The BeachBody P90X workouts are broken down by individual DVD, and each works a different set of muscles.
Here's how it breaks down.
For weeks 1 - 3
Day 1: Chest & Back plus Ab Ripper X
Chest and back workout consists of a variety of pushups and pullups and some light barbell work ( whatever you can do 12 - 20 reps with ). The video is approximately an hour, with about five minutes of warm up ( running in place, stretching, etc ) and a cool down at the end ( more of the same ). Each excericse on the video takes between 30 second to a minute and half to complete. With a short break in between. Even though the X in P90X stands for extreme - the workouts themselves are very basic, its just the fact that you are keeping your heart rate up the entire time that makes it "extreme". The video's even encourage you to take a longer break if necessary in between, but I think maintaining the cardio is what really helps you burn off calories while building muscle.
Ab Ripper X is not as bad as it sounds. About 16 minutes of ab workout with a variety of situps and twists.
Day 2: Plyometrics
This is all cardio. By far the hardest video of the bunch, and the one I think most people don't complete the first time through. Lots of stuff like jumping jacks, hops, lunges, and so on, at a steady pace. I think the P90X book estimates you will burn off about 600 calories during the workout. I totally believe it. It's also the only workout in the first three weeks that lasts longer than one hour.
Day 3: Shoulders & Arms, Ab Ripper X
Arm Curls and Chin Up variations. Save as day one, just focusing on different primary muscle group. Barbells with weight you can do 12 to 20 times. Again, nothing fancy, just a steady pace that keeps you working and keeps your cardio up.
Day 4: Yoga X
Never thought I would sweat during Yoga. But never realized how much it takes to balance and hold some of those positions. But by day 4 the stretching is just amazing.
Day 5: Legs & Back, Ab Ripper X
All basic stuff again for the legs. Lunges, wall squats ( leaning against the wall in a chair position and holding the position till you get the 'burn'), really basic stuff. More pullups for the back and shoulders.
Day 6: Kenpo X
To me, the best workout of the bunch. All punches, blocks and kicks. Steady pace to keep up cardio.
Day 7: Rest or do the X Stretch video
At the end of the first three weeks, you change up for week 4:
Day 1: Yoga X
Day 2: Core Synergistics ( core workout )
Day 3: Kenpo X
Day 4: Stretch
Day 5: Core Synergistics
Day 6: Yoga X
Day 7: Rest or X Stretch
Weeks 5-7 it changes up again with some new workouts.
Day 1: Chest, Shoulders & Triceps, Ab Ripper X
( and so on )
According to Tony Horton, the point is to create "Extreme Muscle Confusion" so you don't just hit a plateau. It also keeps it from getting boring since you're not doing the same video every day.
All the workouts except Plymetrics run just about 1 hour. You pick the time of day you want to do the workout, and just try to stick to the same schedule.
Click here to see more about P90X at the site: P90X.com
