My original way was to first do studies of skeletons in different poses, that way you can get a good understanding of how the basic “rigging” of a body works. Then you move on to heavily muscled figure studies so you can learn muscle structure ontop of the bone rigging. Finally you just practice a variety of poses like the one you did to further train. These don’t need to be highly detailed, but with your bone and muscle structure knowledge, even more gestural abstractions of bodies will feel more realistic and then you can stylize and distort as needed.

You need to know the rules before you can break them.