of injury.

SORT

Level C.

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

Background

Humeral torsion is an important osseous adaptation in throwing athletes that can contribute to arm injuries. Currently there are no cheap and easy to use clinical tools to measure humeral torsion, inhibiting clinical assessment. Models with low error and "good" calibration slope may be helpful for prediction.

Hypothesis/Purpose

To develop prediction models using a range of machine learning methods to predict humeral torsion in professional baseball pitchers and compare these models to a previously developed regression-based prediction model.

Study Design

Prospective cohort.

Methods

An eleven-year professional baseball cohort was recruited from 2009-2019. Age, arm dominance, injury history, and continent of origin were collected as well as preseason shoulder external and internal rotation, horizontal adduction passive range of motion, and humeral torsion were collected each season. Regression and machine learning models were developed to predict humeral torsion followed by internal validation with 10-fold cross validation. Root mean square error (RMSE), which is reported in degrees (°) and calibration slope (agreement of predicted and actual outcome; best = 1.00) were assessed.

Results

Four hundred and seven pitchers (Age: 23.2 +/-2.4 years, body mass index: 25.1 +/-2.3 km/m2, Left-Handed: 17%) participated. Regression model RMSE was 12° and calibration was 1.00 (95% CI: 0.94, 1.06). Random Forest RMSE was 9° and calibration was 1.33 (95% CI: 1.29, 1.37). Gradient boosting machine RMSE was 9° and calibration was 1.09 (95% CI: 1.04, 1.14). Support vector machine RMSE was 10° and calibration was 1.13 (95% CI: 1.08, 1.18). Artificial neural network RMSE was 15° and calibration was 1.03 (95% CI: 0.97, 1.09).

Conclusion

This is the first study to show that machine learning models do not improve baseball humeral torsion prediction compared to a traditional regression model. While machine learning models demonstrated improved RMSE compared to the regression, the machine learning models displayed poorer calibration compared to regression. Based on these results it is recommended to use a simple equation from a statistical model which can be quickly and efficiently integrated within a clinical setting.

Levels of Evidence

2.

Anthropometrics, Athletic Abilities and Perceptual-Cognitive Skills Associated With Baseball Pitching Velocity in Young Athletes Aged Between 10 and 22 Years Old

Objective assessments of players performance and individual characteristics are increasingly used in baseball. However, evidence linking individual characteristics to players' performance are scarce. The purpose of the study was to identify across ages, in younger males and females, and to compare, in younger males, the anthropometrics, athletic abilities and perceptual-cognitive skills associated with baseball pitcher's ball velocity. A cross-sectional design was used to conduct this study. Male and female athletes completed a sociodemographic questionnaire followed by anthropometric, athletic ability, perceptual-cognitive skill and pitching velocity assessments. Athletes were categorized by their age categories (11U, 13U, 15U, 18U, 21U). To evaluate the athletes' anthropometrics, height and weight, BMI, waist circumference, arms segmental length and girth were measured. Athletic abilities were assessed using athletes' grip strength, upper body power, vertical jump height, sprint, change of direction, and dynamic balance. Perceptual-cognitive skills performance was assessed with the Neurotracker platform. Pitching performance assessment was completed using the athletes' average fastball velocity. Kendall Tau's correlation coefficient was used to assess relationships between variables and pitching velocity in male athletes (p &lt; 0.05). A 1-way ANOVA was performed to identify differences between age categories for all variables in male athletes (p &lt; 0.05). In male athletes, without age categories discrimination, all anthropometric, athletic ability and perceptual-cognitive skill factors were associated with pitching velocity with associations ranging from τ = 0.185 for perceptual-cognitive skills to τ = 0.653 for left arm grip strength. The results showed that significant differences exist between age categories for anthropometric, athletic ability and perceptual-cognitive skill assessments. The study showed that associations between anthropometrics and pitching velocity, and athletic abilities and pitching velocity vary across age categories. Descriptive data of female athletes results regarding anthropometrics, athletic abilities, perceptual-cognitive skills and pitching velocity are also presented. Gender differences should be investigated in future studies exploring baseball pitching performance.

Effects of 4 Weeks of Variability of Practice Training in Padel Double Right Wall: A Randomized Controlled Trial

This study aimed to analyze the effect of a variable practice training in the double wall right forehand by using wrist weights. Thirty-four experienced padel players participated in this study. Players were randomly distributed in two groups (control group [CG] and training group [TG]). The TG performed 1 month of variable training, induced by weighted wrist bands, twice a week, with the same number of sessions and volume of training as the CG. TG obtained significant difference in posttest measurements (effect size = 0.437) in terms of the number of successful shots compared to CG (effect size = 0.027). These findings showed a significant effect of the TG with respect to the CG. Results reinforce the role of variability in the exploration and reinforcement of motor learning.

Throwing kinematics and elbow varus torque relative to ball size in junior baseball players

[Purpose] The purpose of this study was to investigate changes in the shoulder and elbow joint angles, upper limb angular velocities, and elbow varus torque when throwing balls of two different sizes. [Participants and Methods] The pitching motion of 26 junior baseball players was analyzed using an optical motion capture system. The balls used were a standard baseball and a small ball of equal weight. Shoulder external rotation/abduction and elbow flexion were measured. The maximum values of shoulder joint internal rotation, elbow joint extension, wrist flexion angular velocity, and elbow joint varus torque were also evaluated. The ball velocity was determined as an index of pitching performance. [Results] The shoulder external rotation and elbow flexion angles were higher when pitching with a small ball. The joint angular velocity was also significantly higher when pitching with a small ball for all items examined. The ball speed was significantly higher with the small ball. The maximum varus torque of the elbow joint divided by the ball velocity was significantly lower for the small ball. [Conclusion] For a junior baseball player with a small hand length, using a small ball enables pitching with low stress on the elbow joint.

Development and internal validation of a humeral torsion prediction model in professional baseball pitchers

BACKGROUND

Humeral torsion (HT) has been linked to pitching arm injury risk after controlling for shoulder range of motion. Currently measuring HT uses expensive equipment, which inhibits clinical assessment. Developing an HT predictive model can aid clinical baseball arm injury risk examination. Therefore, the purpose of this study was to develop and internally validate an HT prediction model using standard clinical tests and measures in professional baseball pitchers.

METHODS

An 11-year (2009-2019) prospective professional baseball cohort was used for this study. Participants were included if they were able to participate in all practices and competitions and were under a Minor League Baseball contract. Preseason shoulder range of motion (external rotation [ER], internal rotation [IR], horizontal adduction [HA]) and HT were collected each season. Player age, arm dominance, arm injury history, and continent of origin were also collected. Examiners were blinded to arm dominance. An a priori power analysis determined that 244 players were needed for accurate prediction models. Missing data was low (<3%); thus, a complete case analysis was performed. Model development followed the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) recommendations. Regression models with restricted cubic splines were performed. Following primary model development, bootstrapping with 2000 iterations were performed to reduce overfitting and assess optimism shrinkage. Prediction model performance was assessed through root mean square error (RMSE), R², and calibration slope with 95% confidence intervals (CIs). Sensitivity analyses included dominant and nondominant HT.

RESULTS

A total of 407 professional pitchers (age: 23.2 [standard deviation 2.4] years, left-handed: 17%; arm history prevalence: 21%) participated. Predictors with the highest influence within the model include IR (0.4, 95% CI 0.3, 0.5; P < .001), ER (-0.3, 95% CI -0.4, -0.2; P < .001), HA (0.3, 95% CI 0.2, 0.4; P < .001), and arm dominance (right-handed: -1.9, 95% CI -3.6, -0.1; P = .034). Final model RMSE was 12, R² was 0.41, and calibration was 1.00 (95% CI 0.94, 1.06). Sensitivity analyses demonstrated similar model performance.

CONCLUSIONS

Every 3° of IR explained 1° of HT. Every 3° of ER explained 1° less of HT, and every 7° of HA explained 1° of HT. Right-handers had 2° less HT. Models demonstrated good predictive performance. This predictive model can be used by clinicians to infer HT using standard clinical test and measures. These data can be used to enhance professional baseball arm injury examination.

Does Velocity Increase From Flat-Ground to Mound Work During a Lighter Baseball Training Program?

INTRODUCTION

There has been recent interest in throwing from flat-ground versus the mound regarding stress on the elbow. Typical throwing progression programs begin with flat-ground work and progress to mound work.

METHODS

All baseball pitchers of ages 10 to 17 years who completed a 15-week pitching mechanics and velocity-training program were included. Players' pitch velocity was tested at four time points during training. Average velocity and maximum velocity of pitches from flat-ground were compared with those of mound, and change in velocity between testing sessions was also compared.

RESULTS

Thirty-six male pitchers (average age: 14.4 ± 1.6 years) were included. Fastball velocity increased by an average of 5.2 mph (95% confidence intervals 2.0 to 8.8 mph) at the end of the training program. When change in average and maximum velocity was compared between the four testing sessions, the most notable increase in velocity occurred between the third and fourth testing sessions. Both sessions were thrown from the mound.

CONCLUSION

The 15-week baseball pitcher-training program markedly improved pitching velocity. Throwing from a mound compared with flat-ground resulted in the largest velocity increase. Therefore, when attempting to increase a pitcher's velocity, throwing from the mound should be an integral part of any velocity program.

Are Wearable Sensors Valid and Reliable for Studying the Baseball Pitching Motion? An Independent Comparison With Marker-Based Motion Capture

BACKGROUND

In recent years, the prevalence of medial ulnar collateral ligament injuries has increased in throwers of all ages and skill levels. The motusBASEBALL sensor possesses an inertial measurement unit (IMU) that has been developed and applied to the throwing arm to allow for measurements of several objective parameters, which may prove beneficial for monitoring, rehabilitation, and injury prevention in the throwing athlete. However, the reliability, consistency, and validity of the IMU have not been independently assessed.

PURPOSE

To evaluate the reliability, consistency, and validity of the motusBASEBALL sensor compared with the historic gold standard of marker-based motion capture.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 10 healthy male baseball athletes with varsity-level high school experience volunteered to participate in this study. Participants were fitted with 37 retroreflective markers for motion capture and the motusBASEBALL IMU sensor. Participants threw 5 fastballs at maximum effort, with measurements recorded simultaneously by motion capture and the IMU. Arm slot, arm speed, arm stress, and shoulder rotation were measured and compared.

RESULTS

Of the 4 metrics generated by the IMU, significant differences were found for 3 of the throwing metrics compared with motion capture including arm slot (5.0°± 6.1°; P = .037), elbow varus torque (9.4 ± 12.0 N·m; P = .037), and shoulder rotation (6.3°± 6.1°; P = .014). Arm speed did not demonstrate a statistically significant difference (29.2 ± 96.8 rpm; P = .375). The IMU consistently underreported pitching performance values. Shoulder rotation exhibited excellent reliability with <5° of error, and arm slot demonstrated good reliability with <10° of error. Arm stress and arm speed were less reliable.

CONCLUSION

The IMU was not accurate or valid for arm slot, arm stress, and shoulder rotation compared with marker-based motion capture. It was relatively accurate for arm speed. Despite its lack of validity, it was consistent and reliable for arm speed and shoulder rotation and relatively reliable for arm slot and arm stress. Caution should be used when comparing values provided by this IMU to the gold standard of marker-based motion capture.

CLINICAL RELEVANCE

IMU technology has potential to be used in monitoring, rehabilitation, and injury prevention in throwing athletes if valid. This study demonstrates that the values provided by the IMU should not be considered equivalent to those generated by the gold standard of marker-based motion capture; however, there may still be a role for this technology when relying on its internal consistency for intrathrower comparisons and tracking.

Nonsurgical Management of Ulnar Collateral Ligament Injuries

Ulnar collateral ligament (UCL) injuries are a common source of pain and disability in the overhead athlete and often result in notable loss of time from competition. Over the past 10 to 15 years, the prevalence of UCL injury and reconstruction has undergone a dramatic increase, making it imperative to determine which patients may benefit from a nonsurgical regimen. Nonsurgical treatment involves a multidisciplinary approach of rehabilitation with tailored physical therapy programs and, in certain cases, biologic adjuncts. Physical therapy protocols should focus on strengthening the periscapular muscles, rotator cuff, core musculature, and flexor pronator mass to help stabilize the injured elbow and prevent injury recurrence before the initiation of a progressive throwing program. The implementation of injury prevention programs has shifted the focus from just the elbow and have included the shoulder, legs, and core in an effort to help decrease the stress on the upper extremity. In addition, biologic therapies such as platelet-rich therapy are promising modalities to augment the conservative treatment of UCL injuries but remain under investigation. The purpose of this study is to review available strategies and outcomes for conservatively treating UCL injuries.

The Safety and Efficacy of Weighted Baseballs

One of the most common methods of training to enhance pitching velocity is the use of weighted baseballs. As with anything else, the excitement and popularity often proceed our scientific understanding. While there is still a lot to learn, our understanding of the science and efficacy of weighted baseball training has grown in recent years. The purpose of this clinical viewpoint is to summarize our current scientific understanding.

The Effect of Straight-Line Long-Toss Versus Ultra-Long-Toss Throwing on Passive Glenohumeral Range of Motion Recovery After Pitching

BACKGROUND

Repetitive throwing in baseball pitchers can lead to pathologic changes in shoulder anatomy, range of motion (notably glenohumeral internal rotation deficit), and subsequent injury; however, the ideal strengthening, recovery, and maintenance protocol of the throwing shoulder in baseball remains unclear. Two strategies for throwing shoulder recovery from pitching are straight-line long-toss (SLT) throwing and ultra-long-toss (ULT) throwing, although neither is preferentially supported by empirical data.

HYPOTHESIS

ULT will be more effective in returning baseline internal rotation as compared with SLT in collegiate pitchers after a pitching session.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 24 National Collegiate Athletic Association Division I baseball pitchers with mean age 20.0 ± 1.1 years were randomized to either the ULT group (n = 13; 9 right-hand dominant, 4 left-hand dominant) or SLT group (n = 11; 10 right-hand dominant, 1 left-hand dominant). Measurements (dominant and nondominant, 90° abducted external rotation [ER], internal rotation [IR], and total range of motion [TROM]) were taken at 5 time points across 3 days: before and immediately after a standardized bullpen session on day 1; before and immediately after a randomized standardized ULT or SLT session on day 2; and before practice on Day 3.

RESULTS

ULT demonstrated significantly greater final ER compared with baseline (+10°; P = 0.05), but did not demonstrate significant IR changes. Similarly, SLT demonstrated significantly greater post-SLT ER (+12°; P = 0.02) and TROM (+12°;P = 0.01) compared with baseline, but no significant IR changes. Final ER measurements were similar between ULT (135° ± 14°) and SLT (138° ± 10°) (P = 0.59). There was also no statistically significant difference in final IR between ULT (51° ± 14°) and SLT (56° ± 8°) (P = 0.27).

CONCLUSION

The routine use of postperformance, ULT throwing to recover from range of motion alterations, specifically IR loss, after a pitching session is not superior to standard, SLT throwing. Based on these findings, the choice of postpitching recovery throwing could be player specific based on experience and comfort.

CLINICAL RELEVANCE

The most effective throwing regimens for enhancing performance and reducing residual impairment are unclear, and ideal recovery and maintenance protocols are frequently debated with little supporting data. Two strategies for throwing shoulder recovery from pitching are SLT and ULT throwing. These are employed to help maintain range of motion and limit IR loss in pitchers. The routine use of ULT throwing for recovery and to limit range of motion alterations after a pitching session is not superior to SLT throwing.

Review of Clinical Trials on the Effects of Tai Chi Practice on Primary Hypertension: The Current State of Study Design and Quality Control

The modulation of Tai Chi in physiological function and psychological status attracts sustaining attention. This paper collected original articles regarding the effects of Tai Chi practice on modulating primary hypertension from 7 electronic databases (PubMed, Excerpta Medica Database, Cochrane Library, Web of Science, Chinese Knowledge Resource Integrated Database, Wanfang Database, and China Science and Technology Journal Database) from their dates of origin to October 1st, 2020. A total of 45 articles were included. The literature analyses have shown that the benefits of Tai Chi practice for blood pressure management have been identified in all of the included 45 studies, and Tai Chi exercise has shown significant efficacy in improving hypertension clinical symptoms and quality of life, compared to the majority of control interventions, though there are also some methodological issues, including small sample sizes, lack of exact randomization methods and quality control criteria, and lack of specific standards used to measure the characteristics of Tai Chi practice. In the future, the inclusion of additional design standards, stricter quality controls, and evaluation measures for the features of Tai Chi practice is required in trials evaluating its effects on hypertension.

The Evidence Behind Weighted Ball Throwing Programs for the Baseball Player: Do They Work and Are They Safe?

PURPOSE OF REVIEW

Weighted baseball throwing programs have gained significant attention recently. They have been promoted as proven option for pitchers wishing to increase their throwing velocity and improve throwing mechanics. However, there is some concern that, if not applied properly, they may increase injury risk. In this review, we aim to (1) give a brief description of the potential mechanisms through with weighed ball programs that could improve throwing velocity, (2) summarize the available evidence regarding their effectiveness in increasing throwing velocity, (3) summarize the evidence on injury risk, and (4) propose directions for future studies.

RECENT FINDINGS

Initial research on weighted ball programs was published in the 1960s. Recently there has been an increase in research as interest from baseball organizations, instructors, players, and medical providers has grown. A recent randomized controlled trial demonstrated that pitching velocity can be increased through a 6-week weighted ball program; however, with that, they found that the rate of injury also increased. An earlier systematic review outlined 10 studies that evaluated weighted ball programs effect on pitching velocity and reported that 7 studies described increases in throwing velocity, while most studies did not comment on injury risk. They note that the results on rate of injury have been variable, likely secondary to the variability in time and intensity of different programs. The inconsistency in the methodology of weighted ball programs and studies has made it challenging to draw (scientifically) meaningful conclusions. Nevertheless, several studies have offered empirical evidence in support of the claim that weighted ball programs can increase pitching velocity through improved throwing mechanics. At the same time, these studies have emphasized the improvements in performance, while the potential effects on injury mechanisms have been less well understood. There is a need for improved standardization of these programs to allow for future study and subsequent modification to optimize performance.

Changes in Muscle Activity among College Pitchers Using 5- to 12-Oz Weighted Baseball

OBJECTIVES Several studies have reported that weighted baseball (WB) training is effective in improving ball speed; however, the weight of the ball suitable for training remains unclear. This study aimed to investigate the changes in muscle activity during pitching using 5- to12-oz WBs and to provide basic data for training programs to improve pitching speed.METHODS The subjects of this study were 10 overhand pitchers who had more than 5 years of experience. Muscle activity was measured and analyzed at 70–85% of throwing baseball maximum effort (TBME) during soft toss (ST) and TBME was evaluated using electromyography.RESULTS As the ball weight increased, muscle activity also increased in all pitching phases. Muscle activity was higher during ST with WBs heavier than 10 or 11oz than during TBME, indicating that the loads on the shoulder and elbow joint muscles increased. Conversely, muscle activity during ST with 5- to 7-oz WBs was lower than that during TBME, although phase and muscle group differences were observed.CONCLUSIONS The results of this study suggest that training with 8- to 10-oz WBs could increase muscle strength and activity, although the effect may vary with fitness level and muscle strength.

Predictors of throwing performance in amateur male cricketers: A musculoskeletal approach

Optimal throwing speed and accuracy is built on a complex interaction of multiple variables. Although strength and power has been associated with throwing speed in cricketers, the individual muscles that contribute to optimal function of the shoulder-complex has not been adequately explored in connection with throwing performance. Consequently, this study aimed to investigate the correlation between musculoskeletal variables and overhead throwing performance in cricketers. Thirty-two amateur male cricketers were tested using a battery of 16 tests (strength, flexibility, scapula positioning) as well as a throwing speed (TS) and a novel accuracy test (TA). Only two of the sixteen tests were correlated with throwing performance in the multiple regression analysis. Non-dominant hip abduction strength correlated positively with TS (p < 0.05): on average, a strength increase of 10 newtons (N) was associated with an increase in TS of 0.60 km/h (95% CI: 0.12-1.08). Non-dominant pectoralis minor length correlated positively with TA (p < 0.01): on average, a one-centimetre increase in the length correlated to an increase, of 0.633 points (95% CI: 0.225-1.041). This cross-sectional study demonstrated that from an array of musculoskeletal variables, only non-dominant hip abduction strength correlated with TS, while only non-dominant pectoralis minor length correlated with TA in amateur cricketers.

Interaction Between Age and Change in Velocity During a Baseball Training Program

Background:

Pitching velocity is one of the most important metrics used to evaluate a baseball pitcher’s effectiveness. The relationship between age and pitching velocity after a lighter ball baseball training program has not been determined.

Purpose/Hypothesis:

The purpose of this study was to examine the relationship between age and pitching velocity after a lighter ball baseball training program. We hypothesized that pitching velocity would significantly increase in all adolescent age groups after a lighter baseball training program, without a significant difference in magnitude of increase based on age.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Baseball pitchers aged 10 to 17 years who completed a 15-week training program focused on pitching mechanics and velocity improvement were included in this study. Pitchers were split into 3 groups based on age (group 1, 10-12 years; group 2, 13-14 years; group 3, 15-17 years), and each group trained independently. Pitch velocity was assessed at 4 time points (sessions 3, 10, 17, and 25). Mean, maximum, and mean change in pitch velocity between sessions were compared by age group.

Results:

A total of 32 male baseball pitchers were included in the analysis. Mean/maximum velocity increased in all 3 age groups: 3.4/4.8 mph in group 1, 5.3/5.5 mph in group 2, and 5.3/5.2 mph in group 3. While mean percentage change in pitch velocity increased in all 3 age groups (group 1, 6.5%; group 2, 8.3%; group 3, 7.6%), the magnitude of change was not significantly different among age groups. Program session number had a significant effect on mean and maximum velocity, with higher mean and maximum velocity seen at later sessions in the training program (P = .018). There was no interaction between age and program session within either mean or maximum velocity (P = .316 and .572, respectively).

Conclusion:

Age had no significant effect on the magnitude of increase in maximum or mean baseball pitch velocity during a velocity and mechanics training program in adolescent males.

Acute Effects of Weighted Baseball Throwing Programs on Shoulder Range of Motion

BACKGROUND

Baseball pitching injuries are increasing at an alarming rate. While weighted ball throwing programs may be effective at increasing pitching velocity, previous research has identified a 24% injury rate and a 3.3° increase in shoulder external rotation (ER) range of motion (ROM) after performing a 6-week program. However, previous research has not investigated, separately, the immediate effects of throwing underloaded and overloaded balls on ROM. The purpose of this study was to examine the acute effects of throwing differently weighted baseballs on shoulder ROM. By analyzing these differences, it may be possible to determine the specific weight range that may lead to the greatest increase in ROM and potential injury risk.

HYPOTHESIS

Throwing with weighted balls will result in an increase in shoulder ER ROM.

STUDY DESIGN

Randomized controlled trial.

LEVEL OF EVIDENCE

Level 2.

METHODS

A total of 16 male high school baseball pitchers agreed to participate in this study. The participants were (mean ± SD) 17.1 ± 1.0 years of age, 1.81 ± 0.09 m tall, and had a mass of 79.2 ± 11.1 kg. Each participant was tested on 3 different days, 1 week apart, with 3 different conditions in random order: (1) underload throwing, using regulation 5-oz baseballs and 4- and 2-oz balls; (2) overload throwing, using 5-, 6-, and 9-oz balls; and (3) extreme overload throwing, using 5-, 16-, and 32-oz balls. Each testing session began by measuring passive shoulder ROM (external rotation and internal rotation) using standard goniometric measurements. Participants then performed 3 throws with each weighted ball from 3 different positions (kneeling, rocker, and run-and-gun) for a total of 27 throws each test session. ROM measurements were repeated at the end of each test session. The effect of each throwing condition on ROM was compared from pre- to posttraining using a paired t test (P ≤ 0.05).

RESULTS

There was no significant difference in ER after throwing at underloaded weights. The overload condition showed a statistically significant increase of 3.3° in external rotation (P = 0.05). The extreme overload condition showed a statistically significant increase in ER of 8.4° (P < 0.001). There were no differences in internal rotation for any group.

CONCLUSION

A significant increase in shoulder ER was observed immediately after throwing overload weighted balls. This effect increased as the weights of the balls increased.

CLINICAL RELEVANCE

Throwing with overload weighted baseballs causes an immediate increase in shoulder ER ROM. It is unknown why these changes occur; however, the results may explain both the increase in velocity and injury rates previously observed from throwing weighted balls. The current study results may be used to develop more scientifically validated weighted ball programs. Heavier balls should be used with caution, and ROM should be monitored during implementation of these programs.

Training With Lighter Baseballs Increases Velocity Without Increasing the Injury Risk

Background:

Pitch velocity has become an increasingly popular metric by which pitchers are graded and compared. Training programs that utilize weighted balls have been effective in increasing velocity but at the cost of an increased injury risk. No studies have evaluated training with lighter baseballs with regard to increasing pitch velocity and the injury risk.

Purpose/Hypothesis:

The purpose of this study was to determine whether a training program utilizing lighter baseballs could increase fastball velocity without increasing the injury risk to participants. We hypothesized that a training program with lighter baseballs would increase fastball velocity but not increase the injury risk.

Study Design:

Case series; Level of evidence, 4.

Methods:

All baseball pitchers who participated in a 15-week program at a single location, with the same coaches, and aimed to improve pitching mechanics and increase velocity were included. The training program was broken down into 3 phases, and each participant went through the same program. Lighter baseballs (3 and 4 oz) and standard baseballs (5 oz) were utilized as part of the training program. Weighted (heavier) balls were not used. Velocity was measured at 4 time points throughout the program with the pitcher throwing 5 fastballs using a standard 5-oz ball at maximum velocity (sessions 3, 10, 17, and 25). Injuries for all players were recorded throughout the entire program.

Results:

A total of 44 male pitchers aged 10 to 17 years (mean age, 14.7 ± 1.8 years) completed the training program and were available for analysis. No pitcher sustained a shoulder or elbow injury during the course of the training program. Fastball velocity increased by a mean of 4.8 mph (95% CI, 4.0-5.6 mph) (P < .001). Overall, 43 of 44 players (98%) had an increase in fastball velocity over the course of the program.

Conclusion:

A 15-week pitching training program with lighter baseballs significantly improved pitching velocity without causing any injuries, specifically to the shoulder or elbow. Lighter baseballs should be considered as an alternative to weighted baseballs when attempting to increase a pitcher’s velocity.

Acute effects of in-step and wrist weights on change of direction speed, accuracy and stroke velocity in junior tennis players

The main aim of this study was to investigate the acute effects of the use of a weighting set (Powerinstep®) on measures of stroke velocity (StV), accuracy and change of direction speed (CODS) in junior tennis players. A within-subjects design was used to evaluate seventeen (6 female and 11 male) tennis players (mean ± SD; 16.5 ± 1.3 years old; 1.75 ± 8.4 m; 67.0 ± 8.1 kg; 22.04 ± 1.8 kg/m2) on StV of three specific tennis actions (serve, forehand and backhand) and CODS for the following conditions: wearing a 50, 100, 150, 200 g weight or no weight at all (baseline). No significant differences were found between conditions for forehand (F = 0.412; p = 0.799), backhand (F = 0.269; p = 0.897) and serve (F = 0.541; p = 0.706) velocity and forehand (F = 1.688; p = 0.161), backhand (F = 0.567; p = 0.687) and serve (F = 2.382; p = 0.059) accuracy and CODS (F = 0.416; p = 0.797). Small-to-moderate effect sizes (ES) negatively affecting StV when using 200 g compared to the baseline (ES = 0.48, 0.35 and 0.45) could be observed. Moderate (ES = -0.49) and trivial (ES = -0.14 and -0.16) ES for a higher accuracy score were noticed in serve, forehand and backhand 100 g compared to the baseline. Moreover, small ES (ES = 0.41) for improvement in 200 g CODS comparing to baseline conditions were found. These results indicate that the use of a weighting set does not significantly affect StV or CODS respectively. Notwithstanding, small-to-moderate changes show impact in accuracy and no variance in velocity production when using 100 g alongside faster execution in CODS when using 200 g.

Individual factors associated with baseball pitching performance: scoping review

Background

Ball velocity, accuracy and game statistics represent three methods used to measure pitching performance. However, individual determinants of pitching performance are more elusive.

Objectives

The aims of this study were to classify the performance factors associated with baseball pitchers, to identify the methods used to quantify their abilities through all features of the game and to document relationships between performance factors and indicators.

Design

Scoping review.

Data sources

Electronic searches of MEDLINE, Academic Search Complete, CINAHL, SportDiscus, PubMed, PsycINFO, Cochrane and of grey literature were undertaken from inception to January 2019.

Eligibility criteria for selecting studies

Cross-sectional studies that investigated the relationship between performance indicators and individual performance factors in healthy baseball pitchers were selected.

Results

Thirty-four cross-sectional studies investigating individual potential factors of pitching performance met the inclusion criteria. The primary performance factors investigated were kinematic, kinetic, timing outcomes, personal characteristics, physical tests and range of motion. Shoulder horizontal adduction (SHA), upper torso forward flexion, maximal shoulder external rotation, upper torso rotation angle, upper torso lateral flexion, lead knee flexion (LKF) and forward trunk tilt (FTT) were identified as key kinematic features associated with increased ball velocity. Shoulder proximal force and peak elbow proximal forces were associated with greater ball velocity. Individual performances in jumping tests and body weight (BW) are also associated with pitching performance.

Summary/conclusion

Based on studies presenting low and moderate risk of bias, we conclude that BW, age and kinematics, such as FTT, LKF, SHA and lateral trunk tilt, are associated with pitching performance.

Induced power analysis of sequential body motion and elbow valgus load during baseball pitching

The flow of mechanical energy of segmental motion during baseball pitching is poorly understood, particularly in relation to the valgus torque at the elbow which is prone to pitching-related injuries. This study employed an induced power analysis to determine the components of muscle and velocity-dependent torques that contribute to the power of throwing arm segments when the elbow is under valgus load during the arm-cocking phase of pitching. The 3D throwing kinematics and kinetics of 10 adult pitchers were included in this analysis. Pitchers threw with a maximum elbow valgus torque of 73 ± 20 N•m. The trunk flexion and rotation components of the velocity-dependent torque were the greatest contributors to the work of the forearm at -0.53 ± 0.22 J/kg and -0.43 ± 0.21 J/kg, respectively. Approximately 86% of the total energy transferred through the elbow by the velocity-dependent torque was due to trunk motion, which appears to drive the power of accelerating the throwing elbow in valgus. These results support the importance of trunk motion as a key component in the development of elbow torque and ball velocity. Therefore, this study has practical implications for baseball pitchers seeking to minimise injury risk while improving performance.