I'm a pretty new cup user. I'm also a distance runner. I have a Diva Cup (size 2) and have used it for 2 cycles now. On my first cycle, I had some learning curve experiences with leakage, I think due to having it poorly inserted/not fully opened. But I did go for a long-ish run without leakage issues. The cup seemed to ride lower while I was running than it did when I was just sitting or walking, but it didn't feel like it was so low it would fall out or anything. I did have some irritation from the stem, which trimming seems to have helped.
On my second cycle with the cup, I seemed to learn how to insert it better and ensure it was fully opened. I had fewer problems with leaking. However, during one of my runs in particular, it felt like the cup was so low it may actually come out. And there was leaking. I know that my cervix could have been in a different position, contributing to the cup being lower. But I'm also wondering about my core muscles being engaged, essentially causing me to "bear down" enough to push the cup partially out. The position of the cup during this run seemed similar to when I am intentionally bearing down to bring the cup lower when I'm removing it.
Do any other cup users who are athletes have feedback on this? Would wearing the cup inside out to make it shorter help? Would I still push it out? Would a firmer or softer cup help? I know I could wear a pad as a backup for leakage, but pads while running are generally unpleasant. And I actually got motivated to buy a cup (after considering one for some time) after a particularly bad fail of both a tampon and a pad during marathon training. :/ So I'd like for my cup to be a good solution! :)
Thanks to anyone who can share thoughts, suggestions, experiences!