My exercise coach, Louis, reassures me, ‘Don’t worry. This isn’t going to be a beasting,’ as he straps a heart-rate monitor to my arm. ‘We work together to find the right intensity and then you set your own pace.’

Puzzled, I look up the definition of beasting on my phone – ‘punishment intended to humiliate, push to the limit and hurt (usually military)’. What have I let myself in for?

I haven’t set foot in the gym for more than 35 years, put off by the shouty male instructors, harsh lighting and general air of body fascism back then. 

Like many middle-aged women, I like endorphin-boosting exercise, but it needs to be gentle and non-competitive. I walk 30 miles a week, swim three times, do Pilates. But if it involves Lycra, count me out.

Yet Orangetheory Fitness, the cult gym studio franchise, founded in America and growing in popularity in the UK, where there are now nine studios, claims to offer a different type of exercise class.

I haven't set foot in the gym for more than 35 years, put off by the shouty male instructors, harsh lighting and general air of body fascism back then

I haven’t set foot in the gym for more than 35 years, put off by the shouty male instructors, harsh lighting and general air of body fascism back then

Community and inclusiveness are the watchwords. It’s for people of all ages, shapes and sizes. Michelle Obama is a fan and, if you watch Netflix show Queer Eye, you’ll recognise it as the place where the Fab Five take clients.

Could this cure my gymphobia?

Orangetheory (or ‘Orange therapy’ as fans call it) runs hour-long circuit classes divided between time on the treadmill and rowing machine and weights and strength exercises such as lunges and squats on the floor. It’s a group class, but you go at your own pace according to your own heart-rate data.

Everyone is set up with a heart rate monitor on their arm. This tracks your beats per minute and the data is projected next to your name on digital screens in the room so you can see how many calories you’re burning and your average heart-rate percentages.

Yet Orangetheory Fitness, the cult gym studio franchise, founded in America and growing in popularity in the UK, where there are now nine studios, claims to offer a different type of exercise class

Yet Orangetheory Fitness, the cult gym studio franchise, founded in America and growing in popularity in the UK, where there are now nine studios, claims to offer a different type of exercise class

Yet Orangetheory Fitness, the cult gym studio franchise, founded in America and growing in popularity in the UK, where there are now nine studios, claims to offer a different type of exercise class

The goal isn’t to be flat-out for the whole time, but to elevate your heart rate, boost metabolism and improve cardiorespiratory health.

Sadly heart health isn’t good in my family. My father and all my grandparents died of heart attacks early in life.

Afamily history of heart disease is defined by having a first-degree male relative who had a heart attack by age 55, or a first-degree female relative by age 65. My dad had his first age 54.

When I consulted a leading cardiologist recently, he told me bluntly to cut out weekly chips, adopt a Mediterranean diet and do more fat-burning exercise. I’m fit but a little bit plump – which is dangerous with my family history.

So could heart-rate based interval training age 60 at the dreaded gym make a difference?

I book into Orangetheory’s studio in Fulham, South-West London. I’m expecting an orange-clad cult. And, yes, the lighting does make the whole room look orange and the super-fit coaches do have a hint of Baywatch about them, but they’re kind, enthusiastic and make you feel their greatest goal is to get porky midlifers into shape.

Everyone is set up with a heart rate monitor on their arm. This tracks your beats per minute and the data is projected next to your name on digital screens in the room so you can see how many calories you're burning and your average heart-rate percentages

Everyone is set up with a heart rate monitor on their arm. This tracks your beats per minute and the data is projected next to your name on digital screens in the room so you can see how many calories you're burning and your average heart-rate percentages

Everyone is set up with a heart rate monitor on their arm. This tracks your beats per minute and the data is projected next to your name on digital screens in the room so you can see how many calories you’re burning and your average heart-rate percentages

At the start, Louis guides me through the five heart-rate zones people go through as they work out. Grey is when you’re relaxed; blue is the easy warm-up zone; green – the ‘endurance zone’ – is when you’re feeling challenged; then there is the orange zone when things start to feel uncomfortable. The red zone – the top one – is reached at maximum effort. 

‘It’s like your mother-in-law’s house,’ jokes Sean Johnson, Orangetheory’s regional fitness manager. ‘It’s fine to pop in, but no one wants to stay too long.’

The aim is to spend a third of the workout (20 minutes) in the orange zone and the rest in green. But the level of effort required will depend on your body and medical history.

I have never done interval training before. The session starts on the rowing machine, where I find myself enjoying the workout of muscles, abs, legs.

Louis encourages us to increase our efforts, get our heart rate up and move from the warm-up grey zone to green.

Soon everyone’s profiles are lighting up green, orange and red on the overhead leader board. Disappointingly, mine doesn’t budge beyond grey (aka a relaxed pace).

I have never done interval training before. The session starts on the rowing machine, where I find myself enjoying the workout of muscles, abs, legs

I have never done interval training before. The session starts on the rowing machine, where I find myself enjoying the workout of muscles, abs, legs

I have never done interval training before. The session starts on the rowing machine, where I find myself enjoying the workout of muscles, abs, legs

Then, It’s A Knockout-style, the group sprint to the other side of the room to try strength exercises. While everyone else is twirling weights around their head, I’m still trying to get my feet out of the rowing machine’s Velcro straps.

I enjoy the Total Body Resistance exercise (stretching using wall-mounted resistance bands), and it’s good to see my profile has moved to blue. I already lift 3kg hand weights at home, but combining weights with lunges is tough. I’m weeping by the third set of reps and shocked by how unfit I feel.

We move on to the treadmills where you can run, jog or walk. I opt for power walking at four miles per hour. As we switch the incline up to 10 per cent (to increase the gradient), I finally get my first green zone reading and feel triumphant.

After, Sean takes me through my results (regular members get them by app). After one high-energy, adrenalin-pumping class, I’ve burned 308 calories in an hour and walked 3,000 steps. In comparison, I had to walk seven miles the day before (14,000 steps over five hours) to burn that amount.

Yes, the lighting does make the whole room look orange and the super-fit coaches do have a hint of Baywatch about them, but they're kind and enthusiastic

Yes, the lighting does make the whole room look orange and the super-fit coaches do have a hint of Baywatch about them, but they're kind and enthusiastic

Yes, the lighting does make the whole room look orange and the super-fit coaches do have a hint of Baywatch about them, but they’re kind and enthusiastic

I was in the green zone for 16 minutes. My peak heart rate was 131 beats per minute (ideally for my age, it should be 80-136). Power walking on an incline is low-impact but will strengthen my posterior chain (the muscles in the backside and glutes), Sean says tactfully.

The day after my session my thighs are in agony – have they ever moved this much before? When I test my blood pressure with my Omron home monitor, it’s down from Grade 1 Hypertension to High Normal. I hate interval training but even I can see the point of getting out of your comfort zone.

Orangetheory is less about body building and more about ‘training for life’; improving strength and co-ordination so you can walk up stairs, carry shopping and other things that can slip in later life.

So yes, I agree to go back every week. And actually do! I’ve even managed to hit the orange zone once or twice and I’m less breathless climbing hills. I have a nasty feeling I’ve been converted.

  • Orangetheory Fitness studios across the UK offer a complimentary class trial. Membership options in London start from £109 per month or £199 for ten classes, orangetheory.com

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