Record-breaking stars have been made at the Tokyo 2020 Olympic Games, but could the biggest stars of all be what athletes run on and run in?
The lightning fast Olympic Stadium track has been hailed the unsung hero of Tokyo 2020, its super-sprung technology giving athletes an edge that has allowed them to smash world and Olympic records.
Meanwhile 'super spikes' continue to stir up debate trackside as people argue they give their wearers a seconds-shaving advantage.
The Tokyo Games undoubtedly keeps producing some of the fastest moments the world has ever seen on the track.
Norway's Karsten Warholm shattered his own 400-metre hurdles world record on Tuesday. He won gold in 45.94 seconds, carving .76 seconds off his previous record. Rai Benjamin’s 46.17 for silver also broke the world record of 46.70 seconds.
Less than 24-hours later, the United States’ Sydney McLaughlin smashed the world record and Dalilah Muhammad broke it as well in an American 1-2 finish in the women’s 400 hurdles.
Meanwhile Elaine Thompson-Herah of Jamaica won the women’s 100 metres on Saturday night in 10.61, shattering Florence Griffith Joyner’s Olympic record set in 1988.
Behind - or rather below - these incredible feats is a track that is also making history as the quickest ever.
Asked after the race about what part the track played in her own race, silver medal-winning hurdler Muhammad said the track "definitely feels fast".
“I can feel that energy return. A lot of people talk about the shoes, but I think it’s one of those tracks that gives you that energy right back and pushes you and propels you forward. Especially when you go into hurdle eight and feel that death. Today I didn’t feel like I was going into death.”
Gold medalist McLaughlin agreed. “It’s one of those tracks that gives you that energy right back and pushes you forward,” she said. “Every time you step on the track there seems to be some sort of record broken and it’s really cool to push the boundaries of what’s possible.”
After his "perfect" race on Tuesday, Warholm described the track as "crazy." The hurdler added: “It’s a great track. It actually gave me London 2017 [world championship] 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.”
The designer behind the "trampoline track" has said it gives a 1-2% performance advantage to athletes.
Andrea Vallauri, track designer for Mondo, said the new surface - the result of years of research at the company factory in Alba, near Turin - allows shock absorption and "energy return" resulting in a "trampoline effect".
“Every time there is an Olympic Games we try to improve the formulation of the material and Tokyo has been no different,” he told the New York Times.
“The track is very thin, 14mm. But we have added a new element: these rubber granules.
“In the lower layer of the track is this hexagonal design that creates these small pockets of air. They not only provide shock absorption but give some energy return; at the same time a trampoline effect. We have improved this combination and this is why we are seeing the track has improved performance.
“In Rio the track was called WS. This new one is called WSTY, for Tokyo. It’s the latest evolution of the track.”
According to the company, more than 290 world records have been set on Mondo tracks.
"The main objective of Mondo's Mondotrack WS surface is to maximise the speed of athletes and improve their performance. What we will see at the Olympics is a cutting-edge surface, the result of research stretching back several years," it said.
What role are 'super shoes' playing in the Tokyo Olympics?
While the track is quite literally putting a spring in athletes feet, what runners put on their feet could also be helping them run into the history books.
New shoe technology has been a hot topic of debate in track circles for years and continues to stir up controversy at this Olympics.
Nike athletes run in a thick slab of super-responsive Pebax foam in sprint spikes.
A combination of foam and carbon plates has given runners more spring in their stride and may have played a role in the faster times.
After his win on Tuesday, Warholm, who did not just break the world record, but went under the 46-second barrier, dismissed his second-placed rival Rai Benjamin's Nike super spikes as "b******t".
He said the American “ran on air”, adding, "he had those things in his shoes, which I hate."
“I don’t see why you should put anything beneath a sprinting shoe,” he said. “In 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******t, and I think it takes credibility away from our sport.”
While he may be scornful of his rival's footwear, Warholm is certainly not running in a pair of old plimsols. His Puma EvoSpeed Future Faster+ have been developed in collaboration with Mercedes Formula One team and Puma and contain a carbon-fibre plate to aid energy transfer. But his racing spikes, he said after his spectacular win, were different to the Nike shoe.
“Yes, we have the carbon plate,” said Warholm. “But we have tried to make it as thin as possible. Because that is the way I would like to do it. Of course technology will always be there. But I also want to keep it down to a level where we can compare results because that is important.”
For his part, Benjamin said he would "still run fast" in different shoes as he too highlighted the advantages of the track.
“It’s a very good track. It’s soft, it has a lot of give, it’s a phenomenal track. People say it’s the track, the shoes, and the conditions were really good," he said after the race.
"But I could wear different shoes and still run fast. No one will do what we just did, I don’t care who you are. Could be Kevin Young, Edwin Moses, respect to those guys, but they cannot run what we just ran just now. It’s a really fast track, it felt good, the conditions were really good.”
World Athletics introduced a maximum legal sole thickness for different events in July 2020: 20mm for track events up to 400m and 25mm for any longer distance.
World Athletics said the rules governing shoe technology “are designed to give certainty to athletes preparing for the postponed Tokyo 2020 Olympic Games and to preserve the integrity of elite competition”.
For many, though, these rules are still too lenient and so it seems that the debate on technology in sport is set to run and run.