Irish Olympian Arthur Lanigan-O'Keefe has completed an extremely difficult endurance challenge in aid of Cystic Fibrosis Ireland.
The Modern Pentathlon athlete has successfully burned 10,000 calories in just 24 hours - warning fans not to try this one at home themselves.
Lanigan-O'Keefe took on the challenge after his plans to represent Ireland at his third Olympic Games were put on hold until next summer.
And the Kilkenny man refrained from sharing his challenge on social media before taking it on - to avoid disappointment if he failed to reach the massive target due to injury.
An athlete can expect to burn just 2,600 calories running a marathon, with the Olympian burning almost four times that.
He took on the majority of the gruelling challenge on an exercise bike, but also found inventive ways to burn calories, such as running up and down stairs, crawling, home gym workouts and more.
Detailing the massive achievement, he recommended that only high-level athletes dare to attempt the challenge.
He told RTE News: "This is not something I would advise anyone to try or do, to be honest.
"I was very prepared, I made sure I had all my meals ready, I carefully scheduled times for recovery. If you're not a well-trained athlete, this is not something you should try."
You can view his video of the challenge in full here.
To donate to Cystic Fibrosis Ireland, you can here or text “Fight CF” to 50300 to donate €4.
