Watch a cat the next time he stands up from a nap. First, he'll raise himself in the classic "Halloween" posture, back arched like a bow. Next, he'll stretch waaaay out in front, then waaaay out in back.
He'll do the same sort of stretching exercise at his scratching post. He doesn't scratch way up high just for the hell of it; he's stretching those muscles. He will reach waaaay up, hook those magnificent claws into the post, and pull down, toning those strong shoulders and legs.
That's partly how a cat stays in such good shape for twisting and turning in mid-air in order to land on his feet. It's also a very good reason why your cat is so laid-back and relaxed while you're rushing to meet a deadline. And, in nature, it's how a Cheetah can run almost effortlessly before raising a giant paw to bring down a fleeing morsel of prey with a powerful blow.
If you want to see the same kind of action with your "house Cheetah," wad up a piece of paper into a ball; get his attention and throw it. Then watch him chase it down, then "dribble" it across the floor.