Associations Between Heel Height, Lower-Limb Flexibility, and Lumbar Curvature in Female Workers: A Cross-Sectional Study

Objective: To examine the relationships between heel height, lower-limb flexibility, and lumbar curvature among female retail workers who regularly wear high-heeled shoes.Material and Methods: We conducted a cross-sectional study among female employees at shopping centers in Southern Thailand. Heel height was measured using a ruler. Plantar flexor and hip flexor flexibility were measured using a digital inclinometer, while lumbar curvature was measured via a Body Level/Scoliosis tool. Data were analyzed using descriptive statistics, correlation analyses, multiple linear regression models controlling for body mass index (BMI) and cumulative heel exposure, and regression-based mediation analyses with bootstrap resampling.Results: Higher heel height was significantly associated with reduced plantar flexor flexibility (r=-0.358, p-value=0.023). Plantar flexor flexibility was positively correlated with hip flexor flexibility (r=0.320, p-value=0.044), and hip flexor flexibility was associated with lumbar curvature (r=0.362, p-value=0.022). Multiple regression showed that heel height was not a significant predictor of plantar flexor flexibility or lumbar curvature, whereas BMI (β = 0.21, p = 0.034) and cumulative heel exposure (β=−0.05, p-value=0.015) were associated with lumbar curvature. Mediation analyses indicated no significant indirect effects through plantar or hip flexor flexibility.Conclusion: These findings suggest that heel height alone was not the primary determinant of lower-limb flexibility or lumbar curvature. Cumulative heel exposure and anthropometric factors may play a more important role in musculoskeletal adaptations among regular high-heel users. These findings highlight the importance of an integrative approach to footwear recommendations.