Over 12 punishing hours, Eoin Ryan, a 32-year-old marketing executive who lives in Ballyfermot, will attempt the Static Triathlon between 9am and 9pm at the top of Grafton Street on a static bicycle, a treadmill and a purpose-built swimming pool.

Asked if he sees himself as Ireland's answer to American illusionist and stunt performer David Blaine, Ryan replied, "Not really, as there are no tricks or illusions here. It is just pure sweat, toil and determination."

Ryan will start his day with a 3.8km swim in an Irish-built resistance pool known as a swim gym.

"It creates a current so it is like a treadmill for swimming. I have swum in one before and it takes a bit of getting used to.

"If you swim in a swimming pool you touch a wall and push yourself off but in the tank you are constantly swimming in the one direction and you don't actually move anywhere."

After becoming the first person to swim on Grafton Street, Ryan will cycle 180km . . . the equivalent of going from Dublin to Limerick . . . over six hours on a static bicycle.

Some members of the Dublin GAA team and Ireland's Special Olympics team will join Ryan on a second bicycle during the day to help raise funds.

When he has completed his rigorous six-hour stint on the static bicycle, Ryan will run a full marathon on a treadmill.

Ryan, who has been swimming for only three years, told the Sunday Tribune, "I hope to raise 50,000 on Grafton Street on Friday. I think that's a realistic target as street collections usually raise 30,000. I approached Telethon with the idea because I was training for the Ironman competition in Austria in July and I thought, why not do another one for the telethon as I have the training in my legs and I'd like to be able to help out with such a worthy cause?"

Ryan hopes that hundreds of people will gather at the top of Grafton Street on Friday evening from 8pm onwards to see him complete the challenge.