What does the term "muscle confusion" really mean?.  First of all, if you are not familiar, this is the "science" behind P90X, and honestly it somehow comes into play in just about every other Beachbody workout, especially TurboFire and ChaLEAN Extreme.  Basically, with muscle confusion, you do a certain set of workouts that stimulate muscles in a specific way for 30 days, and then change it up.  This supposedly helps you bust through plateaus, because just as your body starts to adapt to the routine, you mix it up and instead of hitting the wall, you continue to see your muscles gain and your fat disappear.  

If you read that last sentence, I guess it makes sense, doesn't it?  It seems logical that you should change things up every month or so to avoid plateaus, but there is actually a scientific principle behind it as well, so it isn't just "infomercial science," it's actually a real thing that goes on in your body, and one of the reasons Beachbody just plain old WORKS and other knock-offs don't.

3 Types of Muscle Fibers
First of all, did you know your body has three different types of muscle fibers?  These are not "lean muscle" and "bulky muscle" as some people seem to think.  The term "lean muscle" basically means you don't have huge muscle, and you've burned enough fat to show them.  Another term for that might be "sexy shoulders" or "six pack abs," basically you've burned enough fat to reveal the muscular structure underneath!  There is no way to build a different brand of muscle, lean vs. bulky.  And on that note, women tend to have a hard time bulking up (which for most of you is a good thing!) anyway, since you have less testerone than male members of the species.  

But I digress...for a long time, exercise scientists catergorized muscle into two categories of fibers, Type I, or slow twitch fibers, and Type II, or fast twitch fibers.  In the most generic terms, slow twitch muscle is used for endurance and fast twitch muscle is used for speed and power.  Recently, type II was divided into two separate categories, type IIa and type IIax.  

Type I fibers are loaded with mitochondria.  If you remember from high school biology, mitochondria are those little "engines" that perform the Krebs cycle in our cells and create ATP, the body's energy molecule, by breaking down fat.  This process is also known as "aerobic" or "oxidative" because it can only be performed in the presence of oxygen.  But sometimes we have to react fast, or we have to get a huge burst of speed, and the  type I, slow twitch fibers, literally can't fire fast enough to get us moving.  It is because of this that type II fibers exist.  Type IIa are half oxidative and half anaerobic, which means part of the way these muscles fire is creating ATP anaerobically, typically by glycolysis (the breaking down of stored carbohydrate).  Finally, the type IIax fibers are only anaerobic, and are linked to the "fight or flight" response we have.  These can only fire in the presence of the enzyme creatine kinase, which creates a very limited supply of energy from the phosocreatine system, which might only last you a 10 second burst of speed.

When you train, you want to utilize the energy system that will access the muscle fiber type that is most related to your goals.  In general, over time the composition of your muscle fibers can change, but it is more natural for type II fibers to "convert" to type I fibers since this can occur by "adding" more mitochondria in the cells over time.  So for example, a bodybuilder wouldn't want to go for long slow runs, since that would be utilizing type I fibers.  Likewise, a marathon runner would probably not want to do Insanity every day since that primarily accesses type II fibers.

How Muscle Confusion Works
Now that you understand the composition of muscles, let's look at the first 30+ days of P90X.  In the first two weeks, the gains are all from neural stimulation.  The exercises, which focus on opposing muscle groups (chest and back, shoulders and arms, legs on Plyo and Legs and Back days), introduce your body to completely new muscle actions, and then allows you to recruit type IIax fibers for the first time.  Think about that first day of Chest and Back - ouch!  You've probably never done anything like that and your body is adjusting.  By week 3, you are finally lifting for hypertrophy.  Hypertrophy is the process when you create microtears on the muscle fibers, and then over time (days) they rebuild stronger and bigger.  You've probably noticed you can up your reps a little bit because neurally you have adapted, and that 3rd week is SO key in it's placement of the program because it might truly be the first time you see some real muscle gains from hypertrophy.

The body would naturally plateau around 3 or 4 weeks time, and that is when the whole process changes completely, to activate new muscle patterns.  In Phase II, with the new workouts, you basically go through a similar progression as with phase I.  The way P90X changes it up is creating a "pull" day (back and biceps) and  "push" day (chest/shoulder/triceps).  ChaLEAN Extreme changes it up by doing similar moves as month 1, but all with upped weights, basically doing all hypertrophy exercises where you exhaust by rep 8.  

Finally, in phase III, it's time to really bring it.  In P90X, the diet actually switches to a more athletic diet with higher carbs, and you are ready to hit it harder than ever.  I've told you before, studies have proven carbohydrates are as effective, or even more effective, in increasing athletic performance as a "pre-workout supplement" like creatine or NO boosters.  Every workout is a workout for hypertrophy, and you will see some major changes in your body in that third phase.  

The same exact formula exists in ChaLEAN Extreme.  A similar thing happens in Insanity; notice that the first phase is 4 weeks and just as you are about to plateau, they change it up and month II comes with all new, compound moves!  

So, perhaps, instead of muscle confusion, it's more like "muscle progression."  You teach the nerves, you awaken the type IIax fibers, and you over time shift your diet to a "performance" diet so that by phase III you get the results you want.  This isn't just for men, this is for women too.  The simple thing is that having more muscle on your body means you have a higher basal metabolic rate, and you burn more calories from just "being alive."    In EVERYTHING you should be striving for a higher percentage lean mass, which means higher percentage muscle to fat.  If you are spending your whole time on the elliptical or treadmill, you are likely only stimulating type I fibers, and you will plateau, without a shred of doubt in my mind.  

So for those of you asking me "what is muscle confusion" I hope this gives you a slightly better answer.  Now here comes the big question, have you seen the benefits of this yet?  The ONLY way to see the benefits of this is to be extremely consistent!!  If you mess up one week of P90X, or really any of these programs, you will likely not see the results you are hoping for.  That doesn't mean if you miss a day or two it's all over.  But let's say you dominate week 1 and 2 and then skip out for most of week 3.  You just missed the "hypertrophy" week, and you will actually take a step backwards as you go into a recovery week and then into phase II!  That is why it is SO important to be consistent.  You will still burn calories every time you workout, but if you want the workout to start working for YOU, you need to find it in yourself to stay with it, every day.

I sometimes get angry emails (I'm serious!) from people like "my workout DVD's didn't work!"  Or "I tried Shakeology and it didn't work!"  or "when am I going to see my results??"  I always ask, well how did you do?  99% of the time, the person has a bag with 20 servings left in it after a whole month, so obviously he didn't follow the program and replace a meal a day with it for 30 straight days.  Likewise, I get "well, I started off great, but really fell off the wagon in phase II and some of phase III...but the last 2 weeks I really brought it!"  Knowing what you know about how these programs work, you can see that certainly doing anything semi-consistently for 90 days, you will see some changes, but if you are looking for a TRANSFORMATION you have to be consistent for 90 days!!  Remember, YOU spent money on these programs and you made a decision, but step II of Beachbody's slogan is decide....COMMIT.....succeed.  A simpler and less marketable slogan for Beachbody should be:

Buy It.  Do it.  Flaunt it!!!!  Because if you actually DO it, you will get those results you want so bad!  That's kind of how everything in life is, isn't it?

So, if you haven't felt the benefits of muscle confusion yet, you are missing out!!  If you find yourself making excuses, remember that if you REALLY want your program to transform your body, you have to invest your time, put some "skin in the game," and really work for it too.