Scientists in the UK have found that when it comes to exercising, regular bras and some sports bras are not effective in supporting women's breasts.
Researcher Dr. Joanna Scurr from Portsmouth University conducted a study on women and found that during exercise a woman's breasts move in three directions, including forwards and back, whereas bras are designed only to stop up and down movement.
Dr. Scurr says an estimated 60 per cent of women suffer breast pain when doing even a gentle form of exercise, and others are embarrassed by the bouncing caused when running.
As a rule bras are designed to stop the bounce but according to the researchers breasts also move side-to-side and in and out.
Biomechanical data of 70 women of varying breast sizes was studied and Dr. Scurr says a "smart fabric" is needed that can provide custom-made support for each woman which would contain movement in the three directions.
The study revealed that during exercise, breasts bounce more than was measured in past studies and size made no difference; whether breasts were an A cup or a double-FF cup the impact was exactly the same whether they were doing a slow jog or a fast sprint.
Dr. Scurr who is a sports scientist, says if women wore the correct form of support, the use of pain medication would be reduced and women would be encouraged to be active and therefore lead healthier lives.
Dr. Scurr says the domination of sports science by men and for men, has made the study of breasts in relation to exercise something of a joke, but for women it is credible and they can see the benefits.
For the two-year study seventy women were recruited through the university's student and staff population, gyms and doctors' surgeries and they represented the widest range of breast sizes ever studied including women with cup sizes DD, E, F, FF, G, H, HH, J and JJ.
The Portsmouth team are studying the biomechanics of breasts during exercise and other activities to better understand the stresses and forces involved.
The researchers say the design of bras is in need of a complete overhaul if women are to be encouraged to do more sport.
They reached the conclusion that the best form of support currently available is an encapsulation bra, which has separate moulded cups, which allow each breast to move independently and provide more sideways support.
The research is due to be presented this week at the British Association of Sport and Exercise Sciences's annual conference in Bath.