Map of HIIT classes in London
  1. Guts & Glory (at Sweat IT), Holborn

  2. RIDE (at Psycle), Shoreditch

  3. Fortis (at Everyone Active), Soho

  4. BarreSWEAT (at Barrecore), Islington

  5. EMS with ViveFitness, Westminster

Londoners are always in a hurry, so it is no surprise that high-intensity interval training (HIIT) has surged in popularity here. 

HIIT takes many forms, but it always involves short, explosive bursts of exercise followed by brief rest periods. This makes it one of the most efficient ways to lose fat: more calories are burnt in a short amount of time — and they continue simmering after class too. It increases excess post-exercise oxygen consumption (EPOC), or the ‘‘afterburn” effect, which means the body continues to burn calories after a session.

Attending a HIIT class in London used to mean paying for a monthly gym membership, but independent studios where you can pay per session have sprung up in recent years. I’ve narrowed down some of the city’s best classes on offer again following months of gym closures.

I attended the following classes before lockdown; the studios have since introduced safety measures such as decreased class sizes to accommodate social distancing, temperature checks on arrival and mandatory mask-wearing in common areas. The specific requirements at the time of publication are included below — but do check with a studio directly for the most up-to-date measures.

1. Guts & Glory (at Sweat IT) 

4 keen street, London WC2B 4AS

  • Good for: pushing yourself to the limit. I wince just thinking about the parachute sprints

  • Not so good for: anyone who cares about how they look when working out 

  • FYI: a single class will set you back £21, or you can buy bundles of three for £30 if it is your first time. Sweat IT also offers a laundry service, so you can have your kit washed and ready for your next session if you are planning multiple visits

  • Website; Directions

This is ‘the hardest workout on the planet’, the club claims © Charlie Bibby/Financial Times
You be the judge, if you can last the full 45 minutes © Charlie Bibby/Financial Times

Sweat IT, an underground studio near Covent Garden, says its Guts & Glory class is “the hardest workout on the planet”. I would be lying if I said I’ve tried anything harder. 

The 45-minute class is split between intervals on Skillrun treadmills, which allow you to perform cardio with resistance, and a floor mat, where you execute strength exercises such as renegade rows, lunges and overhead shoulder presses. 

The most punishing segment of the class is what Sweat IT calls the “parachute sprint”. A belt is clipped around your waist and connected to a treadmill. The instructor has the class perform a series of timed sprints with parachute resistance, which mimics the way some sprinters tie parachutes to their backs and use natural wind resistance to improve strength and explosiveness. The monitors on the treadmill display the distance run and the resistance, which increases along with your speed.

The aim is to continue increasing the distance run as the sprint becomes harder. The reality is somewhat different: after a few intervals, the resistance makes the treadmill feel like quicksand. 

After my intervals, the treadmill was soaked with sweat and I collapsed on the floor, sucking in deep gulps of air. But even the most chiselled bodies in the room ended up in a similar state of fatigue — so it does not look like this class is any easier for the super-fit.

In normal times, complimentary protein shakes are made to order before class, to be picked up on your way out — and they are rather good. I opted for the ‘‘Wolverine’’, which blends almond milk, vanilla protein, banana, espresso and peanut butter. I inhaled my shake, unsurprisingly: my fitness tracker said I torched 561 calories in the 45-minute class. 

Sweat IT has made a few Covid-related changes since my last visit: clients are temperature-checked on arrival, face masks must be worn and only removed during workouts and hand sanitiser is readily available. Class capacity has been reduced by 50 per cent to facilitate social distancing; there is no sharing of equipment or treadmills; and, disappointingly, the superb shakes are unavailable for the time being.

2. Ride (at Psycle)

17-23 Whitby Street, London E1 6JU

  • Good for: blitzing calories on a stationary bike. According to my fitness tracker, I burnt 600 calories in the 45-minute class

  • Not so good for: those who lack rhythm and co-ordination 

  • FYI: a single class starts at £22. Psycle also offers barre, strength and yoga classes and has four locations across London

  • Website; Directions

No fancy monitors or other frills here . .. © FRENCH+TYE
. . . just you, a bike and some motivation

Psycle says its signature, 45-minute indoor-cycling class, Ride, is designed to push you beyond the limits of an average spin session. There is little respite: the intensity is high and the intervals are short. 

Unlike some of the high-tech spin classes available in London, with equipment that features monitors or screens displaying distance, speed or RPM data, Psycle is no frills: it’s just you and the bike — and a motivational instructor. The studio is minimal, the music deafening. 

Ride requires rhythm as well as endurance: the speed at which you pedal is dictated by the beat of the music alone. There’s choreography too, such as moving in and out of the saddle or crunching obliques to the beat. The class moves in perfect harmony (well, almost: I always seem to be at least half a beat behind the pack of riders around me).

To challenge co-ordination as well as physical endurance, the class also includes an upper-body workout with mini push-ups on the handlebars — all while continuing to ride. Hand weights also feature, though these have been removed for the time being.

Psycle has also introduced a slew of Covid safety measures. Non-contact temperature checks on arrival are mandatory, masks must be worn outside the studio in communal areas, and the timetable and class capacity have been reduced.

Although the changing rooms are still open, Psycle advises clients to arrive in training gear to avoid usage where possible; locker access is also limited to help maintain social distancing.

3. Fortis (at Everyone Active)

15 Marshall Street, London W1F 7EL

  • Good for: a high intensity workout with low impact and minimal muscle soreness

  • Not so good for: those who like to hide when it gets tough

  • FYI: you’ll need to bring your own towel and shower gel 

  • Website; Directions

Take your neighbour on if you are the competitive type © Marcel
The old-school setting houses a state of the art studio © Alamy Stock Photo

HIIT that doesn’t hurt may sound like an oxymoron, but that is exactly what Fortis says it offers in its new studio at Marshall Street Leisure Centre and Spa, a beautiful Grade-II listed building in Soho.

Fortis claims it is the “ultimate inclusive workout”: all ages and fitness levels are welcome. A 22- and an 82-year-old, in theory, could train side by side, using the Speedflex machines that this 30-minute class is built around. At first glance the Speedflex looks a bit like the lateral pull-down machine that features in most gyms, but it can be used to perform a variety of moves.

Speedflex has a “free motion bar” that uses a hydraulic system, allowing users to perform squats, clean and presses and bent-over rows. Resistance levels react to how much power is put in, and if it becomes too difficult, you can simply let go of the bar.

That might make it sound easy, but it isn’t. This class mixes cardio and resistance: you are encouraged to perform repetitions of each exercise as quickly as possible.

Everyone is provided with a MyZone monitor: calorie burn, effort level and heart-rate figures are projected for all to see on a big screen, which might appeal to those with a competitive streak. Can you beat your neighbour — or the entire class?

Fortis says it delivers the benefits of HIIT without the risk of injury or muscle pain sometimes associated with high-intensity training, because Speedflex machines isolate the concentric movements, or the opening of the joint. (It’s the eccentric phase of muscle contraction, the closing of the joint, that is said to lead to soreness.) I ended the class gasping for breath, having burnt 240 calories, according to the MyZone data — and was pleasantly surprised by the minimal aches and pains the following day. 

Fortis now provides hand sanitisers in the studio, reception and communal areas. The Speedflex machines have been spaced out to allow for social distancing and class sizes have been reduced from 18 to a maximum of eight people. 

Pre-Covid, participants would move around the studio in a circuit but now remain on one machine throughout the class. Studios are also closed and deep-cleaned after each class. 

While the Soho studio is state of the art, the changing facilities are less impressive. The showers are, to put it politely, functional, and you will need to bring your own towel and shower gel. But this is reflected in the price: pay-as-you-go classes are just £15 — a bargain in central London.

4. BarreSweat (at Barrecore)

90-92 Upper street, London N1 0NP

  • Good for: working muscles you didn’t know even existed 

  • Not so good for: anyone who struggles with balance 

  • FYI: there’s no need to pack trainers, but you’ll need socks with grips, which are available to buy at the studio. Pay-as-you-go classes are £28 and private sessions are available from £80

  • Website; Directions

Don’t be fooled: the ‘barre shakes’ will happen
Dodgy joints are not a problem in this low-impact setting

If you like the idea of HIIT but are put off by the prospect of sprinting in a dark studio with a shouty instructor, it’s worth trying a barre-based workout.

The BarreSweat class at Barrecore, a boutique studio with 12 locations across London and the rest of the UK, is a low-impact HIIT workout and therefore kinder to those who suffer from lower-back pain or have dodgy knees. Its roots lie in ballet, so most of the moves are performed around a barre, but this class also combines dance, yoga and Pilates techniques with the sort of strength exercises you might find in a more conventional HIIT class. The exercises are packaged together in lengthy chunks and the rest periods are brief. 

I initially doubted whether this type of workout would leave me breathless — until I experienced the notorious “barre shakes”. My legs trembled uncontrollably from engaging muscles I did not know existed. More than once I had to stop an exercise to shake a muscle out and I struggled to maintain balance, at one point almost falling over. The instructor assured me that the shakes are perfectly normal — even desired — as it shows that the exercise is working.

Class sizes are deliberately small so the instructor has time to spend correcting participants’ form and posture (and there was plenty of opportunity to do so in my case). It is a welcome change of pace from other HIIT classes and feels more civilised; at times it was even relaxing.

At the end of the class, the lights are dimmed and participants are encouraged to lie down on a mat, eyes closed in an almost meditative state, before a lengthy series of stretches.

Unlike some other HIIT classes, I didn’t leave soaked with sweat but instead had an enormous appetite, which is usually a good sign that a workout was tough. (I burnt 356 calories in the 45-minute class, according to my fitness tracker.)

Under Barrecore’s Covid-security guidelines, clients are encouraged to change and shower at home, signs and floor markings are in place and workout stations are marked with tape to help maintain social distancing. Hand-sanitiser stations and wipes are also provided. 

Workout stations are set up before people arrive, with equipment laid out to stop congestion around the storage area, and new air-purification systems are used regularly throughout the day.

5. EMS with Vive Fitness

22 Medway Street, London SW1P 2BA

  • Good for: time-poor people with deep pockets 

  • Not so good for: anyone squeamish about being zapped with electrodes

  • FYI: each session takes just 20 minutes

  • Website; Directions

Once strapped in, you build up the intensity . ..
. . . and with a few twists of the dial, you’ll feel the power

Would the idea of wearing a suit covered in electrodes that force your muscles to contract 85 times per second keep you up at night? Then this class might not be for you.

HIIT comes in all shapes and sizes but I was still slightly apprehensive before trying electrical muscle stimulation (EMS) at the new ViveFitness studio in Westminster. 

Unsurprisingly, EMS requires a fair bit of kit: ViveFitness provides a skin-tight training shirt and shorts, which must be worn underneath a vest and several straps that go around your legs, arms and glutes. The electrodes attached to the vest and straps are hosed down “to improve conductivity”. (Fraser Smith, ViveFitness co-founder and head trainer, assured me that water and electricity are a happy marriage in this case.)

Then the electrodes are turned on. (To my relief, the sensation is not unpleasant.) The session starts with a series of basic bodyweight exercises. As the dial was turned up and the level of electricity increased, I felt my muscles contract more and more. At the end of the 20-minute session, I was dripping with sweat. I burnt 146 calories in the short workout and days later my muscles still felt exhausted. 

I doubt whether this futuristic workout is more effective than a good old-fashioned, low-tech HIIT class, but I can see why it would appeal to time-pressed individuals. All that technology, though, comes at a price. A single 20-minute session is £70. The cost comes down if you bring a friend and “buddy up” or buy packages of multiple classes. 

ViveFitness has added Covid safety measures too. The studio is available for private use only, so no other sessions will be on at the same time. Clients can work out alone, with people from the same household or a “bubble buddy”. The training floor, equipment, kit and changing rooms are sterilised before every use, and hand sanitiser and masks are also provided.

What are your favourite high-intensity fitness classes in London? Share yours in the comments

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