In order to move down, I have to stretch down and equally up

The other day I was pushing hands with Laipeng, I was focusing on a point not to move (let's say the middle of my chest). In order to get him to fall backwards, I figured that I had to go lower than him. Since I couldn't move a point, I realized that I had to stretch down, and equally up in order to get to the new position. This is the way to maintain the non-moving dot.