Yulimar Rojas, the 26-year-old Venezuelan triple jump world record holder, wanted to win a medal in long jump at this month’s World Championships in Eugene. But her dream was dashed even before she reached American shores.

The reason: The thickness of the sole of her shoes when she jumped 6.93 metres to qualify in June was 5 millimetres more than what is allowed in long jump. Rojas had jumped the distance at the Reunion de Atletismo Ciudad de Guadalajara to book her ticket for the Worlds.

As per the current ‘athletic shoe regulations’ which came into force on January 1, 2022, the maximum thickness of the sole of a shoe for field events should not be more than 20 millimetres (two centimetres). However, an exception is the triple jump in which the sole can be 25 mm thick. Rojas is a two-time defending world champion and the Olympic champion in triple jump and may have overlooked the rules. However, it is not clear what exactly resulted in a top athlete like Rojas not wearing the right shoes. There has been no official comment from Rojas or her agent. But there is a shoe control officer at events who can photograph or measure shoes and forward evidence to World Athletics for verification.

There is a shoe thickness table under the regulations. For track events shorter than 800 metres including the hurdles, the thickness of the sole has to be 20mm. In track events over 800 metres, it can be 25mm. When it comes to cross-country races, if it is a shoe with spikes, the thickness can be 25mm and for shoes without spikes, it is capped at 40mm. In road races, like the marathon, and race walking events, it is 40mm, and in mountain races, there is no limit to the thickness of the shoe.

Yes, from November 1, 2024, new regulations kick in. In all track and field events, the thickness of the sole should not be more than 20mm, be it a pair of shoes with spikes or without spikes. In road events, including race walk, it will remain at 40mm, while in cross-country, the thickness of the sole will have to be brought down from 25 mm to 20 mm for shoes with spikes. Again, in mountain races, any thickness is allowed.

Restricting the thickness of shoe soles is one of the steps towards ensuring athletes don’t get an unfair advantage from better cushioning and energy generation off the ground.

A major change was introduced in January 2020 when athletes were told they cannot run in prototype shoes. It meant that a shoe had to be available for purchase in the open market for at least four months before it can be worn by an athlete in an official race. This rule made the sport of running more egalitarian. Earlier, most top athletes who endorsed shoe giants had an unfair advantage as they had access to latest models before they were made available to the general public or competitors who did not have a contract.

A shoe should not have more than one plate or a blade in the sole, regulations state. This rule was aimed at keeping a check on multiple plates, including those made from carbon fibre, used in shoes to help athletes gain more spring-like energy from the ground. Thick shoes with multiple plates have been controversial. Kenyan Eliud Kipchoge, the current two-time marathon winner at the Olympics, ran the first-ever sub-two-hour marathon (a non-competitive one-off event) wearing Nike Alpha Fly (prototype) shoes in Vienna in 2019. It started a debate on the extent of assistance the shoes, said to have more than one plate and thicker than 40mm, gave Kipchoge. Athletes wearing Nike shoes with thick soles have won a majority of marathon races recently raising questions about technological doping.

The legendary Usain Bolt has called advances in shoe technology unfair. Bolt was referring to superspikes – with a plate and foam bedding – introduced in 2019 by Nike after which other manufacturers brought out their own versions.

“When I was told about it, I couldn’t believe that this is what we have gone to. You know what I mean, that we are really adjusting the spikes to a level where it’s now giving athletes an advantage to run even faster,” Bolt had told Reuters in an interview last year.

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At the Tokyo Olympics, the focus shifted to the shoes when Norwegian 400m hurdles champion Karsten Warholm won the event in 45.94 seconds, a new world record, and spoke about assistance athletes get from shoes, especially his main rival USA’s Rai Benjamin. “I don’t see why you should put anything beneath a sprinting shoe,” the Norwegian said. “In middle distance, I can understand it because of the cushioning. But if you put a trampoline in, I think it’s b******t, and I think it takes credibility away from our sport,” Warholm, who wore shoes with thinner soles compared to Benjamin, had said.

In the women’s 400 metre hurdles at Tokyo, USA’s Sydney McLaughlin broke her own world mark to win gold while second-placed Dalilah Muhammad too ran within the old record timing. Both were wearing a version of ‘superspikes’.

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