As one of the top entrants in Saturday’s U.S. Cross Country Championships here, Dathan Ritzenhein has to deal with an obstacle besides strong competition from Ryan Hall: a sore iliotibial band. Ritzenhein, who finished third at last year’s Championships, still feels soreness in his leg from running the Event Scotland Great Edinburgh Cross Country on January 12. That invitational competition utilized the same course which will be used at the IAAF World Cross Country Championships on March 30. “Ritz” found it challenging.