Crossover step? Hip turn? Drop step? Directional step? Plyo Step? Even a crossover drop step!?

There are some interesting comments to this, but IMO these debates are a red herring and don’t help our understanding. We have so many definitions when things aren’t that different. https://twitter.com/Challenger_ST/status/1179991285148594176

What you are seeing here is pretty much the same thing just one with more need to adjust BOS and COM because it’s reactive and maximal. But the terminology means different things to different people making communication difficult.

Crossover seems to be the biggest term with confusion and I think UK and US commonly refer to it being slightly different. And you get a ‘crossover run’ where an athlete turns their hips to a new direction to accelerate but not their shoulders and takes a few steps in that pos...

But this isn’t an initiation movement IMO, it’s a transitional movement (to use Jeffreys game speed terminology) where the athlete isn’t starting a maximal acceleration.

With all COD and sprint initiation ‘techniques’, athlete re-arrange their BOS to apply force fast and in the right direction. The feet lift to optimise their location (force direction) and for SSC benefits (force magnitude).

If it’s pre-planned they won’t lift and plant as much as they can put themselves into the position they need early as they know where they are going and when.

Whether pre-planned or reactive, linear, 90deg or 180deg, the biomechanical principles are pretty much the same and the mechanics athletes use are just what the interacting constraints in that moment result in.

1) Get the BOS into the right place in relation to COM
2) Arm movement to help initiate rotation.
3) Initiate force with the outside leg (propulsion and hip rotation to new direction)

4) Place the inside leg into an acceleration position with your hips facing the target as best as possible
5) Accelerate https://www.researchgate.net/publication/328561167_Change_of_Direction_Technical_Models_Biomechanical_Principles

Get someone with some basic acceleration, ask them to stand in an athletic position and reactively get them to accelerate into different directions and you’ll see the above sequence. Tell them where they are going to go, and they will get prepared to optimise speed if they can

The main issues I see is people not appreciating that the inside leg will be the biggest propulsion step, but will be optimised if it works in a saggital plane. The torso and hips need to have rotated for that to happen. The outside leg plant and the arm movement should do this!