Any longtime Pittsburgh Steelers fan will remember the scary results that playing in Denver had for Safety Ryan Clark. After experiencing some abdominal pain following his first game at Mile High Stadium as a member of the Washington Redskins in 2005, Clark bounced back fairly quickly. Playing for Pittsburgh at Denver in 2007, however, had a much more serious result. Clark suffered illness for over a month, eventually being diagnosed with a splenic infarction and undergoing a splenectomy and shortly after that a surgery to remove his gallbladder. It turned out that Clark, a carrier of the sickle cell trait, couldn’t handle the altitude’s effect on his red blood cells.