Abstract des Autors

In this study, the movement of the tibio-tarsus joint during running activity is analyzed through observing above all the modifications due to difference in speed. Ten subjects of both sexes and aged from 18 to 22 performed a treadmill test at the speed of 8, 12, and 16 km/h. A VICON system was used in this study, allowing three-dimensional analysis movement through image processing by means of four video-cameras connected to an analogical-digital interface. The cameras permit to collect the trajectories described by reflecting markers set on the subject studied. It was thus possible to study the change in amplitude, velocity, and angular velocity related to the tibio-tarsus joint flexion-extension movement. The analysis of the plant to ground and the tibia to vertical angles, and of the height between the floor and the heel and/or the head of the fifth metatarsus permitted to split the stride into three phases: the contact phase, (from foot-plant to heel take-off), the push-off phase (that ends with the forefoot take-off), and the flight phase (ending with take-off from the ball of the foot). The result analysis emphasizes that on increasing running speed, the foot-plant time decreases. The ankle angle is unchanged, but it reaches its lower width at the end of the first phase (maximum dorsal flexion), while its higher values are recorded at the end of the second phase, when the push off is executed with maximum plant flexion. The ankle angular velocity increases when running speed increases and it reaches its highest value of dorsiflexion, during the first phase of the running cycle, and for the plantar flexion at the end of the second phase. Verf.-Referat