Louisville, Ky. ? A high school football coach behaved recklessly by adding sprints to the end of practice on a blistering hot day, a prosecutor said, explaining for the first time why he was charged with reckless homicide in player Max Gilpin’s death.

Jefferson County Commonwealth Attorney David Stengel cited the 50-yard sprints known as “gassers” — as well as Pleasure Ridge Park coach David Jason Stinson’s admonition that the players would run until someone quit — in a routine court document filed late Monday.