The sun was splitting the rocks on Carrauntohil a fortnight ago when John Lenihan brought a group of friends scrambling up the mountain. One of them got as far as Hag's Glen and felt his brain telling him that he was a man not a goat. He turned back.

Lenihan called him later.

"Thought you were gone back to get the suncream, boy?" said Lenihan.

"It's not suncream you want, Lenihan," said his friend, "It's a brain transplant."

He's right. John Lenihan and his ilk need help. You have to be crosseyed crazy to do the things John Lenihan does. There is only one thing stranger than people who run up mountains. People who run down them. Lenihan does both. Nobody has beaten him on Carrauntoohil for a decade.

In Zermatt, Switzerland, back in 1991, he was 20 seconds behind the front pair at the top of the mountain. He was 30 seconds ahead by the time he reached the bottom and heard the voices in the crowd telling him there was nobody else in sight and he was about to become World Mountain Running Champion.

To get to the place where John Lenihan lives and was reared you have to tackle a few ascents yourself. If there is an off, off Broadway, then Glounageenty represents the outreaches of off, off the beaten track. Ask Denis Mannix in the post office, go past the church, the graveyard, the school and left where the Earl of Desmond met his end. On then up a boreen which climbs with a shocking gradient and offers views which you would enjoy if you weren't afraid they'd be your last sight on this earth. Finally, into a yard where four wag-tailed dogs greet you before Lenihan emerges, long haired and baseball capped.

He has 160 acres of land here. Soil which he is master of and slave to. A couple of years ago he milked his cows in the morning drove up country to Croagh Patrick, won the race up the mountain and drove back home again to milk the cows that night. "The cows would tell you I was a bit cranky that night maybe," he says smiling.

One hundred acres of mountain and none of it fit for anything but taking up his own turf and his time. He took the farm over from his father four years ago and in the first year he nearly went under.

"Working with him all those years I was used to doing the things as he laid them out every day. On my own, having to plan it myself, well I nearly went under."

In a way, running saved him. He had a career-long habit of taking notes and records of his training and he did the same with the farm and compared the results every night with leaflets and pamphlets he got from Teagasc. He got through it.

He loves the land and the animals and the belts of fresh air and his easy-going metabolism is tuned to the rhythms of this extraordinarily lonely place. There are regrets, though. When he was younger he got the chance to go to America on a three-year contract with Team Adidas to run the roads. The family and the farm kept him at home, though, and he speaks about that junction in his life with wistful regret.

"I went out afterwards for three months on my own steam." In San Diego he got a reputation for ferocious road racing which got him invitations up and down the west coast. He did odd jobs to keep himself going and the southern California sun kissed his head from morning to dusk every day.

He brought some American friends over to his lonely eyrie when he came back and the first day the skies spilled and he couldn't keep them in, they were so desperate for the novelty of running in the soft Kerry rain.

He wasn't so enamoured by the familiar clouds and found it hard to settle on the mountain again after the three months in America. Guilt at having left the farm for such a period drew him back, but America and the sunshine of San Diego washed around his brain.

"I've never been on drugs but it's what I imagine coming off them is like. It was hard. If I had gone for three years I don't know if I would have come back at all. I regret not having been a full-time athlete, but I wonder when I look back if I could have enjoyed it all any more."

He'll never know. He came home and he farmed and worked in the factory for four years, toiling over braking systems and dreading the effects of the dust which thickened the air. You could put on a white shirt going out at night and within an hour, no matter how much washing you had done, a million little specks of red dust fresh from your pores would be performing a polka on the white cotton. So, he settled on the farm and the 5.30 a.m. starts and reconciled himself to being a farmer first and a runner second.

It might have been different. He came to running by accident but loved it from the first footfall. He went in for football as a kid but his family creased themselves with worry about him, the only boy and the extra hands on the farm out risking broken limbs chasing leather. He persevered. He got called in for some trials for a Kerry vocational school team at 14 but the family didn't want him to go.

Touching 17, he felt the need for some sort of outlet away from the mountain and joined Ballymacelligot GAA club for the company and fitness. The Sunday papers were serialising Be Active Be Alive, a series of leaflets produced by the Department of Health. They became his bible. He used the information for getting fit for football and half way there he saw a race advertised for Castleisland the following Sunday. He put his name down for the craic, came seventh and was a member of an athletics club by the time he got home that evening. Ballymacelligot GAA club had lost him forever.

The running has been his valve, his daydream and his escape. He never wrung an Olympics out of it, but he got some good travel and met some heroes. Willie Counihan, a local runner, who first caught his eye, met him, raced him, befriended him. John Treacy and Gerry Deegan were good to him, he says, and once in Czechoslovakia, he met Lasse Viren, the king of kings.

Towards the end, the discipline of hill running and the lure of Carrantouhil drew him in. The rush of the mountains and the fellowship of the field kept him there.

He has been up Snowdon and down, out ahead of the posse. Up Croagh Patrick for the last three years, winning each time and breaking his own record last year, getting up and down the mountain in 43 minutes, 23 seconds.

"I like Croagh Patrick, it means something to people who know it from walking up it, it means something when they think of you running up it and down it."

But Carrantouhil is the mother lode, the magic mountain. He missed the first running of the race but entered the second time. That was 10 years ago and he hasn't been beaten since. Tomorrow he is looking for 11 titles in a row.

"Carrantouhill," he says, rolling the word around on his Kerry tongue. "How do I explain it. Close on 3,700 feet of climb on the 8.5 mile course. If it's a bad day you wonder what the hell you are doing up there. If it's a good day, you are close to heaven."

Close to heaven. Or very dizzy and close to fainting. John Lenihan describes the course, like a gourmand reading aloud from a menu.

"We go up an unsurfaced road for a mile or so, then onto the shoulder of Caher mountain, there's a fair sting in the tail getting up that, then a series of descents and ascents to get around the ridge up Carrantouhill, then back down. "Mentally, I look at Caher as the finish, if I make it there, going downhill. That's the race, but I suppose there is more to it. Carrantouhil is special."

You look out John Lenihan's kitchen window at the trees and cow parlours huddled on the side of the mountain and there is a connectedness with land and rock which life in a suburban rabbit hutch doesn't provide. Lenihan is in thrall to those rugged contours on the landscape.

"I love mountains. I wouldn't be in the running game now only for the mountains. The beauty of them and I suppose the fact that I can compete on that terrain. There's the attraction for me. There is something special, maybe a bit spiritual. Nobody says I'd really love to run the road between Tralee and Castleisland, but running up Carrantouhil has something special about it. People come from all over to it.

"I just get a rush of adrenalin from being on the mountain. I can't think of any other experience like that. The mountain gives you a strength you don't get anywhere else."

The injury risk is there, but it's overstated, he says. Going up the gradients are so steep that you barely go fast enough to do damage. Some people walk up the steeper bits, but Lenihan keeps jogging, just for the momentum. Sometimes, he looks and sees walkers gaining on him as he jogs.

He is a ferocious climber, leaning into the hill and moving all the time. He has a trackman's awareness of the tactics of racing as well, keeping one eye on the good climbers, measuring out what sort of lead he can afford to grant them if he is to pull them in when his moment comes, that thrilling second when having conquered gravity he turns around and embraces it.

"I love coming down," he says, with a smile looping from ear to ear. "I love descending. That's the thrill. A lot of people find it unnerving. Bouncing through heather . . . You'd be destroyed coming down on rocks. That can be a bit embarrassing because people have this idea built up that I'm a ferocious descender. I am, but on my own terms and my own sort of terrain." There is friendship everywhere you look in hill running and mutual respect, too, but the kudos and the genuflections go to those brave souls who come down quickest. Lenihan knows his rivals and he feels the breath of the best descender on his neck.

"Francis Cosgrove has been closing in on me every year. He caught me on the way down on the rocky terrain last year. God, he was flying. I got onto the heather and we were back on my terms. On the heather you can just blast it. Francis is coming down this year. He rang me the other night. I'll have to be ready."

This week he has been laid low by the flu, but a friend in Castleisland gave him a restorative which he is trying. Some poitin boiled up with water, lemon and honey. It'll kill him or cure him, but either way he'll be on a mountain tomorrow, preferably one step ahead of Francis Cosgrove, with heather under him and Caher in sight.

"I suppose if the run ended, if I stopped winning Carrantouhil, I might ease off, step back a bit. I'd still go out and run, I'll do that as long as I'm able, but the competitive thing might be gone a bit. I'll never stop running, though."

The cows need emptying and the land needs attention and the dogs are barking. Farmer first, runner second these days, but no final summit in sight for the man who runs headlong down the mountains.