cpm machine

I recently had a shoulder arthroscopy. As part of my physical therapy I have to use a cpm machine 6 hours a day that slowly moves my left arm up and down. Does anyone know if using cpm machines burns any calories? Its a slow repetitive move that I break down into 2 hour sessions, 3 times per day. I don't work up a sweat while im using the machine but feel very tired after. Does this count as light exercise?