I would like to give a special shout out to this book I was suggested (read as forced) to buy by my college professor. I was skeptic about it because you know, ew text books right, but no listen this book is actually pretty great.
It's called "The Human Figure: An Anatomy for Artist" by David K. Rubins.
This book is basically everything you need to draw muscular men. It lacks severely in women and children, but for some people that is ok.
For those of you that don't already have this resource, I highly recommend it to everyone.
And to add extra praise to it, it's fairly cheap on Amazon.