i agree with Kathryn. They are pretty intense. I would do the same..one day off, one day on. I did CTX Power Circuit tacked on to IMAX Blasts only the other day and I swear I thought I was going to die..... Next time it will be PC with Intervals 1-5 or 6-10. You really miss those cardio workups to the blasts when you don't have them. I can't get my HR back down in time!!! Plus, I haven't memorized Imax 2 yet so I do still stand there and stare still... Ugghh..I hate that stage. Don't you guys wish Cathe had paired IMAX 1 with IMAX 2 and we could have mixed and matched them together. I miss some of the intervals from Imax1!!
Sorry to go off on my own tangeant there.... I will tell you that I lost a good amount of body fat when I incorporated CTX in my routine. It seems like it broke me through a plateau. Many times though I do it on a 4" step just so I don't feel so wiped afterwards. It is still a very good cardio workout. On the 4" step I can focus on making my jumps as high as i can and my movements are more dynamic. And, of course, it saves my knees as I am only 5'... go ahead and order it. Next to IS and S&H it is one of Cathe's best series...
Janice