THE pictures and names proudly emblazoned across the sweat-soaked tops revealed some of the personal tales inspiring the runners.
A pink soother was hanging around the neck of Paul Harris as he told how he was running in memory of daughter Caoimhe, who was two when she contracted a fatal bacterial infection.
Paul, from Newcastle in the UK, has so far raised €60,000 for the NSPCC.
"She passed away suddenly, within 36 hours," the deputy headmaster said of their loss in 2011. "It was horrible, I run in her memory. I run with her dodie (soother) around my neck, and her little hairband.
"My wife Catherine was 34-weeks pregnant at the time. We had our second child Una four-weeks later, so it is really tough. It is very emotional."
On other yellow singlets, little Gavin Glynn's face beamed out as 'Superteam Gavin' pounded the streets to raise money for specialised treatment for the three-year-old who suffers from a rare form of cancer.
"They couldn't treat Gavin in Ireland so we took him abroad for specialised treatment," said his father John Glynn, from Greystones, Co Wicklow, who was cheering on the team of 24 runners.
After undergoing two operations in Amsterdam to remove a tumour, he was moved to St John's Ward in Our Lady's Children's Hospital, Crumlin, to undergo chemotherapy.
"Hopefully he will be finished treatment soon," said John, who is planning another fundraiser on November 14 in Barefoot Fitness in Kilcoole.
"The support from everyone watching the marathon was amazing, when they saw the name on the jerseys they were cheering even louder," he said.
Kevin Gallagher (40) and Mark Dinsmore were running to raise money for defibrillators after Mark's cousin – Patrick Dinsmore (16), from Warrenpoint – collapsed with SADS during a GAA game and died in 2010.
"It is to get heart checks for kids in schools and buy defibrillators," said Kevin.