IDENTIFICATION OF TOUCHDOWN AND TOE-OFF IN TURF-SPORT SPECIFIC MOVEMENTS USING KINEMATIC DATA

Abstract

The accurate determination of touchdown and toe-off during the stance phase in human locomotion is important for further motion analysis. The aim of this study was to evaluate the accuracy of using kinematic data to detect these events and therefore ground contact time of movements on artificial turf. Seven athletes performed five different turf-sport specific movements in which a single contact was made on a force plate (1000 Hz), while kinematic data of six markers were recorded (CODA, 400 Hz). A force threshold (20N) was set to determine the events of the touchdown and toe-off for the kinetic data. Comparison was made between the kinetic and kinematic derived event times. The errors between the kinetic and kinematic data ranged from 1.6 to 3.4% for the acceleration, hurdle hop and a turn with change of direction of 135°. It was concluded that kinematic data can accurately determine touchdown and toe-off events for certain movements on artificial turf.