"You must crawl. If you stand up, the bungee will fling you back against the wall. It will hurt." The warning rings in my ears as the bungee is tied around my waist and I begin a constrained "bear walk" on all fours across the gym floor. The bungee is designed to provide resistance as I move forward.
I'm sweating and shaking and I'm not sure if that's because of the workout, or the fear I'll be tossed to the other side of the room.
I've signed up for Caveman Circuit Training.
Personal trainer and gym owner Anna Junghans tells me Caveman Circuit Training is one of the latest trends for those who like to get hot and sweaty. "Over the years everyone has been led into this old-fashioned belief that slugging it out in the gym for two hours every day is the only way to get results, but people are finally waking up and saying, 'Hey, how come after doing that for six months, I'm not seeing any difference?'," she says. "That's why something like Caveman Circuit Training is so popular, because it's so effective."
The circuit workout is similar to a boot camp - the previous incarnation of the extreme workout. In the boot camps I've done, the emphasis has been more on cardio, while caveman aims to improve strength, dexterity and fitness through seemingly old-fashioned workouts.
In my 45 or so minutes of "introductory" caveman training I use a sledgehammer, push tyres, lift kettle bells, do burpees and swing ropes. At the end, I'm buggered and sore.
"That's the thing about this sort of training, people come here and think they're fit because they can run – but this really shows how fit you are," Junghans says.
Junghans says the very fit often wear gas masks during microfitness short, intense workouts - to mimic high-altitude training: "It's for people who really want to take their fitness to the edge."
Richie Cranny from Sydney's Platinum Extreme is another advocate of full-on fitness.
The mixed martial arts expert says more people are using combat techniques to reach their fitness goals. "The training is so diverse – you've got all the best elements of 78 martial arts into one. Mixed martial arts used to be for people who wanted to compete, but now the training side of it has really been recognised as a huge plus for anyone looking for new ways to train," he says.
Cranny, who trains The Biggest Loser trainer Shannon Ponting, says fear of the unknown is the biggest factor stopping people getting involved in extreme training sessions. "When they first hear about it, and even if they really want to do it, people can be too scared to take that first class," he says.
But Melody Carstairs from Extreme Body Gym in Melbourne says while fear may initially stop people, the ego eventually drives them into the gym.
"The majority of my clients, I would say, come here because they want that picture-perfect body. They want everything hard, and they want it overnight," Carstairs says.
"A lot of people also initially have lazy attitude, not realising how crucial weight training and diet are. I change all that for them."
The professional bodybuilder and body sculptor also contends people don't have to spend hours in the gym to achieve amazing results.
She lives by an 80-20 rule - put in the hard yards 80 per cent of the time, and give yourself a break in the remaining 20 per cent.
But she says people will not get the look they want unless they consistently work hard.
"I think the key to a sculpted look is getting a trainer who walks the walk," she says. "You don't want someone with perfect genetics. You want someone who's sweated it out and knows what you're going through."
Written by Torny Jensen from mX Newspaper