John Smith explains relay exchange

John Smith explains relay exchange both 4x100 and 4x400.
John Walton Smith (born August 5, 1950 in Los Angeles, California) is a former American athlete, who competed in the sprints events during his career. He is best known for winning the men's 400 metres event at the 1971 Pan American Games.
Smith was the AAU 440y champion in 1970-1971, breaking the world record with 44.5 for 440y at the 1971 meet. He also won the NCAAs in 1971-1972, running for UCLA. Smith was world-ranked #1 in 1971 and was the likely favorite for the 1972 Summer Olympics in the 400 metres. He made the final but an injured hamstring caused him to pull up on the first curve of the final. He has since became a well-known sprint coach, training Maurice Greene and Ato Boldon amongst others.
Taken from Wikipedia, the free encyclopedia.