Amyotrophic lateral sclerosis (ALS) strikes without warning. The condition, which strips nerve cells of their ability to interact with the body's muscles, starts painlessly, with subtle initial symptoms—such as stumbling, increased clumsiness and slurred speech—that are often overlooked. The disease itself attracted little public attention until legendary New York Yankees first baseman Lou Gehrig began dropping balls and collapsing on the field for no apparent reason. Known as the Iron Horse for playing in 2,130 consecutive games over 14 years, Gehrig was diagnosed with ALS in June 1939 and delivered a poignant farewell at Yankee Stadium the next month. Gehrig's loss of muscle control progressed so rapidly that by December he was too weak to attend his National Baseball Hall of Fame induction. Creeping paralysis eventually left him bedridden. He died in June 1941 at the age of 37.