DYNAMIC ANGULAR STIFFNESS OF THE ANKLE JOINT DURING RUNNING AND SPRINTING

The purpose of this study was to compare the moment-angle relationship of the ankle joint during running and sprinting to determine how the dynamic angular stiffness is influenced by different activities. For b oth running and sprinting, the results indicated that the ankle joint produced an exclusively extensor moment, absorbing energy during the f irst half of the stance phase and producing energy during the second h alf. The biphasic nature of the joint absorbing energy followed by the joint producing energy, while continually creating an extensor moment , was similar to a spring being compressed and allowed to extend. The dynamic stiffness of the ankle joint was 5.68 N.m/degrees for running and 7.38 N.m/degrees for sprinting. it appeared that the stiffness of the ankle joint was not a specialized characteristic of each individua l hut rather a specialized characteristic of the activity or demand pl aced upon it.