I could NOT do 4 straight minutes of this insanity. I did 1 minute sessions, 4 times. Then I rinsed and repeated 3 times. The first time I did 1 minute, my thighs were throbbing for what felt like an hour. So suffice to say, if it hurt this badly, it definitely does something! No doubt the most effective and intensive workout yet. Also, have some music (house/electronic - I prefer Daft Punk) to help maintain your energy because it's just that tough.