"You will have bruises tomorrow", says a woman in platform trainers, bright pink disco pants and an electric blue crop top. She hastens to add: "but I like to think of them as war wounds". It's not the opener I expected from a hula-hoop fitness class.
Billed as "a fun way to get fit", Hulafit combines aerobics and conditioning exercises with the added dimension of hula-hooping. As the prospect of getting "bikini ready" looms, it sounds like the perfect antidote to endless hours on a treadmill in a soulless gym.
When I arrive at the community centre in King's Cross I am somewhat dubious - it seems like a deserted building with the lights left on. But as I head upstairs I'm reassured by the faint sounds of Robyn's "With Every Heartbeat" coming from above. The music gets louder and I hear what sounds like hula-hoops intermittently hitting the ground. When I reach the third floor, there's a pink and orange striped hula-hoop hanging from the door handle: the advanced class is in session.
As the previous class wraps up, a friendly voice from inside the room beckons us in. The room is relatively mundane apart from an abundance of hula-hoops that line one wall; there's an eclectic mixture of big, small, sparkly and striped. I notice some grey ones with ridges that look more heavy duty.
Anna, the instructor, explains that the serious-looking hoops are weighted to increase the toning impact of the class. She asks me: "when was the last time you hula-hooped?" as she hands me one of the weighted variety. I tentatively pick it up as I realise that it's been about 12 years since I went anywhere near one.
As the room fills up it's clear this is a female-dominated class, with no men in sight. We begin the warm up and it's apparent who the regulars are as they pick up a hoop and begin expertly spinning it round their waist. I congregate with the women who are obviously new to this too. Everyone is dressed in Lycra apart from one woman who sticks out in jeans. Lycra is not essential but jeans don't allow for much flexibility in a class that revolves around moving your hips.
As we warm up, it comes as a shock that I can actually remember how to hula-hoop -followed almost immediately by the shock at how weighted this hoop is. It's increasingly clear that we will indeed be bruised tomorrow. There's a sense of camaraderie between myself and the other amateur hula-hoopers; we grimace at each other with exaggerated whispers of: "it hurts!"
A woman who appears to be a veteran class member tries to alleviate our concern. "It's my fourth week and I can barely feel it now - you get used to it".
After we master the basic hula-hoop movement, we learn how to control the hoop by bending our knees to stop it falling to the ground. We then embark on the more complicated matter of doing regular exercise while simultaneously keeping the hoop rotating around our hips. Squats and lunges, which are normally fairly straightforward, seem almost impossible while hula-hooping. It's like trying to rub your stomach and pat your head.
Anna encourages us to stick with the weighted hoops and tense our abs as we exercise - "it's like sit ups but more fun". She's not wrong there. Without tensing your abs, "you're basically just giving yourself a massage", says Anna. I beg to differ.
To give our midsections a well-needed break, we then work on the upper body by taking the hula-hoops in our hands to act as weights.
We move on from conditioning to cardio and I'm getting accustomed to having a hula-hoop constantly spinning around my waist. We run on the spot, jump and learn to spin our bodies against the moving hula-hoop.
As the final song comes on Anna instructs us to "do your own thing". The room full of women have no inhibitions as Beyonce's "Run the World (Girls)" blasts out of the speakers. Despite the tentative start, I've gotten used to the weighted hoop and even mastered a few moves. Plus, I've enjoyed myself; you can't really dread a hula-hoop class like you would a gym session.
But hula-hoop fitness isn't just a novelty; I feel like I've had a serious workout. As I bend down to pick up my bag, I'm pretty sure I can feel those bruises developing.