Athens Olympic women's marathon champion Mizuki Noguchi is still struggling to make a comeback, and her coach Nobuyuki Fujita suggested on Friday that she could push herself into retirement by overtraining.

"It has been set back further than we expected," Fujita said, referring to a comeback for the 31-year-old, who has not gotten up to speed since recovering from a left groin injury that forced her out of last summer's Beijing Olympics.

Fujita said that Noguchi has not been experiencing pain in her groin but that she has only been able to jog for about 30 minutes at a time in practices.