“You must confuse your muscles to keep making progress”. “All you need is 5 barbell lifts to grow muscle and get stronger”. When jumping on the gain train, one will find themselves bombarded with claims that directly contradict each other, but are all presented as “the answer” to gains. Which one is it? Do we need to change the exercises we do on a regular basis or is it better to keep the same few exercises and rinse and repeat forever?

Overview

What did they test? The researchers looked at the current available scientific evidence on whether varying exercises has an effect on muscle hypertrophy and strength.
What did they find? Exercise variation can have both positive and negative effects on hypertrophy and strength, depending on how it’s applied.
What does it mean for you? Rather than viewing exercise variation as either “good” or “bad”, a systematic approach to exercise variation is your best bet. For hypertrophy, selecting exercises that allow you to fully target all regions of specific muscles (eg: leg extensions and squats for quads) will allow you to maximize growth. For strength, it may be better to carefully manage exercise variation for exercises that have a skill component to them (eg: squat), but varying other exercises will likely not negatively affect strength gains.

What’s the Problem?

When looking to gain muscle mass or strength, there is one variable that is non-negotiable: progressive overload. Making your exercise routine consistently a bit harder than previously is important to ensure that an adequate stimulus is presented to your body for it to adapt and become bigger and stronger. A well-designed resistance training program should continuously become slightly more challenging, something that can be achieved through manipulating a host of different training related variables (eg: weight, reps, sets). 

If you’ve ever had even the slightest chat about resistance training programming, you’ve probably heard the ol “you must confuse the muscles to keep making progress”, or at least variation of it. This concept was named “muscle confusion”, and was promoted quite a bit by “old school” bodybuilders (eg: Vince Gironda) who were basically treated like peer reviewed research since at the time there were virtually no  scienctific studies for strength and hypertrophy. 

The idea was that you intentionally changed the stimulus everytime your body got used to whatever training you were doing, by varying exercises, rep schemes, technique etc, in order to keep making progress. On a surface level, this makes intuitive sense and even holds some truth, as at the end of the day we want to keep making progress and avoid a muscle or strength growth plateau. Some of the early “muscle confusion” advocates and their followers would recommend that trainees switch their workouts up whenever they “felt” that training was not progressing, something that can be somewhat difficult for the average person to detect. And that’s the (ironically) very confusing issue with the concept of “muscle confusion”. A bad workout or a bad training week, or even a bad training month, are not necessarily signs of your body not making progress and could be explained by a ton of other non-training related factors (eg: high stress, inadequate nutrition, poor sleep etc).

In addition to “muscle confusion”, exercise variation has also been promoted as a potential strategy to support complete muscular development (eg: training different heads of specific muscles). Previous studies have shown that different exercises can result in muscular increases in different areas of a muscle but that can often be an issue of exercise selection itself as specific exercises can lead to gains in multiple regions of a muscle 1 2 3. When it comes to strength adaptations, the principle of specificity seems to point to exercise variation not being favorable for strength gains but some studies have actually found no difference between groups who varied their exercises and groups who kept the same exercises throughout a training intervention 4 5.

Contranstingly, you also have the other “extreme” where people claim that all you need to maximize hypertrophy and strength development is a handful of compound barbell lifts and that exercise variation is not just unnecessary, but may also be deleterious to one’s progress.

Although some evidence exists on the effect of exercise variation on strength and hypertrophy, the literature on exercise variation as a whole remains limited, an issue that is directly addressed by this recent systematic review by Kassiano et al who seeked to investigate whether varying resistance exercises promotes superior muscle hypertrophy and strength gains. Let’s dive in!