A sports bra is an essential piece of running kit, regardless of your cup size. Your breasts move in a continuous figure of 8 motion whilst you run, causing strain to your Cooper's ligaments (the tissue that maintains the structural integrity of your breasts). Left unsupported, impact repetition can lead to irreparable damage of this tissue, causing your breasts to sag and lose their natural shape. There are different types of sports bra designed to support your body throughout low, medium and high impact activities in a way that your regular bra cannot, leaving you free to perform at your best.