While Julius Lenhart always remained an Austrian citizen, he is sometimes listed as an American in Olympic results. This because he represented an American club at the 1904 Olympics. Between 1903 and 1906, Lenhart worked in a machine factory in Philadelphia, and had joined the local turnverein (German gymnastics club). Clubs were allowed to enter members that had signed up at least six months prior to the Olympics, which allowed Lenhart to compete for the Philadelphia Turngemeinde at the St. Louis Games. It is debatable whether his nationality should be considered as Austrian or American at the 1904 Olympics, but he is considered by the International Olympic Committee as a United States competitor, since he represented an American club.
A real gymnast, Lenhart performed poorly in the athletics events that formed part of the all-around competition, but his skills on the apparatuses made up for that and won him the title, while Philadelphia won the team event. Lenhart himself was aware that he was billed as an American champion, writing about his Olympic experiences in the Austrian Sportzeitung in 1936. Lenhart, who had spent some time in Germany prior to his spell in the US, returned to Austria in 1906 and quit gymnastics two years later to work as an engineer constructing machinery. The Austrian Olympic Committee recognized him as an Austrian champion only ten years after his death, using information supplied by Austrian Olympic historian Erich Kamper.