Scientists have for the first time identified the main sources of pain to the breasts during exercise in a bid to draw up new criteria for the ideal sports bra.

"Until now bras have been designed in a completely ad hoc way. It's amazing that the science hasn't been done before," quoted Joanna Scurr, director of the Breast Health Unit at the University of Portsmouth, in UK, who led the project, as saying.

The study monitored the breast movements of 15 female volunteers with a D-cup bra size as they ran on a treadmill.

Using infrared cameras, which monitored sensors attached to their chests, movement was tracked in 3D while the women ran without a bra, with an ordinary bra and with a sports bra.

The women then rated their discomfort on a 1-5 scale.

The study showed that the speed of breast movement accounted for 56 percent of pain during running.

The distance the breast moved accounted for 43 percent and acceleration 37 percent

Scurr's team also found that it was only the side-to-side motion of the breasts that hindered performance, suggesting that horizontal support was an important factor.

The study has been published in The Journal of Sports Sciences.