Medicine ball throw distance weighted with height-to-mass ratio aligns with other physical fitness tasks.

The traditional Medicine Ball Throw (MBTT) for assessing upper-extremity explosive strength inherently favours heavier and taller participants. We designed three alternative indices to adjust for this anthropometric bias: (1) multiplying MBTT by the height-to-mass ratio (MBTA1), (2) dividing MBTT by the product of mass and height (MBTA2), and (3) dividing MBTT by the body mass index (MBTA3). Using age- and sex-adjusted LMS-based z-scores from two independent cohorts (821 children, aged 8.3 ± 0.7 years; 354 adolescents, aged 14.4 ± 2.2 years), we compared the variants' alignment with the concave BMI-profiles of five standard fitness tests (6-minute run, standing long jump, jump sideways, 4 × 10 m shuttle run, push-ups). The three anthropometrically enriched variants yielded significantly better goodness of fit than MBTT with MBTA1 performing best overall. Furthermore, when deployed as independent covariates, the enriched indices demonstrated systematically higher predictive power for standard fitness tasks than the unadjusted distance. We recommend adjusting MBTT via the height-to-mass ratio for a fairer assessment, though its structural overlap with BMI requires caution in predictive models.