This is the progression of world record improvements of the 400 metres W45 division of Masters athletics.
Key
HandAutoAthleteNationalityBirthdateLocationDate56.14Angee Henry-Nott21 December 1975Ames: 23 July 202156.15Marie Lande Mathieu26 November 1956Carolina12 July 200356.82Mary Libal28 June 1950Buffalo22 July 199557.8 Jan Hynes3 April 1944Brisbane1 March 198959.68Colleen Mills23 November 1933Christchurch10 January 1981
References
Masters Athletics 400 m list