2 mins. Sorry for bad photo qualit
I love the twist of the body that's visible in all of these drawings - especially the top left. It makes these poses feel extra dynamic and helps to give a sense of weight shift. Without the twist, the top left image might feel unbalanced, but you have done a great job of instead making it clear that she is mid-gesture.
To continue your studies, you might think about doing more of a focus on legs. In these studies, the thighs look like they have merged a little too much. Even when they are pressed together, they act independently and I think your dynamic style would look even better if each leg looked a little more independent.
You do a great job of finding an S curve in the torsos to make the pose seem more fluid. Even in the top right pose which doesn't naturally have many twists, you have used the curve of the spine really effectively to highlight where the muscles are straining.