An Athletic Union or Athletics Union (AU) usually refers to the group of student sports clubs within a university or other institute of higher education, in the United Kingdom.
Sports clubs affiliate to their Athletic Union for support and finance. If a sports club is not part of the Athletic Union then it is probably not an official or recognized club of the institution.
The Athletic Union is often run and supported by the institute's students' union, but are sometimes operated by the institute itself or semi-autonomous from either the students' union or the university. Athletic Unions can (and most do) affiliate to British Universities and Colleges Sport (BUCS).
In a typical structure, members of sports clubs automatically become members of the Athletic Union with all the benefits of the membership (including insurance and social aspects) included. Individual students who compete in individual sports, where no club exists in their chosen activity, can also join the Athletic Union.
Officers of the sports clubs become ex officio members of the AU Standing Committee and this committee elects an AU Chair and Vice-Chair. The AU President (sometimes called Sports Officer or Activities Officer) is usually elected from the wider student body as part of Executive Committee elections.
Many Athletic Unions employ a person (or persons) to work alongside the AU President in support of the sports clubs, and to keep a continuity from year to year within the Athletic Union.