Do you bust out 10 biceps curls on your right side but struggle to complete 5 on your left? Though it's common to have a dominant side, slight differences in strength, balance and mobility can sometimes signal a muscle imbalance, which could hurt your exercise performance and up your risk of injury.
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Quick refresher: Muscles control the movement of every joint in your body, according to the American Council on Exercise (ACE).
"When muscles are balanced around a joint, it means they are contracting at a rate and intensity to help the joint move as it is intended to move," says physical therapist Sarah Duvall, a certified personal trainer and founder of Core Exercise Solutions.
"With any movement of the body, there are prime movers — which are the muscles that are supposed to provide the primary force for moving the joint — and there are assisters — which are muscles that provide some assistance when the prime movers need help," Duvall explains. A muscle imbalance might occur, for example, when the prime movers are too weak to do their job, forcing the assister muscles to try to compensate.
New York City-based chiropractor Todd Sinett, author of the upcoming book Sit-ups Are Stupid & Crunches Are Crap, says he sees this issue a lot with core muscles. "A core imbalance can cause excessive compression on the spine, significant postural issues and altered biomechanics," he says.
What Causes a Muscle Imbalance?
A sedentary lifestyle is one possible culprit. "We spend our days hunched in front of computer screens, sitting at desks and in cars or with bent necks staring at our smartphones," Sinett says.
Being seated for prolonged periods of time causes your hip flexors to become tight and short, per the ACE, which can set you up for muscle imbalances, including in the glutes.
Doing the same motion over and over can also cause muscle imbalances, Duvall says. That's because when you use the same muscles repeatedly in the same way, they can become overworked and get stuck in a position of semi-contraction, which may ultimately compromise the joint, according to the ACE.
This can take the form of everyday habits such as carrying your gym bag on the same shoulder, which regularly forces one side of your body to exert more effort than the other.
Any time your form fails during an exercise, it can reveal where you're experiencing muscle imbalances.
But it can also take the form of healthy physical activities. Repetitive exercises like running, for example, primarily work your body in one plane of motion; they don't necessarily help you develop the well-rounded strength that you could build through doing activities that involve more varied movement, Duvall says.
Yet another driver behind muscle imbalances is your genes. If, say, your mom and your grandma both have back issues, you might have a predisposition for experiencing similar problems yourself later in life.
"Whether it's the natural curves in our spine or how our joints are built, genetics may play a role in susceptibility to certain issues," Duvall says, adding, "that's why you'll often see similarities within families."
Signs of a Muscle Imbalance
Pain and tightness are prime indicators of a muscle imbalance, Duvall says. For instance, if your paraspinals (the muscles that run up and down either side of your spine) have to compensate for weak abdominals and deep back muscles, your back will eventually start hurting.
Asymmetry is another obvious symptom. This unevenness can manifest in how you look (i.e., one shoulder appears higher than the other) and/or how you perform (i.e., one side is weaker or wobblier).
That means "muscle imbalances can cause someone to lack the strength potential they would have if their prime movers were working properly," Duvall says.
In fact, a muscle imbalance is often the reason why some people can't perform certain exercises correctly, she says. Case in point: pull-ups. People whose lat muscles are too weak to lift their bodies will use their smaller arm and shoulder muscles (i.e., their assisters) to try to make the movement happen — with little to no success.
That kind of situation isn't only true for pull-ups. Any time your form fails during an exercise, it can reveal where you're experiencing muscle imbalances. Do your knees cave in when you squat? You might have weakness or limitation in the hips. Does your lower back sag during planks? That could be a sign of core weakness.
If you suspect you have a muscle imbalance, it's best to get assessed by a medical professional who can properly spot and diagnose irregularities — and give you advice on how to fix them.
Why Muscle Imbalances Are Problematic
A muscle imbalance may seem like a minor nuisance right now —so what if your right leg shakes more than your left during lunges? — but it could lead to more serious problems later.
Left untreated, muscle imbalances can cause pain, dysfunction and injury, Duvall says. That's because they can alter the position of the joint they're attached to, changing its range of motion in potentially hazardous ways, according to the ACE.
If this happens repeatedly over a period of time, your chance of injury is higher, both to your muscles, which can become overtaxed from bearing too big of a load for too long, and your joints, which don't get the support they need to stabilize during strenuous exercise.
The most common example of this domino effect is caused by weak glutes, Duvall says. In that scenario, "the deep hip rotators can take over, which can trigger hip pain and even pinching of the sciatic nerve," she says. Another example: weak shoulder muscles. "When the pec minor takes over for the weak serratus, it can increase the risk of shoulder and neck pain," she adds.
If the imbalance is in your core, it may "cost you a loss of flexibility, poor breathing, disrupted digestion," Sinett says, as well as neck and back injuries or pain.
How To Fix a Muscle Imbalance
Building strength and increasing your range of motion are both essential when it comes to treating muscle imbalances. Once you've pinpointed your particular weak areas, you can focus your strength training and stretching on them. You might want to have a personal trainer, or a physical therapist if you're in pain, to help you develop a targeted routine.
Whatever plan of action you decide upon, know that your healing won't happen overnight. "Muscle imbalances can be hard to fix, especially if the pattern has been ingrained for a long time," Duvall says.
Retraining the muscles is the most difficult part, she adds. Once the assister muscles have grown accustomed to compensating for a weak prime mover, they will stubbornly keep trying to do so. It will take time, patience and repetition to get them to break that unhealthy habit.
"It takes purposeful exercise to target the imbalanced muscle," Duvall says. "And you often have to make the movement a lot easier than people expect." That might mean lifting less weight, refining and simplifying your form or both.
When it comes to addressing muscle imbalances, correcting core issues should be at the top of your to-do list, Sinett says. "Your core is your home base," he notes. "Proper core training is the underpinning of fundamental human motion. No one can afford to neglect this building block of the body."
To start to combat core imbalances, Sinett recommends doing the following simple abdominal stretch a few times per hour: Stand up, raise your arms above your head and slowly lean backward at a 30-degree angle. Hold this pose for a few seconds, then return to your starting posture.
Another helpful option is doing unilateral exercises, i.e. movements that train one side of your body at a time, like single-leg glute bridges or single-arm dumbbell rows. Movements like these will ensure that you don't over-rely on your dominant side, which helps you isolate and remedy muscle imbalances, according to the ACE.
Incorporating exercises that encourage movement in many different directions or planes is another helpful strategy, according to the ACE. Mix up your routine with a variety of pushing, pulling, rotating and sideways motions. Doing exercises like these will help you avoid repetition and overtraining, reducing your risk of muscle imbalances.
It takes time and patience to correct muscle imbalances, but the investment is worth it. In the end, you'll be stronger, less prone to injury and potentially free of pain.