I have a kick boxing instructor that reminds us that our muscles move bones.  It should not be the other way around.  I think it is a very important reminder.  That means you want to strengthen your muscles and notice when your bones are overpowering your muscles.  When you hunch over in exhaustion or as you age, you are letting the bones win.  

The truth is, if you keep your muscles strong every part of your body wins.  Our bones and muscles should work together.