According to the article, how did Bob kersee influence Gail Devers' athletic career

Bob Kersee was the first coach that ever push Gail Devers in overcoming her own limit. He did this by making Gail did a lot of hellish training that put her body into numbness and pain while re-building its capacity at the same time. Without the push from Bob Kersee, Gail Denvers wouldn't be capable in achieving the speed that he had today.