I've also had swelling of my hands, which I don't have with hiking poles.
I don't think it is altitude related, so much as hiking related. I have the problem at low altitudes.
I think, Steve, that your first impressions about kidneys might be very likely. Sitting on a horse is QUITE provocative, which I rediscover every time I ride one 10 miles...and can't walk for a half hour afterwards. One's hands are also somewhat compressed into the sides, which would retard return circulation, also.
I don't get swelling post-riding, though.
so....got me!
