 A 2007 study found that encapsulation-type sports bras, in which each cup is separately molded, are more effective than compression-type bras, which press the breasts close to the body, at reducing total breast motion during exercise.Encapsulation bras reduce motion in two of the three planes, while compression bras reduce motion in only one plane.Previously, it was commonly believed that a woman with small to medium-size breasts benefited most from a compression-type sports bra, and women with larger breasts need an encapsulation-type sports bra.