WASHINGTON, D.C. - Former Iowa wrestling coach Dan Gable is one of 20 Americans recently named, by President George W. Bush, to the President's Council on Physical Fitness and Sports.    President Bush recently presented the new members on the south lawn of the White House at a Fitness Expo where he anounced his "Healthier US" initiative.  The council's platform is to make America a healthier place by encouraging individual responsibility, exercise and healthy life choices.    Besides Gable, some of the new appointees include chairman Lynn Swann, vice-chair Dot Richardson, M.D., Nomar Garciaparra, Marion Jones, Nancy Lopez and Emmitt Smith.    Gable, a gold-medalist at the 1972 Olympic games, is the all-time winningest wrestling coach at the University of Iowa.  From 1977 to 1997 he compiled a career record of 355-21-5.  During his tenure, he led the Hawkeyes to 15 NCAA team titles and 21 Big Ten titles.  Gable also coached the 1980, 1984 and 2000 United States Olympic wrestling squads.  He coached 152 all-Americans, 45 NCAA champions, 106 Big Ten champions and 10 Olympians.