Scientific explanation for success of klapskate

As part of a project funded by the NWO’s Netherlands Technology Foundation (STW), researchers at Amsterdam Vrije Universiteit (VU) have demonstrated why the so-called klapskate produces better speedskating performance. The klapskate (The Dutch word ‘klap’ which means ‘to slap’ is accepted as a universal prefix: German: Klappschlittschuh; Japanese: klapskato) is constructed in such a way that the shoe part can hinge up away from the blade to free the heel.

It turns out that the superiority of the klapskate is not so much because it allows the skater to extend his ankle joint at the end of the push-off phase but because of the location of the pivot point around which the foot rotates. The klapskate was developed by researchers and instrument makers at the VU in 1985 and was used for the first time in competitive speed skating by the junior selection of the Dutch province of South Holland during the 1996/1997 racing season. Since then it has taken the international speedskating world by storm.

The Amsterdam researchers invited ten top speedskaters to take part in experiments wearing standard speedskates and klapskates. It turned out that there was a 12% increase in the external power generated by skaters when they wore klapskates, allowing them to go 5% faster. As far as friction with the ice was concerned, there was hardly any difference between standard skates and klapskates. Although the front point of a standard (unhinged) speedskate scratches across the ice at the end of the push-off phase, this does not in fact lead to any appreciable loss of power. The superiority of the klapskate, which prevents the tip of the base from scratching the ice, cannot therefore be due to a decrease in friction between the skate and the ice.

Analysis of experimental measurements showed that the increase in power delivered using klapskates is to be found in the location of the pivot point around which the foot rotates, namely the hinge under the ball of the foot. With standard speedskates, the foot rotates around the front point of the blade, which is located a considerable distance in front of the wearer’s toes. The long classic blade forms a large lever which is difficult for the skater’s calf muscles to set in motion. The position of the hinge of the klapskate –under the ball of the foot– reduces the length of the lever. When a skater is wearing klapskates, his calf muscles can in a sense switch to a lower gear. This makes his movements more effective, leading to the push-off phase producing more energy.

The position of the hinge would therefore seem to be vital to the effectiveness of the klapskate. Both experimental research on the ice rink and computer simulations have shown that there is indeed a small area under the ball of the foot where the hinge has to be located in order to achieve the optimum result. The actual position seems to vary from one skater to another and depends on such factors as his or her build and skating technique. The complex interaction between all these factors means that it is as yet impossible to determine the optimum position of the hinge for every skater. It is still a question of feel.

The research project also came up with a number of improvements to the hinge mechanism. Adding a second hinge between the shoe and the blade, or a hinge at an angle between them, may make it possible to improve the effect of the skater’s push-off even more. These innovations still have to be tested in practice. STW has applied for two patents on the klapskate improvements, one of which has already been granted.

Further Information:
Han Houdijk (VU, Bewegingswetenschappen)
T 31-20-444 8469 or 20-444 85 30 (secretariat)
F 31-20-444 85 20
E-mail: [email protected]