Dierentiation of Ankle Sprain Motion and Common Sporting Motion by Ankle Inversion Velocity Title Differentiation of Ankle Sprain Motion and Common Sporting Motion by Ankle Inversion Velocity Article Type Short Communication

3 This study investigated the ankle inversion and inversion velocity between various 4 common motions in sports and simulated sprain motion, in order to provide a 5 threshold for ankle sprain risk identification. The experiment was composed of two 6 parts: Firstly, ten male subjects wore a pair of sport shoes and performed ten trials of 7 running, cutting, jump-landing and stepping-down motions. Secondly, five subjects 8 performed five trials of simulated sprain motion by a supination sprain simulator. The 9 motions were analyzed by an eight-camera motion capture system at 120Hz. A force 10 plate was employed to record the vertical ground reaction force and locate the foot 11 strike time for common sporting motions. Ankle inversion and inversion velocity were 12 calculated by a standard lower extremity biomechanics calculation procedure. Profiles 13 of vertical ground reaction force, ankle inversion angle and ankle inversion velocity 14 were obtained. Results suggested that the ankle was kept in an everted position during 15 the stance. The maximum ankle inversion velocity ranged from 22.5 to 85.1 deg/s and 16 114.0 to 202.5 deg/s for the four tested motions and simulated sprain motion 17 respectively. Together with the ankle inversion velocity reported in the injury case 18 (623 deg/s), a threshold of ankle inversion velocity of 300 deg/s was suggested for the 19 identification of ankle sprain. The information obtained in this study can serves as a 20 basis for the development of an active protection apparatus for reducing ankle sprain 21 injury. 22 23 Introduction 24