Both sisters represented Ireland in the 1984 Summer Olympics, Regina in the Marathon and Monica in the 3000 meters.
At home she was the Irish National Champion in the 1500 metres in 1982, 1983 and 1988 with Sonia O'Sullivan a main competitor.
[2] Across the channel, she was the English National Champion in the 5000 metres in 1982 and 1985, beating her sister in 1982.
Both sisters originally competed for England as junior athletes but switched to Ireland in 1982, based on the citizenship of their parents, for competitive reasons.
Before embarking on her international career, she competed for San Diego State University for two and a half years, finishing second in the 1500 metres at the NCAA Women's Outdoor Track and Field Championships in 1981.