I was running the other day (not on a run, but just to my car from my office, about 200 meters) and had my hands in my coat pockets to keep them warm. Now, my coat pockets are up high on my coat, just below the chest at about the bottom of the rib cage at the same level I keep my arms at when I run. The weight of my arms were resting on my coat pockets, but I was till able to swing them at just about full range. It felt easy on my arms. So, my idea is to have like a belt around your chest that has a strap on each side for each arm to be looped through, acting kind of like arm rests. This way you still get the bennifit of swinging your arms, but you don't have to hold up their weight. I think it is worth a shot.