Left arm bigger than right arm? (How to fix this)

left arm bigger than right arm

Left arm bigger than right arm?

This is very common and anyone who trains with weights, one part of their body is somewhat dominated by the other. But if one part of your body is starting to get significantly bigger/stronger than the other (whether it’s biceps, triceps or any one of the sides of your chest or lats), I’ll show you how to fix it in 2 simple steps…

Do you have a left biceps that is noticeably smaller than the right? Is your chest quite developed on one side? Find out how to fix it

Everyone’s got them. Sometimes you notice them, sometimes you don’t. But there is nothing strange in one side being smaller or less developed than the other!

This can happen for a number of reasons, including genetics, low circulation or infection (which is basically the number of nerves going to the muscles), smaller muscles, previous injuries, or even small physical differences.

The following techniques will help you work out those body parts once and forever!

Many techniques work by increasing the amount of training, some work by increasing resistance, while others work by targeting the specific physiological cause of the difference.

If you have a bicep bigger than the other, you’re not alone. Here’s what causes this phenomenon and how you can fix it.

Is it normal to have the left arm bigger than right arm?

You may have one eye that is a little bigger than the other or a leg that is slightly longer. Sure, it’s normal to have one biceps bigger than the other.

When it comes to muscle size, the asymmetry is more noticeable. The main reason for the disparity in muscle size is that we are paying attention and tracking progress. However, there are preventable factors that can influence the variance and become more pronounced with the passage of time.

Why is left arm bigger than right arm?

There are a few reasons why one biceps may be bigger than the other. Three common causes include natural dominance, inherent injuries and improper training form.

  1. Dominant hand

One of the major reasons why one arm might be bigger than the other is in relation to your dominant hand. Throughout the day, you use your dominant hand for more tasks than your non-dominant hand. Those daily tasks of carrying groceries or lifting things off the floor add up over time. Your dominant arm muscles naturally get more exercise, leading to a difference in size.

  1. Tendon Injury

Another reason you may be experiencing an imbalance in the size of the biceps is an underlying injury. If you have a muscle or tendon problem that hasn’t healed properly, it can affect how your bicep looks when flexing.

Tendon injuries are not uncommon and can occur during seemingly mundane exercises. Overtraining or incorrect form can cause the biceps tendon to snap with relative ease.

When your biceps injury heals without corrective surgery, it often realigns in the wrong place causing a bulge appearance. As a result, the bicep looks much smaller than its counterpart.

  1. Cheating Movements

Working with proper form has a significant impact during training.  You may be cheating and using other body parts to assist in the movement there by allowing other body parts to pick up the slack without even realizing it. When muscles other than the one you’re targeting takes over, it’s known as compensation.

Also, in terms of one hand being stronger than the other. For example, if your right hand is stronger than the left, your right hand will compensate for the weakness of the left arm and will bear the load. As a result, the stronger hand will continue to get stronger, making the difference more noticeable.

What to do if the left arm bigger than right arm than the other?

  1. Know Your Compensation

First, it’s essential to be in tune with your body and be aware of your compensation. If you know that you cheat the movement and keep your back occupied during hammer curls, you can lean against a wall for balance.

Use self-recorded videos or work with a coach to help identify imbalances and create opportunities for improvement. Training in front of a mirror can also be helpful during biceps exercises.

  1. Use Unilateral Exercises

One way to correct muscle imbalance is by doing unilateral exercises, working each arm individually to properly isolate them. Swap your barbell curls for dumbbell curls and use more single-arm bicep exercises.

By adopting this approach, you will prevent your stronger arm from picking up the the slack of your weaker hand. You can also vary your training and do a few extra reps on the weaker arm to help build strength and muscle over time.

Whether it’s the barbell bench press, military press or barbell curl, that dominant side can often bear the brunt of the load. So, if one part of your body has become so dominant that it is affecting your ability to perform your exercise properly… put all your focus on unilateral movements.

This goes for machines as well. Skip any machine exercise where both hands work together to move the weight stack and focus only on unilateral machine exercises.

If you do straight bar cable curls regularly, start by doing them with a single handle with one hand at a time. If you do straight bar Lat pulldowns, look for a machine with independent handles. you get the idea.

             3. Start with the weak arm first

This phase now involves starting with the weak arm and not doing any other reps with the strong arm. Let’s use an alternating dumbbell curl as an example, assuming that your left arm is the weak side…

You’ll start by swinging the dumbbell with your left hand for your first rep. You will then do your second rep with the stronger hand. You keep going back and forth in turn. When you start to notice your weaker arm is hitting muscle failure, you can then match that rep with your stronger arm.

So, if you barely squeezed that 7th rep with your left hand, you would perform the 7th rep with your stronger hand and then stop, no matter how much extra strength you had in your right arm.

Example of this would be the one arm triceps push-down. You will do your first set with your left hand. If you hit a muscle failure after 6 reps, you’ll do your second set with the right arm and stop at 6 reps as well. Even if you can do 3 more with the right arm, you’ll still stop at 6 reps.

By using this method your weaker arm gets more stimulation while getting close to failure, while resisting with the stronger arm. It basically allows you to maintain shape/strength in your dominant side while still allowing you to hold the weaker side.

          4. Targeted negative

Finish each body part workout with a set of negative training for the weaker side part.

One of my favorite ways to do negative training for biceps is by using the preacher bench. The bench allows you to stabilize your upper arm more effectively than it can stand.

This technique will help build strength in the target muscles, thereby helping to overcome innervation problems caused by lagging development.

          5. Targeted High Rep Training

Begin the workout of each body part with a light, high-rep set for the weaker side muscles. For example, for a small or weak right tricep, start each triceps workout with a set of high-rep single-arm pushdowns. High-reps in this case means 50+ reps.

This very high rep set will help increase circulation to the target muscle, improving the ability to gain mass. This increase in circulation means more available blood, which means more nutrients get to the muscles, which means more muscle growth!

Exercise To Do When the left arm bigger is than right arm

  1. Concentration Curl

left arm bigger than right arm

How to do it:
  • Sit on a bench with your feet firmly on the ground. Keeping your elbows resting on your inner thigh, hold a dumbbell in a supinated hold.
  • Slowly curl the weight up toward your biceps—your upper arm should be stationary, only your forearm moving.
  • At the top of the movement, pause and squeeze your biceps.
  • Slowly come back to the starting position.

Take your time and do this exercise slowly for best results.

  1. Single-Arm Preacher Curl

Like the concentration curl, preacher curls help prevent shoulder shift when curling and this is a really good isolation exercise to really target each arm individually.

How to do:
  • Sit on a preacher’s bench or lean on a bench adjusted to armpit height. Grab the dumbbell with an underhand grip and rest your arm on the bench, stopping just below the armpit.
  • Keeping your upper arm fixed on the bench, slowly swing the weight upwards.
  • When your forearms are perpendicular to the ceiling, stop and squeeze your biceps.
  • Slowly return back to the original position.
  1. Incline Dumbbell Curl

Incline dumbbell curls are ideal for targeting the long head of the biceps.

How to do:
  • Adjust your bench to a 45-degree angle. Using an overhand grip, grasp a dumbbell on each hand and sit on a bench.
  • Slowly curl a dumbbell, allowing only the forearm to move.
  • At the top of the movement, pause and squeeze the biceps.
  • Slowly bring the dumbbells back to the starting position and repeat on the other side.

Being slow and controlled is the key to the success of this movement.

  1. Lying Cable Curl

Lying down for a cable curl may sound awkward, but it’s an effective way to target the biceps. When performed unilaterally, this exercise is essential when you have a biceps bigger than the other.

How to do:
  • Attach the straight bar or EZ bar to the low pulley cable machine. You can also use ropes.
  • Lie on your back with your feet toward the cable pulleys and hold the bar with an underhand grip, keeping your arms extended.
  • Keeping your upper arms by your sides and still, curl the bar up toward your chest.
  • Squeeze at the top of the motion and slowly lower back to the starting position.

If you don’t have access to a cable machine, you can perform this movement with a resistance band secured to a rack.

  1. Single-Arm Reverse Cable Curl

The reverse cable curl is an often-overlooked biceps exercise. Start with a light weight for this movement, which can be surprisingly confusing.

How to do:
  • Place the D grip on the low pulley cable machine.
  • Hold the handle with an overhand grip facing the machine. Assume an athletic stance with feet at hip-width apart and knees slightly bent.
  • Keeping your elbows and upper arm still, curl the weight toward your shoulder.
  • At the top of the movement, pause, squeeze, and slowly lower back to the starting position.

Consider placing your passive hand on your stomach as a reminder to remain firm and steady.


If you have less developed muscles on one side of your body, try these training techniques. They can help you resolve the differences between your two sides faster.

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