Yes - I did P90X too (and here's my review)

Overview:
This is an extremely overdue write-up (I originally shared it only with a small group of friends).  I completed P90X originally in September of 2009.  I was in decent shape before I started the program, and was in much better shape after I completed it.  

A couple friends from graduate school mentioned the success they were having with a program called P90X from a company called Beach Body. I had never heard of it (I do not watch TV unless it’s MMA-related or children’s cartoons) – so I hopped on the Google machine and looked it up. It is a program of fairly intense exercise and nutrition planning; the main portion of this program was a set of 12 dvds, each featuring a different workout. The program was created by a man named Tony Horton, and he leads each of the workout videos.  These workouts run, at a minimum, 55 minutes (and some are up to 96 minutes!), and combine strength, cardio and flexibility training. They are big into doing pull-ups and push-ups (you can modify them if you are not able to do them or are fatigued). The program costs about $130, and the equipment (dumbbells, yoga mat, pull-up bar, resistance bands) probably cost more (I had all of this already). 

There were some principles that were paramount in the workouts:

1. Muscle confusion:  The scripted workouts ironically do a good job of switching things periodically so that your body doesn't get into a rut.  The P90X guys claim "muscle confusion" does a better job stimulating your body so that you achieve more gains.  My perception is this is probably true, but it certainly keeps you from getting bored from doing the same old thing.
2. Rep count:  They explained in the videos that you do push-ups and pull-ups to failure (or near failure).  For exercises with dumbbells, you pick a weight which allows you to do 8-10 reps if you're trying to build muscle, and 12-15 reps if you are trying to slim down or tone.  The last three repetitions need to be difficult - so pick the right weight.

I won't give away all of the secrets of their program, but I will tell you that it is divided into three phases, with a "recovery week" between each phase.  The recovery weeks are  just as hard as the normal weeks.  You push push push yourself the entire 90 days of this workout.

Things that were great (for me):

• Intensity: Working out on something to the best of your ability, rather than going through the motions, is the best way to make improvement. For example, I used to do a set of curls with 35 lb dumbbells for 8 repetitions in my workouts. In the pre program fitness test, I used 35 lb dumbbells for the “curl to failure” exercise, and did 22 reps (again – this is BEFORE starting P90X). I was leaving reps “on the table” for years.
• Synergistic exercises: Exercises that do more than one thing made a huge difference. Ever wonder why people in the military have such flat stomachs (Navy, Air Force and Coast Guard excluded)? Doing sit-ups or crunches alone is not enough. Pushups, for instance, work your chest and shoulders, but also require you to have strength in your lower back, buttocks and abs to keep good form.  The "Core Synergistics" workout, my favorite workout, is tougher than the line drills I used to do in high school football or the PT which I used to do in the Army.
• Journal of exercises: On Beach Body's P90X website, I found an excel worksheet that had all of the exercises in a journal form.  I’m into numbers. It was great for referring to previous weeks’ weights and/or rep counts, as well as notes like “hard as hell, use less weight” or “try harder, p*ssy”. It also enforced accountability as I do not like graphs with unexplained dips or gaps!
• Proper equipment: Of the fitness equipment I have (and I am spoiled in this area) the most important piece for P90X is a pull-up bar. Power Block dumbbells were great as well.
• Stretching before and after workouts:  The P90X videos each began with a thorough warm-up and stretch.  In my experience, other workout programs do not do nearly as well with this, but P90X makes improved flexibility one of your goals.
• The videos:  I thought Tony Horton was a good instructor, pretty funny, and I found myself keeping track of the other participants rep counts on the videos. 

Things that weren't great (for me):

• Workout duration: These take WAY TOO LONG! Even though the workout videos themselves are generally 45-55 minutes, if you are a human being, you need to take small breaks.  On average, a workout lasts about 1 hr and 20 minutes.
• Arizona heat: If, Heaven forbid, you wake up late, workouts take place in the afternoon when it is >110 degrees F in the garage. Brutal, but I would end up losing 3-4 pounds net during a workout (that includes drinking 2-3 32oz mugs of water).
• The Yoga Workout: I worked my ass off on this, it was extremely tedious, and it never went well. Ironically, flexibility was one of my biggest improvements. Balance...is another story.

Key results:
I will let the table below tell most of the numeric story. I accomplished just about everything I wanted using this program, i.e. I look better and feel better. I’m not quite sporting a 6-pack…but I’m sporting a 4-pack (and hey, some things come in 4-packs). The biggest surprises?

• Much skinnier legs and ass. Good gravy, I didn’t think my legs and butt were that fat. I lost about 2” per thigh and 2.5” off my hips. The bummer is that ab exercises began to hurt because of a massively skinnier pooper.
• Drastic improvement in ab and core exercises, and I only expect to get better at these.
• Massive improvement in flexibility. Before, I was about as flexible as a corpse post rigor-mortis, and my final reach test revealed a 350% improvement in reach (from 1” past toes 90 days ago to 4.5” past toes).
• Increased definition in upper legs, abs, arms, back and shoulders. No real improved definition in chest, and my calves may have gotten weaker.
• My wife bought me new clothes because she was sick of seeing my old ones hang off of me. I have gone from squeezing into a 34” waist to having a comfortably-fitting 32” waist for jeans. She also bought a couple shirts, and now I can fit into a large rather than an extra-large.
• If you push yourself in these workouts, your heart rate stays up (even in the resistance workouts).  A benefit that I found AFTER doing the program is that, when I hike, run hills, etc, my recovery period is much shorter than it used to be.  I attribute this all to P90X's workouts.

The only key result that frustrated me was my final fit test. I felt as though I had an off-day, and ended up messing up one of the tests (the wall squat) and didn’t do push-ups to failure. Oh well, I’ll do better next time…

I left out the reps but showed the % improvement...

I couldn't write everything that I'd like, but I hope this was helpful.  If you have any questions about the workout, please feel free to ask!