Abstract: Objective:This study aims to investigate the kinematics and kinetics of habitually unshod runners and habitually shod runners running.The foot morphological characteristics of abducted hallux of habitually shod runners and adducted hallux of habitually unshod runners is linked in the analysis morphology-related functions while running.Methods:A total of 18 habitually unshod runners and 20 habitually shod runners participated in the running test controlling the speed of 3.0±0.2m/s.The Vicon three dimension motion analysis system was taken to capture the kinematics of lower extremity while running test.Kistler was employed to record the ground reaction force of running under shod and unshod conditions.The Novel Pedar-X insole plantar pressure measurement system was utilized to collect the plantar pressure(peak pressure,contact area and pressure-time integral)in specific anatomical areas.The function of abducted and adducted hallux is analyzed through the comparison of plantar pressure parameters and kinematical results.Results:Owing to the different landing patterns of two participant groups,the dorsiflexion and plantarflexion angle of ankle while landing show significant difference.The Vertical Loading Rate of habitually shod runners is obviously higher than that of habitually unshod runners,which is linked with common injuries to the lower extremities.The peak pressure and pressure-time integral of habitually unshod runners' running are significantly higher than habitually shod runners.As to the hallux part of habitually shod runners,the peak pressure and pressure-time integral are higher owing to the supporting from outsole,thus reducing the loading in the medial forefoot and lateral forefoot.Combining the inversion and eversion of ankle in the coronal plane while pushing off,habitually unshod runners show a bigger eversion angle than habitually shod runners.Conclusion:In the pushing-off phase,the supporting from outsole to the hallux of the habitually shod runners could reduce the loading to the forefoot,thus lowering down the incidence of foot disorders,like plantar fasciitis and metatarsal fatigue fracture,but also improving the running performance through training of pushingoff sling-like action.