Pre-Jump

Distinguished. Pre-jump was named by Alan Launder, describing what he observed in Bubka’s technique: the plant foot completing its takeoff drive and breaking contact with the runway a fraction of a second before the pole tip strikes the back of the box, establishing an air gap prior to pole loading.

It was a real observation. The model does not use the term, for three reasons.

It separates the takeoff into phases. An air gap before loading describes the event as two things with a space between them, which is not how the continuous chain treats it.

The degree of separation is undefined. How large the gap should be is not specified, which leaves it a gray area — and gray areas cannot be standardized.

And it prevents the athlete from using the pole to assist takeoff angle generation. This is the substantive cost. An unassisted athlete redirecting horizontal velocity into vertical lift must use the takeoff leg as a braking lever, and a large fraction of the kinetic energy is lost in the process. With the pole loaded, the redirect happens through the pole instead, which returns nearly all of what enters it. The pole adds no energy — it preserves energy that would otherwise be spent. A takeoff completed before loading forfeits that.

Not the same as free takeoff. The free takeoff covers the interval while the takeoff foot is on the ground. Pre-jump describes what happens after it leaves. The two are often confused.