Shock Absorber Ultimate Run Bra. Focus on RUN When you run, your breasts move in a repetitive figure of 8 pattern. This continuous up and down and side-to-side movement can cause rubbing and chafing. That's why we created a bra specifically for running. Focus on Support The Infinity-8 support system designed for the RUN sports bra offers enhanced support to target excessive breast movement. The seam-free inner and concealed elastic under arms reduces any rubbing or chafing. During testing, we calculated a reduction of up to 78 percent bounce, giving you a more focused running bra for a more focused performance.