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4 Signs You Have a Muscle Imbalance—And Exactly How to Fix It

Weakness in opposing or opposite-side muscles is common, but it can cause pain and injury over time.

By Sarah KleinJuly 3, 2024


Balance is key in so many areas of life, physically and emotionally. A balanced diet provides a wide range of nutrients for fuel. A balanced social life delivers connection while making space for rest. Without literal balance, we’re at greater risk of falls and injuries. And it’s even important within our very muscles.

Yep, there is such a thing as a muscle imbalance. And if it’s left unaddressed for too long, like other forms of imbalance, it can hurt. Here’s everything you need to know about the causes of a muscle imbalance, how to recognize if you have one, and how to restore balance to your body. 

What Exactly Is a Muscle Imbalance? 

There are two types of muscle imbalances, but both involve two muscles or muscle groups being out of balance.

The first is when two muscles (or muscle groups) with opposite functions differ in strength, explains Peloton instructor Andy Speer, such as your abs and your back or your quads and your hamstrings. “Usually, it involves a combination of shortening and tension by one group and lengthening and weakness by the opposing group,” he says.

The second is when the same muscles on opposite sides of your body differ in strength. If you always carry a heavy bag with your right arm, for example, your right biceps, triceps, and deltoids are likely going to be stronger than the same muscles on your left side, according to the American Council on Exercise (ACE).

A muscle imbalance isn’t always a bad thing—and it’s not always avoidable, either—but generally speaking, it can cause you to compensate with other muscles and get into less than optimal movement patterns that could lead to pain and injury over time (more on that below). 

Agonist vs. Antagonist Muscles

Muscle imbalances often occur between what are known as the agonist and antagonist muscles surrounding a joint. These muscles function in opposite ways during a particular movement, according to the ACE:

  • Agonist: the prime mover or main muscle (or muscle group) responsible for a certain action

  • Antagonist: the muscle (or muscle group) that moves in opposition to the agonist

For example, if you’re doing a biceps curl, the biceps muscles are the agonist and the triceps are the antagonist.

When the agonist contracts or gets shorter, the antagonist extends or gets longer. Overtime, a muscle imbalance can lead to permanently shorter and tighter agonist muscles compared to longer and weaker antagonists. 

The Causes of Muscle Imbalances

“Various everyday events, sports, or an injury may lead to the development of this muscular imbalance,” Andy says.

Here are a few examples:

  • Using one limb or unilateral movement pattern more than the other. If your workouts include activities like jumping or powering off of one leg more than the other or throwing with your dominant hand, you could develop muscle imbalances from training, Andy says. But this also applies to everyday activities like crossing your legs on the same side, starting with the same leg when you climb stairs, sleeping on the same side, or always carrying your purse, backpack, or groceries on the same shoulder, per the ACE.

  • Repetitive motions. Anytime you do the same activity over and over again, you’re strengthening the muscles that power that movement. If they’re overtrained, they can remain in a semi-contracted position and throw other muscles out of balance, according to the ACE. For example, if you’re lifting young kids a lot, your back and shoulders might get short and tight while your abs might stay relatively weak.

  • Sitting. Think about it: Sitting is a “long period of static holds in positions that lead to shortening or lengthening of opposing muscle groups,” Andy says. Your hips are shortened while your glutes are lengthened, leading to what’s become known as “dead butt syndrome”. This could happen because you sit a lot at work or if you’re generally not too active.

  • Poor posture. “Constantly being hunched over looking at your screen” is another example of a long static hold that can throw muscles out of balance, Andy says.

  • Previous injuries. “Old injuries can cause diminished function or lack of stability around joints, which causes prime movers to work overtime to perform the movement and stabilize the joint,” Andy says. “These muscles then become short, pulling the joint into a non-optimal position, which can lead to inflammation, pain, and further movement inhibitions.”

  • Wearing shoes with an elevated heel. Shoes that lift your heels higher than your toes change the position of your knees and have the potential to throw off the balance of the muscles in your legs and hips, according to the ACE. And we’re not just talking about high heels: Even running sneakers or other types of shoes that have a higher heel than toe could lead to muscle imbalances over time.

How to Recognize Muscle Imbalances: Symptoms

It’s not always obvious you have a muscle imbalance. You could have general pain in an area unrelated to any specific injury, for example, Andy says.

The most clear symptoms of a muscle imbalance, though, are notable differences in flexibility, stability, or strength on one side of your body compared to the other, he says.

If you’re not sure if you have a muscle imbalance and you’re concerned about your symptoms, check in with a physical therapist or certified personal trainer.

There isn’t a scan or test that will show where you have muscle imbalances, but a professional can do a posture evaluation that helps assess where you have under- or overactive muscles, according to the National Academy of Sports Medicine (NASM). They’ll likely look at your posture to see if your feet, knees, hips, shoulders, and head are in proper alignment. They might also ask you to do an exercise like an overhead squat to assess the range of motion in these joints and your core stability.

What Having a Muscle Imbalance Means for Your Workout Performance

While those differences in flexibility or stability may be subtle, a muscle imbalance can have very real consequences.

Workout Performance Can Falter

For starters, it can hinder your workout performance. “A very important point to remember is that muscle imbalance, like all muscular activity, is driven by the nervous system,” Andy says. “If the nervous system feels that a muscle or muscle group is in an incorrect or dangerous position, it may not give those muscles full access to their power, therefore diminishing performance.” Without full power, you might not jump as high during a HIIT class or pedal as fast while cycling, for example.

You Could Get Injured

Imbalance can also set you up for worse issues down the line. “If a joint that is not positioned properly due to a muscle imbalance is then forced to perform, it is more likely to lead to inflammation, impingement, and other soft tissue injuries,” Andy says.

It Could Be Harder to Recover

If you’re already injured and you have a muscle imbalance to work through, recovery might be a longer road. Getting your biomechanics and imbalances assessed by a physical therapist who is treating your injury can help them prescribe a more targeted exercise program and protect you from reinjuring yourself, according to a May-June 2022 article in The Journal of the Missouri State Medical Association.

How Do You Fix Muscle Imbalances?

Once you (or your trainer or PT) have identified the muscles that are out of balance, you can get started fixing the imbalance. It’s all about retraining your patterns of movement and building strength and flexibility. “Strengthening the weaker muscle while lengthening the shorter muscle through specific exercises and physical therapy is the ideal intervention,” Andy says. 

But it might be tricky to do that on your own. Working with a qualified fitness professional can help you put together a personalized and strategic plan to restore balance, range of motion, and stability, according to the NASM.

How Long Does It Take to Fix?

It’s hard to pinpoint exactly how long it will take to correct a muscle imbalance. The process will depend on the muscles, the severity, your corrective exercise plan, and how dedicated you are to that routine, among other factors.

But don’t delay seeking out help from a physical therapist or certified personal trainer. “If you are experiencing pain or a noticeable lack of performance, go see a professional,” Andy says. “One or two visits can go a long way in understanding the issue and finding simple interventions and exercises to help.”

How to Prevent Muscle Imbalances 

Start with the simplest interventions: Check your posture, take breaks from sitting when you can (that includes taking frequent breaks during long car drives, according to the ACE), and limit your time in heels.

Then, take a look at your current workout program: You want to build in balance from the start, Andy says, by training both sides of your body equally and moving in different planes of motion.

  • Unilateral exercises, where you work one side of your body at a time, can help you address and prevent imbalances between the right and left sides of your body because you can’t “hide” behind your stronger side. Focusing on antagonistic muscles if you’re dominant in a particular area can help, too. For example, if you’re quad dominant, you’ll want to strengthen your hamstrings and glutes.

  • Restricting your activity to a linear path of motion (think: squats, where you’re simply moving up and down) can contribute to muscle imbalances, so make sure your exercise routine includes pushing, pulling, rotating, and sideways movements, per the ACE.

Make sure you’re cross training too, Andy says, so you’re not always doing the same repetitive motion during your workouts. If you do a lot of running, for example, mix in a day of swimming, dancing, or yoga to move your muscles in different ways.

And don’t forget mobility and stability work, he says. These exercises keep your joints moving optimally through their full range of motion, which helps keep the surrounding muscles working smoothly, too.

Ultimately, you’re going to have small differences in strength between certain muscles you use more than others, but you don’t want these muscle imbalances to get in the way of your goals. Leaning on some professional guidance to help you correct or prevent a muscle imbalance can keep you pain- and injury-free.

This content is for informational and educational purposes only and does not constitute individualized advice. It is not intended to replace professional medical evaluation, diagnosis, or treatment. Seek the advice of your physician for questions you may have regarding your health or a medical condition. If you are having a medical emergency, call your physician or 911 immediately.


Featured Peloton Instructor

Andy Speer

Andy Speer

Andy takes a technique-centered approach to fitness, drawing on his experience as an accomplished former gymnast and pole vaulter in his home state of Connecticut.


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