Two body dynamic model for speed skating driven by the skaters leg extension

Abstract

In speed skating forces are generated by pushing in a sideward direction against an environment, which moves relative to the skater. De Koning et al. (1987) showed that there is a distinct difference in the coordination pattern between (elite) speed skaters. Models can help to give insight in this peculiar technique and ideally find an optimal motion pattern for each individual speed skater. Currently there are three models describing and optimizing the behaviour and performance of skaters, of which only two are relevant in terms of coordination patterns (Allinger & Bogert, 1997; Otten, 2003). However, none of them have been shown to accurately predict the observed coordination pattern via verification with empirical kinetic and kinematic data. Therefore, the objectives of this study are to present a verified three dimensional inverse skater model with minimal complexity, based on the idea of (Cabrera, Ruina, & Kleshnev, 2006), modelling the speed skating motion on the straights. The model is driven by the changing distance between the torso and the skate (further referred to as the leg extension), which is also the true input of the skater to generate a
global motion. This input, which is indirectly also a measure of the knee extension of the skater, is a variable familiar to the speed skaters and coaches. In this extended abstract we verify this novel model for two strokes (left and right) of one skater through correlation with observed kinematics and forces.