I would suggest not doing anything with these Shuffles (2nd or 4th) that involves humidity, sweating, or any sort of condensation. Shuffles short circuit and die when exposed to any sort of water. Mine died while I was on a walk a couple of weeks ago because it was 108 outside and it was clipped to my shorts and got some sweat on it. POS.
I listen to mine every day in the sauna at the gym (140-150 degrees in there). That's after lifting weights, biking, whatever..... I wouldn't call it a POS, just some bad luck. It's been going strong for 2+ years after a ton of abuse.