Apple Watch fitness pausing

My Apple Watch (less than a year old) and now replaced twice, can not stay resumed while exercising. It’s almost useless when at the gym as is continuously pauses. Yesterday I ran 2km, and it caught 90m of my workout. I have toggled with the auto pause setting, I’ve tried water lock, I’ve replaced it twice thinking it was the sensor, but nothing works.

am I doing something wrong?