Hey,
as I've been thinking about this for many hours, there are some thoughts from me, too. For sure, it is a kind of Tiefentlastung, but with a bit more specific timing. In push-pulls you start some time before your edge-change with the bending of your legs. This is needed to get up again and gives you much more smoothness. I sometimes do a dynamic Tiefentlastung and then hit the snow very harshly, what is not so "fluid"

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Other difference of push-pull to common Tiefentlastung is that you push much more dynamic. The act of extending your legs is ended, before the turn ends. Exactly in the moment, you're fully laid down, there is no more extension. In push-pulls there is no special Entlasung any more, only edge-change, when your center of gravity crosses the board axis.
But in my opinion Tiefantlastung is a good starting point for extremecarving. From this point your riding style can become smother, you improve your timing and then go on with push-pulls

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Have a lot of fun!
