Moses was born in
Dayton, Ohio. Having accepted an academic
scholarship to
Morehouse College in
Atlanta, Georgia, he majored in
physics and
industrial engineering, while competing for the school track team. Morehouse did not have its own track, so he used public high school facilities around the city to train. Initially, Moses competed mostly in the 120-yard hurdles and
440-yard dash. Before March 1976, he ran only one 400 m hurdles race, but once he began focusing on the event he made remarkable progress. His trademark technique was to take a consistent 13 steps between each of the hurdles, pulling away in the second half of the race as his rivals changed their stride pattern. That summer, he qualified for the US team for the
1976 Summer Olympics in
Montreal. In his first international meet, Moses won the gold medal and set a world record of 47.63 seconds.
After breaking his own world record the following year, Moses lost to
West Germany's
Harald Schmid on 26 August 1977 in
Berlin, his fourth defeat in the 400 m hurdles. Beginning the next week, when he beat Schmid by 15 meters in
Düsseldorf, Moses did not lose another race for nine years, nine months and nine days.
By the time American
Danny Harris beat Moses in
Madrid on June 4, 1987, Moses had won 122 consecutive races, set the world record two more times, won three World Cup titles, a World Championship gold, and earned his second Olympic gold medal in
Los Angeles, where he was selected to take the
Olympic Oath. After losing to Harris, he won 10 more races in a row, collecting his second world gold in Rome in August of the same year, and then he finished third in the final 400 m race of his career at the
1988 Summer Olympics in
Seoul.