Hi, I've been using my Apple Watch to track my stats while playing drums. Over the course of eight hours between getting out of the car at a gig venue to getting back into the car after the gig, the watch is stating that I've burnt three thousand calories. Is this based on heart-rate? I'm just wondering about the accuracy as, if the reading is movement based (like a pedometer), then perhaps the watch is being fooled by my wrist/arm movements during the gig. Does anybody know if the readings are accurate in my case?