“The Enhanced Games gave me the resources and the team to unlock a new level of performance – and now the whole world can see what’s possible,” said Gkolomeev, whose previous 50m freestyle best was 21.44, winning silver behind Britain’s Ben Proud at the European Championships in Edinburgh in 2018.

The Enhanced Games did not reveal what substances he had taken, citing personal confidentiality and concern that others would follow Gkolomeev’s regime unsupervised. It said they were prescribed “medically and legally”.

Organisers say they allow participants to take only “medically prescribable and legally approved” substances under clinical supervision, and that they are confident they will comply with the Drug Enforcement Administration laws in the US.

Ukraine’s Andrii Govorov, the 33-year-old 50m butterfly world record holder, and 21-year-old Bulgarian Josif Miladinov, a European 100m butterfly silver medallist, have also signed up.

Govorov announced his retirement from Olympic sport this week.

“This choice wasn’t easy,” he wrote on Instagram., external

“I spent a long time reflecting – putting everything I care about on the scale. Competing in Los Angeles [in 2028] was my dream. But life had other plans.”

The recruitment of Gkolomeev, Govorov and Miladinov is a coup for the Enhanced Games after critics claimed it would struggle to convince established names, still in their prime, to cross the divide.

Australian former world champion James Magnussen, 34, came out of retirement to join the Enhanced Games in 2024, but his attempt to beat the 50m freestyle world record fell well short, recording a best time of 22.73.

The Enhanced Games have aspirations to have a 100-strong roster of participants in next year’s event.

Organisers will build a four-lane 50m pool, a six-lane sprint track and a weightlifting venue at Resorts World in Las Vegas.

The project also plans to market “performance and longevity enhancements” to the general public this summer.