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

(Sometimes a reader will email me a question that needs a full article to answer properly, and sometimes it’s an answer I think many people will benefit from hearing. This is one of those times.)

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

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45 Comments

  1. David B says

    Now that you mentioned it, I think that you should publish a post with the questions from the emails you get and the answers you give!

    • says

      Not a bad idea. I’ve been thinking about doing some kind of real time “question & answer” type post where I try to answer a bunch of stuff in the comments, but this would work too.

  2. Brenda says

    I will put into practice those tips, I have the problem on lateral abs, obliques.
    One side is leaner than the other.

  3. Phil says

    I have a minor shoulder injury, which seems to be the culprit in my case as my lats, pecs & biceps on that side are all noticably less developed. ( I just thought it was because I was right handed). Will give these tips a try (and see an orthopaedic specialist).

  4. Luke says

    You should never lift on just one arm more to get the proportions right. Just start with your weak arm, then however many reps you do with it, do the same with your dominant arm. NEVER exceed those reps. As long as you match the rep amount with both arms the weak one will eventually catch up and be the same size. A lot of people make the mistake of doing the strong arm first then they can’t do the same amount with the weak arm, making their problem worse.

  5. don says

    I work my left arm alot more than the right, barely the right for the last 7 mos and it does no good right still bigger and alot stronger and i dont hardly work it…confused,disapointed i just dont understand why the left arm is crap to me…Why should you not work only one arm like i do?

  6. Al says

    Well i just learned sonething new reading your post.I had shoulder surgery about two years ago and just started working out again.When i do a shoulder work out it seems that the shoulder that i had surgery on gets all the pump and the other one dosnt get a pump at all and this pisses me right off thinking that the surgery side is the only side thats getting the workout.As much as i want to use heaver on my other shoulder i wont becouse then i will have a bigger problem.But what i leaned from your post is that i would start my workout with the stronger shoulder and couldnt finish with the same reps on the surgery shoulder and i want to thank u for your post it helps me lots.

  7. Stephen says

    Hi Jay,

    I am extremely inflexible. Meaning I can get my fingers to touch the top of my shin on a sit and reach. I’ve been told that the primary culprit is my long distance running (24km everyday for the last 2 years). It is problematic since it prevents me from executing squats at heavier loads with proper form. I’m currently doing SMR foam rolling weekly to try to loosen up my muscles.
    So my question is:
    1. What would be your recommended remedy for inflexibility, and
    2. How much of the tightness is due to running – steady state

    Thank you :-)

    • says

      Honestly, improving flexibility isn’t really something I have all that much experience with, so I’m probably not the best person to ask. Search around Eric Cressey’s site though, he has written plenty about this stuff… especially tight hamstrings.

  8. kay says

    Thank you so much for this post. Have recently started training seriously after nearly 20 years off!! I’ve noticed that my one arm/shoulder is much stronger and this is throwing me off balance. Never thought to check on flexibility but I have now and my weaker shoulder is far less mobile than my stronger shoulder. Thank you so much for this post as it really helps me find a way forward and I love the fact that you don’t respond to questions you feel you do not have an expertise in but redirect to someone who does. Thank you once again. xx

  9. Lucas says

    How would a beginner go about solving this problem?
    I am a beginner and have been following your beginners workout routine for 7 weeks now. Is this an issue I should try and fix now, or should I wait until I am an intermediate?

    • says

      Unless the imbalance is really significant, the average beginner with (for example) one arm slightly bigger/stronger than the other really just needs to start training correctly and get bigger/stronger overall. The problem will often correct itself or at least become less significant.

      If it’s still an issue once you reach intermediate levels, you can work on correcting it then.

  10. Ehsan says

    Thanks alot man, I have an experience of 3 times being forced to not move my left for long times due to clavicle surgerys (once for implementing the plate and once for removing it, totally near 4 months for both) and another 2 months for Cervical Bulge Disks recently happened, but now I’m coming back on the track! From one hand since I’m a right hand person by default, and from the other hand I have a total of 6 months immobility of my left hand in the past, my left hand+shoulder motor is a third of my right hand and its size is 4/5 ~ 5/6 of my right hand. BUUUUUT by readying aforementioned methods I’m going to change my exercises in my WR. and I’ll inform you of the result here.

    Once again thank you for your great advices!

  11. karla says

    Hey,

    So, I do squats and dead lifts with a barbell and then I do side leg lunges, curtsy lunges, and one leg squats with dumbbells. I have noticed that my left side is getting a lot more toned then my right, are you saying I do my squats and dead lifts with dumbbells it will help or that i should stick to the one leg exercises with dumbbells, the difference is really noticeable in my ass area and I really want to even out. PLEASE HELP!

    p.s I also have the same problem with my arms, my left is stronger. I figured it was because I was left handed..

    • says

      Squatting and deadlifting with dumbbells wouldn’t really help your problem, because both legs are still working bilaterally (although this would be useful for your arm training). However, exercises like lunges, split squats, single leg press and various other single leg exercises would be ideal for your problem.

    • says

      It wasn’t removed. All comments need to be manually approved by me, and I don’t do that until I’m ready to answer them. And I don’t always get the time to answer right away… or sometimes at all.

  12. Adam says

    I really enjoyed your post. I’m right handed, but have noticed that the left side of my chest is bigger/thicker/stronger than the right side. Do you have any specific suggestions for the chest? Thanks!

    • says

      A guess would be that your right arm might be your stronger arm, which means on your right side, your triceps (or shoulders) are doing more work than your chest, but on your left side, your chest is doing more work (thus your left pec is bigger).

      The stuff mentioned in this article would be the best place to start.

  13. Arnaud says

    Hi

    Any recommendation to fix chest muscle imbalance?

    I ve been doing db press instead of bench press.

    Should I isolate the smaller side?

    Thank you

    • says

      Depends on the specific cause of the imbalance. Using dumbbells instead of a barbell is a good place to start (assuming the issue is one side had been doing more of the work than the other).

  14. Danny says

    Pls i have a serious body imbalance that currently affecting my self confidence.(1) One of shoulder is out of position.
    (2) My right thigh is bigger than my left thigh.
    (3) One side of my chest is higher than the other.
    (4) My lower back is shifted a bit to one side.
    Please i will surely appreciate your response regarding how to solve this problem.
    I have already planned to engage myself in running exercise every evening.
    Thanks.

  15. jonas says

    hey great tips im an intermediate lifter and i have noticed that one chest is bigger than the other and one lat is smaller than the other, i have incorporated single arm exercises to try and fix the problem, when the muscles have even out, should i start to incoporate bilateral exercises back into my program or keep with the dumbbells and unilaterals ?

    • says

      You can try a combination of both (or switch between them every so often). If you find the problem is happening again, you’ll know you need to stick with unilateral exercises.

  16. a.j.killer says

    What is your take on rest times when doing unilateral stuff not simuntaneosly? So, I say I do bent over one arm DB row and the scheme is 3 sets of 8-10 with 90 seconds rest. If it takes me around 60-70 sec to complete a set, I then rest just 20-30 seconds. Obviously, each arm does get a prescribed 90 seconds between sets, but it cumulates fatigue since I am doing 6 intensive sets with such short breaks. What do you do and recommend?

    • says

      Depends on the exercise. Something like split squats I’ll take a full minute for sure, sometimes a little longer if needed.

      But something like single arm lateral raises or single arm triceps pushdowns? Just enough time to catch my breath and set up with the other arm.

  17. Zack Dimitri says

    Awesome Info man! Definitely going to try to keep these points in mind from now on.
    Also, Love the site! I tend to find myself more so on here than anywhere else these past couple months. keep up the awesome work man!

  18. Wildcat Football says

    Your website is amazing! I appreciate all the advice. I had surgery on my left knee 7 months ago. My left leg is now a lot smaller than my right leg. This week I started to implement unilateral leg excersices in my workout routine. For instance one leg lunges, leg press, step ups, Romanian dead lift etc. Do you reccomend that I workout the legs more than twice a week to even them in size the fastest way possible? Also will cardio benefit or hinder my goal to even them in size the fastest way possible? Such as the stationary bicycle.. Thanks again for all the useful information and good luck to you in all your future endeavors!

    • says

      The ideal training frequency for you at this point would depend mostly on what your doctors recommend as you return to training after surgery. You don’t want to jump back into things to hard with too much frequency.

      As for cardio, I don’t really see it helping or hurting in this case. Although excessive amounts of cardio can hinder overall weight training performance in general.

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