It's a really serious workout, but if you follow it you will, I mean will see results.

I disagree with the poster above about age. I'm 45 y.o. with 10 days left to go. Somewhere around the 3rd week my knees & shins were giving me some trouble. I went easier on the high-impact stuff and used icy gel-packs afterwards for a few days (I don't remember how many, but it was less than a week) and it went away. The 2nd month is a big step up from the 1st in terms of difficulty, and I've had no problems since then (no problems with joint pain, that is; but let me tell you I do NOT get through the workout with the same strength and grace as the folks in the video!). Some workouts involve a lot less impact than others - you're working all of your large muscle groups, as well as isolating some, so there's still a lot to do that won't affect joints at all. (Oh my god those moving push-ups are a b*tch!)

I'm really glad I'm doing it.

Insanity is great. I'm sweaty within 10 minutes. I did it straight thru and saw benefits. Afterwards, I did the p90x/insanity hybrid that was mentioned above. No pre-existing joint issues, so I can't tell what how it would affect a bad knee. It's definitely not low-impact. there's no weights, so I didn't feel sore at all the entire time. I'm about to do the 60 days again to get ready for swim suit season.

Bad knees? Absolutely not. Insanity is not for you. At all.

Insanity lives up to its name. It is sixty days of extreme plyometrics. Your joints, your knees, your Achilles tendons will take a beating with all that jump, jump, jumping for fifty minutes. Unless you're already in excellent physical condition, I'd stay clear of Insanity.

That said, if you're set on doing Insanity, go halfway. Do a P90X-Insanity hybrid. The P90X Plyometrics workout is as hard as anything Insanity has, but some complain that KenpoX and CardioX don't measure up. Fine: substitute an Insanity workout on those days, and keep the P90X resistance training days and YogaX. P90X's Ab Ripper gets a little monotonous three days a week. Solution: Insanity's Core Cardio and Balance or Insane Abs. Insanity really shines with its impact on the abs.

P90X is tough but doable; Insanity is, in my experience, too much for an older body (I'm 43) to handle for two straight months. P90X is also easier to modify than Insanity, both during each workout ("Watch Pam the Blam for the modified moves!") and each workout as a whole. Ninety days is a tough stretch, but I find that as long as you keep the core components -- three days of resistance and one day of YogaX, Plyo, or Core Synergistics -- you'll have a good foundation to add or subtract Insanity workouts as needed.

would like to hear about this as well. i have a bad knee - would it work for me? is it low impact?

Please post some reviews and updates on the program.