IN THE shadow of the East Park trees, a man in army fatigues bellows at a woman in lycra.
"Newbie, what is that? Call that a squat. That's not a squat."
Peering through a veil of perspiration, there is the sinking realisation that Action Man is addressing this woman in lycra.
Each week, people of all ages and professions turn out, whatever the weather, at East Park and Pickering Park to get fit, lose weight and meet new friends at British Military Fitness (BMF) classes.
In Hull, 70 per cent of men and 61 per cent of women are overweight. And, according to Public Health England, 28.2 per cent of adults living in Hull and 25.9 per cent in the East Riding were classed as obese last year.
With East Yorkshire facing an expanding problem, BMF classes are becoming increasingly popular as people take charge of their own health.
There are three groups – blue for beginners, red for intermediate and green for advanced.
Michelle Chick, 29, is a medicines management technician at Castle Hill Hospital in Cottingham and she is in the blue group.
Once weighing 17st 2lb, she got down to 10st 6lb through healthy eating and exercise before becoming pregnant. Her baby now eight months old, she started BMF three weeks ago and attends twice a week.
"The first night, I got soaked and was pulling grass out of parts I never knew I had for the next two days. And I could barely move," she says.
"Now, I'm getting my fitness back again. I can run more and do more sit-ups."
Given the nature of BMF, most imagine a Sergeant Major roaring at hapless underlings.
"Oh, we will shout at you, but it's only shouts of encouragement," says East Park BMF manager Paul Baigrie.
"We train you to your own level. In the blue group, it's more fun with games and partner work. The red class features more difficult exercises but still with fun. The green will be tougher but in a good way as you're at a fitness peak and you want to be pushed."
Unlike most BMF instructors who are either former or serving members of the military, Paul is a physical training officer (PTI) in the prison service.
A PTI for more than 20 years, he joined the BMF staff in 2009. He is taking the class tonight with fellow camouflage-clad instructors Tony Barenskie and Mark Pearson.
"Something like this is really needed in Hull," Paul, 47, says.
"We are in the fresh air and this is like having a personal trainer for £30 a month instead of £30 an hour. All you need to do is turn up.
"We do your thinking for you. You just do it."
While £30 might sound a lot and there are cheaper ways of getting fit, it is not much when you consider a recent survey showed families in the East Riding are spending £68.43, while families in Hull are shelling out £62.09 on takeaways each month.
We are split into groups and set off running in two files for the warm up. Within five minutes, death would be a welcome release.
Paul is taking the blues tonight – a merry band of ten women.
We jog, we do press-ups and sit-ups. They squat, I kind of crouch down. We link hands through our legs to snake through the park in a race. We push and pull our partners and then we jog some more. Throughout it all, Paul roars us on. But it is friendly, encouraging and not in the least intimidating.
But fall foul of him at your peril. Twice we mess up and our reward is press-ups in the mud while families and couples out walking their dogs stroll by in the fading sunshine.
Midway through, trying to run up a slope at the end of a short sprint for about the ninth time, there is a strong desire to stop.
But my partner's doing press-ups until I get back and it drives me on.
Despite a lack of co-ordination and an inability to tell right from left under pressure, it is immensely enjoyable.
Somehow, we make it to the end of the hour and join the red and green groups, still at it.
School nurse Michelle West, 34, has been coming three times a week for six months and she is wearing a red bib.
"I had terrible fitness and I couldn't run, so I started doing this in January as I needed to get fitter and lose weight," she said.
"At the first session, it really killed but I loved it. The instructors are fantastic.
"The link between physical and mental fitness is under estimated."
Father-of-two Charles Whiteford, 47, has lived in east Hull for more than 20 years. He starting BMF at East Park more than four years ago.
"I'm not a great fan of gyms but I'm a great outdoors person," he says.
"I have gained some wonderful friends through it and that's more than a gym can give you.
"You're not only concentrating on individual effort, there's a lot of team effort, games and exercises.
"There are tremendous health benefits. I've gained a lot of upper body strength. Now I do ultra runs, which is fell running of 30-plus miles.
"One of the best bits is the buzz you feel after doing it. "
Staggering back to the car park, everything aches. But there is an unfamiliar sensation – fizzing with life and high on living. And that has to be worth shouting about.
Visit www.britmilfit.com for more information on the Hull classes.
'One of our members is 85'
Former Royal Marine Mark Pearson (above right) says: "British Military Fitness (BMF) started in 1999 in Hyde Park, London and our staff are former or still-serving members of the Armed Forces.
"Most people's perception about BMF is there's a sort of Sergeant Major standing over you, shouting, but it's not like that or no one would come back.
"A cross-section of the community comes – all ages and backgrounds, men and women. We've got a member who's 85 in London.
"We have people who want to join the forces, people who want to lose weight, people who want to train for fitness and people who come for leisure.
2Because it is military led, there is belief in us by the members. They know we are at certain level of fitness. The only thing that changes is it's a lot more friendly.
"It is a great stress reliever. A lot of people come for that reason.
"And we do it all outside. That's what our members would never change for a gym."