A detailed description of the swim suits worn by the US Olympic Team can be found in the US patent application by Speedo International, US 2008/0141431.  These sophisticated garments are multilayer, multipanel affairs that the inventors claim will reduce surface and form drag in the water. According to section [0066] of the description, the stretch constant of a given panel can be defined by the manufacturer so as to provide more or less compression to a particular part of the torso.