Chances are you’ve been told to “keep your muscles guessing” to see fitness results. Perhaps you heard it from a group instructor, an online training app, or on your social media feed. In fitness circles, “muscle confusion” is wildly popular.
The SAID principle goes hand-in-hand with another basic training principle… confusing. What does it actually mean? And is it real? Here, experts help us separate fact from fiction.
Is muscle confusion a real thing?
Spoiler alert: You can’t actually “confuse” your muscles, scientifically speaking.
“[Muscle confusion] is just a fancy marketing term for [exercise] variation, which personal trainers and exercise physiologists have been talking about forever,” says Tom Holland, C.S.C.S., exercise physiologist and author of The Mircro-Workout Plan.
The term was heavily featured in marketing for the fitness program P90X. (ICYMI: P90X was a popular workout program released in 2005 that had constantly changing high-intensity routines.) “I think that’s where a lot of people first heard [‘muscle confusion’], or where it became popular,” Holland says.
The idea behind P90X and similar programs is that continually introducing your muscles to new exercises keeps them guessing, so they’re always adapting—and your results never stall. But your muscles can’t actually get “confused.”
What actually happens when you lift a weight or run is your central nervous system (made up of the brain and spinal cord) fires electrical impulses that tell your muscles what to do. If that movement is unfamiliar, it takes your nervous system a little longer to send the signals that communicate with your muscles. But the more you practice an exercise, the better your nervous system is able to coordinate the movement, per a review.
“A beginner exerciser is ‘learning’ how to lift for weeks after beginning a strength training program, which is why they don’t see visible results right away but increase strength due to recruiting more muscle fibers, and recruiting these fibers faster over time,” Holland says.
So while “confusing” your muscles (or really, your central nervous system) may build strength in new ways, this doesn’t necessarily mean you need to change up the moves you do all the time to keep your nervous system guessing. (There are benefits to doing similar movements regularly but lifting heavier and heavier weights, for example). But it is one way to add variety to your workout.
Still, for Christopher Gagliardi, C.S.C.S., scientific education content manager at the American Council on Exercise (ACE), muscle confusion is another way of plainly explaining the often-complicated science behind muscular training. “The term ‘muscle confusion’ is used to describe the idea of adding constant variety to your exercise selection to create novel stimuli and enhance muscular adaptations,” he says. The idea is that by switching up your workouts, you progress your training so you avoid plateaus.
What are the benefits of switching up your workout á la confusing your muscles?
The principle of regularly changing your workouts How to Overcome Your Workout Plateau.
“We know that our muscles grow in response to the demands that we place on them,” Gagliardi says. This is known as the Specified Adaptations to Imposed Demands (SAID) principle, and the idea is, repeatedly exposing our bodies to exercise causes them to adapt and become more effective at handling it.
The SAID principle goes hand-in-hand with another basic training principle: progressive overload. What it means is that you must continuously modify different elements of your workouts (sets, reps, weight, exercises, pace, etc.) to increase the demands on your body, per the National Academy of Sports Medicine (NASM).
“I always say our bodies are really smart machines, they get better at what we ask them to do when we put stress upon them, and they react by getting stronger and getting better at it,” Holland says. “So we need to mix it up to continue to make adaptations.”
There’s an additional perk to switching up your workout—and it has nothing to do with performance or muscle gains.
For a study published in 2019 in PLOS One, researchers divided 19 healthy men with resistance training experience into two groups. One group performed the same strength routine (fixed exercises and repetition ranges) for eight weeks, while the other was given an app that delivered a random selection of exercises, so their routine varied each session. Still, both groups trained the same muscles and lifted approximately the same amount of weight four days per week, doing three sets of six exercises.
At the end of the study, all the men showed similar gains in muscular strength and size, regardless of whether they had stuck to the same routines or switched them up regularly. But there was one key difference between the groups: Those who tackled a new assortment of exercises each session reported feeling way more motivated to work out than those who repeated the same lineup.
Benefits of Lifting Light Weights fun factor by introducing variety and offering the challenge of learning a new movement or piece of equipment, notes Gagliardi, who was not involved in the study. Injecting fun into your workouts can make them more enjoyable, helping you stay consistent.
Are there any caveats to muscle confusion?
The Best Resistance Bands workouts helps spark adaptations that ultimately lead to results, but “variety” doesn’t involve choosing random exercises in the hopes of “shocking” your muscles to progress. In fact, too much change can have the opposite effect.
Picking new or random workouts every day or week doesn’t give your training structure, and without structure, it’s tough to challenge your body in the ways it needs to reach your goals or to see results.
You’ve heard the saying, “practice makes perfect?” The same applies to training. In fitness terms, this idea is known as the principle of specificity. As NASM defines it, the principle of specificity states that you only get better at something you perform regularly. That means, if you want to bench press a heavier weight, you must bench-press—a lot. And if you're aiming to build up your hamstrings for running, you must target them often and you can’t really accomplish that by doing random Instagram routines that don’t target these muscles.
“If you’re constantly changing your routine, how will you know if what you’re doing is working or which element of your program led to your desired goal?” Gagliardi asks.
To that extent, you need a balance between switching up your workouts and creating enough repetition that you see gains in the goals you’re chasing.
So how often should you switch up your workouts?
Switching up your routine is essential for progressing toward your goals and keeping your workouts feeling fresh. But when and how you vary your workouts isn’t one-size-fits-all.
“There’s an art to designing your program based on your goals and how frequently you’re working out,” Holland says.
If, for example, you’re trying to improve in a specific movement or exercise, it would behoove you to keep that exercise in your weekly rotation. “If I don’t do push-ups every week, I’m not going to get better at them,” Holland notes. Introduce variation by changing the reps and sets or by performing different versions of the exercise, like decline or incline push-ups or push-ups with renegade rows. published in 2019 in.
Similarly, if you’re training for an event, rehabbing an injury, or aiming to increase muscle strength or size, you’ll want to stick to the same overall routine for roughly four to six weeks, as that’s how long it typically takes to see results (for most people). In general, that means repeating exercises, sets, and reps but tweaking weight so you’re still being challenged. “The last few repetitions should be difficult without losing form,” Holland says.
Then, change your program (sets, reps, exercises) once you reach the end of a four-to-six-week training block.
On the other hand, maybe you get bored easily, and it keeps you from following through with an exercise routine, “then regularly switching up your exercise type may be a good idea,” Gagliardi says. You may benefit from workout-hopping: doing Pilates one week, kickboxing the next, and cycling the next—but maintaining a regular run and strength workout during those weeks. “However, we are looking [to make] specific demands in most cases,” Gagliardi adds.
Overall, you don’t want to keep doing the same exercises week after week and you don’t want to change every exercise you do every time you work out. Find the balance that works for you, based on your goals and what keeps you engaged.
Lauren Bedosky is a freelance health and fitness writer who specializes in covering running and strength training topics. She writes for a variety of national publications, including Runner’s World, Prevention, Experience Life and Women’s Running.
