The defending London Marathon champion has hit out at the race's highly-fancied Spanish contenders, saying he is suspicious of their methods. Portugal's Antonio Pinto said of chief Spanish challenger Abel Anton: "I am very suspicious of Anton's methods. He has made progress very quickly."

Anton won the title in Athens last year after a long duel with compatriot Martin Fiz and is among the favourites for the men's race on Sunday. Pinto is not the first athlete to raise doubts about the strides Spain's marathon runners have made in the past four years. As well as winning the last two world championships, they have finished first, second and third in the 1994 European Championships, and Fabian Roncerco leads the 1998 world rankings with the time of two hours seven minutes 26 seconds he ran in Rotterdam last Sunday.

Last year Pablo Sierra, a two-hour 11-minute marathon runner, was suspended for six months by the Spanish federation after accusing Anton and Fiz of using erythropoietin, or EPO, a drug that stimulates the growth of red blood cells which increases endurance. It is difficult to distinguish naturally-occurring EPO from the synthetic version, which cannot be detected by urine testing.

There is no evidence that Spanish marathon runners have used performance-enhancing drugs because none has ever tested positive for them. "I have no idea what he is going on about," Anton said when asked about Pinto's allegations. "We are good friends."

A study released yesterday claims that nearly one-in-four top women runners suffer from eating disorders. Low body weight, weakened bones and reduced fertility are among the common effects of such disorders, according to the University of Leeds' research, released to coincide with this weekend's London Marathon.