Known for his versatility, he is the only male swimmer to represent Australia at the Olympics in all freestyle distances from 100 m to 1500 m. During his career, Windle set six world records and won six Commonwealth Games gold medals.
Aged 15, his second-place finish in the 1650 yd freestyle earned him a place on the team for the 1960 Summer Olympics in Rome.
He won three individual titles in 1964 and proceeded to the Tokyo Olympics where he was eliminated in the heats of the 400 m freestyle after attempting to save energy for the final.
In response, Windle took an aggressive approach in the 1500 m and set Olympic records in the heats and final to win gold.
He competed in his second Olympics in Mexico City in 1968, racing the 100 m and 200 m freestyle and the corresponding relays, having completed his transition to sprinting.
After a fortnight of training, he entered the district age group championships and won a place in the top three.
[1] A turning point for Windle was the 1960 Australian Championships; he came second in the 1650 yd freestyle behind John Konrads and was selected for the 1960 Summer Olympics in Rome.
He dropped out of high school to attend a three-month training camp in Queensland with the Olympic swimming team.
[6] Talbot lamented to "never [being] astute enough to realise that he [Windle] didn't have the subtleties of pace that would have added to his armament as a swimmer".
Murray Rose, who had returned from competition in the United States college system, won both events.
[9] Windle also won gold in the 4 × 220 yd freestyle relay, along with Rose, Allan Wood and Anthony Strahan, setting a world record in the process.
[7] His quest to sweep all of the freestyle events failed when David Dickson defeated him in a touch finish in the 110 yd race.
[6] On the other hand, the two other Australian representatives who he defeated at the national championships did make the final, including Wood, who went on to win bronze.
[9] Windle broke the Olympic record in the heats with a time of 17 min 15.9 s to qualify fastest for the final by more than six seconds.
Having rested their two individual medalists—Wood and Windle—in the heats, Australia struggled to fourth place and were the slowest qualifier for the final.
He did so after getting advice from Australian teammate, Olympic gold medallist and Indiana student Kevin Berry.
"[7] However, Windle enjoyed his time in the United States, approving of the additional emphasis on relays and team spirit and the social life that it entailed.
Windle also enjoyed learning from Counsilman, who was regarded as an expert in mechanics, resulting in an improvement in his swimming technique.
[7] Windle's performances in the United States for Indiana earned him selection for the 1966 Commonwealth Games in Kingston, Jamaica.
He was not selected for the 1500 m freestyle, ending the defence of his Olympic title before the team had reached Mexico City.
[7] In the 100 m freestyle, Windle came second in his heat in a time of 54.8 s, making him the sixth fastest qualifier for the semifinals.
[20] In the 4 × 100 m freestyle, Windle combined with Wenden, Robert Cusack and Greg Rogers to win bronze behind the United States and the Soviet Union.
In retirement, Windle stayed in the United States for a few more years, working for Allis-Chalmers, an agricultural equipment corporation.