It is 7am on Sunday. A furious wind tries to stop me opening the car door. The forecast is for 50mph gales. I have scheduled a four-hour run in the Pentlands, the green and brown hills that back on to Edinburgh’s southern fringe. From the car park, the ascent of my first hill – 478-metre Caerketton – starts immediately, and I am exhausted immediately. My limbs are hopelessly weary. Every step is an effort of diabolic proportion.

What am I doing here, I think, running up this hill? It is a question I have been asking throughout 2016.

David Brown faced the urinal and sighed. ‘Best-thing-worst-thing I’ve ever done,’ he announced. I nodded sagely. There is only so much emotion a man can display at a urinal. It was January 2; today was Brown’s fourth Greenmantle Dash, a two-mile up-and-down punishment above the Borders village of Broughton. Brown had got progressively slower in each attempt, with 11 minutes separating his debut to today where he had finished 85th in a field of 90. But that was not the point.

‘You have to be mad,’ was the 52-year-old’s retort when I asked him why he ran in the hills, why anyone ran in the hills. ‘The other thing is the camaraderie.’ My shorthand training as part of a journalism diploma did not stretch to Borders’ colloquialisms, but as I desperately scrawled indiscernible shapes across a pad, I got the gist. There was a woman called Kirsty who overtook him on the ascent. He caught her on the road to Broughton, geed her on when she said her hips hurt, and – with a competitive streak overcoming chivalry – snuck in front of her at the finish line. Kirsty did not mind. ‘She gave me a cuddle at the end. What a laugh!’

Standing close by in Broughton Village Hall was Andrew Douglas. Brought up in Caithness, the Inverclyde AC runner was aiming to compete in the European and world championships of hill running in 2016. He was clutching something that would be of very little assistance: a crate of Broughton Ale, presented to him as the race winner. There is irony, I thought – like giving a leg of lamb to a vegetarian. ‘Do you drink?’ I asked.

‘Yes,’ he replied indecisively, ‘although it’ll take me a while to get through this.’

I asked him the same question as Brown. ‘The attraction of hill running is going to different places and having fantastic scenery,’ he said, ‘but in terms of the racing and the guys you race against, there is a community spirit in that, a camaraderie that you don’t really get with track running. Track running is quite intense, people are really focused and don’t socialise much with each other. In hill running you feel like you are all in it together. You can race seriously, but afterwards or beforehand you can have a good chat, good banter, with the other guys.’

‘Do you enjoy the view?’ I ventured, immediately regretting the inane question. During the climb, a flash of light had drawn my gaze from the ground to the sky. A shaft of sunlight was bursting through grey clouds. It was beautiful. But in an instant, my eyes snapped back to mud.

‘Racing? I guess I don’t really. Certainly when you are training, you can have a look about at the scenery. It feels like you have left all your normal life behind and you can just be at one with nature.’

Three weeks rolled by and Scottish hill running bandwagon rolled into Falkland in Fife, where the annual Devil’s Burdens relays are held. The heat of the race was over and we were driving home to Edinburgh when I asked Carnethy runner John Busby ‘why’.

‘Running in the hills allows me to connect with the landscape around me,’ he said. ‘Living in the city, I feel it’s quite an unnatural way to live your life, and getting out into the hills is great. Walking is good, but when you are running, I think it’s a deeper connection because you find a rhythm with the landscape.

‘In Scotland, if you go the Highlands, the landscape is different but you don’t appreciate how different until you feel it with your feet. The size of the hills is different: you can look at that from a distance, but you don’t feel it until you are there. Every landscape is obviously different, but running allows you to not just see it, but feel it.’

The Devil’s Burdens was Busby’s last race before starting a year-long course of study in Amsterdam. ‘I have an idea of what the Dutch landscape may be like.’ A long pause. ‘It is going to be flat,’ he said solemnly.

It is April when I meet Davie Duncan in the Perthshire village of Aberfeldy. No-one has run more races than Duncan. Upon retiring in 2000, he pledged to run as many as possible in the Scottish hill running calendar. He has proved unstoppable. In one year, he ran 97 races; in another, he climbed Ben Cleuch, a 721-metre peak in the Ochil Hills, on 123 occasions. That does not mean he is having fun, however. ‘I never enjoy the race,’ Duncan said flatly. ‘But will I be back next year? The answer is always yes.’

‘Why do you keep coming back?

‘I’m not sure… because it’s hard, grinding, punishing.’

‘Is it obsession?’ He neither agreed or disagreed.

Eventually, he spoke. ‘I suppose,’ he said, ‘it’s a way of life.’

Colin Donnelly can empathise with Duncan. The ‘why’ for Donnelly – British hill running champion in 1987, 1988 and 1989, and the youngest winner of the Ben Nevis Race at 19 – has been complicated over the years. It began as a yearning to see the high places of Scotland: in his search for a summer waiting job during university, he only wrote to hotels close to Munros. Success led to obsession, however. ‘It cost me relationships because I put the running first. I took competitions first. I can remember one girlfriend I was with said, ‘Colin, you know I really like being with you, but the trouble is you put your running first and you put me second,’ and she was right, I do.’

It was one of those magical summer evenings – an evening you wish could last forever – in the Pentlands, with the brilliance of the light sharpening every dimple of the hills.

I was running with Manuel Zeller, an engineer brought up in the Black Forest region of southwestern Germany. Manuel’s first taste of life as a Carnethy athlete was a Thursday hill repetition session on Arthur’s Seat, a weekly fixture known fondly as Wintervals. It was raining and long dark when he arrived at Holyrood Park. After a short warm-up, the runners climbed onto the inky slopes of the Seat.

‘I did not have hill running shoes, only my road running shoes. I was slipping. I hated the downhill. It was still fun and friendly, though. ‘You should get proper running shoes and come back next week,’ they said.’ ‘They’ were Iain Whiteside, the then club captain who was leading the session, as well as Liam Braby and Konrad Rawlik, two of the club’s leading senior runners. There was a woman, too. ‘I saw her and I thought, at least there’s a girl, I won’t be last. And then she kicked my ass on the first rep. I thought, even the girls are super-fast here.’ Zeller had made the acquaintance of Jasmin Paris.

Zeller was not daunted. He raced in Scotland for the first time at Glamaig on Skye, having hitch-hiked from the mainland when his car broke down. ‘At the top I noticed the scree was super-dangerous. I saw two guys with open knees. I said, ‘are you okay?’ and they were just like, ‘yeah, yeah, just go for it!’’

And so to August on Caerketton: my four-hour fathoming of ‘why’. In the lonely, windy wild, I could not think of a reason. Nothing. So I thought of them all: Brown, Douglas, Busby, Duncan, Donnelly and Zeller. There was something of them in me, I realised. I was them; they were me. I kept moving, crossing 17 summits, covering 21 miles. Most of all, I thought of Brown.

I have lost the path. I am cursing tussocks. I have twisted an ankle. I am slogging uphill, forever uphill. But then I am on a ridge, the summit is ahead, and the world drops beneath my feet.

And that is hill running: the ‘best-thing-worst-thing I’ve ever done’. That is ‘why’.

@MuirJonny