A good sports bra provides more than sturdy support alone for female runners.
The increased breast support affects biomechanics in other parts of the body -- and, a new study shows, the right sports bra could actually boost a woman's running performance by 7%.
"Our study represents one of a series of research studies on the topic of breast support and whole body biomechanics," said Douglas Powell, of the Breast Biomechanics Research Center at the University of Memphis. "We wanted to identify strategies to reduce activity-induced breast pain for females, a group that makes up approximately 50% of the population."
For the study, published April 21 in Frontiers in Sports and Active Living, the researchers looked at the influence of breast support on knee joint stiffness during treadmill running. Knee joint stiffness is a measure of the knee's resistance to movement when force is applied.
It has been linked to lower oxygen consumption, improved running performance and running-related injury.
There were 12 recreational runners between 18 and 35 years of age professionally fitted with two sports bras. One had high support; the other, low support. The women had self-reported cup sizes of B, C or D.
As a control, participants were also asked to perform the experiment bare-chested.
Each runner did three-minute running bouts in each of the three randomized breast support conditions: high, low and bare.
With high support, the women had 5% increases in knee joint stiffness compared to no support. With low support, they had a 2% increase.
Combined with previous research by Powell and Hailey Fong of the Breast Biomechanics Research Center, this showed that a high-support sports bra can improve a female's running performance by 7%.
"The findings show that breast support not only influences movement of the breasts but that compensations occur across the entire body," Powell said in a journal news release. "These compensations can lead to reduced running performance, increased injury risk, and even the development of chronic pain such as back and chest pain."
Running offers many heart, vascular, musculoskeletal and mental health benefits. Good-quality running gear, such as supportive shoes, improves running performance and reduces injury risk. Yet, up to 72% of women experience breast pain while running.
"Our findings, in conjunction with previous research studies, show that sports bras should be considered not only as apparel, but also as sports equipment that can both improve performance and reduce the risk of injury, playing a role in women's health," Powell said.