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Exercise unleashes a bounce bras can't handle
Breasts fly up and down a distance of up to 8 inches, study says
LiveScience

Updated: 1:45 p.m. ET Sept 11, 2007

Whether women are said to be flat-chested or big-busted, ordinary bras
fall short when it comes to supporting bouncing breasts, a new study claims.

And during exercise, women's breasts bounce more than previously
estimated, moving a vertical distance of up to around eight inches
compared with a past maximum measurement of six inches.

The bouncing, in some cases with breasts weighing 20 pounds or more, can
prove painful and damaging to the limited natural support system.

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.

In A-cup women, wearing a sports bra reduced overall breast movement by
53 percent, compared with a 55-percent reduction for G-cup women.

A pair of D-cup breasts weighs about 15 to 23 pounds.

But breasts have little natural support, Scurr says, although ligaments
and the skin are thought to do most or all of the work. Breasts are made
up of fat, milk ducts and connective tissues, such as collagen,
ligaments and blood vessels. The momentum created by intense bouncing
can stretch the breast's connective tissues, causing sagging and pain
for many women.