Muscle Imbalances: Is One Side, Arm or Leg Bigger or Stronger Than The Other?

Question: I’ve noticed that one of my arms (or legs, or any other muscle group) is a little bigger and stronger than the other. What can I do to fix this and make both sides equal in strength and size?

Answer: Having one side that is a little (or a lot) bigger or stronger than the other is actually a fairly common problem.

Usually it’s one arm or leg that tends to be a bit bigger and/or stronger than the other, but it can really be any muscle group.

Some people notice one shoulder or one side of their chest is bigger than the other, or that the barbell moves unevenly because one side is stronger and therefore moving the weight slightly faster than the other.

The cause of this can be any number of issues that are occurring in the gym or just within your regular day-to-day life. Whatever it is, let’s focus less on what caused it and more on how to correct it.

Here now are 4 common ways to fix muscle imbalances in strength and/or size…

1. Switch to dumbbell/unilateral exercises.

If one side is stronger than the other, that stronger side will quite much always take over during an exercise where both sides are being trained together.

For example, a barbell curl. If your right bicep is stronger than your left bicep, your right arm will always do more work during those curls than your left arm will.

You probably won’t even realize it either… it will just naturally happen.

The way around this is to start replacing your bilateral exercises (where both sides are used simultaneously, like a barbell curl) with unilateral exercises (where both sides are used individually, like a dumbbell curl).

I’ve actually mentioned this before as being one of the benefits of using dumbbells over barbells. It guarantees that each side will do an equal amount of work and eliminates the possibility of the stronger side “stealing” some work from the weaker side.

So, in this case you can replace barbell exercises with the dumbbell version of those same exercises, replace squats and leg presses with single leg presses and split squats, bilateral machines with unilateral machines, and so on.

2. Always start with the weaker side.

There’s a good reason why you have a muscle on one side that is bigger or stronger than the other side. Whether you realize it or not, you give that dominant side special treatment.

You know, it’s the side you use most often in your everyday activities. It’s the side you naturally go to when you need to hold, carry, move, lift, open or close something. And during your workouts, it’s probably the side you like to use first when doing a unilateral exercise.

The problem with that last part is that you are at your strongest and freshest with whatever side you use first, and you are at least slightly more fatigued with the side you use second. For this reason, whenever you do an exercise where you train each side individually, always start with your weaker side.

It’s the side that actually deserves the special treatment.

3. Let your weaker side dictate what your stronger side does.

When you follow the 2 steps mentioned above, you may notice that your stronger side is STILL your stronger side. Meaning, you may lift 50lbs for 10 reps on an exercise with your weak side, but then go on to lift 50lbs for 12 reps with your stronger side.

If you keep allowing that to happen, your weaker side will never catch up to your stronger side.

What you need to do instead is let your weaker side dictate what you allow your stronger side to do. So, if you can only do 10 reps with your weaker side, then you should only do 10 reps with your stronger side… even if you could have done more.

Doing this will give your weak side a chance to finally catch up to your strong side, at which point you can allow both sides to progress equally from that point on.

4. Solve the underlying problem.

In many cases, people just have a dominant, stronger side that just ends up doing more of the work in the gym and in everyday life in general. As a result, muscle strength and size imbalances are created over time.

In cases like this, any and all of the methods mentioned above will usually help fix the problem.

However, there are other cases where underlying issues are at play that not only cause these muscle imbalances in the first place, but prevent them from being corrected using the aforementioned methods.

For example, there might just be an issue with flexibility or mobility that is preventing you from training both sides evenly. Maybe one side is tighter than the other and it’s keeping that side from doing what it should be doing during various exercises.

In a case like this, changes may need to be made to the way you train or warm up to fix this and prevent more serious injury-related problems from arising in the future.

In my personal experience, I’ve found that I benefit from doing some additional hamstring stretching before most leg workouts, and I definitely need to do a thorough shoulder mobility warm up before all upper body workouts.

So, my advice would be to try the 3 methods described above and see if that gradually helps improve your size/strength imbalance over time. If it does, awesome!

If it does not, it’s likely that something like this is the true culprit and you need to dedicate some special attention towards fixing it.