Samenvatting

A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 258wereelicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delayafter left heel strike, an electromagnet released the box on the treadmill. This delay enabled the subject to step on the box withouthaving to change the walking cadence. During the jumping task, subjects jumped from a 30 cm high platform on the box in astandardised way. In both tasks 20 stimulus and 20 control trials were presented randomly. The average tiltingvelocity of the trapdoor during the stimulus trials was 4038/s during the walking task and 5958/s during the jumping task. For the control trials a tiltingof 08was used. With this method it is possible to evoke reproducible ankle inversions causing characteristic EMG responses in sixlower leg muscles.