The Sony WI-C310 are very good for sports and fitness with the caveat that there's no IP rating against moisture or dust. These headphones are very portable and easy to carry around to the gym. Their bud design is very small and doesn't trap heat inside your ear, which is great since you won't sweat more than usual wearing them. They are also stable enough for working out, but since the cables are very long, they create big loops, and pulling the headphones out of your ears is easy.