The association of foot type and foot orthoses to jump performance and lower limb biomechanics in basketball players with and without flat feet

Introduction: Jumping is one of the most common manoeuvres performed by basketball players. Flat-footed individuals are believed to have poorer ankle control compared to normal-arched individuals, which may impact jump performance. Foot orthoses are commonly used to support the deformed foot arch, and restore normal foot function. However, it is unclear if foot orthoses use improves jump performance. Our study aims to investigate if foot type and/or foot orthoses influence countermovement jump (CMJ) and standing broad jump (SBJ) performance and lower limb biomechanics in basketball players. Methods: Twenty-six male basketball players were classified into normal-arched (n=15) or flat-footed (n=11) groups using the Chippaux-Smirak index, navicular drop test and the resting calcaneal angle measurement. They performed jumps with and without foot orthoses. We measured jump height and distance for CMJ and SBJ respectively. Hip, knee and ankle joint angles, angular velocities, moments and powers during take-off were also measured. A 2 × 2 (Foot type × Orthoses) mixed ANOVA was used to analyse the data. Level of significance was set at p<0.050) Results: There was no difference in jump performance due to foot type and foot orthoses for both CMJ and SBJ. For CMJ, the flat-footed group exhibited less ankle plantarflexion (F(1,24)=8.407,p=0.008,ηp2 = 0.259) and less hip joint power (F(1,24)=7.416,p=0.012,ηp2 =0.244) than the normal-arched group. Foot orthoses reduced ankle eversion in the normal arched group and in the flat footed group (F(1,24)=6.702, p=0.016,ηp2 = 0.218). For SBJ, the flat-footed group produced lower peak hip angular velocity (F(1,24)=7.115, p=0.013,ηp2 = 0.229) and generated lower horizontal GRF (F(1,24)=5.594, p=0.026, ηp2 = 0.189) than the normal-arched group. Wearing foot orthoses reduced ankle eversion (F=5.453, p=0.028, ηp2 = 0.185), peak horizontal GRF (F(1,24)=13.672, p=0.001, ηp2 = 0.363) and frontal plane ankle moment (F(1,24)=4.932, p=0.036, ηp2 = 0.170). Discussion: Foot type and the use of foot orthoses influence take-off biomechanics, but not actual CMJ and SBJ performances in basketball players. The different jump biomechanics between normal arched and flat footed athletes suggests possible compensatory movement strategies to maximise jump performance. Future studies may investigate whether these altered biomechanics may have implications on lower limb injuries. The use of foot orthoses resulted in biomechanical changes in both groups but also did not enhance performance. The results of this study provides no evidence supporting the use of foot orthoses for the purpose of enhancing jump performance.