Gretchen D. Oliver

Baseball biomechanics has expanded rapidly across academic, clinical, and professional settings, driven by advances in measurement technologies such as markerless motion capture, wearable sensors, and in-game tracking systems. As the volume and diversity of baseball biomechanics research increase, variability in study design and reporting practices has emerged as a critical limitation to reproducibility and translation. This paper presents recommendations and standards from the American Baseball Biomechanics Society for rigorous study design, data acquisition, and reporting in baseball biomechanics. Guidance is organized around project conceptualization, selection of appropriate measurement systems, pilot testing, and transparent reporting, with an emphasis on baseball-specific considerations. Our objective is to provide clear and comprehensive guidance that benefits a diverse audience, including researchers at various career stages and professionals working in academic, clinical, and professional settings.

The high volume of pitches in softball generates substantial shoulder forces, making it a common injury site. Effective proximal-to-distal energy transfer through the lower extremities and lumbopelvic-hip complex is critical for force distribution, although this relationship has not been well examined in youth. The purpose of this study was to assess the relationship between single-leg squat compensatory mechanics and upper extremity kinetics in youth softball pitchers. A total of 72 youth softball pitchers participated. Participants performed isometric hip strength testing, bilateral single-leg squats, and pitched 3–10 fastballs. Separate ordinary least squares regression models were conducted for each pitch kinetic variable, with all single-leg squat variables entered together as predictors for each separate pitch kinetic dependent variable. Drive knee valgus and hip strength ratio, along with pitch velocity, were associated with relative peak shoulder distraction force, while stride trunk lean and age were associated with relative peak EDF. Drive trunk rotation was the only variable associated with shoulder resultant force and shoulder extension torque, and no variables were associated with shoulder or elbow flexion torque. The current findings support the concept that proximal trunk control and lower extremity stability during single-leg tasks may be related to distal joint loading during the pitching motion in softball.

Baseball pitchers experience significant physical demands throughout the throwing motion, and upper extremity injuries remain common across all levels of play. Thus, it was our purpose to examine the relationship between arm slot determinants and shoulder loading in National Collegiate Athletic Association Division I pitchers during in-game performance. A total of 309 pitchers were included. Fastball pitches within the middle 80% of pitch velocities were included in the analysis. Time-series associations between shoulder rotational torque and resultant force with arm slot determinants were assessed with one-dimensional Statistical Parametric Mapping regressions. Linear regressions were conducted between arm slot and shoulder rotational torque and resultant force. A maximum shoulder resultant force was significantly associated with shoulder elevation from 96 to 100% of the pitch (p=0.017; R=0.20, R 2=0.04). Shoulder elevation was associated with a maximum shoulder resultant force in Division I pitchers during in-game environments. These findings highlight the importance of upper-arm placement at ball release in understanding shoulder kinematics during high-velocity throwing. This information may be useful for clinicians when evaluating shoulder stress, as higher shoulder torques and peak humeral loading have been linked to increased injury risk in pitchers. Incorporating shoulder elevation into routine monitoring may provide a practical means of evaluating shoulder loading without requiring mechanical changes.

Two distinct baseball pitching stride styles, tall-and-fall and drop-and-drive, are characterized by center-of-mass movement. Our purpose was to determine whether forward center-of-mass and vertical center-of-mass velocities are related to fastball velocity and peak elbow valgus torque for each technique. In-game motion capture data were recorded for 251 Division I pitchers. Multiple backward linear regressions and statistical parametric mapping regressions were performed. No significant findings were found in drop-and-drive pitchers between forward center-of-mass or vertical center-of-mass and fastball velocity or peak elbow valgus torque, nor in tall-and-fall pitchers between forward center-of-mass and fastball velocity or peak elbow valgus torque. However, in tall-and-fall pitchers, backward multiple linear regression showed that the maximum downward vertical center-of-mass velocity was associated with increased fastball velocity, and Statistical Parametric Mapping regressions showed that the association between vertical center-of-mass and fastball velocity occurred between 39.4 and 69.1% of the stride phase. Specifically, greater peak downward vertical center-of-mass velocity was associated with higher fastball velocity, suggesting that tall-and-fall pitchers seeking to improve fastball velocity could benefit from increasing downward vertical center-of-mass velocity during the middle of the stride. No significant findings were found between vertical center-of-mass velocity and peak elbow valgus torque in tall-and-fall pitchers; therefore, modifying vertical center-of-mass velocity in tall-and-fall pitchers may enhance performance without increasing peak elbow valgus torque, yet further work is needed to elucidate the effects on other kinematics or kinetics.

Efficient baseball pitching relies on coordinated trunk–arm coupling during the acceleration phase. Shoulder elevation is commonly maintained near 90°, and prior work has focused on discrete metrics rather than continuous regulation. Our purpose was to examine whether the deviation of shoulder elevation from 90° during the acceleration period was associated with ball velocity. Markerless kinematic data were collected from 362 National Collegiate Athletic Association pitchers (7,239 pitches). Shoulder elevation was defined as the relative angle between the trunk and the upper arm, and root mean square deviation from the 90° reference was calculated across the acceleration period. Two-level linear mixed-effects models were used to evaluate within- and between-pitcher associations. Shoulder elevation deviation demonstrated high between-pitcher consistency (intraclass correlation coefficient=0.95). Reduced root mean square deviation was associated with higher ball velocity at both the between-pitchers (β=− 0.06 mph·deg–1, p = 0.006) and within-pitchers (β=− 0.07 mph·deg–1, p = 0.004) levels. Allowing pitcher-specific slopes significantly improved a model fit, indicating heterogeneity in the magnitude of this association and suggesting that the reduced deviation of shoulder elevation during acceleration is associated with higher ball velocity. Continuous quantification of shoulder elevation during the acceleration phase provides a complementary perspective to discrete joint angle analyses and may serve as an indicator of pitching performance.

Background: Baseball pitching requires precise coordination of the upper extremities to generate and transfer angular momentum efficiently while minimizing joint loading. Although the importance of temporal sequencing is recognized, few studies have examined how segmental momentum sequences vary across arm slot styles. Therefore, the purpose of this study was to evaluate the temporal sequence of peak angular momentum across segments and determine its capacity to predict ball velocity and upper extremity joint loading among overhead (OH), three-quarter (QT), and sidearm (SA) collegiate pitchers. Purpose: To (1) quantify the timing of peak angular momentum in the torso, upper arm, forearm, and hand across different arm slot styles during baseball pitching; and (2) determine whether the relative timing of these segmental peaks predicts ball velocity and kinetic loads at the shoulder and elbow among various arm slot styles. Study Design: Descriptive laboratory study. Methods: A total of 363 National Collegiate Athletic Association Division I pitchers (90.99 ± 10.22 kg; 1.88 ± 0.49 m; 90.35 ± 40.39 ± 3.19 m/s) were analyzed using markerless motion capture and radar-based ball tracking during competition. A mixed-model multivariate analysis of variance tested interactions between arm slot and segmental timing, and multiple linear regressions within each arm slot predicted ball velocity and upper extremity kinetics. The overall significance level (α) was set at .05. Results: Across all arm slot styles, pitchers demonstrated a consistent proximodistal sequence (torso → upper arm → hand → forearm). Earlier torso peak momentum and later hand peak momentum predicted greater ball velocity in OH and QT pitchers, whereas SA showed weaker relationships between sequencing and velocity. In OH and QT, early forearm peak momentum and delayed hand peak momentum were linked to higher shoulder distraction force, suggesting that timing disruptions may elevate joint loading. In contrast, kinetic loading in SA appeared less timing dependent and more influenced by the magnitude of angular momentum. In OH and SA, delayed forearm peak momentum and early hand peak momentum were linked to higher elbow varus torque. In QT, early hand peak momentum were linked to higher elbow varus torque. Conclusion: These findings suggest that segmental sequencing influences both performance and joint loading across arm slot styles and that deviations from efficient timing may elevate injury risk. Training that improves trunk rotation and distal timing may enhance performance and reduce joint stress. Clinical Relevance: The association between segmental timing and upper-extremity loading suggests that timing characteristics may be an important factor when evaluating throwing-related injuries. Assessing arm slot–specific timing patterns may help clinicians and performance staff interpret mechanical variability and guide monitoring strategies in overhead athletes.

Biomechanical theory and coaching heuristics suggest that contact depth meaningfully constrains swing mechanics and batted-ball outcomes. Our purpose was to examine the relationship between contact depth and key hitting metrics during live collegiate competition. Markerless motion capture and ball tracking data were collected during live NCAA Division I games from 2779 batted balls from 239 hitters. Outcomes included contact depth, exit velocity, maximum swing speed, swing speed at contact, and vertical and horizontal attack angles. Regressions assessed relationships with velocity and swing speed variables, while partial least squares regression evaluated attack angles. The mean contact depth was 20.1 ± 7.2 inches in front of the hitter’s center of mass. Contact depth weakly explained exit velocity (r² = 0.04, p < 0.001) but significantly predicted maximum swing speed (r² = 0.20 p < 0.001). No meaningful relationship was observed with swing speed at ball contact (r² = 0.01, p > 0.01). Contact depth showed a strong association with the combined structure of vertical and horizontal attack angles, with the primary PLS component explaining 80.0% of the contact depth variance. Contact depth appeared to influence swing mechanics and attack angles and was associated with peak, but not contact, bat speed. These findings highlight contact depth as a critical covariate for interpreting swing metrics and designing biomechanical assessments, analytic models, and on-field interventions.

Background: Pitch velocity plays a critical role in fastpitch softball success because it reduces the time a batter must react and contact the ball. Despite its importance, there is limited literature on the biomechanical contributions to pitch velocity, particularly from the lower extremities. Purpose: To examine the lower extremity and pelvic kinematic, kinetic, and center of mass (COM) velocities associated with fastball pitch velocity. Study Design: Descriptive laboratory study. Methods: A total of 90 female high school and collegiate softball pitchers were included in the analysis. Motion capture data were collected for each participant, and the fastest 3 fastballs were averaged for analysis. Kinematics and kinetics were extracted for subsequent analysis. A Pearson correlation and a backward stepwise multiple regression were performed to identify kinematic and kinetic variables associated with, and predictive of, fastball velocity. Results: Peak vertical COM velocity ( r = 0.51; P < .001) showed the strongest positive association with pitch velocity, followed by anterior COM velocity ( r = 0.44; P < .001), mediolateral ground-reaction force (GRF) ( r = 0.38; P < .001), and vertical GRF ( r = 0.31; P = .001), while negative (clockwise) pelvic rotational velocity was inversely related ( r = −0.26; P = .006). Backward stepwise regression identified COM velocities, GRFs, pelvic rotational velocity, and body mass as significant predictors, explaining 57% of the variance in pitch velocity ( R ² = 0.57; F (7, 82) = 15.51; P < .001). Conclusion: These results suggest that the lower body plays a critical role in generating pitch velocity. Continued research is needed to determine how to optimize lower extremity function to enhance pitching performance while minimizing injury risk. Clinical Relevance: Improving fastball velocity in softball pitching depends on effective lower body and COM kinematics and kinetics. These findings support training the lower extremity to generate high force to improve pitch velocity while potentially reducing the mechanical demand placed on the upper extremity.