In 1989, she won the first of three consecutive Australian Junior 100 m titles, also winning the Junior 200 m championships in 1989 and 1991.
At the 1990 World Junior Championships Gainsford reached the semi-finals of both the 100 and 200 metres sprints and assisted the Australian 4 x 100 metres relay team to a new national junior record of 45.01 seconds.