Over 50% of women who exercise experience pain because their breasts bounce more during a workout, said a University of Portsmouth researcher.
Dr Joanna Scurr said that her new study showed that regular bras and some sports bras were not effective.
They are designed to stop the bounce but Dr Scurr's study shows that breasts also move side-to-side and in and out.
She is hoping to develop a "smart fabric" that can provide custom-made support for each woman.
Size does not matter
Her studies have lead to invitations to work with the military, the NHS and with lingerie manufacturers.
The challenge is to find a material and a design that would contain movement in the three directions, she said.
"Sports science has always been dominated by men and for them, studying breasts is seen as slightly laughable"
During exercise, breasts bounce more - up to 21cm (8in) rather than the maximum 16cm (6in) bounce measured in past studies.
Size makes no difference - from an A cup to a double-FF cup the impact is the same whether they are doing a slow jog or a fast sprint, the study showed.
"If women wore the correct form of support, if we can get that right, the use of pain medication is reduced and women can be active and lead healthy lives," said Dr Scurr.
"Sports science has always been dominated by men and for them, studying breasts is seen as slightly laughable. For women, though, it's completely credible - they can see the benefits."
Seventy women were recruited for the two-year study through the university's student and staff population, gyms and doctors' surgeries.
Those chosen represent the widest range of breast sizes ever studied including women with cup sizes DD, E, F, FF, G, H, HH, J and JJ.
The glamour model Jordan has a cup size of F, six sizes smaller than Dr Scurr's biggest breasted subject.
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