No guarantees of world record in Paris - Warholm

World 400 metres hurdles champion Karsten Warholm hedged his bets on Wednesday about the possibility of breaking his own record at the Paris Olympics, but said new running spikes he has developed with his sponsor Puma were giving him confidence.

"When you're at the starting line, if your focus is the world record I think it's more difficult," Warholm said in an interview with Reuters. "I wouldn't say no to a world record, but at the same time I know it's not that easy.

"What I for sure know is that my shoe is a lot better than it was three years ago, and you have all these things that also give you confidence but at the same time there are no guarantees. That's why we love sport, I guess," he added.

Warholm visited Puma suppliers in Vietnam to test shoes and materials as part of his work on the new spikes, which were shown for the first time on Wednesday at an event in Paris.

Warholm said he used to be a critic of shoe technology, feeling early "supershoes" gave some an unfair advantage.

"When you train every day to be the best human, and you realise there is another X-factor coming into this, at least you want it to be as even a playing field as possible," he said.

"I think it has evened out now, and a lot of good things are coming from it - a lot of brands are investing a lot more in running right now, and a lot of other brands are coming into the running world."

Puma launched a new campaign on Wednesday featuring key Olympic athletes including Warholm, as it seeks to win more market share in the highly competitive running shoe market.