What Makes a Sports Bra Actually Work?

A conversation with Nicola, senior researcher in bra and breast biomechanics at the University of Portsmouth

In this episode, I speak with Nicola about the science behind sports bras, breast movement, and what actually contributes to support during activity.

Nicola works in breast and bra biomechanics, a field that looks at how breast tissue moves, how that movement changes during different activities, and how bras can help control that movement. We talk about why sports bras are much more than a comfort item: they are an important piece of equipment that can affect whether women feel able to run, train, compete, and stay physically active.

A major focus of the conversation is a University of Portsmouth study looking at how different sports bra design features affect performance. The study tested 98 sports bras on 77 women in 34B and 34D sizes to understand which design features reduced breast movement during running.

The paper identified five key sports bra characteristics linked to performance:

• Bra style: Encapsulation and combination styles performed better than compression-only styles.
• Material: Bras made primarily from nylon performed better than those made primarily from polyester.
• Underband adjustability: Adjustable underbands were linked with better support than pullover styles.
• Padding: Padding appeared to contribute to movement reduction, not just modesty.
• Neckline height: Higher necklines were associated with better support than lower necklines.

One of the most interesting parts of the episode is the idea that sports bra performance is not just about making a bra tighter. Breast tissue moves forward and back, side to side, and up and down, and different sports create different movement patterns. This means a bra that works well for running may not be the same bra someone wants for weightlifting, rowing, golf, or other sports.

Nicola also explains why compression bras are not always enough, especially for larger cup sizes. Compression styles hold the breasts against the chest wall, while encapsulation styles support each breast individually. Combination styles can offer both the structure of encapsulation and the familiar “held in” feeling of compression.

We also discuss how much is still unknown. Even after identifying several design features that contribute to sports bra performance, a large portion of what makes a sports bra work remains unexplained. That leaves room for more research into fit, materials, movement, comfort, breathing, and sport-specific design.

Sports bras are often treated as a simple clothing purchase, but this conversation frames them as a health and participation issue. A poorly fitting or poorly performing sports bra can affect comfort, confidence, posture, breathing, and whether someone wants to keep participating in sport or exercise.

Nicola also talks about the importance of getting this information to the people who need it, including athletes, school girls, and everyday consumers. The goal is not just better products, but better education, so women and girls know they do not have to accept pain, discomfort, or lack of support as normal.

Referenced paper: Norris, M., Blackmore, T., Horler, B., & Wakefield-Scurr, J. (2021). “How the characteristics of sports bras affect their performance.” Ergonomics, 64(3), 410–425. doi: 10.1080/00140139.2020.1829090

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