Awww, what a great picture! I think that's called the "ultimate weightless kitty yoga" pose (mommycat required for best benefit)

We used to have a kitty that would love to be held upside down so she could get into "full stretch" position.

Ritzy likes to be helped with stretches (pick her up just under front legs so she can "reach high"), but really has never liked to be upside down in my arms (even as a tiny kitten) although she goes belly-up on the floor for me all the time.