So during Bikram class yesterday I noticed that my fingers were pruning up like they do when you're in a bath, or washing dishes. Bikram yoga is a method popularized (and unfortunately copyrighted) by Bikram Choudhury: a series of 26 yoga postures done in a specially heated studio -- at least 105 degrees F and 60% humidity. Although I don't agree with his attempts to prosecute other teachers of hot yoga for copyright infringement, I have found this style of yoga to be especially beneficial for me personally. The heat helps your muscles relax so that you can make good progress in flexibility and in healing old injuries. It's been great for my oft-injured ankle, and helpful for shoulder strain brought on by too many hours at the computer.
So anyway I had to go find out why your fingers prune up. Basically, the outer keratin cells take on water and to compensate for their increased size your skin wrinkles. Who knew?
I guess it was pretty humid in class yesterday.