Paula Radcliffe has withdrawn from the London Marathon on 13 April because of a toe problem. The 34-year-old Briton, who was aiming to win her fourth title, picked up the injury to her right foot when altitude training at her base in New Mexico. "I am desperately disappointed that I have to pull out of this year's race," said Radcliffe. "I love running in London and this race would have been the perfect test for me before the Olympic Games."