Author(s): CHANG, H.Y.1, CHEN, S.C.1, CHIU, C.W.2, YANG, S.C.1, Institution: NATIONAL TAIWAN SPORT UNIVERSITY, Country: TAIWAN, Abstract-ID: 232

INTRODUCTION:
Movement screening is widely used to identify modifiable risk factors, functional deterioration, and potential movement deficiencies and compensatory patterns in baseball players. However, few screening tools have been specifically designed to evaluate baseball-specific movement demands. The OnBaseU test is a baseball-specific movement screening tool adopted by several Major League Baseball organizations, targeting key physical qualities such as mobility, stability, motor control, and coordination. Despite its growing application, evidence supporting its measurement reliability remains limited. Therefore, the purpose of this study was to examine the intra- and inter-rater reliability of the OnBaseU test in high school baseball players.
METHODS:
Ten male high school baseball players from Taiwan (age: 22.8 ± 0.8 years; height: 172.8 ± 6.1 cm; body mass: 69.3 ± 5.3 kg) participated in this study. The OnBaseU test consists of five components: core control, rotation, stride, upright posture, and arm function. For inter-rater reliability assessment, two trained raters independently evaluated all participants. For intra-rater reliability assessment, one rater reassessed the same participants after a one-week interval. Reliability was analyzed using Pearson product–moment correlation coefficients (r).
RESULTS:
Excellent intra-rater reliability was observed across all OnBaseU components (core control: r = 0.939~0.974, rotation: r = 0.921~0.956, stride: r = 0.926~0.968, upright posture: r = 0.924~0.983, and arm: r = 0.947~0.955). Similarly, inter-rater reliability between the two raters was excellent for all components (core control: r = 0.906~0.922, rotation: r = 0.903~0.964, stride: r = 0.856~0.937, upright posture: r = 0.895~0.943, and arm: r = 0.924~0.931).
CONCLUSION:
The findings demonstrate excellent intra- and inter-rater reliability of the OnBaseU test when administered by trained evaluators. These results support the OnBaseU test as a practical and reliable baseball-specific movement screening tool for use in high school baseball players. Future research should investigate its ability to discriminate movement deficiencies across different competitive levels and to identify physical impairments and injury risk factors.