A sprinter, McManemin was a member of the Old Grammarians' Club in Auckland.[4] He became involved in athletics administration, and was elected to the committee of the Auckland Centre of the New Zealand Amateur Athletic Association in 1944.[5] He went on to become a sprint coach, mentoring New Zealand representatives including Doreen Porter, Valerie Morgan and Maurice Rae.[6]
He served on the organizing committees for both the 1950 British Empire Games in Auckland and the 1974 British Commonwealth Games in Christchurch.[7] With Norman Coop, he was co-founder of the 1990 Games Promotion Committee, which successfully bid in 1984 to stage the 1990 Commonwealth Games in Auckland.[8] McManemin then went on to chair the organizing committee for that event.[6]
McManemin served as president of both Athletics Auckland and Athletics New Zealand.[6] A Freemason, he was grand master of Freemasons New Zealand from 1986 to 1988.[1]