How to choose a sports bra, with advice from a bra fitter, netball player and scientist

How do you tell if a sports bra is the wrong size?

One of the biggest mistakes shoppers make is assuming that if a sports bra feels tight, that’s enough. In reality, support comes from the right fit rather than simply compressing your chest.

Cardwell advises thoroughly testing a sports bra by moving in it in the same way as you will during the sport you will be doing. “Your breasts don’t just move up and down,” she says. “They move all around – circles, up, down, left, right. We want to try and restrict that as much as possible, but not to the extreme where you’re not able to breathe.”

What is a high impact sports bra?

High-impact sports bras are designed for activities where your breasts experience the greatest movement, such as running, HIIT, tennis and netball. Their job is to minimise breast movement in every direction, helping reduce discomfort while allowing you to move more efficiently.

To measure how high-impact a sports bra is, Wakefield-Scurr asks women to run in a laboratory, both without a bra and while wearing different sports bras. “For a bra to be classed as high support, it has to reduce breast movement above certain thresholds,” she says. “If your breasts move 10 centimetres without a bra and five centimetres in a sports bra, that bra has reduced breast movement by 50 per cent.”

In the lab, Wakefield-Scurr and her team found that “if you run in low support compared with high support, you reduce your stride length by four centimetres. Four centimetres might not sound like a lot, but over the course of a marathon, those four centimetres add up to around a mile.” This proves that wearing a high-support bra doesn’t just keep you comfortable, but it can improve your athletic performance.

Cardwell, who wears a double G cup, says high-impact support has improved dramatically in recent years. “There has been a lot more research into high-impact sports bras, especially for larger-chested women.” She also warns against assuming that every sports bra offers the same level of support. “If it’s the same material as a smaller cup size, it’s probably not going to be sufficient for someone like me with double Gs.”

How often should you replace your sports bra?

There’s no set rule for replacing a sports bra, according to Wakefield-Scurr. This is because its lifespan depends more on how you care for it than how often you wear it. “The lifespan of a sports bra is affected more by how you wash and dry it than by how often you wear it,” she says. In one of her team’s studies, support dropped by around a third after 25 washes. “Always follow the washing instructions,” she advises. “You’d be surprised how many sports bras should be hand washed or washed at a lower temperature.”

Looking after your sports bra properly will help it last longer, but no bra lasts forever. Once the underband loses its elasticity or the support noticeably decreases, it’s time to replace it to ensure you have the right level of support.