BOSTON -- For more than a century, runners at the start of the Boston Marathon have faced a breeze blowing in from the Atlantic and a dread that Heartbreak Hill will sap their strength.Long regarded as one of the world's toughest courses, Boston has spurned professional pacesetters while encouraging tactics that favor strategy over speed. But Kenyan Robert Kiprono Cheruiyot upended that mindset last year, dashing from Hopkinton to Copley Square in 2 hours, 5 minutes, 52 seconds to shatter the course record by 1:22."I always knew it was possible to run fast times here. He showed us that it is," said Ryan Hall, who finished third in 2009 and last year ran the fastest ever time for an American in Boston. "You've got to be ready to run fast. You can't think, 'I'm going to run 2:09, 2:10 in Boston and blow everyone's socks off.' The game has definitely changed."