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.
Lamentations on Chemistry
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Lamentations on Chemistry 
I heard the suits only last 15-17 uses before they fall apart (sort like planned obsolescence in car parts?). At over $500 a pop that’s a good way to keep the market active.
I see no reason why this should not be a test of ACTUAL FITNESS rather than technology. In ode to ancient Greece the swimmers should (m/F) be nude and compete on the basis of their God given gifts. It’s like handing out calculators to kids in basic math.