A SUPER-fit fireman who has conquered some of the planet's toughest mountain peaks is battling to overcome his biggest challenge yet - a mysterious medical condition that struck him powerless virtually overnight.

John Robson has helped raise nearly £100,000 for charity through the daring adventures of Fire and Ice Expeditions, which he co-founded in 2004.

But in March last year, he was struck down with polymyalgia rheumatica (PMR), an obscure condition causing extreme pain, usually in the neck, shoulders and hips.

Mr Robson, of Durham City, lost two-and-a-half stones in just three weeks and was left virtually bed-ridden, unable to muster the strength to flick a light switch.

Last April, he was due to run the London Marathon. Instead, he was reduced to tears as he could only watch the race on television from his sick bed.

Friends feared he had cancer.

But, after PMR was diagnosed, Mr Robson was put on a course of steroids and he has slowly regained his strength.

Poignantly, he found himself using facilities his fundraising had helped pay for, at a Fire Fighters Charity rehabilitation centre in Penrith and Sunningdale School, Sunderland.

"Through it all, I had a vision of running through Houghall woods with the wind in my hair," the 52-year-old said.

That dream came true last September.

Now back at work as a group manager with County Durham and Darlington Fire and Rescue Service, Mr Robson has started climbing again and hopes to raise awareness of PMR by tackling this September's Great North Run.

In the longer term, he hopes to run marathons and climb Mount Kilimanjaro again.

The married father-of-two said: "I'd never heard of polymyalgia. I thought it was the name of a yacht.

"But I never thought I wouldn't get through it. I had a positive attitude, strength in my body and good mates.

"Fire and Ice's motto is: I'll find a way or I'll make a way. I remembered that throughout.

"I had great help from the support group (PMR and Giant Cell Arteritis North East Support) and I'd like to do more for it."

For more information, visit pmrgcauk.com