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Why Is It Harder to Flex My Left Arm? Find the Solutions!

Arm workouts are an integral element of any fitness plan. However, if you notice an inconsistent muscle tone or a variation in arm strength, take it seriously. Sometimes it’s as simple as making some adjustments to your regimen. But it could also be a significant problem as well. 

One of the issues is that one arm is much more bendable than the other. It can be either the right or left arm, though the left is more common.

So, people often wonder,  why is it harder to flex my left arm?

Poor mind-muscle connection primarily makes it harder to flex your left arm if you are right-handed. There are other reasons that can make flexing difficult. Like biceps insertions, overused muscles, and tendon injuries. You can fix them either by unilateral exercise or medical assistance.

Do you want to know why this occurs and how to avoid it? Continue reading to learn more about these factors.

You are most likely a right-handed person. It’s common for people to be strong and more muscular on one side of their body. This usually depends on which hand is stronger, it could be either side. 

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Possible Reasons: Why is It Harder to Flex My Left Arm

It’s very common to find one arm easier to flex than the other. This is frequently true with the dominant hand. This commonly occurs at the start of a bodybuilding workout. However, there are a couple more explanations as to why you are having this problem. 

Let’s take a closer look.

Poor Mind-Muscle Connection 

You are most likely a right-handed person. It’s common for people to be strong and more muscular on one side of their body. This usually depends on which hand is stronger, it could be either side. 

If they are right-handed then, on the right side, their mind-muscle relationship is better. At the start of a workout, people tend to use their dominant arm. It improves the flexibility of that particular arm. As a result, the other arm is stiffer. The dominant arm is also the reason why one arm is more vascular than the other.

Different Biceps Insertion Points

Where your muscles attach are some of the most mysterious aspects that affect your strength. Insertions are totally hidden from our sight. But little variations can result in major distinctions in the amount of weight you can lift.


For the biceps, there are two insertion points: long and short. On both biceps, most persons have the same insertions. Although it’s rare, people can be born with two different insertions.

This explains why one arm is more difficult to flex than the other. The bad news is that muscle insertions are entirely genetic. You have no control over them. However, you can bulk up your muscles.

Probable Tendon Injury

If you have sudden and severe pain in the upper arm or elbow, the tension is damaged. Tendons are connective fibrous tissues that attach muscles to bones.

Tendon tears occur when you raise anything too heavy or just too quickly. This can also be caused by frequent overhead motions.

Continuing to train with a torn tendon will cause your brain to send a signal. The joint then will be locked because of this signal. And it will be impossible to move it fully afterward.


Overworked Muscle

Another option is that you’ve overworked your arm. Many people suffer from muscular imbalances. It’s possible that you’re placing more strain on your left arm when doing curls. 

As a result, it is completely drained. And due to this extreme weariness, your arm is more difficult to flex.

How Can You Flex Your Left Arm Easily?

Now, we can already assume that you are eager to flex both your arms equally. And perhaps you want to improve the strength of your arms. Don’t worry, we’ve got you covered.

For all of the aforementioned cases, we will provide a solution below.

Weak Mind Muscle Connection

Although having one arm that is stronger is natural, a major imbalance might cause long-term issues. Even a minor strength difference might restrain muscle development and strength increases.

Unilateral exercise is recommended rather than doing extra reps on your weak arm. Exercises like the flat unilateral dumbbell press or dumbbell shoulder press are highly effective.

You can also do a prone 30-degree unilateral reverse fly or 30-degree dumb-bell unilateral row. In comparison to a standard bilateral workout, unilateral training encourages the nerves and muscles to react strongly.

These exercises will allow the development of your weaker arm. Consult a trainer for the correct procedure for unilateral workouts. Do the advised sets with your weak arm first. 

Swap the weight to your opposite hand. Wait for a few seconds before repeating with your preferred arm.

For Bicep Insertion

As this is entirely genetic, you will not be able to change the insertions. However, with more specialized exercises, you can alter a muscle’s volume and shape. The bench press is a great way to bulk up your muscles.

It helps in the formation of shoulder, tricep, and chest muscles. You can also try this supplement, which strengthens your back muscles and increases your flexibility.

FlexoBliss is a natural supplement that helps to maintain your back muscles and bones healthy, allowing you to stay flexible and active.

You can gain muscle mass if you can bench more weight. For your own safety, you should do this workout with the supervision of a spotter. 

Additionally, you can eat carbs like ramen for bulking as well. Some individuals opt for bulking supplements as well.

For Tendon Injury

If you have tendon difficulties, you should get medical attention as soon as possible. However, you can perform a hook test first to make sure it’s a damaged tendon.


The hook test will require the assistance of another person. First, try to flex your elbow to 90 degrees, and then try to turn your forearm completely. The examiner should now try to grasp the tendon within your elbow with their index finger. 

If your biceps tendons are torn, the examiner will be unable to hold them. In such cases, you should seek medical assistance immediately.

For Overworked Muscle

The amount of discomfort you feel will be based on the duration and intensity of your workout. After a muscle-stretching activity, normal muscular pain and exhaustion occur around 24 and 72 hours. In a few days, it should be completely gone.


To aid with overworked muscles, gentle stretching, muscle massage, and rest should be enough. Ice can also be used to relieve inflammation. The hot bags can be used simultaneously.

Heat will help to enhance blood circulation to your muscle thus relieving the pain.

Can’t Flex Arm At All – Is It Alarming?

If you can’t physically flex your bicep, the tendon may have ripped. You should see your doctor as soon as possible. Because tendon scarring can have a detrimental impact on surgery repair and recovery. 

If it has ruptured, surgical treatment is required right away. If the tendon is not treated, it will not recover by itself. And you will suffer long-term consequences.

In such circumstances, a surgeon must open the incision to access the injured tendon. And close the incision after it has been repaired. This is riskier than primary treatment.

Following that will be a period of rest and physical treatment. So that your body can regenerate and heal. So when there are multiple indicators of a serious problem, it’s always best to visit a doctor. 


Is It Natural to Have Muscle Imbalances?

Yes, it is. Muscle imbalances occur when the power or growth of a muscle differs from one side to another. This is a common and understandable problem, especially among beginners.

What is the Strength of Your Non-dominant Hand?

It is typically 10% less powerful than your dominant hand. Scientists have often conducted tests on each hand in order to uncover the answer. The results revealed a 10.74 percent difference in grip strength among dominant and nondominant hands. This discovery backed up the 10% rule.

Why Does One Arm Appear to Be Stiffer Than the Other?

This is absolutely normal. Many individuals have some level of arm imbalance since one is stronger than the other. If you are right-handed, your right arm is more likely to be stronger than your left. This is the reason why one arm appears to be stiffer than the other.

Will the Muscular Imbalance Resolve Itself?

Yes, your muscles will ultimately balance out. Once the weaker side has caught up, increase the set and weight on the stronger side. The muscle will become balanced over time.

Final Words

That’s it, folks. Now you know everything about why is it harder to flex my left arm.

Always strive to achieve your objectives and stay motivated. But avoid becoming anxious and pushing yourself to your limit because of that. 

We hope you found our post useful in resolving your issue. Until next time, have a good day.

Good luck with your future goals!

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