When you exercise your muscles (including your vaginal muscles), it improves blood flow in the vulvovaginal tissues and may make them more supple and elastic (and stronger! which is a good thing).

If you're literally taking out your Perifit Care (which has a size and width) and starting physical activities right away, your vaginal tissues just haven't returned to their resting state yet (they must have expanded, temporarily, to accommodate the Perifit Care).

It's a matter of waiting a little for your pelvic floor muscles to 'cool down' after their workout (and adjust to no longer having the Perifit Care filling the vaginal canal).

But apart from that, make sure that you don't overtrain! The pelvic floor is a muscle group that fatigues pretty quickly. Aim to keep your training between 3 to 5, ten-minute sessions per week.