[2] In 1912, at the age of 36, Østrup was appointed as the coach of the Danish squad that competed in the football tournament of the 1912 Olympic Games in Stockholm.

[5] Østrup became a member of the board of the Danish Football Association in 1911, and became its new vice-chairman later that same year, at the same time as Ludvig Sylow became the new chairman.

At DBU's representative board meeting on 25 February 1918, Østrup was elected as the 6th chairman of the country's football association, thus replacing Sylow in the post.

[1] His mandate ended in 1935 when he resigned from the union's board due to personal disagreements, being replaced by former Danish international Kristian Middelboe.

[2] He received the Order of Vasa of the 1st degree, the Norwegian Football Federation's badge of honor in gold, the Netherlands Football Association's badge of honour, the Boldklubben Frem's gold pin in 1946, and was posthumously named an honorary member of the club in 2009.