Russian twins Elena and Olesya Nurgalieva admitted they produced the worst performance in their decade-long dominance of the Comrades Marathon, despite bagging another one-two in the women's race on Sunday.

The siblings won the race for the eighth time in nine years, but neither felt in their best form in the 86th edition of the ultra-marathon, an 87km 'up' run between Durban and Pietermaritzburg.

"The was the worst run I've had, and it was my worst result in nine years," Elena said after crossing the line in 6:24.11, almost 15 minutes off her own course record and the slowest winning time since 1999.

"I wasn't feeling well today -- I had a problem with my stomach -- but of course I'm happy to have won."

Olesya said they had not yet recovered from the Two Oceans 56km ultra-marathon in Cape Town in April, which resulted in their slower than usual performances.

"I think Two Oceans hindered us today, because it was only five weeks ago and maybe we didn‘t recover well enough," Olesya said.

"We were both sick after that race and we needed 10 days to recover, so we had only three weeks to prepare for the Comrades."

Elena, who secured her sixth victory, tumbled at the 27km mark after colliding with some male athletes at a water point, but she said that fall had not hampered her performance.

"I didn't really pay attention when I fell. I just got up and ran, so it didn't really affect me," she said.

Stephen Muzhingi of Zimbabwe, who secured his third straight title in the men's race, said he had struggled over Polly Shortts, the last of the race's five big hills, but managed to pull clear of second-placed South African Fanie Matshipa in the closing stages.

Muzhingi won in 5:32.45, almost eight minutes off the course record set by Russian Leonid Shvetsov in 2008.

The Zimbabwean had predicted before the race that he would improve Shvetsov's record for the ‘up' run, but he realised going up Polly Shortts, with eight kilometres to go, that he would miss the mark.

"I was aiming to run 5:24 and I was working at it," Muzhingi said.

"After halfway I was trying to break away from that guy [Matshipa] but I was in pain.

"I was still in with a chance right until Polly Shortts, but I think I lost it there." Muzhingi's countryman, Point Chaza, had gone out hard, passing the halfway mark more than seven minutes clear of his closest challenger, but Muzhingi admitted Chaza had been ordered to set the pace for the rest of the Formula One Bluffs Meat team.

"We sent Point to the front as a ploy, to help set the pace for us," Muzhingi said.

"He did a good job, even though it was tough out there."

Matshipa, who worked hard with Muzhingi to open a gap on the rest of the field in the second half, said he had fallen ill before the race, which affected his performance in the latter stages.

"I tried to catch him [Muzhingi] but I had flu before the race and I had no energy left," Matshipa said.

"I was determined to push the pace, which I did until just before Polly Shortts, but then I had nothing left."

Muzhingi said he would have another crack at the record, and was confident he could improve the mark in the next ‘up' run in 2013.

"When I come here next time I will have a different strategy, perhaps one that will help me break 5:24," Muzhingi said.

"I know I have it in me to break the record. I want the record and I will get it. I know it."