Ex-world champion James Magnussen says he will take banned drugs in an attempt to swim faster than a world record.
The Australian, 32, will come out of retirement to compete in the Enhanced Games, where doping is allowed.
Magnussen will try to swim faster than the 50m freestyle record, though it would not be official because there would be no drug-testing regime.
“I’ll juice to the gills and I’ll break it in six months,” said Magnussen, who will be paid $1m (£792,000).
The men’s 50m freestyle world record of 20.91 seconds was set by Brazilian Cesar Cielo in 2009, though he was wearing a performance-enhancing, non-textile swimsuit that was banned a few months later.
The Enhanced Games was founded by Australian businessman Aron D’Souza in 2023 and would not be subject to World Anti-Doping Agency rules.
It is planned to include athletics, swimming, weightlifting, gymnastics and combat sports, though no date or venue for the event has yet been set.
However, the proposal has attracted criticism. Last year the UK Anti-Doping Agency said it was “extremely concerned by the concept of an Enhanced Games”.
“The premise of sports competitions that allow performance-enhancing drugs is unsafe, dangerous to athletes’ health and wellbeing, and flies in the face of fair play,” it said.
D’Souza told the Australian Associated Press said: “An Australian swimmer, the most important sport in the Australian psyche. I am just so proud that it’s another fellow Aussie.
“I have no doubt now that James has done this publicly there will be dozens, hundreds of athletes [ready to join]. My phone is blowing up.”
Magnussen, who won 100m freestyle world titles in 2011 and 2013 and Olympic silver at London 2012, has a personal best of 21.52 in the 50m that he achieved 11 years ago.
Despite being free to take whatever performance-enhancing drugs he likes, Magnussen says he does not want to take any risks with his health.
“I thought it was an interesting concept from the first time I heard it,” Magnussen, who retired in 2019, told Sydney’s SEN radio.
“We’re pretty aware as Olympians, particularly in Australia, that performance enhancements are going on in other countries, but it’s not a level playing field internationally.
“I want to go to America, I want to get the right advice and take the right supplements.
“I’d like to document it through video form. Show how it can be done safely, properly, and create an athlete we haven’t seen before.”
