These sports bra engineers know a thing or two about supportive activewear.

By Rachel Jacoby Zoldan
October 18, 2017
Photo: Shutterstock

Sports bras are probably the most important piece of fitness apparel you own-regardless of how small or large your breasts may be. What's more, you could totally be wearing the wrong size. (In fact, most women are, according to experts.) That's because while cute leggings may be your athleisure budgetary priority, not wearing a supportive enough bra during those intense, high-impact workouts can cause a ton of unpleasant side effects. Think breast discomfort, back and shoulder pain, and even irreversible damage to your breast tissue-which can lead to sagging, as we previously reported.

Luckily, the best sports bras are both fashionable *and* functional these days. (Like these cute sports bras you'll want to show off when you aren't working out.) But how to decide between all the options out there? We tapped sports bra engineers from some of your favorite activewear brands for their bra shopping tips.

1. Shop IRL and employ the assistance of a fit specialist.

You might *think* you're an expert when it comes to your own boobs, but there's an important reason to turn to a fit specialist: Your breasts change in shape and size when you gain or lose weight, have a child, or simply age-so you could easily be wearing the wrong cup size and not know it. A fit specialist-someone whose job it is to literally fit the perfect bra to your exact measurements-will be able to offer a litany of advice and help you choose the best size and style for you, according to Alexa Silva, the Women's Creative Director at Outdoor Voices. Good news? Most sporting goods shops will have a fit specialist, and every single lingerie store will have at least one available for individual consultations or full-on appointments. Just wander to the sports bra section and you're good.

If you're dying to shop online or really can't make the time-because yes, the struggle can be real-Silva suggests shopping online only when you "feel confident in your size and there's a good return policy." Just make sure you try it on long enough to be sure it's the right bra for you. "It's great to wiggle, bounce, and stretch to make sure you've really got the right fit," Silva says.

2. Your size should help dictate the sports bra style you choose, but it's ultimately a matter of personal comfort.

There are two main types of sports bras: The compression kind and the encapsulation kind. Compression bras are the OG sports bra that you're picturing in your head. They work to reduce breast bounce with a high elastane fabric, giving you that 'locked and loaded' feeling by compressing the breast tissue against the chest wall, says Alexandra Plante, the Director of Women's Design at Lululemon.

Encapsulation bras, alternatively, look more like your everyday bra and encapsulate each breast in separate cups, which can provide more support as your breasts move during a workout. "The breasts continually move up and down, side to side, and in and out in a complex, three-dimensional manner," says Plante. "When the breasts are fully encapsulated-when the breasts are lifted and separated-they act independently rather than as a single mass," explains Plante. "This creates a sensation where the breast and bra move together in harmony, rather than fighting against each other."

Generally, the larger your breasts are, the more you should err toward encapsulation styles, explains Sharon Hayes-Casement, Adidas Senior Director of Apparel Product Development. These bras can also provide a "more feminine aesthetic." However, she adds that when choosing between the two, it's ultimately a matter of personal preference, and most importantly, comfort.

3. Keep whatever workout you love-or do most often-top of mind.

"The breast does not have any muscle," says Hayes-Casement. "Therefore, delicate breast tissue can easily be under strain if not adequately supported." That's why you should always keep in mind the level of impact of your workout. Low-impact activities-think yoga or barre-require less support, which means you can get away with thinner bands, skinnier straps, and generally no encapsulation. But as soon as the impact ramps up-think high-impact activities like HIIT or running-you're going to want to opt for a more supportive style. TL;DR? No, you cannot wear your trendy yoga bra on a run.

4. Keep your eyes on the straps and band.

Construction on every bra's band differs, which makes it imperative to take note of where the band sits when you try it on. "The band is the foundation of the bra, and should sit firmly but comfortably around the bust, ensuring the band is not too high to sit on the breast tissue, but not too low, either," says Plante. Turn to the side and check yourself out in the mirror: "A correctly sized band should be parallel to the ground, not hiking up your back."

Straps are also crucial. Since the support of the bra should come from the band, it's important to make sure that the shoulder straps do not dig into the skin, Hayes-Casement says, which is why she designs Adidas' bras with adjustable straps that let you find that sweet spot that works for the apex (or most prominent point) of your own bust.

Luckily, as sports bra companies focus more on customized fits, you'll be seeing band and strap features that are engineered for your size. For example, with Lululemon's latest sports bra innovation, the Enlite Bra (which took two years to design, BTW) strap widths vary by size and larger sizes have additional bonding, Plante explains.

5. Always choose function over fashion.

This may seem like a given, but before designing their Enlite bra, Lululemon conducted research which found that most women are compromising on aesthetic, comfort, or performance when it comes to buying a sports bra. Bottom line: "Nothing should be digging in, cutting into, or poking into any part of the breast tissue," says Plante. So while you may want that strappy number in that sleek, metallic fabric, if it doesn't fit well, choose the "uglier" alternative instead. Your boobs will thank you later for the support-literal and figurative.