[4] As a young man, Frederiksen was an active football player in Akademisk Boldklub, where he was a big and heavy defender, helping the club win the Danish championship in 1919.
[4] He held that position for 15 years and one of the first tasks of district court prosecutor Leo Frederiksen was to contribute to the introduction of the Tips service.
20,000 participants, who went from the Sports Park to Christiansborg to support the cause, was for 21 years vice-chairman of the tip service's board.
[4] From 1957 to 1965, Frederiksen was chairman of Denmark's Olympic Committee, was a supporter of the Olympiad's original idea that participation was more important than victory, and was strongly dissatisfied with the commercialization of sports and the competitive hysteria that surrounded the international events, so rather that the amateur work in the small clubs was promoted, had as its motto "sport for all of all".
Became a Knight of Dannebrog in 1939, Dannebrogsman in 1948 and was honored as Denmark's Sports Confederation's first honorary president upon his departure in 1962.