Le Sang was born to Le Van Hien (also known as Duc Quang) (1887-1959) and Nguyen Thi Mui (1887-1993). He was ill as a child, which made it difficult for him to walk, and his mother advised him to study a martial art in order to strengthen his legs.
In Hanoi he learned Vovinam at Nguyễn Lộc's Vovinam school. Soon Le Sang was a teacher himself and, together with Nguyễn Lộc, continued to develop Vovinam.
In 1954 Le Sang accompanied Nguyễn Lộc to Saigon to open a Vovinam class. He continued to open additional Vovinam schools and, as of 2007, is still teaching the higher-ranked students.
In 1960, Nguyễn Lộc passed the leadership of Vovinam to Le Sang.