A lot of science has gone into developing footwear that provides runners with optimal support so they can avoid injury. However, there is another part of the body that requires extra support. The female breast contains no muscles and has only two weak support structures, the skin and the Cooper’s ligaments. When a woman runs, unrestrained breasts move independently, stretching the ligaments and skin, causing tension and often pain.
Like many sports medicine experts, Douglas Powell, of the University of Memphis, was focused on how footwear affects running biomechanics. Then one day he asked researcher Hailey Fong to run on a treadmill for one of their studies and she replied that she couldn’t because she wasn’t wearing her sports bra.
“I asked her how much it really mattered,” recalls Powell. “And every woman in the room looked at me with daggers in their eyes.”
Powell learnt this was an area where comparatively little research had been done. UK scientists had looked at how much the breasts move when a woman runs – for an average-sized person, it’s about 15cm of independent movement. Powell was interested in investigating how this may impact on the rest of the body. That is what he and his colleagues are now busy doing at the Breast Biomechanics Research Centre.
Their most recently published research confirms that the type of sports bra makes a difference. Using motion capture photography and an instrumented treadmill, they asked 12 participants to run without any breast support, and in two different bras, one high support and the other low.
They found the type of bra influenced more than breast movement. Compensations occurred across the entire body. Basically, without adequate support, the women unconsciously ran in a different way as they tried to minimise bouncing and discomfort.
“Those compensations can lead to reduced running performance and injury,” says Powell.
In another, as yet unpublished, study, the team has looked at the effect of quick changes of direction.
“As the trunk rotates, if there isn’t sufficient breast support, then the breasts actually lag behind,” explains Powell. “This changes how the lower extremities interreact with the trunk in a way that is associated with cruciate ligament damage.”
There is no shortage of willing participants for this research. “When you start to tell women what you’re doing, they’re 100% on board because the equipment as it is right now is not good enough.”
Powell believes at least part of the problem is that we tend to view sports bras as apparel rather than protective athletic equipment, so there has been limited evolution in design. “The million-dollar question is how can we make the best sports bra?”
Currently, they tend to come in two types. The compression style hugs the breasts firmly to the chest, while the encapsulation style supports them in two separate cups. Powell says a combination of both seems to be best.
“Some of our preliminary data suggests that an encapsulated bra is better at controlling breast motion. And you need it to be compressive enough around the ribcage to maintain breast position, but not so compressive that your ribcage can’t expand to breathe.”
Other complicating factors include that women come in many different shapes and sizes and that the menstrual cycle changes the size of the breasts and therefore their mechanical force – one of the centre’s projects is to measure exactly how much breasts change during a cycle.
Up to 72% of women experience breast pain while running. This can be a deterrent to exercise, but there is no evidence it is actually harmful to breast health.
“There is no evidence that it isn’t, either,” says Powell. “If we’re creating strain that exceeds the breast tissue’s ability to absorb, we’re going to produce an inflammatory response.”
His team aims to produce improved designs for sports bras, as well as new ways of modelling and measuring breast movement. It is tricky work for a male researcher – there are ethical hoops to jump through and he can’t be present at any of the data collections. Powell says some people seem surprised to find a man doing this kind of research at all. “But by the time my eldest daughter, who is seven, reaches maturity, I hope to have developed a better product than what is out there right now.”
