Ever catch a glimpse of yourself in the mirror at the gym during a particularly challenging set of lateral raises and wonder why Elvis is staring back at you? Lots of (confused) weightlifters notice lip snarls or face twitches when they strength train, and plenty want to get to the bottom of this involuntary reaction.

If you’re among the crowd wondering why your face twitches when you lift weights, here’s everything you need to know about what causes this lifting-induced lip snarl—and what to do about it if it bugs you.

Why Your Face Twitches When You Lift Weights

So there you are, lifting your heavy weights for your last few reps, and it’s getting harder to heave the dumbbells as high. “Your brain is telling your body to keep going. Your body activates additional, non-essential muscle groups (your neck and face muscles) to complete the task, which would cause the face twitches, neck muscles activation, and grimace facial expression,” says physical therapist Raquelle “Rockie” Felder, founder and owner of San Diego Mobile Rehab and Physical Therapy.

This actually has a medical name: motor overflow, which is when your body involuntarily activates additional muscles that aren’t directly involved in voluntary movement. Motor overflow is often associated with neuromuscular disorders, but it can also happen “under increased load and strain,” she says.

The nerves that manage movements in your face, neck, and shoulders are controlled in nearby parts of the brain, so it’s possible, too, that under the strain of a tough workout, the wrong nerves get activated and you find yourself making involuntary facial expressions, Felder says. And that’s particularly common during arm or shoulder exercises. 

“Exercises like overhead presses, shoulder flies [aka lateral raises], and shrugs are some examples that tend to cause facial twitches or grimacing,” she explains. “This occurs due to proximity of facial and spinal nerves to the voluntary activation of shoulder muscle groups, leading to pathway crossover, along with motor overflow caused by physical strain.”

It’s also possible that the same mechanism that causes some people to grunt when they lift weights also causes other people to twitch or grimace, she says. The Valsalva maneuver, as it’s called, involves holding your breath and bracing your core, which increases pressure in your face and head in ways that could activate nerves or muscles there, she says.

“Heavy compound lifts also cause facial twitches due to exertion and increased intra-abdominal pressure,” she adds, for anyone who grimaces involuntarily during squats or deadlifts, for example. 

That said, a lip snarl or face twitch can technically happen during any activity or exercise. And it’s not entirely clear why it occurs seemingly randomly to some people and not to others. But some lifters may have picked up a lip snarl and subconsciously made it into a habit, the same way that some professional baseball players stick to a specific pre-batting ritual or some basketball players stick their tongues out during free throws, Felder says.

Whether it’s learned or involuntary, a face twitch during exercise is “a very common experience, especially in individuals who push themselves with heavy weights or high-intensity training,” she says.

And it’s very rarely anything to worry about. Lip snarls and grimaces are largely due to working hard and feeling at least a little tired, says James J. Murphy, MD, an orthopedic surgeon with OSF HealthCare. You’ve probably noticed it goes away when your workout (or even that particular exercise) ends.

But there can be other exercise-related factors that contribute to face twitches that you can address. For example, dehydration and electrolyte imbalances can lead to muscle spasms or make existing spasms worse, Dr. Murphy says. High doses of caffeine—such as those found in energy drinks and pre-workout supplements—could also cause twitching, snarls, or spasms, he says.

Medical Causes of Face Twitching

There are, however, underlying reasons your face may twitch more generally, including sometimes while you’re lifting weights. One example is a condition called hemifacial spasm, Dr. Murphy says. If you have a hemifacial spasm, your face twitches only on one side, often starting with one eyelid, according to the National Institute of Neurological Disorders and Stroke. It’s usually caused by a blood vessel pressing on the facial nerve. “While still not a serious problem in general, there are treatments available if this becomes persistent or problematic,” Dr. Murphy says.

If your twitching happens outside of activity and is accompanied by “unexplained, progressive numbness; weakness; dizziness; and vision changes … it would be a good idea to seek medical attention because there may be a neurological disorder,” Felder says.

Can You Stop or Prevent Your Face from Twitching When Lifting Weights?

As you can see, it’s often entirely involuntary and absolutely harmless for your face to twitch or your lip to snarl while you’re lifting. You don’t have to do anything to stop or prevent it if it happens to you and you don’t mind the look or feel.

But if you want to try to get that mid-lift lip curl under control, the first step, as is so often the case, is mindfulness. “As you’re lifting, notice your facial expressions,” Felder says. “When you feel your face start to snarl, relax your facial muscles. Take a deep breath to prevent the Valsalva maneuver (unless you’re using it to brace your core during a heavy lift). Try breathing in sync with your movements to decrease facial twitches and ensure adequate oxygen during exertion.”

If you think your lip snarl could be hydration-related, make sure you’re drinking plenty of fluids and getting enough electrolytes like sodium and potassium. “Proper hydration is always a good idea with exercise,” Dr. Murphy says. If you could use a little more support figuring out how to stay hydrated and how to fuel properly for exercise, you can always speak with your primary care doctor or a registered dietitian. You can also make sure you’re sticking to the recommended limit of 400 milligrams of caffeine a day. Limit stress and anxiety (as much as possible) with relaxation techniques like meditation, yoga, and deep breathing, all of which are available on the Peloton App.

And while there’s currently no scientific evidence linking a lip snarl to skipping a warm-up, it’s worth doing a little experiment of your own to determine if that could be another cause at play. See if the twitch still happens if you devote some quality time to warming up before you lift. “A warm-up is always good, and if you are experiencing muscle spasms in the face or anywhere else, it may be your body letting you know to ease in a bit,” Dr. Murphy says. The Peloton App has lots of five- and 10-minute warm-up routines you can follow along with to get limber.

If you’ve tried these at-home tactics and you’re still eager to tame the twitch, it never hurts to explain what’s going on to a doctor. If they determine there’s an underlying medical cause of your grimaces and snarls, there are treatments available including medications, injections, and even surgery (in extreme cases), Dr. Murphy says.

The Takeaway

Plenty of weightlifters notice their lip involuntarily twitches, snarls, or curls during a workout, especially when they do arm or shoulder exercises. This is usually due to increased strain on your nervous system during a tough workout and nothing to worry about. Staying hydrated, limiting caffeine and stress, warming up properly, and trying to relax during the movement may help calm your twitching facial muscles. If you notice any numbness, dizziness, weakness, or vision changes in addition to the twitching, talk to a doctor, as these could be signs of a neurological condition.