The baseline entree point into internal strength - pointing at lots of common ground (pun intended), commonalities and similarities laid out by many giants in both CMA and JMA is that notion of balancing the intersection of gravity pulling you down and the earth below you pushing up - basics of groundpath to use the Sigman terminology - so that any external force that's presented to you, is able to be directed to the ground in as pure a form as possible. That's by no means the full extent of "sourcing power from the ground" but it's the very basic entry point that most point to when you talk commonalities and overlaps of varying noted perspectives of IS.
The idea that the "earth" is pushing
anything up - is incorrect. The Earth "sucks," literally.
That pushing up is not occurring. What is occurring is the releasing of the temporarily-stored positive energy. If you squat down, and then jump up - the power is not coming from the earth. It's coming from the stored energy in your legs that you compressed when you did the squat. And the energy is not released up. It's released down. That why we go up. The energy is drained - most effectively - and "in as pure a form as possible" through the decoupling of the body and the earth - through the inverted cones created by mainly the toes. And out of the toes - mainly at a point on the bottom of the big toe.