Wochit News - Chris Borland, a 24-year-old linebacker for the San Francisco 49ers and one of the most promising rookies in the NFL last year, says he's quitting the game because he doesn't want to risk long-term brain injury. He told ESPN's "Outside the Line" on Monday, "I just honestly want to do what's best for my health. From what I've researched and what I've experienced, I don't think it's worth the risk."