Isn't walking on the balls of your feet just "good athleticism"?
here's a stock photo of a runner:
https://images.stockcake.com/public/7/1/2/7124d219-0531-40c1...
and here's one of volleyball:
https://www.games-eshop.com/wp-content/uploads/2020/07/web.s...
We're not talking about how to use the body when performing in their sport/art, but how they hold their bodies at all times.