(45) RELATIONSHIP BETWEEN ISOKINETIC ARM STRENGTH AND GAME PITCHING METRICS IN DIVISION I COLLEGIATE BASEBALL PITCHERS

Purpose: To determine the relationship between isokinetic arm strength and game pitching metrics for collegiate baseball pitchers.

Methods: Thirteen Division I pitchers (age = 20.5 ± 1.5 yr; height = 185.8 ± 6.5 cm; body mass = 93.5 ± 11.6 kg; lean body mass (LBM) = 77.6 ± 6.8 kg; body fat percentage = 16.6 ± 4.4%) participated in this study. Prior to testing, all pitchers completed a warm-up (WU), which consisted of 6 standing upper body dynamic arm swing motions followed by a 5-minute seated upper body ergometer WU (300 kp of work at 50 rpm and 50 W). Testing was performed in a pitcher selected range of motion (ROM), with each pitcher encouraged to achieve his full ROM on each repetition. Before testing, each pitcher performed 4 WU repetitions at 25, 50, 75 and 100% of their perceived maximal effort at each speed. Isokinetic strength was tested during the offseason on 4 separate days using the Biodex System 3 isokinetic dynamometer in the seated position. Tests included throwing (dominant) arm shoulder diagonal abduction/adduction and shoulder 90° internal/external rotation at 180, 300, and 450°·sec^-1 (5, 10, and 15 repetitions, respectively), forearm pronation/supination at 120, 180, and 240°·sec^-1 (5 repetitions at each speed), and wrist flexion/extension at 120 and 180°·sec^-1 (5 repetitions at each speed). A 2-minute rest period was allowed between the test speeds. Peak torque data were collected at each velocity using the Biodex dynamometer and software. Additionally, individual isokinetic values were combined and divided by the number of speed settings to create an average score. Pitching metrics were recorded using Rapsodo In-Stadium unit during the competitive baseball season where the team had a win-loss record of 28-31 and included velocity, top spin, side spin, total spin, horizontal break, and vertical break recorded for three pitch types: fastball (FB), breaking ball (BB), and change-up (CH). Pearson product-moment correlations were run with an alpha level of 0.05.

Results: Multiple statistically significant relationships were observed between isokinetic forearm and shoulder strength values and game pitching metrics (Table 1).

Conclusions: Significant relationships existed between isokinetic forearm supination and pronation and FB velocity and total spin; BB velocity, top spin, total spin, and vertical break; and CH velocity. Isokinetic shoulder abduction and adduction had significant relationships with FB velocity, top spin, and vertical break; and CH top spin and vertical break during games. PRACTICAL APPLICATIONS: An isokinetically stronger arm relates to better pitching metrics, which could help the team be successful. Coaches and practitioners should promote data-based individualized throwing arm strength programs because lower arm strength could equate to reduced game performance and team losses.

Acknowledgements: We would like to thank the Louisiana Tech pitchers for participating in this study.