The RW Takeaway: We retested the Knix Catalyst to reassess its performance on other runners. Fortunately, our testers found the brand’s declarations of de-bouncing to be true.

  • Molded cups for a supportive, encapsulating fit
  • Perforated holes provide breathability between breasts
  • Ladder straps that don’t slide

Price: $89
Impact:
High
Sizes:
32A to 42G
Colors:
Black, and limited colors Eclipse, White, Palm Green, Titanium

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Back in 2018, I tested the Catalyst, Knix’s “miracle bra” that, according to the brand, outperformed 800 of its competitors during product testing. After I ran in the bra a couple times, I praised it for its comfort and stability. I’ll admit, however, that it’s a stretch to take only my 32D-chest-sized word for it.

And so, to truly see if the Catalyst supports runners of all shapes and sizes during high-intensity activities (i.e., running), we enlisted the help of our photographer Lakota Gambill, who wears a 36C/D, and our 36F tester, Hannah W. They road-tested the sports bra, subjecting it to miles of sweat and strength-training sessions at the gym. Here are their hot takes.

Knix Catalyst Sports Bra

Catalyst Sports Bra

Knix Catalyst Sports Bra

$89 at Knix
Credit: Lakota Gambill
Pros
  • Adjustable ladder straps
  • Molded cups with ventilation in-between
Cons
  • Extra strap length can be bothersome for smaller-chested runners

Lakota, 36C/D: “The Knix Catalyst Bra is literally the answer to all my prayers.”

For all my life sports bras have had this one issue: If you are a runner who has a lil’ beer belly like myself, the bottom portion of the sports bra either flips, rolls, or in some manner, folds in under your breast when doing crunches—or even just getting in your car. Plainly stated: It’s irritating.

If you haven’t lived with this problem, then consider yourself lucky and equate the annoyance of a mosquito buzzing in your ear to understand the pain of what curvier runners deal with. When it comes to support, it’s always finding what is less “roll-y” with each bra and accepting what’s been given to me. It seemed like there would never be a solution to this problem until Knix completely changed the game.

knix catalyst sports bra
Hook-and-eye closure in the back for a snug underband.
Lakota Gambill

The Catalyst has a thinner bridge between the two molded cups, which makes it have a form-fitting shape over each breast. Everything fits inside the cups; there are no removable pads that bunch up or hang out. I haven’t felt such support since I tested the Outdoor Voices Apex Bra. And you know the little gap between your boobs where the bra often holds the most stench? The Catalyst has breathable, perforated holes—called Tri-Flo ventilation—in this area to keep you cool and non-smelly. Another highlight is the grippy lining, which reduces any sort of slippage or movement. The grip sticks to your skin making this bra basically become a part of you.

I have so far put the Catalyst through four workouts, mixing it up on trail runs and in the gym, and have yet to wash it. While there is maybe a little smell beginning to foster, it seems to still be up for one more workout before needing to wash.

best running sports bra
Despite being wireless, the bra stabilizes breast movement with molded cups.
Lakota Gambill

To add one note of critique, the straps, as far as I was concerned, were its only flaw. While Knix made the “ladder” feature (straps with adjustable ridges) as a highlight, I wasn’t exactly able to test out its full usage. Bustier runners will likely appreciate this tightening and loosening mechanism, but for smaller chested runners like myself, the extra strap length after tightening felt flimsy while running. However, it’s something I am completely fine dealing with just because the bra is that great. I was unfamiliar with Knix before testing, but I plan on keeping this brand under my radar—and investing in another Catalyst.


Hannah, 36F: “Excellent support..but it has nothing on Shefit.”

The Knix Catalyst adjusts like a regular bra with three sets of hooks for individualized band width (I used the middle setting). The hooks make it super easy to take off; however, the bra itself has very little stretch, so it is slightly more difficult to put on than a regular bra.

Because of the lack of stretch, it feels a little tight and awkward when you first put it on, and I had to reposition the straps to stop them from rubbing my shoulder blades. Once this was corrected, the straps did not budge; no sliding off the shoulders!

knix catalyst sports bra
Secure, adjustable ladder straps.
Lakota Gambill

The Catalyst provides excellent support, and made me feel very secure while running and working out. Bonus: The molded cups prevented the smushed boob look, which tends to happen when I wear other sports bras.

But—it has nothing on Shefit. That’s still my favorite sports bra. The Catalyst is nice, and I think my boobs look better wearing it (major plus) but as far as fit and comfort are concerned, Shefit is my top pick.