I was jogging on the treadmill on the submarine when they announced we were going to periscope depth (shallow). Come to find out, the weather on the surface was rough. I decided to ride it out and keep running. I did okay for a couple of minutes, but we took a big roll and I stepped on the edge of the treadmill. from there, I fell sideways and landed with my right leg getting sanded by the belt. I jumped up pretty quick, looked around, turned the treadmill off, and went to watch TV.