International normative values for the weight-bearing lunge test across age and sex in 899 healthy adults

BACKGROUND: Ankle dorsiflexion is essential for lower extremity function and limitations in this motion are associated with musculoskeletal injury and decreased performance during functional tasks. The distance-based weight-bearing lunge test (WBLT) is a reliable and valid clinical measure of ankle dorsiflexion, yet normative data across age and sex are lacking. OBJECTIVES: To establish adult age- and sex-specific normative values for the distance-based WBLT. DESIGN: Cross-sectional, multi-country observational study. METHOD: A total of 899 adults from Canada, Spain, and Iran completed demographic and clinical measures including height, Foot Posture Index (FPI-6), supination resistance, and bilateral WBLT performance using a standardized knee-to-wall protocol. Participants were stratified into seven age groups and by sex. Between-limb differences were examined with paired t-tests. Associations between WBLT and height, FPI-6, and supination resistance were assessed using Pearson correlations. Age and sex effects were evaluated using two-way ANOVA with Bonferroni-adjusted comparisons. Percentile-based clinical categories were generated for each age-sex subgroup. RESULTS/FINDINGS: No meaningful difference was observed between limbs (p = 0.172, d = 0.05). WBLT performance declined progressively with age (p < 0.001, η² = 0.283), with greater reductions evident beginning in the 60-69 age group. Males demonstrated slightly greater dorsiflexion than females across age groups (p = 0.003, η² = 0.010). Height, FPI-6, and supination resistance showed small, non-clinically meaningful associations with WBLT scores (R² ≤ 0.09). CONCLUSIONS: This study provides robust age- and sex-specific normative values for the distance-based WBLT, improving clinical interpretation of weight-bearing ankle dorsiflexion across the adult lifespan.