Update - I have now done 5 workouts in 6 days. (I was too exhausted on Thurs to do the workout, due to graveyard shift + extra 4 hours of taking care of baby while my partner works.) I decided that my 'day off' will be Thurs rather than Sun, so I had to change my workouts a bit.
As I stated previously, I'm also scaling the workouts back significantly as a part of "building up a base" of conditioning. Even still, doing approx 1/2 or less of the workouts (which is quite challenging for me), I'm noticing all kinds of improvement -- back and chest feel stronger, my arms and legs feel powerful.
Another observation -- I dubiously bought "Muscle Milk" from GNC to try after a workout. Despite being somewhat sore generally, I did the "Legs & Back" workout -- but skipped the Ab-Ripper X (actually b/c of time, but also I thought 2x in the first week was enough). I was surprised how many reps I could do and how good I felt. Doing pull-ups, I did noticeably more -- even though I was still easily exhausted and did nothing like what they do in the videos.
So after I showered & got ready for work (@ 9:30pm), I grabbed the Muscle Milk and took a big swig, then ran out the door to get some dinner on the way to work. I stopped at Gordo's (an ok Mexican restaurant nearby) and got a beef & chicken taco (rather than normal 'super burrito', which has rice & more tortilla and cheese). On my way to work, I finished the drink -- and it did taste chemical-ish. Not 'bad', but not wonderful.
But at work, I noticed through the night that almost all the muscle soreness was gone. I feel that my muscles are still swollen, puffy from the workouts, but no pain. ZERO. And normally I drink a lot of coffee to do the graveyard shift, but I only drank 1 1/2 cups. That's significantly less -- maybe there's stimulants in the drink? Now I'll consider trying the 'Whey Protein' powder I have (it's a lot cheaper), and see if it has a similar effect.
I have to admit -- I'm impressed. If this is the secret path to doing extreme workouts and not having any pain, I may do it. But I don't really want any ingredients going into me which are unhealthy for long-term.
Another note: despite it's challenging nature, I like Ab-Ripper X and am stunned at my improvement after just a few repetitions of the video. In preparation, I could barely do 20 situps. In my first playback, I could not do most of the situps, but I tried to do some. In the second playback, I could do noticeably more reps of each move -- but my abs were too sore to do some moves. So I didn't push it. I guess that's a good way to go -- just build the base, don't let my ego get involved.
Well, I got in 1 week of P90X and then stopped. First I missed a day, which became 2 & then 3 and then it was hard to start back up.
Observations: I really liked the workouts, and doing 1/2 workout might be a good way to get 'a base' to someday do whole workout. I'm not in physical shape to do 10 pullups, let alone 50+. But the workouts were damned good and hit every area.
My knees were a little beat up from Yoga & Jump Training, but the Kenpo X was surprisingly one of the harder workouts -- which surprised me bc my martial arts background is better than all the other stuff. Maybe it's b/c I did that workout 100%, while I slacked deliberately on the others...?
So I got the '10 Minute Trainer' videos & will give them a try. I'm not done w/P90X, though -- but w/new kid and working graveyards, it's a hard time in my life to devote 60-90 min's a day for workouts...