This exercise is a stretching exercise and is very useful when you have the feeling that you get pushed out to the side when you are in the basic shin box position. This is a sign that you need probably a bit more training on the internal rotation.
However, what do we mean, when we talk about internal and external rotation.
When you are sitting on the floor with outstretched legs and straight upper body and you are placing a coin on each of your thighs. Now you are moving into the general basic shin box position. The coin from the front leg which forms the triangle falls outside, which means that you leg did an external rotation, meaning you’re opening your hip. The other leg which moved to the back experienced an internal rotation, the coin felt inside in your lap, conclusion you are closing your hip.
Whenever you want to know if your rotation is an internal or external rotation, remember the coin.
In order to improve the internal rotation, do the following: