The Truth About Muscle Confusion Training

by Tom Venuto

The muscle confusion theory says that by changing your workouts constantly, your body can’t adapt to the workouts or that the new exercises will “shock” your muscles into new growth. This concept has been back in the spotlight recently largely because an infomercial fitness trainer, Tony Horton, has been promoting it as the basis for his wildly popular exercise program called P90X. As a result, I’ve been getting tons of questions about this “new” muscle confusion technique.

But muscle confusion isn’t a new idea – it goes back decades in the bodybuilding world.

I have bodybuilding books by Joe Weider from the early 1980s that discuss the muscle confusion training principle.

Weider, the former Muscle and Fitness Magazine publisher and bodybuilding promoter, was famous for cataloguing (and putting his name on) every weight training technique in the book. He called it the Weider System, and his “Weider principles,” including the muscle confusion principle, date as far back as far as the 1960’s.

Controversy over the Muscle Confusion Principle

I’ve seen all kind of criticisms of muscle confusion – articles calling it a myth, forum posts dismissing it as “bull” and even video parodies on you tube. I’ve heard respected trainers and exercise physiologists saying things like, “a muscle doesn’t have a brain so saying that it can get confused is idiotic.”

In fact, I’ve heard pretty much nothing BUT criticism lately.

The critics continue by saying that the best results come from sticking with a routine, not hopping from one program to the next.

In addressing these criticisms, I should first agree that “muscle confusion” is not a scientific term and I’ll also concede to the ambiguous nature of the phrase, leaving it open to misinterpretation.

There’s no doubt that consistency and progressive overload are important components of a strength training program, especially for beginners who haven’t built a foundation yet.

Furthermore, the idea that simply changing your workout alone is enough to stimulate muscle growth, greater strength or an increase in fitness is not true in all cases. What if you change your workout to something that’s substantially less intense or less of a physical challenge than what you’re doing now? That’s a step backwards isn’t it?

Change alone usually isn’t enough. There are certain thresholds that must be crossed before you can stimulate strength and muscular growth and not only that, it must be approached in a progressive and systematic fashion.

However, I think it’s unwise to dismiss the muscle confusion concept outright without taking a closer look at what it really means and clearing up some of the semantics and definitions.

Support for the Muscle Confusion principle

Even though there are some valid criticisms (depending largely on how you define it), muscle confusion is not only a legitimate technique, it’s a foundational principle of all effective training programs.

Consistency in training is important, but think about this: should your leg workouts consist of nothing but barbell back squats forever, never changing the exercise, and never changing the rep ranges; the only thing you ever do is try to slap more weight on the bar? Is this lack of variety really an intelligent approach?

I don’t know any trainer worth his salt who wouldn’t say that changing some program variables – at least every so many weeks – would improve the results. This is called periodization, also known as cycle training.

Numerous studies published in exercise science, sports conditioning and physiology journals have found that the pre-planned variation of acute program variables is more effective at producing strength and lean body mass improvements than non periodized programs.

The periodization concept is based on Selye’s general adaptation syndrome which states that systems will adapt to any stresses they experience in an attempt to better meet those demands in the future. Training is a stress and at first it’s a shock to the body. The body adapts by becoming stronger and more muscular.

But after a certain amount of exposure to a stress, your neuromuscular system adapts and there’s no further improvement unless a greater stress is applied. This usually means increasing the amount of weight lifted, but a change in exercise selection, number of repetitions or other program variables can also represent a new stressor and trigger new adaptations.

The difference between periodization and muscle confusion is that periodization implies planned variation, where the workouts change when the time is right, sometimes frequently, but the changes are meticulously planned in advance.

Muscle confusion implies random variation, where you might go into the gym with no plan and just do something different every time – whatever you feel like doing. This goes hand in hand with “Instinctive training” (another controversial principle which could be the subject of a separate article).

Change – the only constant?

When you look at program change as a planned and organized process, designed to “outsmart” the body’s adaptive nature, you can realize that there’s nothing controversial about it – continuous change is a critical part of program design. The real questions are:

1. Should all changes be pre planned as part of a long term strategy, or is it beneficial to make frequent program changes at random?
2. How often should you change your exercises and acute training variables?

With traditional training protocols, you might change your workouts every 4, 6, 8, or 12 weeks. With muscle confusion, you might change training variables more often – even at every workout.

Muscle confusion often implies that the changes are done randomly and that all the exercises may change. The downside of random variation is that if you change your workouts every session haphazardly, you may lose the progression element that’s so important for those early foundational gains. Your workouts need to have some kind of continuity where each workout builds on the last one.

On the other hand, your plan has to be flexible at times. Let’s suppose you go to the gym and you feel a little twinge in your lower back. You might decide you want to change your plan for heavy back squats and make it a lighter squat day, or you might do leg presses instead, just to play it safe. That’s a spur of the moment program change and you could call that instinctive training. This is an intelligent use of “instinct”, not some bodybuilding myth.

I actually find it very funny that certain groups of training experts criticize the decades-old bodybuilding terminology like muscle confusion and say the concept is “a bunch of bull,” and yet they use amazingly complex periodization programs where the workouts vary all the time! The changes are simply very well planned.

These same highly analytical people may also criticize the bodybuilding term, “instinctive training principle” yet they use a technique called “cybernetic periodization.” That’s a fancy way of saying if you go to the gym and something feels “off” you change your workout spontaneously. Excuse me, but isn’t that instinctive training?

Alas, these “sophisticated” science-minded trainees don’t want to use bodybuilding lingo so they coin a proper scientific term for the same thing bodybuilders were already doing.

Frequency of program change

It’s standard practice and highly beneficial to change workout programs at least every few months or even as often as every 4 weeks. After weeks or months on the same exercise, you will often plateau in strength, muscle development and interest/motivation. At that point, a change alone can often stimulate new progress.

For example, you might switch from back squats to front squats, leg presses or lunges. On changing the exercise, you may notice a renewed spurt of muscle development, and a progression cycle is introduced once again on the new exercise, whereas you were flat-lined on the old exercise.

If your goal is to keep back squatting and adding weight to the bar at every workout, you’ll soon be frustrated to discover that you can’t add weight forever, you always plateau eventually.

It’s counter-productive to get stuck on the idea that the only thing you need to do is basic exercises with heavy weight and lift more weight forever. That’s an attitude among certain training factions that will eventually lead its followers to plateaus, burnout and injuries, especially as you get older.

When you’re 20 years old, you can hit it hard and heavy all the time, it seems, with no repercussions. Do that for 20 more years and see what your joints feel like. Take my word for it – your body can’t take a non stop pounding.

At some point, after you’ve established a nice foundation of strength and muscle size, your training approach has to mature as you mature. You need to find other ways to apply progressive overload than just progressive resistance.

Progressive resistance vs progressive overload

The need for progressive overload is an indisputable principle. However, most people don’t realize that progressive resistance (ie, adding weight) is not the only way to do it. The idea behind muscle confusion is that a change in your workout can actually be a form of overload or at least it can optimize the effectiveness of overload by developing different aspects of the muscular and nervous systems and by improving recovery.

The beginner needs to build their foundation on the basics and that means sticking with the basic exercises and progressive resistance longer before making a change to a new routine. Changing the workouts every day is not necessary for beginners. The more years you’ve been training, the more advanced you are and the closer you get to your genetic potential, the faster you adapt and the more you’ll benefit from periodization and frequent training changes (aka muscle confusion).

In fact, if someone has been training for many years, the frequency of change and the complexity of the workouts needs to increase dramatically to continue to make gains. The linear periodization model just doesn’t work well anymore. Advanced trainees can adapt to an exercise in as few as 3-4 exposures. After that, something needs to change. It doesn’t have to be the entire workout, but at least part of the workout must change.

Which training variables should you change?

Variation doesn’t just mean changing exercises. In fact, most strength coaches agree that you’ll adapt to the repetition range faster than you’ll adapt to the exercise.

For example, it’s wise to spend a lot of time working on squats, but why do 8-12 reps at every squat workout? Why not do workout A which might be 6-10 reps and then workout B that’s 15-20 reps? You might even use three repetition brackets – heavy, medium and light. From a muscle building and bodybuilding point of view, I’ll place my bet on the workout which has variation in rep ranges over a single rep range every time.

The research says that daily changes are better for strength increases too. A study out of Arizona State University published in the Journal of Strength and Conditioning Research found that making program alterations on a daily basis was more effective at producing strength gains than making changes every 4 weeks. The exercises stayed the same but the repetition ranges and intensity rotated at every workout. This method is known as undulating periodization.

Another application of this concept might have you staying on the same exercise, but changing how you perform it: switch the grip, hand position, foot position, stance width, type of bar/attachment, tempo, mechanical advantage, number of sets or range of motion. You might utilize techniques such as extended sets, supersets or drop sets. The list is endless.

Random change (aka “confusion”) – good or bad idea?

Now that we’re clear about the importance of change and the difference between random change and planned change, here’s the last big question: Is there any benefit to random change at every workout, which is “muscle confusion” in the truest sense of the term?

Progressive overload and continuity are important in any training program. However, you could make a strong argument that an advanced trainee who adapts very quickly to any workout, especially a bodybuilder who wants to develop every aspect of his physique, would benefit greatly from frequent change to the point of daily variation.

If you do something different that you’ve never done before, you could certainly achieve new muscular development from that, provided there was enough tension and resistance on the muscle. You could say that the fact that you’ve never done it before is actually a form of overload itself (a “shock” to the body, as muscle confusion implies).

However, ideally, program changes aren’t made randomly. It’s a bad idea to go into the gym without knowing what you’ll be doing when you get there. Even if you’re an advanced trainee changing some of your training variables at every workout, those changes should be planned in advance. This lets you mentally prepare yourself and have a goal for when you walk into the gym.


Changing exercises, rep ranges and other acute training variables on a regular basis, sometimes even daily – is an accepted part of periodization and training science. Using a wide variety of exercises is especially important for bodybuilders who need to develop every aspect of their physiques. Frequent change of training variables is even more important as your training age increases and your body adapts faster.

Staying with entirely the same exercises and training variables for months and years on end, using only progressive poundage as the sole method of overload is almost a guaranteed way for you to hit a plateau and eventually get injured.

And let’s not forget that other benefit of mixing it up: Avoiding boredom. If you’re bored to death with your workout, it’s likely that you won’t perform at your maximum capacity.

It’s understandable why muscle confusion has been controversial and even made fun of. But I think the debate has been caused by misunderstandings about the accepted definition of the principle. You might not choose to call it “muscle confusion,” you might call it “undulating periodization” or “planned variation.” But by all means, mix it up and change your workouts regularly for best results, simply do it in a planned and intelligent fashion – never wing it.

The TNB training program uses planned variation and periodization in all the weight training programs. This workout system is included with the Holy Grail Body Transformation program as part of an integrated nutrition and training system. Visit the holy grail home page to learn more.

P.S. By the way, no offense to people who love P90X, but “muscle confusion” or workout variation has absolutely ZERO to do with getting ripped. If you want to get super lean, it’s about the calorie deficit and dialing in your nutrition – check out Burn the Fat, Feed the Muscle if you want to get ripped the way bodybuilders and fitness models do:

About Fitness Author and Fat Loss Coach, Tom Venuto

Tom Venuto is the author of the #1 best seller, Burn the Fat, Feed the Muscle: Fat Burning Secrets of the World’s Best Bodybuilders and Fitness Models. Tom is a lifetime natural bodybuilder and fat loss expert who achieved an astonishing ripped 3.7% body fat level without drugs or supplements. Discover how to increase your metabolism, burn stubborn body fat and find out which foods burn fat and which foods turn to fat by visiting the home page at:


Prestes, J. et al, Comparison between linear and daily undulating periodized resistance training to increase strength. Journal of Strength and Conditioning Research, 23(9) 2437-2442. 2009. University of Kassel, Germany.

Rhea M, et all, A comparison of linear and daily undulating periodized programs with equated volume and intensity for strength. Journal of Strength and Conditioning Research, 16:2, 250-255. 2002. Arizona State University.

Selye H. Stress Without Distress. JB LIppincott, New York, 1974.

Fleck, SJ. Periodized strength training: A critical review. Journal of Strength and Conditioning Research. 13: 82-89. 1999. Sports Science Department, Colorado College.