Comparison of OnBaseU Tests with Biomechanical Motion Analysis in Youth Baseball Pitchers.
Tessa Hulburt, Taylor Catalano, Kristen F Nicholson
PMID 34909256WHAT IT FOUND
Most OnBaseU tests did not match 3D motion capture data for youth pitchers.
Only the side step walkout test correlated with stride length, and even then only at the extreme scores. The screen should not be used to assess pitching mechanics.
Key findings
01The OnBaseU seated trunk rotation, push-off, and shoulder 90/90 tests showed minor or no correlation with corresponding 3D motion capture metrics of pitching mechanics.
02Only the side step walkout test was moderately correlated with stride length, with statistically significant differences found only between the lowest (score 1) and highest (score 3) test grades.
03OnBaseU seated trunk rotation scores did not correlate with motion capture seated trunk rotation data, questioning the validity of the visual scoring method.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was performed by a single evaluator, so inter-rater reliability was not assessed. Very few participants achieved the lowest or highest scores on three of the four tests (n=0-4), making it difficult to determine if those categories are physiologically relevant or achievable. The OnBaseU screen was performed prior to warm-up, while motion capture was performed after, which may affect flexibility and range of motion comparisons. The study did not assess injury outcomes, only biomechanical correlations.
Declared interests
The authors have no conflicts of interest to declare. The work was supported by departmental funding.
The easy way to misread this
Do not assume the side step walkout test is a valid standalone tool for assessing stride length. The correlation was moderate and only significant when comparing the extreme low and high scores, with no distinction for intermediate performance, and the other three tests failed to correlate with their respective mechanics.