Why Aussie swimming queen retired at her peak?

IMAGE: Ariarne Titmus of Australia her third individual Olympic gold medal in a 400m freestyle final dubbed ‘the race of the century’. Photograph: Clodagh Kilcoyne/Reuters Australian......

PIX: Titmus times it perfectly to beat rival Ledecky

IMAGE: Australia's Ariarne Titmus celebrates after winning gold medal in the women's 400m freestyle at the Tokyo Olympic Games at Tokyo Aquatics Centre on Monday. Photograph: Davis Ramos/Getty......

CWG: Australia's Titmus wins women's 800m freestyle

IMAGE: Australia’s gold medallist Ariarne Titmus, silver medallist Jessica Ashwood and bronze medallist Kiah Melverton on the podium. Photograph: David Gray/Reuters Ariarne Titmus assumed......

PIX: Summer Time for Canada; O'Callaghan stuns Titmus

Images from Monday's swimming action at Paris La Defense Arena, Nanterre, France. IMAGE: Canada's Summer McIntosh celebrates winning gold in the Olympics swimming women's 400m Individual Medley at......

PIX: Titmus gets Australia off to a golden start in the pool

IMAGE: Gold medallist Ariarne Titmus of Australia, silver medallist Summer McIntosh of Canada and bronze medallist Katie Ledecky of United States on the victory stand for the Olympics women's 400m......