ouch, isn't 64lbs a little high for target practice? Since I dislocated my shoulder years ago, it feels 70lbs gets the pain flowing pretty quick.

In my opinion, you should target practice for the most part at the weight you want to hunt at. If all you are doing is target practicing, that is a different thing, but for hunting, keep it the same. Perhaps with an injury you need to limit the # of shots you take at one time. Just take one arrow out with a broadhead or a practice broadhead on it and shoot it a few times from different distances. Makes it more like real hunting situations and doesn't tire the muscles and hurt the joints as much. I also like to do various things, such as come to full draw, hold it for 30 seconds and then shoot, or give myself to the count of 5 to make the shot before having pulled back. You don't have to shoot as many arrows in a row, and it is more fun to me. To each his own, though. I am sure that many of you folks do things like this as well.
If, with a shoulder dislocation or something similar, you are unable to consistently and comfortably shoot at the pull you want to hunt at, you may want to trade in for a lighter weight bow.