Is your sports bra hindering your running performance?

Most people who wear sports bras have experienced the unpleasant sensation of a too-tight fit that restricts your breathing. If you’ve ever wondered if the tightness of your sports bra could be slowing you down, you’re in luck—a group of scientists (including American Olympian Shalaya Kipp) decided to put this to the test. “Have you ever wondered if the underband of a sports bra can restrict breathing mechanics and increase oxygen consumption? Yeah, me too,” Kipp shared on Instagram. Here’s what you need to know.

 

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A post shared by Shalaya Kipp (@shalayakipp)

The study

Scientists from the University of British Columbia partnered with Lululemon to fit a custom bra for nine elite women athletes. They then changed the underband tightness of the bra, while measuring band pressure, with the runners completing a day of harder running and a day of easier running in the different bra conditions.

Kipp explains that the research team used balloon catheters inserted into the esophagus, measuring the pressure in the area around the lungs and the amount of air that moves into or out of the lungs, to calculate the work performed by the respiratory muscles. Check out Kipp’s post to view how the esophageal balloons were placed (“Yes, the women in our study completed all the running like this,” Kipps writes) as well as to check out where the catheter was situated.

“What did we find? Increasing the pressure of the sports bra underband increased the amount of mechanical work the respiratory muscles had to perform, and increased whole-body oxygen consumption (running economy was worse),” Kipp says. “On average, we saw a 1.3 per cent increase in VO2 [the difference between oxygen taken in and breathed out in a unit of time] from the loose-to-tight condition (range: -0.3 to 3.2 per cent).” An increase in VO2 means that the respiratory system is working at a higher intensity, and would limit performance. The researchers also noted that the runners changed their breathing patterns, taking faster, shallower breaths as band tightness was increased.

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The takeaway

Kipp puts the study into context for regular runners: “…for an individual running a three-hour marathon, a two per cent improvement in VO2 would equate to a three-minute improvement (some women could see some real performance benefits if they loosened their sports bras).”

Spoiler: the answer might be yes 😉

Great work @ShalayaKipp & team! https://t.co/7U3PAVrSIQ

— Sian Allen (@DrSianAllen) February 19, 2024

Pro athletes chimed in on social media, suggesting further areas of discussion around this issue. “This is fascinating! I have wondered about this and also wondered if it heated up the core of women on hot days compared to the men’s loose singlets,” wrote American Olympian Kara Goucher. “I’ve also been thinking about the increase in mechanical work of respiration when you put on a running vest for trail/ultra running, adding another layer of tightness AND 500mL soft flasks on top of each side,” ultra-trail pro Corinne Malcolm wrote.

Kipp added: “Something that I think about a lot now is most women pick a sports bra size based on how the bra feels at rest and not exercise, which might contribute to women wearing bras that provide too much restriction during exercise.”