Okay, your biggest problem is that you started with the muscles. This will never end with a good drawing, unless your very advanced. The first and most important thing you must do is lock in the pose. We do this by creating a gesture drawing to get the "story" or idea of the pose. Once we have that, we can work out our structure, perspective and angles. Then, and only then, do we add the anatomy and details. I did a sketch to show you the progression of doing it this way. I would love to see you take another reference and try this. I hope this is helpful :)