We do this in our family.
It can be done with shoes on - I actually can't think of a Chinese style off the top of my head that practices without shoes. Can anyone? Although I would say there is a strong argument for shoes without heels due to how it changes the mechanics. Even running shoes change our mechanics.
Within our family it represents a dynamic concept and not static tension in the feet. The movement gives a pumping action at the jung cyun jyut 湧泉穴 Gushing Spring Point (Ki 1) to help with root, power, and internal energetics. Jung cyun is important on many levels...
There are different historical definitions as to the location of Jung cyun but the current standard can be easily found online.
JE