Members of the McClintock High School Chargers football team practice for their upcoming season in Tempe, Arizona August 4, 2011. In a summer that has seen record heat, severe droughts and four football-practice deaths, scientists and climatologists say the risks for players are higher than ever. And they're cautioning coaches and teams to put health over victory as practice kicks off across the United States this week amid a historic heat wave. REUTERS/Joshua Lott (UNITED STATES - Tags: ENVIRONMENT SPORT)