Answer
In 1923, Paavo Nurmi became the first runner to hold simultaneous world records in the mile, the 5000 m and the 10,000 m races. He had previously set the world record in the mile in 1921 and the world record in the 5000 m in 1922. In 1923, he broke his own world record in the mile and also set a new world record in the 10,000 m.