Re: Gravity and the body
Well, this is a worthwhile topic indeed . . given that gravity is one of the two major external "forces" you are learning to manage inside yourself from a "beginning body training for budo" (also known as IT/IP/IS yadda yadda) perspective. As you get better in managing how it affects you, you can better control how it affects someone else based on your skill level/points of contact, etc. Again, beginner steps, but key beginner steps (and something you're always working on improving and cultivating).
That cultivation part plays a big role in the OP, I think, because as you condition your body to better automatically handle the forces acting outside of you (Gravity pulling you down, the Ground pushing you up) via whole body connectivity and less reliance on local muscles . . in addition to applicability in a martial arts setting, your overall quality of life should get the net benefit of being able to do more for longer as you age. Whereas continued use/wear on local muscle/joints has a pretty observable resulting degradation effect.
Anyway, just some of my own ramblings of the brain that I think are relevant.