This is the first direct study in preparation for the piece I'm working on, so rather than just general muscle structure I'm doing part of the pose that the character will eventually end up in. I'll probably do more on it today, and possibly tomorrow as well, but I'm hoping to get the actual piece posted by the end of the weekend if all goes well. I really want this one to turn out well, so I'm putting in the work I need to beforehand.

Yes, you're supposed to be able to see the muscles.

2H pencil