Kinematic analysis on segment angle and angular velocities of recovery leg of world elite race walkers regarding race-walking judgement on world elite competition of athletics

BACKGROUND: The present study aimed to analyze the kinematic point which relates to the practical judgement to reveal the judgement criteria for loss of contact in race-walking competitions.METHODS: Subjects were world elite sixteen walkers for each three race-walk events (men's 20 km race walking: M20 kmW; men's 50 km race walking: M50 kmW; and women's 20 km race walking: W20 kmW) on world elite competition of athletics held on an official 2-km circuit. Kinematic data from each subject in the sagittal plane at the fastest 2-km lap time were calculated from the digitized data on images of a digital camera, calibrated with the cross-road markers on the road. The number of yellow paddles and red cards issued by the appointed race-walking judges were counted from the judge summaries, which were obtained from international race-walking judges.RESULTS: For the kinematics related to the judgement of loss of contact, the forward swing angle and the forward swing velocity of the shank in the first half of the recovery phase were detected as the critical viewpoint of loss of contact. Additionally, the vector angle of the heel velocity in the first half of the recovery phase was detected as viewpoint of loss of contact.CONCLUSIONS: The kinematic findings of the forward swing angle of the shank at toe-off (TO) were related with the judgement of LC, and thus determined as a critical viewpoint. Also, the vector angle of heel velocity at TO was detected as a viewpoint of LC.