THE START IN SPEED SKATING - FROM RUNNING TO GLIDING

The purpose of this study was to describe the push-off kinematics in s peed skating using three-dimensional coordinates of elite male sprinte rs during the first part of a speed skating sprint. The velocity of th e mass center of the skater's body v(c), is decomposed into an ''exten sion'' velocity component v(e), which is associated with the shortenin g and lengthening of the leg segment and a ''rotational'' velocity com ponent v(r), which is the result of the rotation of the leg segment ab out the toe of the skate. It can be concluded that the mechanics of th e first strokes of a sprint differ considerably from the mechanics of strokes later on. The first push-offs take place against a fixed locat ion on the ice. In these ''running-like'' push-offs the contribution o f v(r) in the forward direction is larger than the extension component v(e). Later on, the strokes are characterized by a gliding push-off i n which v(e) increases. In these gliding push-offs no direct relation exists between forward Velocity of the skater and the extension in the joints. This allows skaters to obtain much higher Velocities than can be obtained during running.