I've used the product almost every day for 10 days or so. I will say that my knee's, my back and shoulders were hurting after the first few days. This was more likely due to my lack of Core Strength and due less in part to the machine itself. It felt similar to the pain I felt in the gym after staying away for a few weeks so I worked through the initial discomfort and after the first few days, those initial pain points are no longer an issue. I would say that i feel it's more of a cardio machine than one of those ab specific workouts. It's a pretty good workout that's easy to do while in front of a tv.