For decades, women have accepted an uncomfortable tradeoff when it comes to sports bras.
If it's supportive, it must be tight.
If it keeps everything in place, it's supposed to leave marks.
If you can't wait to take it off after your workout, that's just part of being an athlete.
But what if we've been thinking about sports bra fit all wrong?
That's the question Ruby Wyles has spent years exploring.
A recent graduate with a master's degree in exercise physiology, an NCAA Division I runner, and one of the athlete fit testers behind Paradis Sport's first sports bras, Ruby sits at the intersection of science and sport. She's just as comfortable reading research papers on respiratory mechanics as she is logging miles on the roads and trails, and she's passionate about helping women better understand how the gear they wear can influence both comfort and performance.
Throughout graduate school, Ruby kept coming back to one surprising reality: women remain dramatically underrepresented in sports science research.
"Only about six percent of sport and exercise science research has focused exclusively on women," she says.
Think about that for a moment.
Women's performance apparel is a multi-billion-dollar industry, yet much of what we know about human performance has historically been built from research conducted on men. While that gap has begun to narrow, there is still remarkably little evidence focused specifically on women's physiology and the products designed for them.
"It's one of the reasons I'm so passionate about this topic," Ruby says. "Women deserve better—not just better products, but better research and better education."
Ask almost any woman how a sports bra should feel, and chances are you'll hear words like tight, compressive, or locked in.
The problem?
Those beliefs didn't necessarily come from science.
"For centuries, society has sold women the idea that chest support comes at the cost of comfort," Ruby explains. "We've been conditioned to believe that support and restriction go hand in hand."
The result is that many women assume discomfort is simply part of wearing a sports bra.
Pressure marks around the rib cage.
Difficulty taking a deep breath.
Counting down the minutes until they can finally take it off.
We've normalized all of it.
"But supportive and restrictive aren't the same thing," Ruby says. "They don't have to coexist."
Like many athletes, Ruby spent years choosing sports bras that felt as snug as possible.
Then she read a study that completely changed the way she thought about fit.
In 2024, former Olympian and researcher Dr. Shalaya Kipp and colleagues published groundbreaking research examining how sports bra restriction affects breathing during exercise. The researchers found that overly restrictive sports bras limited chest wall expansion, increased the work required by the muscles involved in breathing, and reduced breathing efficiency during exercise. They also found that many women were choosing sports bras that were more restrictive than necessary.
"When I read that paper, a light bulb went off," Ruby says.
"Of course the bottom band matters. If it restricts the movement of your diaphragm and rib cage, it's going to influence how you breathe during exercise."
The science challenged something she'd accepted for years.
Rather than sizing down for a tighter fit, she actually sized up.
"It was a no-brainer," she says. "I haven't looked back."
Hearing that tighter isn't always better doesn't mean women should wear loose sports bras.
Quite the opposite.
The goal is finding the balance between support and freedom of movement.
Research has shown that inadequate breast support can increase breast movement, alter running mechanics, and increase the forces absorbed by the body while running. Too little support has consequences, too.
"The conversation shouldn't be tight versus loose," Ruby explains. "It should be about finding support that allows you to move naturally and breathe comfortably."
Ruby offers a few surprisingly simple guidelines.
If your sports bra feels restrictive while you're standing still, it's probably too tight.
"If it feels too tight at your resting breathing rate," she says, "it most certainly will restrict your breathing mechanics once your respiratory rate increases during exercise."
She also recommends paying attention after your workout.
Deep pressure marks around your rib cage are often a sign that your bra is doing more squeezing than supporting.
On the other hand, visible gaps or creases in the fabric can indicate the bra isn't providing enough support.
Her biggest piece of advice?
Don't be afraid to experiment.
Many women have spent years—sometimes decades—wearing sports bras that all fit similarly. Trying a different size or a different style may feel unfamiliar at first, but that doesn't necessarily mean it's wrong.
"It can take time to adjust to a different feeling," Ruby says. "Just because a bra isn't squeezing you doesn't mean it isn't supporting you."
One of the ideas Ruby keeps coming back to has nothing to do with elite athletes.
It's about girls.
Long before women ever line up for a race or join a gym, they're learning what a sports bra is "supposed" to feel like.
Those lessons usually come from mothers, sisters, coaches, and teammates—not from science.
"Girls inherit their beliefs about sports bra fit from the women around them," Ruby says. "Without better education, we continue passing along the idea that support has to mean discomfort."
Research has even linked breast-related concerns—including discomfort, excessive movement, and difficulty finding a well-fitting sports bra—to girls dropping out of sport during adolescence. That's a powerful reminder that sports bra conversations aren't just about performance—they're about participation.
Helping women understand how a sports bra should actually fit doesn't just benefit today's athletes.
It helps shape the experiences of the next generation, too.
When Paradis Sport began developing its first sports bras, athlete feedback wasn't an afterthought—it was central to the process.
Women representing different sports, body types, support needs, and activity levels wore multiple prototypes over months of testing, providing detailed feedback throughout development.
For Ruby, one design choice stood out immediately.
"The wide, stretchable bottom band."
Rather than relying on an extremely rigid band for support, Paradis designed both the Merino Blend Racerback Bra and the TurboDry Sports Bra with four-way stretch fabrics and an interior support system intended to move with the body while still providing support.
"I was really interested in how Paradis would balance support with unrestricted breathing," Ruby says. "I tested multiple sizes, and I was impressed that neither felt restrictive while still providing support."
She admits she was initially skeptical of how such soft fabrics would perform during hard workouts.
"I honestly wondered if they'd hold onto sweat."
Instead, she found the opposite.
The TurboDry fabric wicked moisture efficiently and dried quickly, while the Merino Blend delivered the natural temperature regulation, moisture management, and comfort merino wool is known for.
Months into testing, she's continued reaching for both.
Perhaps the biggest takeaway from Ruby's work isn't about one particular sports bra.
It's about changing the conversation.
Support shouldn't require sacrificing comfort.
Performance shouldn't come at the expense of breathing.
And women shouldn't have to accept discomfort simply because that's how it's always been.
"Performance," Ruby says, "is the outcome of optimizing all the variables that contribute toward a goal."
Sometimes those variables include training.
Sometimes they include nutrition.
And sometimes, they're as simple—and as overlooked—as the sports bra you're wearing.
Editor's Note: Ruby Wyles participated as one of the athlete fit testers throughout the development of the Paradis Sport Merino Blend Racerback Bra and TurboDry Sports Bra. Her feedback, alongside that of a diverse group of athletes across sports and body types, helped inform the final designs.
