I was in the gym this weekend and I overheard two guys talking to each other about their workout routines. The conversation went something like this:

“Hey bro, what kinda workouts are you doing?”

“Oh man, I found this sick routine online from a fitness model, but you gotta work out two times every day and you do different workouts every single week.”

“Oh ya, why is that?”

“Muscle confusion. You know, you gotta switch stuff up all the time and keep the muscles guessing. Otherwise they’re not gonna grow.”

I cringed a little, turned up the volume on my headphones to avoid hearing the rest of the conversation, and wondered how even regular gym-goers could be so easily duped by such baseless broscience.

Muscle confusion is the idea that muscles quickly adapt to exercise routines, and therefore you need to “surprise” your muscles by constantly switching up your workout routine and incorporating different exercises.

I hate to break it to you, but your muscles are not “confused” by anything. You can’t trick your arms into growing because you decide to do a different type of bicep exercise than the one you did last week. There’s no scientific evidence to support this claim, and it just doesn’t make any logical sense.

How Muscles Actually Grow

Muscles only grow if they’re forced to grow. There is no reason for the body to generate more muscle tissue unless there is a sufficient stimulus.

By lifting heavy weights, you’re actually causing tiny tears in your muscle fibers called micro-tears. The body wants to repair these tears, as well as add additional muscle in order to adapt to the increased strength demands you’re putting on it through weight training. As long as it has enough nutritional resources to repair and adapt, you will see muscle growth. That’s why it’s true to say that muscle doesn’t grow in the gym, but when you’re resting.

I’ve said it before, and I’ll say it again now: striving to make incremental progress in the gym on a week-to-week basis is the most important thing you can do to initiate muscle growth. Overload your muscles with a new stimulus every week (whether it’s one more rep or a little more weight), cause new micro-tears in the muscles, and eat enough so your body can repair and adapt to the damage. That’s how your muscles grow.

Why Muscle Confusion Can Slow Down Your Progress

People who buy into the muscle confusion myth are changing their exercises all of the time. There’s a big problem that comes into play when you do this:

You cannot measure progress and aim for weekly improvements when you’re constantly changing your workouts.

Each week, you’re floundering. You’re doing an entirely new set of exercises, trying to figure out the appropriate amount of weight to start with for each exercise. You have no previous record that you’re trying to beat. You’re basically just blindly following a routine without purpose, hoping that it will create enough of a stimulus to initiate muscle growth.

It doesn’t have to be this way. Muscle growth can be much more scientific and consistent. Measuring your progress in a workout log shows you exactly how you performed the previous week, and then you can try to beat those numbers. Increase the stimulus, improve a little week by week (or sometimes a lot), and you will continue to grow.

One Thing Muscle Confusion Is Great For

You know, I’ve been hating on muscle confusion theory, but there’s one thing I really do have to give it credit for: making a whole lot of money from people who don’t know any better.

If you have to be changing routines all the time in order to see progress in the gym, then you’re always going to need a new routine to follow. And guess what? There are a whole lot of companies willing to sell them to you – bodybuilding magazines, fitness websites, fitness gurus, gyms, personal trainers, etc.

This is one of the reasons so many personal trainers are constantly changing up their clients’ workout plans. They’re creating an illusion of value because the clients are thinking, “Wow, my trainer is giving me a new workout every single week. I would never be able to work out like this without his help, it’s so complicated!” Unfortunately, a lot of these people don’t see results, but they continue to pay anyway.

Changing It Up

I want to be clear about something: I am not saying to never, ever change up your workout, and to only do the same few exercises forever and ever with no variation. Changing up your workouts is important for several reasons.

First of all, it’s boring to do the exact same workout over and over again. You need to keep yourself interested in working out so you always bring 100% to the gym. We’re humans, we like change, and switching up our workouts now and then can help us maintain the intensity needed to keep seeing results.

Also, different exercises for the same body part can more strongly activate certain muscles. Here’s a great example using the chin-up and the pull-up. In the December 2010 issue of the Journal of Strength and Conditioning Research, using EMG analysis, researchers found that both the chin-up and pull-up were initiated by the pectoralis major and the lower trapezius, and then completed by the biceps brachii and latissimus. But the chin-ups more strongly activated the pectoralis major and biceps brachii, whereas the pull-up more strongly activated the lower-trapezius. Pull-ups also tend to work the forearms more than chin-ups do.

Because exercise variations can more strongly activate different muscles, it’s important to switch up your exercises every so often in order to achieve balanced muscular development and to make sure you’re hitting all of your muscles regularly.

Conclusion

The theory of muscle confusion is an old gym myth that just don’t die. The concept is completely baseless and there’s no evidence at all to suggest that muscles are “confused” by doing different exercises. Stick with a proven set of exercises, work on getting stronger week after week, and switch up your workout routine every so often (say 4-6 weeks) to keep yourself interested and your development balanced.