This Is What Happens When You Wear the Wrong Sports Bra (and How to Choose the Right One)

We have sad news: Your favorite, most comfortable sports bra might not be the right one for that hip-hop cardio class—and also why your boobs are so uncomfortable during workouts. "One of the biggest reasons breasts can bug you during a workout is because we tend to wear the wrong bra for our sport," says Tamara Hill-Norton, founder and creative director of Sweaty Betty. "If the bra you're wearing doesn't have the supportive technology you need, it's basically like wearing socks without shoes to run a marathon."

Why Choosing the Right Sports Bra Is So Important

If you have the right fitting bra for your sport you'll improve your comfort and confidence and prevent more serious damage. To get a little technical: "When you move, your breasts bounce in a 3D motion, so without a supportive sports bra the Cooper's Ligaments—an internal band of elastic tissue that supports the breasts and keeps them upright—can stretch irreversibly," Hill-Norton says. "Once they've stretched there's no going back."

Now, this doesn't mean you have to get rid of your favorite sports bra (unless it's super old, which we'll get to in a minute). But it is a wakeup call to start looking for the right sports bra for specific activities—oh, and your chest size, too. (Less-endowed ladies, you still need ample support from your sports bra! And busty ladies, don't let your big boobs stop you from getting the exercise you deserve!)

How to Choose the Right Sports Bra

So, how to choose the right sports bra? You have to know what's out there and understand sports bra sizing. The best-quality sports bras, especially sports bras for large breasts and high-impact workouts, typically come in actual bra sizes—rather than simply small, medium, and large. This also means you (or a professional) will need to measure your bra size. Then you can accurately choose the undergarment with the best support for your body and chosen type of exercise.

Compression sports bras do exactly what they sound like: compress breasts to stop them from moving around uncomfortably during exercise. Depending on your breast size, compression sports bras are a comfortable choice and safe bet for medium-impact activities like elliptical workouts, moderate hiking, and cycling.

Encapsulation sports bras surround each breast separately (like your everyday T-shirt bra does), giving you a flattering, natural chest silhouette, but not always as much support as a compression bra. It's best to save encapsulation bras for low-impact activities such as yoga, walking, and Pilates. (For something like yoga or Pilates, super soft fabrics and light support, like the Sweaty Betty Shanti Yoga Bra, will provide enough comfort.)

Encapsulation-compression sports bras combine the support powers of both overall compression and individual bra support, making them the ideal choice for women with large breasts, and for high-impact workouts (intense cardio like running, dance workouts, jumping rope, and interval training). If you're a runner, aim for a high-support bra with padded shoulder straps and either encapsulation or compression technology, Hill-Norton suggests. "Carefully placed seams on the outside of the bra also ensure no unwanted chafing."

How Long to Keep Your Sports Bras

Don't hang on to your favorite bra forever—you need to replace your athletic wear at least twice a year, sports bras included. "A sports bra has an expiration date of around six months because they stretch over time," Hill-Norton says . Once the elastic has worn off and the seams have stretched, you're back to square one wearing a lack-luster bra. So don't be afraid to shop for a new one, even if it seems like you just bought it.