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.