Per MSNBC: Exercise unleashes a bounce bras can't handle

While brassieres have evolved throughout history from body-binding corsets to cleavage-enhancing "miracle" bras, only recently have researchers injected a dose of science into the design of undergarments that go beyond conferring a more "perky" look, the researcher says.

"It is only recently that bra design has turned to science," said study author Joanna Scurr, a biomechanics professor at the University of Portsmouth in England. "There was no research. It’s like designing a car or kitchen equipment without first thinking 'what is the purpose of this?'"

Scurr will present her research this week at an annual meeting for the British Association of Sport and Exercise Sciences in Bath.

Breast biomechanics
Scurr recruited 70 women, including students and faculty from the University of Portsmouth, with bra sizes ranging from A-cup to extra-large (DD, E, FF, G, H, HH, J and JJ were included).

Each woman walked, jogged and ran while wearing different bra types. During the exercise, Scurr took biomechanical measurements, including the amount of breast movement in three directions: up-and-down, side-to-side and in-and-out.

During walking exercise, the women's breasts moved relatively the same amount in all directions. But when participants sped up to a jog or run, their breasts moved proportionally more in some directions than others: More than 50 percent of the total movement was in the up-down direction, 22 percent side-to-side and 27 percent in-and-out.

The overall pattern of the movement resembled a figure-8.

Typically, bras are designed to minimize up-and-down motion and not the other two dimensions of breast movement found in Scurr's study.

For all cup sizes, the so-called encapsulation bras in which each cup is separately molded provided the most support, beating out the compression bras, which limit only the up-and-down motion. The encapsulation bras limit some of the movement in the other directions as well.