Do baseball pitchers improve mechanics after biomechanical evaluations?

Video-recorded Endotracheal Intubations: An Educational Tool in Airway Management Training for Pulmonary and Critical Care Fellows

Background

Expert airway management is an essential skill for pulmonary and critical care fellows. Providing high-quality real-time feedback to trainees performing emergent intubations is often limited because of the acuity of the situation and the lack of full airway visualization by the supervising provider.

Objective

We sought to improve the quality of airway management education in a pulmonary and critical care fellowship training program by recording all emergent intubations and systematically reviewing select videos at a regularly scheduled airway management conference.

Methods

We introduced several modifications to our airway training curriculum, including the recording of all fellow-performed emergent tracheal intubations along with a regularly scheduled conference in which selected videos recordings were systematically reviewed. Surveys completed by trainees before and after the redesign of the curriculum were used to determine the efficacy of the individual curriculum modifications. Paired Student's t tests, χ2 tests, and Kruskal-Wallis tests were used for statistical analysis. A P value lower than 0.05 was considered significant in all analyses.

Results

After completion of the redesigned curriculum, trainees (100% response rate) demonstrated improved technical knowledge (P < 0.04) and procedural confidence (P < 0.04) with regard to airway management. Of the modifications incorporated into the curriculum redesign, fellows ranked the video-recorded intubation review conference as the most beneficial (P = 0.001) of the educational interventions.

Conclusion

Recording of trainee-performed intubations and subsequent review of these videos using a standardized rubric was a highly valued modification to our fellowship airway training curriculum.

Biomechanical effects of foot placement during pitching

Baseball coaches often focus on the landing position of a pitcher's front foot as a key aspect of mechanics. Furthermore, controversy persists regarding positioning the rear foot on the first base or third base end of the rubber. The purpose of this study was to determine the effect of rear and front foot placement on pitching biomechanics. Our hypotheses were that there would be significant kinematic and kinetic differences associated with foot placement. This was a retrospective review including 144 healthy right-handed adult baseball pitchers divided into groups based on their rear and front foot placements: first base open (1B-Open), first base closed (1B-Closed), third base open (3B-Open), and third base closed (3B-Closed). Two-way ANOVAs detected no statistically significant main effects for kinetic variables but several for kinematic variables. Open pitchers had less shoulder abduction at the time of ball release and greater maximum shoulder internal rotation velocity in comparison with closed pitchers. They also had less forearm pronation at the time of ball release and greater maximum elbow extension velocity. Additional statistically significant results were found; however, low effect sizes may lessen the clinical significance of many of the results.

An Analysis of Intrapitch Variation in Joint and Segment Velocities With Throwing Arm Kinetics in High School and Professional Baseball Pitchers

BACKGROUND

Improper sequencing order of maximal joint and segment velocities has been identified as an important predictor for both throwing arm kinetics and ball velocity.

PURPOSE

To investigate the intrapitcher variation of maximal segment velocities and the relationship to throwing arm kinetics and ball velocity in high school (HS) and professional (PRO) pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

HS (n = 59) and PRO (n = 338) pitchers, instructed to throw 8 to 12 fastball pitches, were evaluated with 3-dimensional motion capture (480 Hz). Maximal joint and segment velocities were calculated for each pitch, and the standard deviation of the maxima was calculated per pitcher. These standard deviations were used to classify pitchers as "low variance" or "high variance" for each segmental velocity subgroup, "overall low variance" or "overall high variance" based on cumulative segment velocity variation, or "population," with any pitcher eligible to be included in multiple subcategories. Maximal velocities and throwing arm kinetics were compared among the various subgroups.

RESULTS

The HS low-variance shoulder internal rotation velocity subgroup (4949 ± 642 deg/s) had significantly lower maximal shoulder internal rotation velocity compared with HS population (5774 ± 1057 deg/s) (P < .001); similar findings were observed for PROs (5269 ± 835 vs 5824 ± 1076 deg/s; P < .001), as well as lower shoulder superior force compared with the PRO population (14.8% ± 8.8% vs 17.8% ± 8.8% body weight; P = .001). The PRO low-variance lead knee extension velocity subgroup had significantly lower maximal lead knee extension velocity (216 ± 135 vs 258 ± 125 deg/s; P = .001) and shoulder distractive force (111.5% ± 14.4% vs 115.6% ± 15.9% body weight; P = .003) compared with the PRO population. The PRO overall low-variance subgroup had significantly lower shoulder distractive force (111.8% ± 14.1% vs 119.6% ± 15.5% body weight; P = .008) and elbow anterior force (40.6% ± 5.0% vs 43.6% ± 6.2% body weight; P = .008) compared with the PRO overall high-variance subgroup.

CONCLUSION

HS and PRO pitchers with low variance for joint and segment velocities achieved significantly lower maximal velocities in the subgroup of interest, while preserving ball velocity. PRO pitchers with overall low variance among multiple maximal joint and segment velocities demonstrated decreased shoulder distractive and elbow anterior force.

CLINICAL RELEVANCE

PRO pitchers with low intrapitch variation in maximal joint and segment velocities may be viewed as kinetically conservative throwers. These pitchers with similarly maintained mechanics between pitches may have an increasingly regimented form that preserves kinetic forces about the throwing arm. The opposite may be true for PRO pitchers with increased variability in segmental velocities during their pitching motion, as they showed increased throwing arm kinetics including shoulder distractive and elbow anterior force compared with the overall low-variance group, theoretically increasing their risk of injury.

Feasibility of the pitch efficiency rating: A novel tool for systematic assessment of pitching mechanics in developing throwing athletes

BACKGROUND

Injuries in younger baseball athletes continue to increase despite work characterizing risk factors. Three-dimensional (3D) motion capture may identify suboptimal pitching mechanics that predispose an athlete to injury, but 3D-motion analysis is often inaccessible. Thus, there is a gap between the current biomechanics literature and its practical application in young athletes. The current study aims to assess the reliability of the pitch efficiency rating (PER) as a systematic tool to evaluate throwing mechanics in developing baseball pitchers.

OBJECTIVE

To determine the feasibility of application and reliability of a novel, scientifically informed tool (PER) for the assessment of pitching mechanics.

DESIGN

Reliability study using Bland-Altman methods for assessing agreement between two raters.

SETTING

Academic medical center through community outreach.

PARTICIPANTS

Pitching mechanics were assessed and rated with the PER for 40 athletes (26 high school, 14 Division III), average age 19.0 years old (range 15.3-23.7 years old).

INTERVENTIONS

N/A.

MAIN OUTCOME MEASURES

Interrater and intrarater reliability as calculated by intraclass correlation coefficient (ICC).

RESULTS

For initial readings comparing interrater reliability between Rater 1 and Rater 2, the ICC was calculated at 0.80 (95% confidence interval [CI] 0.66-0.89) and 0.76 (95% CI 0.60-0.86) for the second set of ratings. Regarding intrarater reliability across reads, ICC was found to be 0.63 (95% CI 0.43-0.79) for Rater 1, and 0.91 for Rater 2 (95% CI 0.85-0.95).

CONCLUSIONS

The present study introduces the PER as a potential tool for evaluating pitching mechanics. However, the intrarater reliability of the PER did not meet preestablished criteria in one of the two pilot raters. Further study is needed to continue to assess the reliability of the tool across diverse demographics.

Relationship Between Arm Path, Ball Velocity, and Elbow Varus Torque in Professional Baseball Pitchers

Background

Currently, most pitching instructors suggest a shorter arm path-the total distance the arm travels during pitching. Theoretically, this combination allows for better body segment sequencing, a more efficient energy transfer through the kinetic chain, and increased ball velocity, while limiting elbow varus torque.

Hypothesis

Shorter arm paths would be associated with increased ball velocity and decreased elbow varus torque.

Study Design

Descriptive laboratory study.

Methods

A total of 182 professional pitchers threw 8 to 12 fastball pitches while evaluated by 3-dimensional motion capture (480 Hz). The arm path was calculated as the total distance the hand marker traveled during the pitch. The pitch was divided into early, late, and total arm paths. A linear regression model assessed the interpitcher relationship between arm path, elbow varus torque, and ball velocity. A linear mixed-effects model with random intercepts assessed intrapitcher relationships.

Results

Interpitcher comparison showed that total arm path weakly correlated with greater elbow varus torque (P = .025). Strong correlations were found between ball velocity and early (R2 = 0.788; P < .001), late (R2 = 0.787; P = .024), and total arm paths (R2 = 0.792; P < .001). Strong positive intrapitcher correlations were found between elbow varus torque and early (R2 = 0.962; P < .001) and total arm path (R2 = 0.964; P < .001). For individual pitchers, there was a large variation in the early (30.1 ± 15.7 cm) and late (21.4 ± 12.1 cm) arm path. For every 30-cm (11.8-inch) increase in early arm path (the mean range for an individual pitcher), there was a 1.29-N (β = 0.0429) increase in elbow varus torque and a 0.354 m/s (0.79 mph) (β = 0.0118) increase in ball velocity.

Conclusion

A shorter arm path correlated with decreased elbow varus torque and decreased ball velocity in intrapitcher comparisons. Determining the individual mechanics that decrease elbow varus torque may help coaches and trainers correct these patterns.

Clinical Significance

A shorter arm path during the pitch can decrease elbow varus torque, which limits the load on the medial elbow but also has a detrimental effect on ball velocity. An improved understanding of the impact of shortening arm paths on stresses on the throwing arm may help minimize injury risk.

Influence of stride length on upper extremity joint moments and ball velocity in collegiate baseball pitchers

The initial stride down the mound is an important aspect of the baseball pitch. Understanding the implications of stride length is essential to appropriately coach baseball pitchers. The purpose of this study was to determine the association between normalised stride length and the elbow varus and glenohumeral internal rotation moments, ball velocity, trunk and pelvic rotation and forward trunk tilt. Motion analysis data collected from 99 collegiate pitchers were analysed for this study. A random intercept, mixed-effects regression model was used to determine if there were statistically significant associations between normalised stride length and the variables of interest. Secondary analyses were conducted to determine if an optimal stride length existed in this cohort. No significant associations were found between normalised stride length, ball velocity, or upper extremity joint moments. Additionally, no optimal stride length was identified; however, trends indicate that stride lengths between 131%-137% of a pitcher's leg length may be beneficial. Normalised stride length was associated with both trunk and pelvic rotation at foot contact (p < 0.001). Trunk and pelvic rotation has been previously shown to be associated with ball velocity and joint moments, indicating that stride length may have an indirect effect on ball velocity and joint moments.

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

Background

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.

Purpose

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.

Study Design

Descriptive laboratory study.

Methods

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.

Results

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.

Conclusion

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.

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.

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

Objectives

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).

Methods

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.

Results

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.

Conclusion

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.

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.

Editorial Commentary: Baseline Motion Analysis of Baseball Pitchers Provides a Valuable Tool for Evaluation, Rehabilitation, and Return to Play Should Injury Occur

The role of motion analysis to study throwing athletes has blossomed as the technology resolution and accuracy have continued to improve and the relative cost has decreased. As applied to baseball pitchers, including professionals, a challenge is the wide spectrum of pitching motion that successful, uninjured pitchers demonstrate. Although most pitching coaches agree on some common elements of effective pitching mechanics, each pitcher may have specific and unique characteristics of delivery. These are related to the player's age, workload, conditioning, and genetic aspects. Perhaps the best "control" when evaluating throwing kinematics in an injured pitcher is the same athlete before injury. Although the data may not always be available, obtaining baseline motion analysis (in spring training, preseason, and so on) for high-risk players (pitchers) would be optimal. This information may serve as a rehabilitation and training tool for research and may help to facilitate "return-to-play" determination. Preinjury and post-treatment kinematics assist with the initial evaluation and subsequent treatment of the injured athlete. Furthermore, this information may elucidate the cause of the abnormal kinematics, that is, whether the injury caused the irregular motion or the abnormal kinematics induced the injury.

Biomechanical Analysis of the Throwing Athlete and Its Impact on Return to Sport

Throwing sports remain a popular pastime and frequent source of musculoskeletal injuries, particularly those involving the shoulder and elbow. Biomechanical analyses of throwing athletes have identified pathomechanic factors that predispose throwers to injury or poor performance. These factors, or key performance indicators, are an ongoing topic of research, with the goals of improved injury prediction, prevention, and rehabilitation. Important key performance indicators in the literature to date include shoulder and elbow torque, shoulder rotation, kinetic chain function (as measured by trunk rotation timing and hip-shoulder separation), and lower-extremity mechanics (including stride characteristics). The current gold standard for biomechanical analysis of the throwing athlete involves marker-based 3-dimensional) video motion capture. Emerging technologies such as marker-less motion capture, wearable technology, and machine learning have the potential to further refine our understanding. This review will discuss the biomechanics of throwing, with particular attention to baseball pitching, while also delineating methods of modern throwing analysis, implications for clinical orthopaedic practice, and future areas of research interest.

Level of Evidence

V, expert opinion.

Machine Learning and Statistical Prediction of Pitching Arm Kinetics

BACKGROUND

Over the past decade, research has attempted to elucidate the cause of throwing-related injuries in the baseball athlete. However, when considering the entire kinetic chain, full body mechanics, and pitching cycle sequencing, there are hundreds of variables that could influence throwing arm health, and there is a lack of quality investigations evaluating the relationship and influence of multiple variables on arm stress.

PURPOSE

To identify which variables have the most influence on elbow valgus torque and shoulder distraction force using a statistical model and a machine learning approach.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A retrospective review was performed on baseball pitchers who underwent biomechanical evaluation at the university biomechanics laboratory. Regression models and 4 machine learning models were created for both elbow valgus torque and shoulder distraction force. All models utilized the same predictor variables, which included pitch velocity and 17 pitching mechanics.

RESULTS

The analysis included a total of 168 high school and collegiate pitchers with a mean age of 16.7 years (SD, 3.2 years) and BMI of 24.4 (SD, 1.2). For both elbow valgus torque and shoulder distraction force, the gradient boosting machine models demonstrated the smallest root mean square errors and the most precise calibrations compared with all other models. The gradient boosting model for elbow valgus torque reported the highest influence for pitch velocity (relative influence, 28.4), with 5 mechanical variables also having significant influence. The gradient boosting model for shoulder distraction force reported the highest influence for pitch velocity (relative influence, 20.4), with 6 mechanical variables also having significant influence.

CONCLUSION

The gradient boosting machine learning model demonstrated the best overall predictive performance for both elbow valgus torque and shoulder distraction force. Pitch velocity was the most influential variable in both models. However, both models also revealed that pitching mechanics, including maximum humeral rotation velocity, shoulder abduction at foot strike, and maximum shoulder external rotation, significantly influenced both elbow and shoulder stress.

CLINICAL RELEVANCE

The results of this study can be used to inform players, coaches, and clinicians on specific mechanical variables that may be optimized to mitigate elbow or shoulder stress that could lead to throwing-related injury.

Elbow varus torque and ball velocity associations in high school and professional pitchers with increased sagittal-plane trunk tilt

BACKGROUND

Increased sagittal-plane trunk tilt is thought to increase drive in the anterior direction toward home plate, transferring energy from the trunk to the distal upper extremity, ultimately generating greater ball velocity. Increased sagittal trunk tilt has also been implicated in the risk of upper-extremity joint loading in baseball pitchers by way of elbow varus torque (EVT), a metric previously associated with elbow injury in professional pitchers. The purposes of this study were (1) to compare sagittal trunk tilt positioning between high school and professional pitchers throughout the pitch and (2) to identify the potential associations between sagittal-plane trunk tilt, ball velocity, and EVT for both cohorts.

METHODS

Professional and high school pitchers were instructed to throw fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Sagittal trunk tilt motion throughout the pitching motion was compared between cohorts from maximum knee height to maximum shoulder internal rotation. To assess the effects of sagittal-plane trunk tilt on ball velocity and EVT, linear mixed-effect models were created.

RESULTS

Professional pitchers (n = 100, 882 pitches) achieved greater sagittal trunk tilt than high school pitchers (n = 57, 519 pitches) during early portions of the pitching motion, including maximum positive sagittal trunk tilt (46.6° ± 8.3° vs. 43.6° ± 10.2°, P = .042). Professional pitchers also had greater sagittal trunk tilt excursion throughout the pitch motion (68.0° ± 11.4° vs. 62.5° ± 11.0°, P = .004). For every 10° increase in sagittal trunk tilt at ball release for professional pitchers, ball velocity increased by 0.36 m/s (B = 0.036 and β = 0.194, P < .001) or 0.9% average ball velocity whereas EVT increased by 0.14% body weight × body height (B = 0.014 and β = 0.159, P < .001) or 2.9% average normalized EVT. For every 10° increase in sagittal trunk tilt at ball release for high school pitchers, ball velocity increased by 0.34 m/s (B = 0.097 and β = 0.025, P = .025) or 1.1% average ball velocity whereas EVT increased by 0.07% body weight × body height (B = 0.007 and β = 0.086, P = .016) or 1.7% average normalized EVT.

CONCLUSION

Increased positive sagittal-plane trunk tilt was significantly associated with greater ball velocity and increased EVT for both professional and high school pitchers. Peak EVT estimates were consistently more pronounced than ball velocity benefits for both populations, suggesting that no specific time point may provide a ball velocity benefit while concomitantly minimizing EVT. Both professional and high school pitchers should consider this trade-off, which may influence injury risk, when engaging in higher degrees of positive sagittal-plane trunk tilt.

Lead Foot Progression Angle in Baseball Pitchers: Implications to Ball Velocity and Upper-Extremity Joint Moments

The instant of foot contact is an important transition point during the pitch cycle between the linear portion of the pitch, as a pitcher strides down the mound and the rotational portion of the pitch. Understanding the implications of lead foot angle at foot contact is an essential information needed to assist pitching coaches in their work with individual pitchers. Therefore, the purpose of this study was to determine the association between lead foot progression angle at foot contact and ball velocity, elbow varus moment, and pelvic rotation. Kinematic and kinetic data were collected from 99 collegiate pitchers and analyzed using a random intercept, mixed-effects regression model. Significant associations were found between lead foot progression angle at foot contact and elbow varus moment (P = .004), as well as pelvic rotation throughout the pitching motion (P < .001). The data indicate that increased lead foot internal rotation at foot contact is associated with increases in the elbow varus moment but is not associated with ball velocity. This study provides scientific evidence that the rotational positioning of the lead foot can affect both pelvic motion and upper-extremity joint moments.

Beyond animated skeletons: How can biomechanical feedback be used to enhance sports performance?

Biomechanical feedback technologies are becoming increasingly prevalent in elite athletic training environments but how the kinematic and kinetic data they produce can be best used to improve sports techniques and enhance sports performance is unclear. This paper draws on theoretical and empirical developments in the motor control, skill acquisition, and sports biomechanics literatures to offer practical guidance and strategic direction on this issue. It is argued that the information produced by biomechanical feedback technologies can only describe, with varying degrees of accuracy, what patterns of coordination and control are being adopted by the athlete but, crucially, it cannot prescribe how these patterns of coordination and control should be modified to enhance sports performance. As conventional statistical and theoretical modelling paradigms in applied sports biomechanics provide limited information about patterns of coordination and control, and do not permit the identification of athlete-specific optimum sports techniques, objective criteria on which to base technical modifications that will consistently lead to enhanced performance outcomes cannot reliably be established for individual athletes. Given these limitations, an alternative approach, which is harmonious with the tenets of dynamical systems theory and aligned with the pioneering insights of Bernstein (1967) on skill acquisition, is advocated. This approach involves using kinematic and kinetic data to channel the athlete's search towards their own unique 'optimum' pattern of coordination and control as they actively explore their perceptual-motor workspace during practice. This approach appears to be the most efficacious use of kinematic and kinetic data given current biomechanical knowledge about sports techniques and the apparent inability of existing biomechanical modelling approaches to accurately predict how technique changes will impact on performance outcomes for individual athletes.

The association of stride length to ball velocity and elbow varus torque in professional pitchers

Professional basebal pitchers (n =315) were divided into quartiles based on increasing stride length and random intercept linear mixed-effect models were used to correlate stride length with ball velocity, pelvis and trunk rotation at foot contact, and throwing arm kinetics. Average stride length among all pitchers was 78.3±5.3%body height (%BH). For every 10% increase in stride length, ball velocity increased by 0.9 m/s (B =0.089, β =0.25, p <0.001) and trunk rotation initiation occurred 4.23 ms earlier (B =-0.42, β =-0.14, p <0.001). When divided into quartiles pelvis rotation was less towards home plate in Q1 compared to Q3 and Q4 (70.0±10.7° vs. 60.9±8.9° and 58.6±9.1°, p <0.001). No significant differences in shoulder internal rotation torque (p =0.173) or elbow varus torque (p =0.072) were noted between quartiles. Professional baseball pitchers who reached stride lengths of 80%BH or greater achieved faster ball velocity without an increase in elbow varus torque. This may, be a byproduct of rotating the pelvis for a greater proportion of the pitching motion and thereby more effectively utilising the lower extremities in the kinetic chain. Encouraging players to achieve this threshold of stride length may enhance ball velocity outcomes.

A Review of Forward-Dynamics Simulation Models for Predicting Optimal Technique in Maximal Effort Sporting Movements

The identification of optimum technique for maximal effort sporting tasks is one of the greatest challenges within sports biomechanics. A theoretical approach using forward-dynamics simulation allows individual parameters to be systematically perturbed independently of potentially confounding variables. Each study typically follows a four-stage process of model construction, parameter determination, model evaluation, and model optimization. This review critically evaluates forward-dynamics simulation models of maximal effort sporting movements using a dynamical systems theory framework. Organismic, environmental, and task constraints applied within such models are critically evaluated, and recommendations are made regarding future directions and best practices. The incorporation of self-organizational processes representing movement variability and “intrinsic dynamics” remains limited. In the future, forward-dynamics simulation models predicting individual-specific optimal techniques of sporting movements may be used as indicative rather than prescriptive tools within a coaching framework to aid applied practice and understanding, although researchers and practitioners should continue to consider concerns resulting from dynamical systems theory regarding the complexity of models and particularly regarding self-organization processes.

Stride-Phase Kinematic Parameters That Predict Peak Elbow Varus Torque

Background:

During baseball pitching, a high amount of elbow varus torque in the arm cocking-to-acceleration phase is thought to be a biomechanical risk factor for medial elbow pain and injury. The biomechanics of the stride phase may provide preparation for the arm cocking-to-acceleration phase that follows it.

Purpose:

To determine the kinematic parameters that predict peak elbow varus torque during the stride phase of pitching.

Study Design:

Descriptive laboratory study.

Methods:

Participants were 107 high school baseball pitchers (age range, 15-18 years) without shoulder or elbow problems. Whole-body kinematics and kinetics during fastball pitching were analyzed using 3-dimensional measurements from 36 retroreflective markers. A total of 26 kinematic parameters of the upper and lower limbs during the stride phase leading up to the stride foot contact were extracted for multiple regression analysis to assess their combined effect on the magnitude of peak elbow varus torque.

Results:

Increased wrist extension, elbow pronation, knee flexion on the leading leg, knee extension on the trailing leg at stride foot contact, and upward displacement of the body’s center of mass in the stride phase were significantly correlated with decreased peak elbow varus torque (all P < .05). Moreover, 38% of the variance in peak elbow varus torque was explained by a combination of these 5 significant kinematic variables (P < .001).

Conclusion:

We found that 5 kinematic parameters during the stride phase and the combination of these parameters were associated with peak elbow varus torque. The stride phase provides biomechanical preparation for pitching and plays a key role in peak elbow varus torque in subsequent pitching phases.

Clinical Relevance:

The present data can be used to screen pitching mechanics with motion capture assessment to reduce peak elbow varus torque. Decreased peak elbow varus torque is expected to reduce the risk of elbow medial pain and injury.

The Association Among Trunk Rotation, Ball Velocity, and the Elbow Varus Moment in Collegiate-Level Baseball Pitchers

BACKGROUND

The incidence of upper extremity injuries in baseball pitchers is increasing. Over the past decade, research has attempted to elucidate the cause of these injuries, focusing mainly on pitching arm mechanics with little examination of other important segments, such as the trunk. This is surprising, as trunk motion has been shown to have significant effects on pitching mechanics.

PURPOSE

To determine the associations between trunk rotation, ball velocity, and the moments about the elbow joint.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Data collected using 3-dimensional motion analysis techniques from 99 collegiate pitchers (18.0-24.8 years) were analyzed. A random intercept mixed-effects regression model was used to determine if significant associations existed between trunk rotation and ball velocity or elbow varus moment.

RESULTS

Significant associations were found between trunk rotation angle at ball release and elbow varus moment (P = .019, β = 0.254) as well as ball velocity (P = .016, β = 0.060). For every 10° increase over the average trunk rotation angle at ball release, the elbow varus moment increased by 2.54 N·m and the ball velocity increased by 0.60 m/s. Additionally, the maximum rotational velocity of the trunk was positively associated with elbow varus moment (P < .001, β = 0.029) and ball velocity (P < .001, β = 0.007). For every 100 deg/s increase over the average maximum rotational velocity of the trunk, the elbow varus moment increased by 2.90 N·m and the ball velocity increased by 0.70 m/s.

CONCLUSION

In collegiate pitchers, trunk rotation angle at ball release was significantly associated with ball velocity and elbow varus moment. Also, an increase in maximum rotational velocity of the trunk was significantly associated with an increase in the ball velocity and elbow varus moment. This work demonstrates the importance of trunk mechanics in the kinetic chain of the pitch cycle.

CLINICAL RELEVANCE

Pitching coaches and trainers can use the results to stress the importance of trunk mechanics in pitching, specifically, combining adequate core function with increased trunk rotational velocity in an effort to increase pitching velocity without increasing elbow joint stress.

Baseball Pitching Biomechanics Shortly After Ulnar Collateral Ligament Repair

Background:

The probability of returning to competition for injured baseball pitchers is similar after ulnar collateral ligament (UCL) repair as after UCL reconstruction, but the time to return is significantly quicker after UCL repair. Previous research has found no differences in pitching biomechanics between pitchers with and without a history of UCL reconstruction, but pitching biomechanics after UCL repair has not been studied.

Hypothesis:

There will be significant differences in pitching biomechanics between pitchers returning to play after UCL repair and pitchers with no injury history.

Study Design:

Controlled laboratory study.

Methods:

A total of 33 pitchers were tested shortly after UCL repair (9.8 ± 2.6 months) and compared with a matched group of 33 uninjured pitchers. Each group comprised 14 college pitchers and 19 high school pitchers. Shoulder and elbow passive ranges of motion were measured. The biomechanics of 10 fastballs was then collected using a 12-camera automated motion capture system. Ball velocity was measured using a separate 3-camera optical tracking system. Data were compared between the UCL repair group and the control group using the Student t test (significance set at P < .05).

Results:

There were no differences in passive range of motion or fastball velocity between the 2 groups. There were no differences in joint kinetics during pitching, but 3 kinematic variables showed significant differences. Specifically, the UCL repair group produced less elbow extension (flexion: 27° ± 6° vs 24° ± 4°, respectively; P = .03), less elbow extension velocity (2442 ± 367 vs 2631 ± 292 deg/s, respectively; P = .02), and less shoulder internal rotation velocity (6273 ± 1093 vs 6771 ± 914 deg/s, respectively; P = .049 ) compared with the control group.

Conclusion:

Elbow extension, elbow velocity, and shoulder velocity differed between pitchers with a recent history of UCL repair and a matched control group, but it is unclear whether this has clinical significance, as there were no differences in ball velocity and passive range of motion. Furthermore, it is unknown whether these few differences in pitching biomechanics resolve with time.

Clinical Relevance:

Elbow and shoulder kinematics during pitching might not be completely regained within the first year after UCL repair, although passive range of motion and pitch velocity show no difference in comparison to other healthy pitchers.

A Clinician's Guide to Analysis of the Pitching Motion

PURPOSE OF REVIEW

This review examines recent literature regarding analysis of the throwing motion in baseball players and how modern technology may be used to predict or prevent injury.

RECENT FINDINGS

Proper throwing technique is vitally important to prevent injury and it is easier to correct poor mechanics prior to foot strike. Recent findings suggest that the inverted-W position may not lead to an increased risk of injury, but incorrect trunk or pelvis rotation does. Three-dimensional motion analysis in a laboratory setting is most commonly used to evaluate the throwing motion, but it does not allow for assessment in real game scenarios. Wearable monitors allow for this and have proven to reliably assess pitching workload, kinematics, and kinetics. Injuries in youth baseball pitchers have increased along with the trend towards more single sport specialization. To prevent injury, assessment of a pitcher's throwing motion should be performed early to prevent development of poor mechanics. Classically, three-dimensional motion analysis has been used to evaluate throwing mechanics and is considered the gold standard. Newer technology, such as wearable monitors, may provide an alternative and allow for assessment during actual competition.

Effects of a six-week weighted-implement throwing program on baseball pitching velocity, kinematics, arm stress, and arm range of motion

BACKGROUND

Weighted-baseball training programs are used at the high school, collegiate, and professional levels of baseball. The purpose of this study was to evaluate the effects of a six-week training period consisting of weighted implements, manual therapy, weightlifting, and other modalities on shoulder external rotation, elbow valgus stress, pitching velocity, and kinematics.

HYPOTHESIS

A six-week training program that includes weighted implements will increase pitching velocity along with concomitant increases in arm angular velocities, joint kinetics, and shoulder external rotation.

METHODS

Seventeen collegiate and professional baseball pitchers (age range 18-23, average: 19.9 ± 1.3) training at Driveline Baseball were evaluated via a combination of an eight-camera motion-capture system, range-of-motion measurements and radar- and pitch-tracking equipment, both before and after a six-week training period. Each participant received individualized training programs, with significant overlap in training methods for all athletes. Twenty-eight biomechanical parameters were computed for each bullpen trial, four arm range-of-motion measurements were taken, and pitching velocities were recorded before and after the training period. Pre- and post-training period data were compared via post-hoc paired t tests.

RESULTS

There was no change in pitching velocity across the seventeen subjects. Four biomechanical parameters for the holistic group were significantly changed after the training period: internal rotational velocity was higher (from 4,527 ± 470 to 4,759 ± 542 degrees/second), shoulder abduction was lower at ball release (96 ± 7.6 to 93 ± 5.4°), the shoulder was less externally rotated at ball release (95 ± 15 to 86 ± 18°) and shoulder adduction torque was higher (from 103 ± 39 to 138 ± 53 N-m). Among the arm range of motion measurements, four were significantly different after the training period: the shoulder internal rotation range of motion and total range of motion for both the dominant and non-dominant arm. When the group was divided into those who gained pitching velocity and those who did not, neither group showed a significant increase in shoulder external rotation, or elbow valgus stress.

CONCLUSIONS

Following a six-week weighted implement program, pitchers did not show a significant change in velocity, joint kinetics, or shoulder external rotation range of motion. When comparing pitchers who gained velocity versus pitchers who did not, no statistically significant changes were seen in joint kinetics and shoulder range of motion.

Sagittal Plane Trunk Tilt Is Associated With Upper Extremity Joint Moments and Ball Velocity in Collegiate Baseball Pitchers

Background

The trunk is a major contributor to the kinetic chain during baseball pitching by helping to transfer energy from the lower limbs to produce the desired ball speed. However, most of the research detailing the trunk's contribution to the pitch is focused on rotational timing and coronal plane lean, with little attention focused on sagittal plane positioning of the trunk.

Purpose

To determine the association between sagittal plane trunk motion and elbow varus moment and ball velocity in collegiate baseball pitchers.

Study Design

Descriptive laboratory study.

Methods

A total of 99 collegiate pitchers were recruited for this study and underwent a comprehensive biomechanical assessment of their pitching motion using 3-dimensional motion techniques. A random-intercepts, mixed-effects regression model was used to determine whether statistically significant associations were noted between sagittal plane trunk motion and the ball velocity and elbow varus moment.

Results

There were a number of significant associations between sagittal plane trunk tilt and the elbow varus moment and ball velocity. Increased forward trunk tilt at the time of ball release was associated with an increase in elbow varus moment and a small increase in ball velocity; for every 10° of increased forward trunk tilt greater than 28° at ball release, the elbow varus moment increased by 2.9 N·m (P = .007), and the ball velocity increased by 0.7 m/s (P = .002).

Conclusion

Sagittal plane positioning of the trunk plays a role in pitching mechanics, as it can affect both pitching performance and elbow moments. The results also indicated that there is a potential optimal trunk position and range of motion during the acceleration of the pitch that could limit the stress placed on the elbow joint. Implementing proper trunk mechanics from an early age could lead to a reduction in joint moments.

Clinical Relevance

The results provide evidence for coaches and trainers to emphasize the importance of proper trunk positioning through the inclusion of core strengthening and motor control in their practice and coaching sessions in an effort to reduce the moments placed on the elbow during the pitch.

Return to Throwing after Shoulder or Elbow Injury

PURPOSE OF REVIEW

Throwing places high demands on the human body, and specific characteristics are developed over time unique to these athletes. When returning to throw after injury, it is important to follow a criterion-based progression that allows the body to be prepared appropriately for the stresses that throwing will require. There is currently a void in the literature for criteria-based progression that helps these athletes return to the highest level of play.

RECENT FINDINGS

As injury rates continue to rise in baseball, there is increased evidence showing contributions of the core and lower extremity to the baseball pitch. There is also additional data showing pitcher specific characteristics such as range of motion and scapular position in this unique population. The rehab professional should take into account every phase of the pitch starting from balance through ball release when designing a comprehensive return-to-throwing program. Returning an athlete back to a throwing sport can be an overwhelming task. The rehabilitation specialist must have a sound understanding of the throwing motion as well as any biomechanical implications on the body, contributions throughout the kinetic chain, range of motion, and strength characteristics specific to the thrower as well as proper tissue loading principles. It is important that these athletes are not progressed too quickly through their programs and that a criteria-based progression is followed. They should have normalized range of motion, strength, and scapular mechanics, followed by a sound plyometric progression. Once this is achieved, they are advanced to an interval throwing program with increasing distance, effort, and volume which should be tracked for workload, making sure they do not throw more than their body is prepared for.