I'm sure you're right, Jon. In fact, I think when one gets nervous and has a hard time drawing the bow to full draw, one reason is because opposing muscles are being contracted at the same time, in other words, working against each other. Many years ago, when I was learning to rock climb, we would do a lot of pull-ups (which incidentally, aren't a bad exercise for archery, either). Initially, I had a hard time doing 3 pull-ups, but within a year I was doing 20. I'm sure I didn't get 7 times as strong, or even twice as strong, during that year, but I did learn to use only those muscles needed to do a pull-up, and to relax the ones that weren't needed.