Why Is One Arm Bigger Than The Other? (Even Out Your Biceps)

Do you have an imbalance in your biceps or feel an imbalance between your arms? When you're bodybuilding, it's normal to have muscle imbalances in different parts of the body.

If you're struggling with one arm being bigger than the other, you might be slightly concerned with how you train arms.

This article will cover how this happens and what you can do to fix it.

There are several factors to consider if you have one arm bigger than the other arm, which is a common problem for bodybuilders.

However, muscle imbalances, especially one bicep bigger than the other, are relatively easy to fix and prevent in the future.

Here are a few factors that can contribute to having one arm bigger than the other or other imbalances with your arms.

man in gray t-shirt doing dumbbell bicep curls

1. Dominant Hand

We’ve all got a more dominant arm and dominant hand (strong arm). Hand dominance can involve your left hand or right hand.

Even if you’re ambidextrous, you will have a slightly bigger, more dominant arm and a weaker arm. The use of our more dominant arm can be seen throughout our day.

You will generally use your dominant hand to perform the majority of tasks.

We perform many small daily tasks, like packing a bag, brushing our teeth, or opening doors.

These actions are completely unnoticeable throughout the day, but these actions do compound after days, weeks, months, and years. This can cause imbalances in your arms.

This means that you’re training your dominant side more. So keep in mind dominance as it’s important to consider this when you train your dominant arm naturally.

You don’t want your right side way bigger than your left side.

2. Tendon Injury

Another possible reason you might have one arm bigger than the other or a weaker arm is because of a muscular or tendon issue.

If you’ve ever had a tendon injury that didn’t heal properly, it can affect how your arm looks when you flex it or give you a weaker arm.

Tendon injuries are pretty common and can happen during your daily routine. For example, carrying something heavy the wrong way can cause a tendon to snap fairly easily.

3. Bad Form When Training

When training any part of your body, you must use the correct form for every exercise. Cheating the movements while lifting weights might help you get an extra rep here and there.

But it will damage your muscles in the long run. You might compensate by using different muscles to take over the movement.

This is known as compensation. For example, if you start tired of dumbbell bicep curls, you might be tempted to use your shoulders and traps to help finish the exercise.

The same thing happens when one arm is stronger than the other. Your right arm might compensate for your left arm being weak.

This leads to the right arm being stronger than your left arm, making any asymmetrical difference even more noticeable.

4. Genetics

Your genetics often determines your body composition. Genetics affect how fat is transported to fatty tissues around your body, how you lose fat, and how your muscles are formed from your training.

It’s a simple reason for people having one arm or one leg bigger than the other. It can be the deciding factor because your larger arm will get more blood flow from bigger blood vessels.

There are also extra nerves going to that muscle on that side, so the muscle is more stimulated during exercise. These are reasons we don’t often think about for having a smaller arm.

5. Different Rep Ranges

If one arm is bigger than the other, then you may be able to do more reps of exercises with the bigger and stronger arm compared to your smaller arm.

If you’re doing unilateral exercises, you can focus on your muscles more and concentrate on the lifts. You should also do extra reps on the smaller, non-dominant arm to even things out.

Unilateral exercises are great for fixing muscle size imbalances and naturally letting your smaller arm catch up with your dominant arm.

man flexing his bicep in the mirror

What To Do If You Have One Arm Bigger Than The Other

Slow Down To Create Focused Movements

When trying to fix muscle imbalances, physics plays a crucial role in your training. If you're doing a pressing exercise with 40 pounds of weight, it can feel very different, depending on your lift speed.

Several factors contribute to these differences. The biggest one is momentum.

By slowing down and adding more torque, you can ensure that the muscle is doing the work rather than relying on momentum.

In addition, slowing down lifts ensures that you're targeting your muscles correctly and not compensating.

For example, you can slowly lower the barbell during a pressing exercise to focus on your form and explode back up.

Watch For Compensations

You should always be aware of your compensation. If you know that you cheat on a particular movement, then you can take actions to prevent it.

For example, if you’re using your back to take over during bicep curls, you can put your back against the wall for balance.

By doing so, you’re preventing your body from making swinging motions and using momentum. This transfers the movement from the biceps to the traps.

To analyze your movement, you can take a video of yourself or work with a personal trainer to help you identify some of the muscle differences in your movements and find a way to improve your form and increase muscle growth.

Training in front of a mirror is also a great way to analyze your form during bicep exercises. You can also use a tape measure to track the growth of your biceps.

Proper form is key to preventing injuries and muscle imbalances.

Ditch The Barbell & Try Unilateral Exercises

One of the best ways to even out biceps is to use unilateral movements and exercises, which means you work one arm at a time to isolate the biceps on each side.[1]

This will benefit your non-dominant hand.

So, you can switch the barbell for a pair of dumbbells and start doing single-arm bicep exercises.

Doing something like this can prevent your stronger arm from doing more work than your weaker one.

You can also try out different ways of training and do a few extra reps with the weaker arm to help build a lot more strength and muscle mass over time.

Many unilateral exercises can be performed with high loads or high training volumes to help you produce the kind of overall muscle gains you're searching for.[2]

Related Article - Barbells Vs Dumbbells

Use Resistance Bands

Using resistance bands instead of weight training for some exercises can also improve your balance on both arms. They target more muscle groups by creating more tension in your muscles.

When you do a curl with a dumbbell, you might notice that the weights seem lighter at the top of the movement.

However, with the resistance band, the more you stretch, the greater resistance you will feel.

At the top of the concentric part of the movement, you will feel a lot more resistance when you’re using the band, and the eccentric movement will become easier.

This is known as flipping or inverting the strength curve. It should help to balance out the size difference in your arms. It’s also a very suitable exercise for those looking for big arms.

Increase Volume & Intensity

If you have one arm bigger than the other, you'll need to pay extra attention to your weaker arm.

You should incorporate additional reps or use more weight for that arm in every set. And focus less on your other arm.

man in dark blue shirt doing a light dumbbell bicep curl

Exercises To Even Out Your Biceps In No Time

1. Single-Arm Preacher Curl

Single-arm dumbbell preacher curls are an exercise that concentrates on building the biceps, specifically the biceps peak.

It's a great exercise to increase arm size and to make both arms equal strength. Single-arm preacher curls can be completed with an underhand or overhand grip and on a preacher bench.

You can have your elbow resting on a bench specifically designed for these curls. Most gym-goers will go light on this exercise, performing for moderate to a high volume of reps.

Single-arm preacher curls are excellent for fixing muscle size differences and strengthening each arm separately. They’re a great alternative to barbell curls.

2. Single-Arm Reverse Cable Curl

The reverse cable curl is one of the best unilateral exercises that is often overlooked and underrated. Your starting position should be standing.

It’s best to start with light weight for this exercise. Unilateral exercises can be difficult for beginner and intermediate lifters but great for muscle mass.

See Related - Best Cable Exercises For Arms

3. Incline Dumbbell Curl

Incline dumbbell curls are great for targeting the long head of the bicep muscle. 

This increase in range of motion in this exercise sets it apart from many other curl variations you might be used to.

4. Concentration Curls

The concentration curl is a classic exercise for building the bicep muscles one arm at a time. They are the same movement as incline curls.

It can be performed from a starting position that's kneeling or bent over. However, it is more often done seated on a bench.

It's great for emphasizing the biceps peak, or short head, and is often used to finish a biceps workout. Like most curl variations, they are primarily performed with moderate to high rep ranges.

This is a great exercise to build muscle mass in your biceps.

5. Dumbbell Shoulder Press

Another popular exercise for building muscle and strength gains in your shoulders. Many lifters find two dumbbells easier to use for this lift than a barbell.

However, you can also use one dumbbell instead of two. Once you have chosen your equipment, you can lift the weights to your shoulders and press them over your head.

More Info - Best Compound Dumbbell Exercises

6. Lying Cable Curl

Laying down cable curls might seem like a weird exercise, but it can be a great way to prevent motion transfer and better target your biceps.

When performed unilaterally, this exercise can be very effective.

man in black shirt doing lying cable bicep curls

7. Alternating Dumbbell Curls

The alternating dumbbell curl is a single-joint exercise for building bigger and stronger biceps, one arm at a time. This is popular amongst all levels of lifters.

It can be done seated or standing. It’s an excellent exercise for arm-focused workouts and balancing out your arms.

8. Hammer Curls

This curl is performed simultaneously with dumbbells but without wrist supination. Hence its name is the “hammer curl,” like a carpenter hammering a nail.

Another great exercise to balance out your arms, especially if one arm is bigger than your other arm.

See Also - Hammer Curls Vs Bicep Curls

9. Overhead Tricep Extension

The cable overhead triceps extension uses a cable exercise performed in a seated or standing position.

While it hits all three heads of the triceps, the overhead position helps to target the long head in particular.

The seated position helps to avoid the use of momentum. It is usually performed to a moderate to a high amount of reps.

10. One Arm Lateral Raise

The single-arm lateral raise is another shoulder exercise that targets the upper arm, medial or middle head of the deltoid muscle.

It’s a great exercise to strengthen your weaker side and increase arm and shoulder muscle, especially if one arm is bigger than the other.

Just ensure you aim to get your upper arms tucked in once you lower the weights.

11. One Arm Bench Press

This is a variation of the classic barbell bench press.

The single-arm bench press is an upper-arm and chest exercise targeting the pectoral muscles, which involves unilateral movements of one arm and then the other.

Because balance can be an issue, this press variation is usually performed with lighter weight for moderate to high reps, such as 8-12 reps per set.

12. One Arm Dumbbell Row

The single-arm dumbbell row is a popular exercise for building the lats and back muscles. The bench is used to support the rowing motion.

It's a great exercise to eliminate poor strength in your weak arm and any back muscle size differences.

If you have uneven lats, this exercise can help you even out those imbalances.

Also Check Out - Best Compound Exercises For Arms

man in red shirt doing a single dumbbell row

Frequently Asked Questions About Uneven Biceps

How long does it take to fix uneven arms?

It takes roughly 2-4 weeks to fix a small muscle imbalance and 5-12 weeks to fix a larger imbalance. For most people, it takes about 3-4 weeks to get most muscle imbalances sorted. You could also consider getting corrective surgery in extreme cases.

Do muscle imbalances fix themselves?

You can work on building up the volume and total weight lifted with your weaker muscle group. Eventually, your muscles will balance themselves out. Increase the weight or reps for the stronger side once your weaker side has become the same size.

Can a physical therapist help with muscle imbalance?

If you’re experiencing muscle imbalance, you may be able to address it via targeted exercise. Consider working with a physical therapist. They can save you a lot of time and energy by diagnosing the problem and helping you with any imbalances you may have.

Do push-ups cause muscle imbalance?

If you do your push-up in the correct form, it shouldn’t cause muscle imbalance. However, it’s advisable to balance push-ups with a pull movement, like a pull-up.


Conclusion

To conclude, it’s perfectly natural for bodybuilders and gym-goers to develop one big arm faster.

You’re not alone; many people want to know how to even out their arms for a more balanced appearance.

The first step is identifying any underlying issues and being aware of your body and training.

You should use unilateral exercises to even out imbalances, it takes time, but muscle imbalances can generally be evened out.

We hope you found this article helpful and hope that it will help you achieve your fitness goals and symmetrical physique.

References: 

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4314602/
2. https://www.stack.com/a/study-finds-unilateral-exercises-significantly-strengthen-the-unused-side-of-the-body-too/

Last Updated on December 18, 2022