THE EFFECT OF KLAPSKATE HINGE POSITION ON THE KINEMATICS OF SPEED SKATING

Abstract

611 This study was designed to establish the relation between location of the hinge in the klapskate and push off kinematics. 14 elite speed skaters skated on an instrumented klapskate in which the hinge was located either on the location they normally use (HN), 15 mm forward (HF) and 15 mm backward (HB) of HN. In each randomly assigned condition, three 400 m laps had to be skated at maximal effort. On the straight of the 400 m rink 3D film recordings (100 Hz) of the push off were made. Skating velocity was higher for HF and HN then for HB, resp. 12.21, 12.15, 12.03 m/s. This difference in skating velocity coincided with significant differences in push off kinematics. Knee extension at the end of the push off was smaller for HB then for HN and HF, resp. 161, 165 and 165 degrees. The range of ankle plantar flexion was similar for all conditions. Plantar flexion velocity was higher for HB then for HN and HF, resp. 826, 759 and 760 deg/s, whereas knee extension velocity was significantly lower for HB compared to HN and HF, resp. 500, 537 and 533 deg/s. These differences originate from the fact that the plantar flexion for HB was initiated earlier in time compared to HN and HF. This early plantar flexion goes at the expense of knee extension and push off duration. It was concluded that backward displacement of the hinge of the klapskate, compared to the normal position, results in an incomplete leg extension and hence a reduction of the capacity to do work. No significant differences were found between HN and HF. Supported by NWO-STW 790-23-667, NOC*NSF