Arthur Cusack was the coach of Olympic Gold medal winner David Theile, who, under the guidance of Cusack, won gold in the 100m backstroke in the 1956 Melbourne Olympics and the 1960 Rome Olympics. He also won the silver in the 4 x 100m Medley Relay team at the same games in Rome.
Arthur Cusack also coached his nephew Robert Cusack, who won a bronze medal along with Michael Wenden, Bob Windle and Greg Rogers in the 4x100m freestyle relay at the 1968 Mexico City Olympics. He also coached Ann Margaret Nelson, a finalist in the 110-yard backstroke in the Cardiff 1958 British Empire and Commonwealth Games, where she finished fifth with a time of 1.15.5, behind Judy Grinham of England.
Arthur Cusack is the great uncle of Simon Cusack, Robert Cusack's son. The head Coach of Indooroopilly Swimming Club, Simon Cusack is the coach of Australian swimmers Cate Campbell and triple Olympic Gold medalist Jodie Henry.
Arthur Cusack introduced a controversial backstroke turn and a bent-arm stroke to assist David Theile in his quest for Olympic gold. This new turning technique was seen as suspect by some officials during the heats of the 100m Backstroke at the 1956 Olympics, who wanted Theile to give a demonstration for their review, a request Cusack refused. The turn was not subsequently used by Thiele during the final, but during the 1957 Queensland Championships, Theile was disqualified for the only time in his career when officials ruled that the turning style was illegal. However, this turning style was soon adopted by other swimmers copying the turn and is still used primarily by Backstrokers today.
In 1938, at just 18 years old, Cusack became the Secretary of the newly formed Maryborough Amateur Swimming Club. He, along with Des Ramsay, became a Coach at the club at the end of the Second World War. David Thiele was initially coached by Ramsay, but soon switched to Cusack, even though Cusack was thought to be a difficult coach by many swimmers, as he would require long, tiring sessions in the pool. In 1958, Cusack left Maryborough.
In 1962, Cusack was appointed as a coach on the Australian 1962 Commonwealth Games Team in Perth. In the mid-60s, Cusack took over the lease of the Centenary Pool in Brisbane. It was from here that he would take on the coaching of his nephew Robert Cusack into the Australian Olympic Team. In 1970, Cusack was again named a coach on the Australian Commonwealth Games team for the Edinburgh Games, this time as coach of the Women's team.
Cusack was a member of the Australian Olympic Committee for many years. He is a Merit Award Recipient and is on the Honour Roll of the Australian Olympic Committee, - Queensland Olympic Council for his services to Olympic Swimming and the Olympic Movement in Australia.
Arthur Cusack passed away in 2000.
On December 24, 2007, at the Queensland Swimming championships in Brisbane, Queensland, Arthur Cusack was posthumously inducted into the Queensland Swimming Association Hall of Fame.