“YOU look nervous,” says trainer Patrick O’Brien when I turn up for a taster session of Fight Camp.

“It’s been a while since I’ve been to a gym,” I say. Then, just in case he thinks I mean a couple of months, I add: “Maybe eight years.”

Nerves therefore don’t seem unreasonable. Particularly given that Everyday Athlete is no ordinary gym, but one run by a team that includes three Muay Thai fighters, two of them champions, and John Valbonesi, a weightlifting fanatic who also happens to personal trainer to Outlander star Sam Heughan.

Particularly given that this gym’s logo is a skull and crossed bar bells, has a boxing ring as its central feature and uses promotional material with slogans like: “If it doesn’t challenge you, it doesn’t change you.” Particularly when Valbonesi says that one of his favourite motivational lines is: “It’s only fat crying.”

That said, not having gone to the gym doesn't mean I've done no exercise. It's just that, between having my first child and my second, I ditched the squandering of money on gym membership, in favour of running – free, convenient, and perpetually available outside my front door. I swore I would probably never join a gym again. After all, all I’d ever really done there was swim a few laps of the pool, sit in the Jacuzzi reading Alice Munro stories, and occasionally catch up on global news while pounding the running machine.

But Everyday Athlete is a whole different breed of gym from the one I used to go to. There are no screens here; no rows of exercise machines with earphone sockets. A dog sits curled in the middle of the gym floor. Def Leppard blares out of the sound system. And, as if to drive home the Sam Heughan connection, several of the personal trainers, bearded and buffed, look as if they might have stepped off the set of Outlander and possibly should be working out with claymores not kettle bells, while wearing loose white shirts and tantalising kilts.

“But it’s OK,” I add. “I do some exercise. I just did a Race for Life 10K about a month ago.” I decide not to mention that I occasionally do Pilates. This does not look like a gentle Pilates sort of place.

The smell of sweat hangs in the air. Already I’m aware that this may be the kind of gym session where I have to leave my dignity at the doorway. Any slight rise in heart rate and my skin weeps perspiration like a squeezed sponge. But all that seems to fit with the gritty glamour to this place.

The brainchild of a group of fitness industry friends – personal trainers and Muay Thai fighters who fought together, flat-shared and bounced ideas together – it opened earlier this year. But the concept was developed some years ago, when fighter Patrick O’Brien came back from training and competing at the close combat boxing sport of Muay Thai in Australia, with talk, which he shared with his friends, of how the whole “boot camp thing had gone wild in Oz”.

“Originally,” says Tommy Young, “we were looking into doing a boot camp along the lines of a thing called Heavy Haulers. It was a big thing in Australia. They used car parts, tyres, underground parking areas. They had this industrial vibe. But then we observed that Ultimate Fighter was going through a boom, and since me and Paddy were still fighters, we thought, ‘Why don’t we get people fighting and do almost like a mini fight camp and combine the two?'”

The team soon gained a reputation for highly effective fat loss camps partly based around principles the fighters used when attempting to hit a certain weight for competing. “When a fighter is training for a fight, he does a six week camp to get to the specific weight," explains John Valbonesi. "We thought, 'How can we bring that weight-loss, but the safe ways to do it, to people? That was one of the things we became known for, why the boot camps are so popular. We’ve got so many testimonials. The methods that we used worked.”

Patrick O’Brien, it turns out, is to be my personal trainer for the next 45 minutes. His dog, part-retriever, part-collie, trails us round the room. O’Brien is also an actor and musician out of hours. Just an easy session, he promises. Nothing too hard, though we will end up at some point an exercise bike he refers to as the “machine from hell”. At this stage I’m not worried. It looks innocent enough – like many an exercise bike I’ve pedalled before.

We begin gently, with a warm up. There’s a voice in my head telling me not to overdo it. I decide it might be best to be just a little half-hearted – though this is clearly not the Fight Camp way. By the time we start the circuits, though, O'Brien is having none of this. Perhaps he has detected that I need an extra push. After a couple of rounds of hauling a medicine ball into the air then slamming down on the ground, doing crouches with kettle bells and pushing some kind of trolley across the floor, he is barking at me to go faster, push harder, squat lower.

Hence, by the time I put on my boxing gloves, I am already panting, dripping and possessed of the kind of ruddy glow most people only get after a long session in an overheated sauna. My photographer keeps checking if I am OK and reassuring me that I look like a “Celtic goddess”. I know what this is a euphemism for. Some people seem to manage to maintain some semblance of composure while doing aerobic exercise. I am not one of them. But at least I get to catch my breath while O’Brien teaches me the art of the basic Muay Thai jab.

A whiff of old sweat. This is the kind of gym where, putting on boxing gloves, you stick your hands inside the perspiration of others. At fight camp you have to be happy with human contact. If you’re punching pads you’re doing this exercise with someone, looking them in the eye, interacting with them.

But at the same time this isn’t really that hardcore – rather it’s where Muay Thai meets the mainstream. “We’re not really a hardcore fighting gym," says O'Brien. "I came from a hardcore fighting gym and it’s great but your average Joe will come in and feel intimidated – by the smell of the place, the guys walking about with tops off. If you’re some wee guy or girl coming in you’re a bit like – 'What the hell?'”

The team here pride themselves on friendliness, camaraderie and banter. As much as this gym is about punching a few pads and kicking up a bit of sweat, it’s also they keep telling me about “community”. The next generation of Muay Thai fighters is being trained here. “We’ll encourage bringing the babies in as well,” says Valbonesi. “It’s dog-friendly, baby-friendly, all ages.”

Nor are the clients mainly six-packed men oozing testosterone. “When I started off,” says Valbonesi. “I was thinking I would be training all these bodybuilders, guys, and it ends up being a higher ratio of females in the gym. And they can hold their own with the guys as well. Sometimes we’ll have a fighter training who needs to up his conditioning in the same class as a 50-year-old mum of two and it’s quite good the way they play off each other. She’ll be shouting at him, he’ll be shouting at her.”

It strikes me that I’ve come at the wrong time of day – during the quiet stretch of the afternoon. There’s only one other person in the room training as O'Brien and I dance round the boxing ring and he calls on me to “one-two” jab at his pads.

A few rounds of burpees and some pummelling at the punchbag and it's time for a turn on “Satan’s bicycle”. My mission, says O'Brien, is to cycle off 15 calories as fast as I can. I’m surprised at how small that challenge sounds; 15 calories is nothing. It’s a carrot stick, a cake crumb if you’re lucky. And in fact, as I pedal down the calories, it doesn’t really feel that bad.

It’s only as I dismount that I start to reel. O'Brien is telling me stories about previous victims of this bike, but it’s all seeming a little distant. I nod at him as I place a hand on the seat of the bike, hoping he won’t notice I’m using it to prop myself up. Really all I can think about is how good it would be to sit or lie on the ground, though when O'Brien asks if I’m OK, I tell him yes. Meanwhile, he goes on with his tales of how this machine has left strong men floored, vomiting, in need of leg massages, unable to return to work for several hours.

It turns out almost every trainer has some story about this machine from hell. “When you’re doing it often you’re okay but as soon as you get off, your legs start to give way,” says the youngest trainer, 24-year-old Martin McCann. “We did this calories challenge: 30 calories as fast as you can, then 20 then 10, competing to beat everyone else’s time. I couldn’t finish it. My legs after the 20 calories gave out and they were super-hard. I was rolling on the floor, in agonising pain, someone had to massage my legs. It took me almost half an hour to stand up.” One of the other trainers, he says, was “sick in the toilet twice”.

“We had one guy who did the 50-calorie challenge in under one minute, and got the best time in the gym so far," says McCann. But it took him an hour and a half to get back to work. Because he was so ruined. It’s just disgusting that bike.”

For the most part, this place isn’t about machinery. It's about the people. The interactions. The contact, and though there are bars and frames, mostly it's not high-tech.

Tommy Young suggests people like Fight Camp because it’s “real”. “People are seeking what’s real. A lot of the stuff we do is very physical so you feel it when you’re doing it. The Muay Thai stuff is hitting pads, hitting bags. It’s very practical. Wrestling and ju jitsu are on a boom at the moment. It’s very hands on, quite gritty. And people just love that right now.”

Young believes it’s an antidote to our desk-centric and sedentary work lives. “People come here and it’s just this lease of pure life. They get to hit, jump around, kick stuff, throw stuff. The exercise world has changed in the 13 years I’ve been a trainer. This stuff that we’re doing now was such a minority back in the day. But now you’re seeing gyms pop up everywhere.”

It’s also what I like about it. Fight Camp represents the opposite of everything the running machines of gyms had come to represent in my head – the hamster wheel of modern life and the soullessness of today’s exercise. This gym isn’t like that. It’s not, as John Valbonesi describes, “rows and rows of machines, people plugged in with headphones on, people not speaking to each other any more”. This is training that is absolutely personal, not impersonal. About people, not the system.

For more information look at www.fightcamp.org

Meet the team

John Valbonesi, 30

Background: Studied software engineering, but started spending more and more time at the gym, then dropped switched to studying sports management.

Favoured exercise: “I do more strength and lifting-based exercise and I like the heavier weights and lots of bar bell work. The other three are all ex fighters. I don’t like getting hit. In this gym, there’s the fighter’s office and my office.”

Training style: “I’m known as the cheesy one. Over the course of a session you’ll hear some godawful motivational chat. 'It’s not sweat, it’s success.' Or, 'It’s just fat crying.'"

Claim to fame: Personal trainer to Outlander star Sam Heughan, with whom he set up My Peak Challenge, a campaign in which people raise money for blood cancer by setting themselves personal health and fitness goals.

Lifestyle tip: “It’s not just about when you’re in the gym. We want you to live a healthier life outside. We will give you stuff to do in the house as well. We try to give you healthy meal plans. A lot of people who come are going on holiday soon and they’re like, 'I want to look like this in four weeks'. That’s not lifestyle change. If you’re looking a certain way it’s because of the lifestyle. We want to change that lifestyle, for the rest of your life.”

Patrick O’Brien, 37

Background: Raised in Ballybay, a small town in Ireland where "there wasn't much going on". I did karate when I was kid and then boxing but the club closed down and the karate guys went away. While studying music at university in Northern Ireland, "I saw there was kickboxing and I was like, I’m going to join that. I was hooked.”

Claim to fame: “I was Scottish middleweight Muay Thai champion in 2011. But I quit after that. It’s hard graft. You’re training five hours a day, morning and evening, for six weeks, and at the end you get £200. You do it for love, but then you realise you have to pay bills.”

Lifestyle tip: “There’s a nutrition company called Precision Nutrition created by John Berardi, I’ve done a couple of his courses. He gives you 10 habits – one might be take a multi vitamin every day. You keep that habit for a month; then you move on to the next habit change. Over the period of a year you’ve created all these new habits, but it’s not all at once, because if you do it all at once you’re never going to stick to it.”

Mentor: My old coach, Guy Ramsay from the Griphouse. I did one of his classes and I was like what the hell is this. I’d done kickboxing and Bruce Lee’s martial art, but when I did Thai kickboxing it was like what is this because everyone was kicking so hard. It was full on."

Martin McCann, 24

Background: Aged 10, he "fell in love with" Muay Thai. "I’ve pretty much always been keen on fitness. At seven I was doing karate.

Training expertise: "I mainly teach the kids. Mostly it’s squatting, push-ups, burpees, as well as Muay Thai. It’s to get them prepared for when they’re older, to recognise that fitness is part of a lifestyle. And this is the next generation of fighters: boys and girls."

Teaching style: “I suppose I kind of slag them a wee bit, so that they maybe get a wee bit annoyed. If I give them a challenge – who can get the 50 kicks fastest – and one of them puts their hand up, I say, I bet you I can do it faster."

Favoured exercise: “I just came off an eight-week programme in which I was doing a lot of volume and lifting. Right now I’m back down to just lifting for strength. I feel much stronger. But I’m still doing Muay Thai."

Tommy Young, 33

Background: A "martial arts freak" since aged six, he got a black belt in karate then tried Kung Fu and "stumbled into Mai Thai and loved it. It wasn’t that I wanted to be a fighter. When I started I just loved the sport. Then eventually I got better and better and started doing more fighting and I got bitten by the bug of getting better.” He gave up studying design to fight Muay Thai. “I was moving away from this idea of being stuck doing some sort of desk job."

Claim to fame: Scottish and British welterweight Muay Thai champion. “I managed to knock up a British and a Scottish title, got world ranking, went and fought in Thailand as well. That country had a big part to play in my love the sport. I would go over for six months at a time."

Philosophy: “Dominate humbly. That’s a term that has stuck with me. It isn’t something from Muay Thai but it’s directly relatable to it. It says be the best and kick ass and win, but be humble. Because there’s always going to be someone comes along better than you. Muay Thai is steeped in respect. It doesn’t matter who you are or where you’re fighting, if you get in the ring, then hats off to each other, it’s not an easy thing to do."