Wilma Unlimited: How Wilma Rudolph Became the World's Fastest Woman

""No one expected such a tiny girl to have a first birthday,"" begins this inspiring biographical sketch of a legendary track stars. Born in 1940 in Tennessee, the chronically sickly though ""lively"" Rudolph contracted polio just before her fifth birthday. Though not expected to walk again, the fiercely determined girl persevered with her leg exercises; by the time she was 12, she no longer needed her steel brace. Eight years later, Rudolph represented the U.S. in the 1960 Olympics in Rome, where, despite a twisted ankle, she became the first American woman to win three gold medals during a single Olympic competition. Krull's (Lives of the Musicians) characteristic, conversational style serves her especially well here. Through her words the nearly superhuman Rudolph seems both personable and recognizable. Rendered in acrylic, watercolor and gouache, Caldecott Medalist Diaz's (Smoky Night) imposing, richly hued illustrations have a distinctive, cubist feel. The artist's bold design superimposes this art against sepia-toned photographs of relevant background images: playground sand, wooden fence slats, the gravel of a running track. This juxtaposition yields busy, effectively textured pages, flawed only by the text's curiously embellished font-the letters look as though they have been speckled with either ink blots or dust. A triumphant story, triumphantly relayed. Ages 7-12. (Apr.)