When the L.A. Marathon takes place Sunday, one of the runners will attempt to set the record for the heaviest person ever to complete a marathon. Kelly Gneiting of Fort Defiance, Arizona, weighs about 400 pounds. “I am a sumo wrestler and I’ve represented the United States for the last seven years at the World Sumo Championships or World Games,” he said at a news conference Saturday at Dodger Stadium. “I don’t think anyone has used the word `marathon’ and `sumo’ in the same sentence,” he said. “I like the aspect of the two opposite-spectrum sports — sumo and marathon...