I also have the Sennheiser twist-to-fit earphones - and they stay put well, but I have to say that they don’t maintain Sennheiser’s high reputation for sound quality. They sound kinda tinny. I use them for running, but I may put them aside for my next run . . .
The next time I go out for a run, I’m going to try my Lenntek Sonix canalphones, which seem to be a great complement to my Sansas. Normally, though, in ear headphones aren’t recommended for running because they do such a good job at blocking outside noise - like an oncoming car.
