THE RELATIONSHIP BETWEEN INSTANTANEOUS POWER AND PHYSICAL FUNCTION IN JUNIOR HIGH SCHOOL BASEBALL PLAYERS

K. Yoshikawa¹, T. Jiroumaru², M. Ikeya³, Y. Hyodo¹, Y. Oka¹

¹Kanazawa Orthopedic & Sports Medicine Clinic, Shiga, Japan, ²Bukkyo University, Kyoto, Japan, ³Biwako Professional University of Rehabilitation, Shiga, Japan

Background: Pitching ability (ball speed) is related to instantaneous power, such as sprinting and jumping ability, in baseball players (Hoffman et al. 2009; Nakata et al. 2013). Several previous studies have reported that instantaneous power is an important predictor of pitching ability. However, it is still unknown which types of physical function contribute to improving instantaneous power among junior high school baseball players.

Purpose: We aimed to clarify which types of physical function are related to instantaneous power in junior high school baseball players.

Methods: 26 junior high school baseball players (mean age: 13.6 ± 0.5; height: 159.5 ± 9.5 cm; weight: 51.8 ± 8.7 kg) participated. Instantaneous power was measured during 30-m sprint and standing broad jump. To measure physical function, we evaluated Deep Squat Test (DST) performance, leg split, Straight Leg Raise (SLR), grip strength, and trunk stability using the Sahrmann Core Stability test (SCST). For the 30-m sprint, the time taken to run 30 m was measured using the SprintTimer app with an iPhone fixed on a tripod placed at the finish line. Elapsed time was measured in 0.01-second increments and the fastest time of the two trials was used. For the standing long jump, the results of one trial were retained for analysis after three trials. For the DST, we assessed performance using six grades according to the position of the upper limbs and the distance between the buttocks and heels. For leg splits, we assessed performance using six grades, depending on the part that can be grounded and the angle of the leg-spread. For the SLR, we assessed performance in six stages depending on the angle. Grip strength was measured using a grip dynamometer and the strongest result of two trials was used. Trunk function was measured bilaterally using SCST, and the bilateral average was used. Statistical analysis was conducted using Pearson’s correlation coefficient. The level of significance was set at ρ < 0.05. This study was approved by the Ethics Committee of the Kanazawa Orthopedic and Sports Medicine Clinic (Kanazawa-OSMC-2022-003) and was conducted in accordance with the Declaration of Helsinki.

Results: 30-m sprint performance was significantly correlated with grip strength (r = −0.685, p < 0.05), SCST (r = −0.494, p < 0.05), DST (r = 0.456, p < 0.05), and SLR (r = 0.400, p < 0.05). Standing broad jump was also significantly correlated with grip strength (r = 0.744, p < 0.05) and SCST (r = 0.529, p < 0.05).

Conclusions: In the current study, 30-m sprint performance and standing broad jump performance were correlated with grip strength and SCST. Grip strength reflects whole body muscle strength, and SCST is a measure of trunk stability functioning. Furthermore, 30-m sprint performance appeared to be related to flexibility of the lower leg, such as DST and SLR.

Implications: Whole-body muscle strength, trunk stability, and flexibility of the lower leg may be related to improving instantaneous power in junior high school baseball players. This type of training may help to enhance pitching ability in baseball players.

Funding acknowledgements: The authors have no conflicts of interest to declare.

Keywords:
Baseball
Instantaneous power
Physical function

Topics:
Sport & sports injuries

Did this work require ethics approval? Yes

Institution: Kanazawa Orthopedic & Sports Medicine Clinic

Committee: The Ethics Committee of the Kanazawa Orthopedic & Sports Medicine Clinic

Ethics number: Kanazawa-OSMC-2022-003