Advantage of the Flexible Vaulting Pole
Although fibreglass vaulting poles have been around since the early 1960s, there has not been a convincing explanation of how they work.
A pole vaulter can jump 50-90 cm higher with a flexible fibreglass pole than with the-old style poles made of steel or bamboo.
Contrary to popular belief, the advantage of the flexible pole has little to do with any 'catapult' effect.
The vaulter does not get 'flung' higher into the air.
Rather, the vaulter achieves the greater height height by using a longer pole.
To understand why a vaulter can use a longer pole, I developed a model of vaulting with a flexible pole and a model of vaulting with a rigid pole.
Results from computer simulations showed that the benefits of a flexible pole are mostly in the take-off phase.
A flexible pole reduces the energy dissipated in the vaulterís body during the pole plant, and it also lowers the optimum take-off angle so that the athlete loses less kinetic energy when jumping up at take-off.
Greater energy at take-off means that the vaulter can safely use a longer pole.
This new understanding of pole vaulting mechanics should help coaches devise more effective take-off techniques, and it may help pole manufacturers in designing better poles.
To find out more about pole vaulting mechanics, see:
Energy loss in the pole vault take-off and the advantage of the flexible pole.
Sports Engineering, 3 (4), 205-218.
Soviet pole vault coach, Vitaly Petrov, has used his version of vaulting technique with great success (particularly with Sergey Bubka).
One key concept in Petrov's technique model is the idea of a 'pre-jump', where the vaulter is supposed to be airborne before the pole is planted into the take-off box.
Although the technique described by Petrov has been widely accepted, slow motion video analysis (not available to Petrov when he first proposed the concept) has shown that a more accurate description of Bubka's take-off is that it is a 'simultaneous take-off'.
That is, the vaulter leaves the ground at the instant the pole strikes the back of the take-off box.
A simple test for determining the instant when the pole strikes the back of the box is to look at the position of the upper hand relative the vaulter's head.
During the final stride of the pole plant almost all elite vaulters extend their upper hand directly above their head.
When the pole strikes the back of the box, the vaulter is unable to completely counteract the force exerted on his arms by the pole, and so the vaulter's arm is forced back behind his head.
The instant the pole strikes the box is therefore the time when the upper hand first begins to move backward relative to the vaulter's head.
To see a video of a Sergey Bubka, go to the TakeOff & FlyAway website and look at the vault from the 1997 World Championships in Athens.
Bubka's pole strikes the back of the take-off box one frame before his take-off foot leaves the ground.
Other vaulters who are up on their toes when the pole strikes the box include Guiseppe Gibilisco and Svetlana Feofanova.
To see a video of a pole vaulter who gets airborne before the pole strikes the back of the take-off box, go to the TakeOff & FlyAway website and look at the vault by Dmitry Markov at the 2001 World Championships in Edmonton.
To find out more about the 'pre-jump' controversy, see:
Linthorne, N.P. (1990).
The pre-jump pole vault.
Modern Athlete and Coach, 28 (1), 39-40,
and in Track Technique, 112, 3579-3580.