had pretty good experience with these today at the gym. some exercises where my shoulders go up by my ears, like close grip lat pulldowns, i noticed a bit of loosening up during some of my sets.
i also feel towards the end of my workout, which i was sweating like shit, that they were starting to slip a little bit too and i had to adjust them quite a bit after some sets than i did in my earlier workout. nothing too drastic or anything, but the noise isolation definitely was loosening up a bit and i noticed it with bass loss.
overall i like them a lot but still need to figure out if i can adjust the ear piece to be a little bit better, since it did start slipping just a tad towards the end. this is my first wireless bluetooth headphones so i've never had that ear piece, but that definitely helps hold them in and keeps the noise isolation up.
it was really nice not hearing all the bs around my gym, especially this one guy who's annoying as shit and never stops talking. it was also awesome to just not have any wires getting in the way. and when i did some exercises where my hand would go near my pocket (curls) i just put the phone on the ground to the side and it was fine. had no dropouts at all.