It's much better to use real life or photographs for your references than drawings, trust me. I learned this much too late and basically had to relearn everything I thought I knew about drawing peeps. Don't make the same mistake I did, it set me back a good number of years on my artistic development.
If you need macho chiseled folks, google image 'male models' and use them for refs. ^_^
Indeed. Like I said to another comment, it's hard for me to apply really curvy human anatomy to my very sharp and chiseled characters. Lol. But I'm working on it. I probably need to use human anatomy more than I use manga style. XP
I say the best thing you can do is find realistic standing poses an adapt those to manga. It will be more accurate and anatomically correct if you inspire yourself from real life and adapt it to the manga style.
I do try to use real life poses, but considering my male manga characters (which is what I'm working on atm) are usually very sharp and chiseled, it gets confusing when looking at normal human anatomy because of all the curves. XP But I'll work on that. Thank you! ^_^