OK I did write 'press,' it is push, and as any (other) physics teacher (only 8th grade, no phd) will tell you Force is a push or a pull.
Units of force are Newtons (mass x acceleration, but pounds and kilos are easier to think about.)
---The paddle applies force to the water, that force is transferred through your body to the kayak which then moves forward. It's usually done so smoothly most people aren't even aware of it. (experiment: 100 people handed a paddle and a kayak, then asked to figure out how to go faster, how to apply more force.... I'll bet only 1-2 people stumble by chance on torso rotation. I've seen whole kayaking classes--nobody we know--all shoulders.)

If the force is transferred through your bottom, the kayak still moves forward and all the muscles between your hand and bottom are to some degree involved.
As we all know if we can rotate our torso and transfer the force to the kayak through our feet, we 1. get a greater extension--(basically more travel distance between the paddle blade and our foot) and 2. involve more and larger (stronger) muscles. More force is applied and we move faster (I think we are mostly more powerful than fast. If we could convert some of that power to speed I think our kayaks would move faster.)

Foot straps are a good idea. They were on the To Do list of my ugly foot braces, but became 'did not' (yet), pulling on a foot strap might seem like undoing the push, but what it actually accomplishes is to pull your bottom back, or rotate your bottom back into position for the next stroke. Basically we should be all feet, all rotation and extension with our bottoms just being pivot points.

I liked the video of Zsolt, I'm psyched to go paddling right now. He's fully connected with his surf ski and pumping his legs.
A hundred pounds of force applied to the foot braces 60 times a minute over 25 km is a lot, but consider the force our legs apply to the ground when walking? Probably about a hundred pounds per step.
I think about kayaking as being similar to a fast walk.