(47) RELATIONSHIP BETWEEN ISOKINETIC ARM STRENGTH AND GAME PERFORMANCE IN DIVISION I COLLEGIATE BASEBALL PITCHERS

Purpose: To determine the relationship between isokinetic arm strength and game pitching performance 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 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. Game pitching performance data; earned-run average (ERA), wins, losses, innings pitched (IP), hits (H), H/IP, H/9IP, runs, earned runs, base on balls (BB), BB/IP, BB/9IP, strikeouts (SO), SO/IP, SO/9IP, walks plus hits per inning pitched (WHIP), WHIP/9IP, and opponents’ batting average (BA), were acquired after the competitive season through the official university athletics website. Pearson product-moment correlations were run with an alpha level of 0.05.

Results: Multiple statistically significant relationships were observed between isokinetic wrist extension, shoulder diagonal abduction, and shoulder external rotation strength values and game pitching performance (Table 1).

Conclusions: Greater isokinetic wrist extension strength values related to less H/IP, H/9IP, WHIP, and opponent’s BA. Greater shoulder diagonal abduction strength values at various speeds related to more wins, IP, and SO as well as lower ERA, less H/IP, H/9IP, BB, WHIP, and opponent’s BA. Greater shoulder external rotation strength values related to lower H/IP, H/9IP, and opponent’s BA. PRACTICAL APPLICATIONS: An isokinetically stronger arm relates to better game pitching performance, which could help produce more wins. Coaches and practitioners should promote data-based individualized throwing arm strength programs because lower arm strength could result in poor game performance and team losses.

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