our bodies

The Best Sports Bra For Large Breasts

January 04, 2020
Team Knix

Have you ever held onto your boobs while running because your bra wasn’t supportive enough? You’re not alone; in fact, over 80% of women do it! It’s so important for women to wear a supportive sports bra, especially if they have large breasts. The problem is it’s also so difficult to find one that is supportive enough for those larger cup sizes.

That’s why we designed a high impact sports bra that’s supportive enough for women with large breasts — up to a size 42G. Read on to learn why women should always wear a supportive sports bra, and what makes The Catalyst the best sports bra for larger cup sizes. 


What’s the big deal about sports bras anyway?

No matter what your breast size is, you should always wear a good sports bra while working out. And if you don’t? Well, we asked Professor Joanna Wakefield-Scurr, who is the Head of the Research Group in Breast Health at University of Portsmouth. She led the testing team for our high-impact sports bra, the Catalyst

She explained that because there are no muscles within the breast (yep, “it is really a lump of fat and tissue, which can be quite heavy for some women”), the only thing supporting the breast is a bra. As a result, when you don’t wear a supportive sports bra, you may experience breast pain, damage to the skin and ligaments (“which is where we see stretch marks and sagging breasts”), and changes to your muscles and breathing. In addition, many women may feel embarrassed by too much movement, which may hold them back from participating in sports.

Catalyst Sports Bra

This is the most supportive high impact sports bra you’ll ever put on. Designed to drastically reduce breast movement, the Catalyst outperformed over 800 bras it was tested against. Get comfortable performing your best, with sizes up to 42G.

Catalyst Benefits

Performance Molded Cups
Supportive, breathable design separates and encapsulates your breasts, dramatically reducing movement by 76%.
Adjustable Straps
Get the fit and feel you want with ladder straps that fit comfortably and securely.
Tri-Flow™ Ventilation
Increased airflow where your body gets its hottest – right between your breasts.

Catalyst Bra FAQs

They are strap slots allowing the customer multiple adjustability options to tighten the strap length as needed for maximum security.

No, the straps are ‘fixed’ and feature adjustable ladder straps for length flexibility.

Absolutely. We have many customers who prefer the high level of support that the Catalyst and Front Zip Catalyst provide for their day to day.

How To Measure Your Bra Size

What makes a good sports bra?

The ultimate goal of a good sports bra is to limit the movement of the breast. Sports bras are designed with either compression or encapsulation to prevent the breasts from moving and bouncing as you run, jump, and twist.

Encapsulation involves two distinct cups that separate the left and right breasts and rigidly encase the breast. Bras built for compression hold the breasts close to the chest, but because compressions bras typically contain a lot of elastic, they may stretch over time and result in more movement.

The Catalyst offers both.

And because it offers six support zones, molded cups, and adjustable straps, the support it provides is, according to Business Insider, "a gamer-changer for large breasts." And it’s available in 11 sizes, up to a 42G.

Knix Extended Sizes


What high-impact sports can I do now?

75% of women avoid exercising because they can’t find a bra that fits. This ends now. Because the Catalyst is a high-impact sports bra, it allows women to feel supported in a wider range of sports. Some high-impact activities that the Catalyst will support you in include:

  • Running
  • Boxing
  • Dancing
  • Football
  • Basketball
  • Soccer
  • Gymnastics
  • Jump rope

If you’re looking for a little extra support for medium-impact activities, you can also wear the Catalyst for things like hiking, hot yoga, spinning, or skiing.

Is it easy to remove?

Wondering how hard it’s going to be to take this thing off? We get it. 90% of women have struggled to get out of a sports bra. That’s why, after learning there was no test for ease of removal, we created our own. The Catalyst was rated as the easiest to remove, with hooks on the back that’s more like a typical bra closure. Sports bras are often pullover bras, and this can be a workout in and of itself! These typical sports bras are often difficult for people to put on or take off if they have larger breasts or mobility issues. With clasps on the back, not only does it make the Catalyst a breeze to remove, but also makes it more versatile size-wise.

The Catalyst sports bra will transform the way you feel before, during, and after working out, and was designed for women, by women—just like the very first sports bra.