I followed their schedule all week last week. I thought I was sore on Tuesday from the video, but realized I was sore from the strength training I did on Monday. I wasn't sore the rest of the week from any of the other videos. It's possible that because I had a sinus infection that' I didn't put as much effort into it. I sweat a lot, my heart rate went up, but I didn't feel any soreness from doing the workouts. I'm not sure if that really means anything though.