1976 saw Sanderson's Olympic debut, at 1976 Summer Olympics. Aged 20, she was the youngest of the competitors in her event, and threw to finish ninth. In July 1977, at the European Cup semi-finals in Dublin, she achieved , at the time a UK record and the second longest distance achieved by a woman; Ruth Fuchs, holder of the world record, qualified in second place. At the European Cup finals it was Fuchs who won the gold, with Sanderson taking the silver. At the 1977 IAAF World Cup, Sanderson won bronze.