Ex-Wales rugby player Richard Webster ran the marathon leg of the fourth Ironman Wales triathlon on crutches.
The ex-British and Irish Lions flanker suffers from arthritis so has adapted his running style with his arms taking his weight.
Webster, 47, was one of 1,616 athletes to complete the Pembrokeshire event, finishing in 13 hours, 8 minutes and 55 seconds.
"Somebody told me I couldn't do it so I had to prove them wrong," said Webster.
Competitors swam 2.4 miles, cycled 112 miles and then ran 26.2 miles.
Webster said the pressure on his hands using the crutches was not a problem, and that he found the swim, which started on Tenby's north beach, the most difficult part of the event.
"The swim was a nightmare," said Webster.
"I had so much salt in my eye that I wasn't able to see out of my right eye all the race."
Webster, who has coached Swansea, Neath, Maesteg and the Wales Under-20s, had dropped four stone in training.
Competitors must complete the course within 17 hours, with professional athletes expected to finish it in under nine hours.
The former rugby forward thought he would fail to finish as he started the run.
"The first lap is always hard and I just thought I was going to keel over a couple of times," said Webster.
"But then with the crowd support and knowing what I wanted to do, I just kept going."
South Africa's Matt Trautman won the men's race in 9:07:28, just under three minutes ahead of Great Britain's Fraser Cartmell.
There was home success in the women's race with Amy Forshaw first and Amy Ogden third.
A special feature on the Ironman race, including Richard Webster and fellow ex-Wales international Andy Moore, will be on Friday's Sport Wales programme (BBC Two Wales, 19:00 BST)