Emotions ran high Monday night as family and friends of a runner who collapsed in punishing heat during Sunday's Tely 10 road race finished the route on his behalf.

Mark Didham, 30, was nearing the end of the 10-mile road race when he was overcome by the heat, which felled more than two dozen other competitors.

Didham's condition, though, is critical, and he is in a medically induced coma while doctors try to stabilize him.

"I wanted to finish the Tely 10 for him, to get that last kilometre," said Didham's wife, Jill, who was joined by a large group of supporters who walked the final stretch of the Tely 10 route to Bannerman Park.

"It was a rushed decision, but of course I had to be here and I had to do it for him," said Didham, who wore her husband's race bib.

Mark Didham is an experienced runner who frequently took part in organized races. He was also aware of what heat and humidity can do.

"Good luck to everyone running tomorrow. Be careful in the heat," he posted Saturday on his Facebook page.

'Everything is out of whack'

His mother, Betty Didham, said the family was shocked by the turn of events.

"Everything right now is out of whack," she told reporters.

"They can't even consider getting him off a ventilator until it's stable."

Betty Didham, who said doctors have told her they have never seen such a severe heat-related illness in a local running competition, said the family's immediate focus is on his recovery.

"We just want to get him off the ventilator right now and make sure there's no long-term effects from this, that there is no damage to any of his organs and that he'll be back to himself," she said.