New Olympic champion Karsten Warholm criticised Nike's super spikes and questioned if they are taking the credibility away from the sport.
The Norwegian smashed his own world record to take the 400 metres hurdles title in 45.94 seconds in Tokyo on Tuesday.
He finished ahead of the USA's Rai Benjamin (46.17s) and Brazil's Alison Dos Santos (46.72s) – with both coming inside Kevin Young's time of 46.78s, which the American set nearly 30 years ago – with the race already labelled as the best ever.
Warholm is working with Puma and the Mercedes F1 team on his own footwear but questioned the shoes worn by his rival Benjamin as he felt it was wrong Nike athletes could run in a slab of responsive Pebax foam in sprint spikes.
He said: "He had those things in his shoes, which I hate. I don't see why you should put anything beneath a sprinting shoe. In the middle distance, I can understand it because of the cushioning.
"If you want cushioning, you can put a mattress there. But if you put a trampoline I think it's b*******, and I think it takes credibility away from our sport."
Warholm only broke the 29-year-old world record last month in Oslo but took almost a second off it in Tokyo.
Athletes have said the track is fast and the 25-year-old agreed, although preferred to give credit to his rivals.
"That track is crazy," Warholm added. "It's a great track. It actually gave me London 2017 vibes – it's the place where I got my first gold medal and it's a very fast track. But it's not just the track, it was the guys as well pushing each other on."
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