Author(s): HATA, K., Institution: FACULTY OF PHYSICAL EDUCATION, Country: JAPAN, Abstract-ID: 832

INTRODUCTION:
The foot arch is a mechanically important structure for human locomotion, and higher arch stiffness allows more efficient utilization of the mechanical energy generated by the ankle joint during the pushing-off. Therefore, understanding the characteristics of the foot arch can provide important insights into human locomotor performance. Among the foot arch, medial longitudinal arch (MLA) has been extensively studied, whereas research focusing on the transverse tarsal arch (TTA) remains limited. However, recent study has reported that, in terms of contributions to foot arch stiffness, MLA curvature accounts for approximately 25%, whereas TTA curvature accounts for approximately 50% (Venkadesan et al., 2020). It was suggested that the morphology of the TTA during running may be an important factor associated with running performance and running-related injuries. Accordingly, the purpose of this study was to clarify the morphology of the foot arch in long-distance runners and its relationship with running performance, with a focus on both the MLA and TTA.
METHODS:
Thirty-nine male middle- and long-distance runners participated in this study. Magnetic resonance (MR) images of the dominant foot were acquired at 0.3 T. From the obtained foot MR images, MLA height and TTA curvature, estimated from the torsion of the fourth metatarsal and foot morphology. To account for potential changes in the foot morphology by training, relationships between MLA and TTA morphology and performance were examined using 5,000-m personal best times recorded within ±1 month of the MR measurement date. Statistical analyses included Pearson’s correlation analysis, simple linear regression analysis, and multiple regression analysis incorporating polynomial terms. The contribution of each explanatory variable to the 5,000-m performance was evaluated using the change in the coefficient of determination (ΔR²). The level of statistical significance was set at 0.05.
RESULTS:
Simple regression analysis revealed a significant U-shaped relationship between the 5,000-m performance and TTA curvature (R² = 0.23, p = 0.040). Furthermore, a multiple regression model incorporating polynomial terms was constructed with TTA curvature and MLA height as explanatory variables, which explained 21% of the variance in 5,000-m performance time (p = 0.049). Block-wise analysis demonstrated that TTA curvature provided an additional explanation for 16.5% of the variance in performance, while MLA height also contributed 13.2% to the explained variance.
CONCLUSION:
Among the foot arch morphology of long-distance runners, the TTA showed a greater contribution to competitive performance than the MLA, explaining 16.5% and 13.2% of the variance, respectively. In addition, a U-shaped relationship was observed between competitive performance and TTA curvature, indicating the existence of an optimal curvature value (estimated at approximately 24.3 m⁻¹).