Rowing, particularly sculling, inflicts on the individual in every race a level of pain associated with few other sports. There was certainly pain in football during a head-on collision, pain in other sports on the occasion of a serious injury. That was more the threat of pain; in rowing there was the absolute guarantee of it every time.
David Halberstam (2012). “The Amateurs: The Story of Four Young Men and Their Quest for an Olympic Gold Medal”, p.73, Open Road Media