I don't know if that is correct for all.
However, someone may get some hints or some ideas form this.
The first performance:
I play with the just relaxing body.
The second:
I play with a good body position for my body. It's comfortable for my body. Just comfortable.
The third:
I play with the drawing up position like a military style.
The forth:
It's my best or better position for the playing trumpet.
The first, it doesn't make enough energy for the trumpet playing.
The second, It's better than first position and third position. However it's not enough for the long phrase of the high part, the big sound, very small sound, and the widely resister. It needs much staminas for the long playing with that position.
The third position is made by my muscles of the outside. My inside is fixed and cannot move freely.
The forth and second, those position are small difference, but it's big diefferent.
The looks, Third and Forth are close. But it's very different in my body.
The forth position makes inside of my body by a good breathing. It's very freely for the trumpet playing and my mind is kept cool in some tough situations.