Yes, it is a very tough, non stop leg workout. BUT, it is fun, too. It's hard to say if it is 'tougher', because diff things are tough to diff people. It's an endurance workout, so your weights may be lighter than if you were using MIS, but there are more reps per exercise. I think it is fun because in addition to the great leg workout you get, it's non stop, so it feels challenging cardiovascularly, as well, and also Cathe switches around CONSTANTLY. First your doing squats. Then lunges. Leg press. Calf pumps. Etc., etc. You get the idea. She keeps you busy, so after awhile, on that last round of squat/plie/calf pumps, you're pretty impressed with yourself LOL!
Kathy