In Rendina's first Olympic competition in Munich, 1972, she set an Olympic record (51.90 seconds in her heat) on her way to the 400 metres final, where she eventually finished in sixth place in 51.99 seconds. She was also in the final of the 4 × 400 m relay where she ran a 50.7 leg for the Australian team that came in 6th in 3:28.84.
At the 1976 Olympics, Redina was eliminated after finishing 5th in the 800m semi-final in 2:00.29. She was part of the Australian 4 × 400 m relay team that finished 4th in 3:25.56 – her leg being timed at 51.6 seconds.
In her career, Rendina won five national championship titles at 800m and two at 400m.