Algebra, Tinder matches, the New York subway system. These are things that can be confusing. But muscles? Can they get confused? That's the gist of the trendy workout term "muscle confusion."
But it's not a term you'll find in an exercise science textbook. "Muscle confusion is a fitness buzzword for a workout routine that is supposedly better than all other workout routines... but no one really knows what it means," says Kristian Flores, CSCS.
That's why we put together this muscle confusion cheat sheet. Scroll down to learn where this term came from, how it applies to workouts and if it's actually legit.
What Does Muscle Confusion Even Mean?
Popularized by boutique fitness culture and P90X trainer Tony Horton, there's not one widely accepted definition of muscle confusion. But generally, it refers to the premise that constantly switching up your workouts — and as a result, "confusing" your muscles — is the fast way to gains.
"The hypothesis says that by constantly varying the stimulus of your training, your muscles never get acclimated, and you continuously make progress," Flores says. Because doing the exact same workout over and over and over again can lead to halted progress, it makes sense that this type of training has gained traction.
But Does Muscle Confusion Work?
While muscle confusion sounds like a pretty legit way to dodge a plateau, you'd be hard pressed to find a certified trainer or fitness coach who'd sign off on this being the best approach to meeting any fitness goal (unless your goal is to try every workout class in your city).
For starters, "your muscles can't get confused, they don't have a brain," says Carol Ferkovic Mack, CSCS, owner of CLE Sports PT & Performance in Cleveland, Ohio, who says the phrase itself is confusing. "Because your muscles can't actually get confused, there's no objective way to measure exactly how confused they are."
Second, "muscle confusion" is in complete contrast with the long-established Specific Adaptations to Imposed Demands (SAID) principle. Basically, "the body makes training gains based on what it does over and over again," Mack says. That means consistently working toward one fitness goal (for example, building strength, improving mobility or increasing cardiovascular fitness) is the faster way to reach it, she says.
Let's say, for instance, you want to run a marathon. You shouldn't train for it by going to spin class every other day. The best way to prepare yourself is by running. Or if you wanted to get better at push-ups, you would have to do a certain amount of them each week and not, say, squats.
"There may be some carryover between activities," Flores says, but you'd benefit from being a little less random in your approach.
Muscle Confusion vs. Progressive Overload
Despite what this fitness buzzword implies, muscles respond very predictably to exercise. "Your muscles get stronger when you continuously challenge them by varying things like the amount of weight lifted, the intensity of the workout or rest time between moves, or the duration," Mack says.
At first glance, this may sound like muscle confusion, but it's actually an approach to strength training called "progressive overload." Unlike muscle confusion, which usually entails mixing up your workouts at random, progressive overload involves intentionally altering specific factors within a workout — weight, intensity, reps, sets, rest time — in accordance with a specific exercise program.
The goal of progressive overload, according to Mack, is to challenge (not confuse) your muscles as efficiently as possible in order to avoid plateau.
"Even programs like CrossFit — which preaches 'constantly varied movements' as its cornerstone — don't throw random workouts at participants," Mack says. The movements may be different every workout, but they're thoughtfully chosen and put into a program that will make an athlete fitter. "Progressive overload is the principal at play here, not muscle confusion."
The One Thing Muscle Confusion Can Help With
You might be wondering why "muscle confusion" has maintained traction — given that there's another, more effective training method out there. The answer is that while progressive overload can be boring, muscle confusion is comparatively less boring.
In fact, a January 2020 piece in the New York Times reports on a small December 2019 study in the journal PLOS One, using it to suggest that because "muscle confusion" is less boring, it may be more effective.
For the study, researchers split 19 men with strength-training backgrounds into two groups. Half were put on an 8-week plan that entailed completing the same exercises in the same order every week. The other half completed the same exercises and lifted approximately the same amount of weight as the other group, but varied the order, completing the movements based on a randomized computer app.
At the end of the study, both groups showed similar strength gains, but the group with exercise variety reported more motivation to work out. Brad Schoenfeld, an associate professor of exercise science at Lehman College in New York and a co-author of the study, concluded, "The differences in motivation scores at the end were substantial [...] From a purely motivational standpoint, variety matters."
The New York Times article uses this to suggest that "muscle confusion" has its benefits — especially for the unmotivated.
But here's where it get's tricky: The study is measuring the effects of varying the order of exercises from week to week. Which, according to the most pervasive definition of the made-up fitness term, is not "muscle confusion," but actually, progressive overload.
Generally, "muscle confusion" is about varying the type of workout (strength training, Pilates, yoga, running, etc.) day to day and week to week, not about changing the order of different strength-based moves like leg presses, squats and deadlifts on leg day from week to week (which, again, is what the study participants were doing).
So, can "muscle confusion" lead to increased motivation? If you're somebody who gets easily bored at the gym and are more likely to exercise if you get to do a completely different workout every time you go, then yes, "muscle confusion" (in this case, workout variety), may be motivating.
As Mack says, "If you have a general fitness goal or get bored easily with your workouts, doing a completely different workout every day is perfectly fine. But, if you have specific goals for improving strength, fitness, mobility or losing weight, muscle confusion is just not going to be as effective."
Read more: 6 Moves Every Workout Routine Should Include
How to Actually Overcome a Weight-Loss Plateau
What the NYT article is really arguing, and what science and sports and conditioning experts can get behind, is that variation within your workouts is beneficial to both gains and motivation.
As Flores says, "Variation — for instance variation in the movement order, reps or weight — is necessary to get you closer to the specific fitness goal you're working toward." That's not usually how "muscle confusion" is defined, he says. That's how progressive overload is defined. Whatever nomenclature you attach to it, (intentional) variation is essential to continuous growth.
Honing in on other non-fitness factors can play a role, too. "Sleep quality, nutrition habits, stress and your workout regimen can all contribute to weight loss and strength plateaus," says Mack, who recommends anyone who's hit a plateau take a look at lifestyle factors that could be contributing to the stall.
But, she says, "If your workout schedule has no consistency or structure, adding that in can help you break through it."
Both she and Flores recommend working with a trainer who will be able to write you a progressive overload program with intentional variation based on your specific goal.
"In my opinion, just as you shouldn't give yourself a root canal or build your own house, you shouldn't program your own exercise routine. Especially if you actually want to have success," Flores says.