Adolph Plummer was an American track and field athlete. He is best known for breaking the world record in the 440 yard dash in 1963, the last runner to hold the 400 m record with a time recorded for the longer 440 yards. Adolph Plummer (United States) set the men's 400 m world record of 44.9 in Tempe, USA on May 25, 1963. It stood 16 months, until Mike Larrabee's 44.9 on September 12, 1964 (equalling it). Wiki link