Joe is a 17-year-old high school football player who is 6' 1" and weighs 291 pounds. He practiced with his team in 95-degree heat in mid-August. Joe was pushing himself to do well—recruiters might be at the next game—and had been sweating profusely for the last few minutes. He began missing assignments and became confused during the plays. Steve, a teammate, noticed that Joe had stopped sweating and seemed incoherent.