Regan Wong

Wong, R, Laudner, K, Amonette, W, Vazquez, J, Evans, D, and Meister, K. Relationships between lower extremity power and fastball spin rate and ball velocity in professional baseball pitchers. J Strength Cond Res 37(4): 823–828, 2023—Lower extremity power has been hypothesized to increase ball spin and velocity during pitching in baseball. Therefore, the purpose of this study was to determine the relationship between lower extremity power and fastball spin rate in professional baseball pitchers. A secondary purpose was to determine the relationship between lower extremity power and ball velocity. Fifty-three asymptomatic professional pitchers participated (24.5 ± 3.6 years; 189.9 ± 6.1 cm; 92.6 ± 10.3 kg). Each athlete performed 3 separate bilateral jump tests on force plates: countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). The average fastball spin rate and ball velocity for each pitcher was calculated using a 3-dimensional Doppler radar and video system over the course of a competitive season. Standard multiple regression analyses (p ≤ 0.05) revealed significant relationship between ball spin and summation of variables for the CMJ (peak force, peak power, rate of power development, and jump height) (R ² = 0.20, F = 3.1, p = 0.03). However, no individual variable was significantly associated (p > 0.09). There was also a significant amount of variance in ball spin explained by summation of variables for the SJ (peak force, peak power, rate of power development, and jump height) (R ² = 0.19, F = 2.8, p = 0.04); rate of power development was the only variable that significantly predicted ball spin within this model (B = 0.27; 95% confidence interval [CI]: 0.003–0.75, p = 0.05). Ball spin was not associated with summation of DJ variables (peak power, rate of power development, jump height, reactive strength index, and total peak power in watts) (R ² = 0.18, F = 2.0, p = 0.09). For ball velocity, there were no significant relationships for the summation of either the CMJ variables (R ² = 0.10, p = 0.28) or the SJ variables (R ² = 0.07, p = 0.44). However, there was a significant amount of variance in ball velocity explained by summation of variables for the DJ (R ² = 0.30, F = 3.93, p = 0.005). The reactive strength index was the sole unique contribution to this model (B = 1.18; 95% CI: −10.34 to 2.36, p = 0.002). These findings highlight the relevance of increased lower extremity power on increasing fastball spin rate and ball velocity.

Objectives: Baseball pitchers frequently present with varying levels of glenohumeral internal rotation deficits (GIRD) in their throwing arms when compared to their non-throwing arms. However, excessive bilateral differences in internal rotation motion have been associated with several shoulder pathologies including both subacromial and internal impingement. Additionally, patients diagnosed with subacromial impingement commonly present with decreased subacromial joint space and increased forward scapular posture. These characteristics have not been, as of yet, evaluated and associated to those pitchers who present with excessive GIRD. The purpose of this study was to determine if a group of baseball pitchers with excessive GIRD have differences in subacromial joint space and forward scapular posture when compared to a control group. Methods: Twenty-five asymptomatic professional baseball pitchers with excessive GIRD were matched with 25 pitchers with acceptable levels of GIRD. Excessive GIRD was classified as an amount greater than 10% of the total arc of motion (i.e. dominant shoulder total arc=160°; 0.10x160°=16°; excessive GIRD=>16°). A digital inclinometer was used to measure glenohumeral internal and external rotation range of motion with participants in a supine position and their scapula stabilized. Diagnostic ultrasound was used to measure the distance of the subacromial joint space with the throwing arm resting at the side of the participant’s body (0° abduction). Bilateral forward scapular posture was assessed with each participant standing against a wall and then the distance between the wall and their anterior acromion was measured using the double square technique. The bilateral difference between these measurements was used to determine the amount of forward scapular posture for the throwing arm. Separate t-tests were run to determine significant differences between groups (p<0.05). Results: Results are summarized in Figure 1. The total arc of motion and GIRD for the excessive group was 153.7°±13.4° and -23.5°±5.1°, and 160.5°±16.1° and -3.6°±9.0° for the acceptable level of GIRD group. The excessive GIRD group presented with significantly less subacromial space (9.4mm±2.6 mm) than the control group (11.1mm±2.4 mm) (p=.02). The excessive GIRD group also had significantly more forward scapular posture (10.8mm±11.0 mm) of their throwing arm than the acceptable level of GIRD group (3.9mm±8.8 mm) (p=.01). Conclusion: We found that baseball pitchers with higher levels of GIRD had less subacromial space and more forward scapular posture in their throwing arms compared to pitchers with acceptable levels of GIRD. Our findings suggest that increased GIRD may be a precursor to pathologies associated with decreased subacromial space and forward scapular posture such as subacromial impingement. We suggest that players identified with excessive GIRD perform shoulder strengthening and stretching exercises designed to improve scapular positioning.