For many, the words "training camp" and "summer" are synonymous with American football and particularly the NFL.
Ever since George Plimpton's 1966 book "Paper Lion" first drew back the curtain on what takes place inside a professional football camp, sports fans have been fascinated by the annual rite of passage.
Training camp has grown from obscure practice in Plimpton's day to full-on extravaganza in recent years, with spectators flocking in their thousands to university campuses around the United States to watch their favorite players run drills and participate in one-on-ones.