Well, I would recommend the noise cancelling headphone models of Bose. One reason is that there would probably be a lot of noise in a gym and you dont want to hear them with your music, another reason is I realized that those headphones do not have cushions that store the speakers in them and that are the parts that actually are in contact with your ears but they have a leather kind of thing that definitely does not get affected by sweat. Believe me you don't feel comfortable with headphones or earphones that are wet with your sweating. Another reason is, even though they are headphones and not earphones, they do not fall of your head when you jump or row. Personally I didn't have any problem with them when biking. The only thing is, people might get angry with you when you don't respond to them. (the noise cancelling feature works so well you can not hear a single thing from the outside world, once I was going down a very steep road, obviously very fast, and I din't hear what the other bikers said, which resulted in an accident)