Pilates is having a serious moment—and for good reason. Whether you’re looking to improve your posture, rehab a sports injury, or deepen your core strength, there are a ton of legit functional benefits to getting on the Pilates bandwagon. The problem? Aesthetic benefits sell. It’s why the idea that Pilates can help you sculpt “long, lean lines” or achieve a dancer’s body is so damn persistent.

So let’s finally clear this up: Can your mat or reformer class actually elongate you in any way? And what does your Pilates instructor really mean when they talk about “lengthening” your spine? We spoke to a physical therapist, exercise physiologist, and Pilates instructors to break it down.

How did Pilates get a reputation for sculpting ‘long, lean lines?’

It’s easy to see why Pilates became associated with a lean dancer’s physique. When Joseph Pilates brought his method to the U.S. in the 1920s, his first clients and trained teachers were dancers.

“From the beginning, the method was an excellent way to rehab dancers after injuries and help them build strength and stability to reduce the risk they’d get injured again,” says Anna Maltby, CPT, an ACE–certified personal trainer, mat Pilates instructor, and the author of How to Move, an anti-diet newsletter about exercise.

Fast forward 100 years and many, many, Pilates instructors are dancers or former dancers—and many dancers gravitate towards Pilates. “The misconception that Pilates gives you a dancer’s body is directly connected to the fact that it was largely popularized by the dance community who already had dancer’s bodies,” says Helen Phelan, a body-neutral certified Pilates instructor and founder of Helen Phelan Studio.

It’s selection bias at play that leads people to believe Pilates can override genetics and give you a leaner, more elongated physique, Maltby says. “I know so many incredible Pilates instructors and people who do Pilates regularly who are neither long nor lean, you know?”

The thing is, you can’t actually “lengthen” your muscles

Let’s get this out of the way: Pilates can’t actually make your muscles longer than they are. “The length of your muscle is primarily determined by the length of your bones and where your muscles attach to your joints,” says Jason Machowsky, MS, CEP, CSCS, a clinical exercise physiologist and owner of JM Wellness.

“I think the word ‘lengthen’ can be really confusing in an exercise context because it is a thing—but it is not the thing that people think it is,” Maltby says. Yes, muscles do shorten and lengthen, she says. For example, the biceps will shorten when you flex your elbow under load during a biceps curl or when you’re just crossing your arms, and your biceps will lengthen when your elbow is relaxed and your arm is hanging straight by your side. But while Pilates involves stretching and lengthening your muscles, that won’t make your muscles visibly longer, she says.

When people talk about “lengthening their muscles,” they’re usually referring to the idea that you can strengthen without “bulking,” Phelan says. But (putting aside the fact that it’s quite challenging to bulk up in the first place) the only way to increase strength is to increase muscle mass, she says. “What that looks like on each individual body is completely unique to each person and has more to do with genetics and lifestyle than choice of exercise modality.” (Diet also plays a huge role when it comes to getting the lean and slender body type that Pilates promotes.)

If you’re tall and don’t carry a lot of body fat, Pilates can make your muscles appear long and lean. But if you have shorter limbs and more body fat, your muscles probably won’t have that same appearance, Maltby says. In other words, some people will never achieve “long, lean lines”—and that’s okay. “I think that’s a hard pill for people to swallow who are doing Pilates for aesthetic reasons.”

“The misconception that Pilates gives you a dancer’s body is directly connected to the fact that it was largely popularized by the dance community who already had dancer’s bodies.” —Helen Phelan, Pilates instructor

But there is some truth to the lengthening claims

Pilates can’t change the length of your muscles (or bones) themselves, but there’s some validity to the idea that Pilates can make you appear, well, longer. “By improving flexibility in certain muscles and improving strength and stability in others, Pilates can change the way that you carry yourself,” Maltby says.

Think about your muscles when sitting in a hunched, rounded posture versus sitting up straight, says Machowsky. The actual length of the muscle hasn’t changed, but you’ll appear taller when your muscles are less compressed. “Pilates can help with better posture and possibly flexibility and mobility, which can make us look longer because we’re standing up straight.”

Of course, not all Pilates classes look the same. The key to an effective, “elongating” Pilates workout is that it incorporates active rather than static stretching, says Grayson Wickham, DPT, DPT, CSCS, physical therapist and founder of Movement Vault. Active stretching is when you maximally stretch out and then contract your muscles at the end of your range of motion, helping to improve the active mobility of your muscles and joints, Grayson says.

Lastly, it’s possible your Pilates instructor has something else in mind when they talk about “lengthening” during class. “Pilates instructors often use the word ‘lengthen’ in cues (e.g. “lengthen your spine”)… but that’s to help people find the right form and alignment for the exercise so they can engage the correct muscles for that movement,” Maltby says.

Why we should stop caring about ‘long, lean lines’

Of course, everyone has their own motivation for working out, and for some that might be to change the way they look, Maltby says. But marketing lingo that promises a specific body type from Pilates (or any workout or diet) alone can be misleading. “I think we all just need to get a little bit more into the practice of asking: Does this sound too good to be true?”

While this is largely a problem with Pilates culture, individual instructors can also be guilty of perpetuating the “long, lean lines” myth. But body-neutral Pilates instructors, like Maltby and Phelan, are much more interested in helping you become in tune with how you’re feeling and moving (aka the mind-body connection), Maltby says. And when you’re in tune with your body, you’re able to notice all of the functional benefits of Pilates, including improved strength, mobility, balance, and posture. “When you’re moving through the world more in your body, that’s sustainable and that helps you feel motivated,” Maltby says.

Focusing solely on the aesthetic benefits, especially when there are so many important mental health benefits, can also create a transactional, and potentially unhealthy relationship with exercise, Phelan says. She created her own studio to offer an anti-diet approach to Pilates that’s still physically challenging, with a focus on muscle activation and building strength rather than gentle stretching. In fact, Phelan describes her method as a satisfying, cathartic workout for those who roll their eyes when they hear the phrase “long, lean lines.”