Body-mass normalization of powerlifting performance: development and independent validation of sex- and age-specific regression-residual scores.

PURPOSE: To develop sex- and age-specific regression-residual W-score equations for powerlifting performance and to determine whether equations estimated in one group of lifters reduce residual body-mass association when applied unchanged to independent lifters. METHODS: The May 23, 2026 OpenPowerlifting release was filtered to 760,048 raw, drug-tested, sanctioned full-power entries from 282,164 reconstructed lifters aged 10 years or older. Lifters were allocated 70:30 to development and validation samples with no overlap. Eighty sex-age-outcome log-log allometric models were estimated using development lifters; coefficients and residual dispersion were frozen and applied to 84,651 validation lifters. Sensitivity analyses examined one entry per lifter, calendar period, equipment, federation, functional form, and body-mass extremes. RESULTS: Mean absolute W-score-body-mass correlations were 0.041 (95% confidence interval 0.026-0.059) across 56 adult models and 0.064 (0.033-0.101) across 24 youth models. For adult totals, mean absolute correlations were 0.473 for ratio scaling, 0.105 for Wilks, 0.066 for Goodlift, 0.064 for DOTS, and 0.042 for power-law W-scores. One-entry-per-lifter analyses corroborated the primary findings. Transportability was weaker across calendar periods, federations, equipped lifting, and selected older-female and youth boundary groups. CONCLUSION: Regression-residual normalization reduced average dependence on body mass among independent raw lifters but did not confer universal invariance. W-scores should be interpreted as population- and model-specific statistical normalizations, not as measures of physiological 'true strength' or as proven replacements for competition-ranking systems.