Hi Deb,

I certainly do have arm weakness (RSD left hand/wrist) and while the muscles in my left hand dwindled significantly quite early on, the muscles in my whole left arm, specially my upper arm, are now wasted noticeably.

I was trying to do something the other day that I should have been able to cope with, and could have maybe a year ago...and realised I just plain didn't have enough strength in the muscles. Then - worse than that - realised I didn't have *any* muscles in my left arm. Went and looked at myself properly in a mirror - bit of a shock - I've always been quite strong. Little skinny stick arm. So I've decided to do the PT exercises daily from now on (swinging the old soup tins, etc), I slackened off a bit, but I reckon it's a necessity, drat!

I also have spinal stenosis and cervical spondylosis, but this isn't happening because of that.

BTW, the best posture exercises I've come across are these (very simple):

Drop you shoulders and sit straight-backed, looking straight ahead. Tuck your chin right in, keeping your head in line with your back so you make as many double chins as poss. Don't look down, though, keep looking straight ahead. You'll feel it it at the base of your skull and down the back of your neck. Keep your shoulders dropped. Hold this for 10 secs, relax. Do it again, but turn your head slowly to the right, hold for 10 secs. Relax. Then same again turning left.

Then, sit in a chair, do the same chin-tucking, and, keeping your body straight, bend your head to your shoulder as far as you can, as if you're trying to touch your shoulder with your ear. Don't bring your shoulder up to meet your head, keep it dropped and relaxed. Do this both sides, left and right, and grab the edge of the chair to help you stretch the neck muscles - bending the head to the left shoulder, grab the chair edge with your right hand, you can lean over sideways and pull against the chair; then the reverse for the right side.
Good thing about this exercise is that you can do it anywhere! Just makes you look like The Amazing Multi-chinned Turtle for a bit, LOL.

I suppose it's a domino effect; once one bit of you weakens, it must affect the rest of the body. Aaaaaagghhhh......
all the best!