The HIIT Bible

The HIIT industry has gone from zero to hero in less than five years, and looks like it will continue to grow (which means ‘stealing’ the market share from other types of activity, as well as attracting more new participants). The brands that have sprung up can be carved up into three very distinct groups: venues, methods and licensed programmes.

On the surface, there is a simmering rivalry and a healthy respect between the competing brands. Victory, you would think, would be demonstrated by a combination of positive results in the testing lab and/or people power (commercial success). In reality, the industry is as much about creating hype as it is about needing to provide any evidence, other than perhaps some fantastic before and after pictures of participants. For this reason, choosing a programme from the countless brands can be something of a minefield, but here are a few that I would say have either already proved beneficial or are tipped for greatness:

In the lab, the leaders of the pack are Tabata™, which was created in 1996 by Professor Izumi Tabata in Japan; and Sprint 8™, created by Phil Campbell and Dr Mercola in the USA. Both systems were developed via research programmes before they were launched to the public.

Then there are the venues – boutique gyms such as Barry’s Bootcamp™, SoulCycle™ and Orangetheory Fitness™. I doubt many new customers ask for a copy of the white paper that proves their method’s effectiveness, because these companies are more about the atmosphere, instructor and wrap-around features than they are about demonstrating biological outcomes.

The home-workout methods of INSANITY^®, P90X™, The Little Method, Les Mills Grit™ and Turbulence Training, meanwhile, have either developed organically over time or been fast-tracked to success via boardroom investment.

Categorising CrossFit™ is something of a challenge (a nice one). This is because while it is a venue, method and programme (which requires the payment of a licence fee), it’s also to some people a way of life that perhaps borders on being an obsession.

This method could so easily have ended up being called Izumi, since this is the first name of its creator, Professor Tabata. I’m pretty certain that back in the 1990s when the Japanese scientist and his colleagues started testing his theories on the Japanese Olympic speed-skating team he could never have imagined that 20 years later the rights to his method would be of interest to Hollywood, but that’s exactly what happened. The reason Tabata™ has become such a household name in the world of fitness today is in no small part to do with Universal Pictures and Big Shot Productions investing in the method.

I digress. Back to the ‘90s, when researchers pitted two workouts against each other, using students at Ritsumeikan University Graduate School of Sport and Health Science as subjects (the ice-skating connection is a distraction used to lend authority to the findings; most of the activity took place in a lab using a Monarch Ergometer bike rather than in an ice rink and using skates). During the tests, group one (the control group) cycled at 70rpm and at 70 per cent of their VO₂ max for one hour. Group two (the Tabata™ Protocol group) cycled hard for 20 seconds at 170 per cent of their VO² max, then took a 10-second rest before repeating the effort/rest cycle for a total of eight rounds. Both groups performed their sessions five times per week for six weeks. The results showed that although group 1 had increased their aerobic systems, their anaerobic systems remained the same. Group 2, however, had not only increased their aerobic systems, but they showed a 28 per cent increase in their anaerobic systems, too.

In response to the findings, Professor Tabata then carried out a second round of experiments to compare his ‘20 seconds on 10 seconds off’ (Tabata™ Protocol) method against what happened when subjects went up another HIIT protocol to 30 seconds on with 120 seconds’ recovery. Apparently, both methods delivered improvements, but the Tabata™ Protocol gains were measurable after just one week.

So, what happened next? Well not much actually, until Universal Pictures became involved in 2013 and the phrase ‘Four-minute fitness, scientifically proven’ was born. After this, the programme migrated from an exercise bike to a bodyweight studio group-exercise format, and the PR team came up with a way of insulting every PT and instructor who ever wrote a training programme, with their statement: ‘This is the first fitness system born in the lab. It hasn’t been made up by a fitness instructor or dancer, it’s the result of an internationally renowned scientists clinical findings.’ As the method boomed, some awesome videos were released showing beautiful people doing the Tabata™ workouts, which morphed into a combination of functional circuit moves blended with martial arts-style Capoeira primal movement patterns. (Primal is terminology for any style of exercise that encourages the body to move naturally rather than creating an artificial environment – running, jumping, squatting or throwing are all primal, while cycling or using seated weights machines aren’t.)

Personally, though, I have never been able to easily achieve the levels of intensity required for the method to work using the Capoeria-style moves, whereas on a studio spin bike I can do this almost instantly. To sum up, then, Tabata™ Protocol is a good method, but it generally works better on a spin bike or if you use simple hardcore moves such as the ones outlined in this book.

If you happen to turn on your TV late at night or early in the morning and flick through the channels, the chances are that it won’t be long before you have Shaun T. on your screen bellowing at a group of sweaty people in a space that looks like my old school gymnasium. You have found the Beachbody Workout infomercial for the INSANITY^® workout, the headlines for which include: ‘I’ll get you a year’s worth of results in just 60 days’; ‘Are you crazy enough for INSANITY?’; and ‘The hardest workout ever put on DVD is now the #1 workout in America’.

The entire approach is summed up with this following statement from Shaun T. on the homepage of the INSANITY^® website:

‘When I created the INSANITY workout, I knew it would produce insane results in 60 days, but I wasn’t sure if anyone was brave enough to try it. Turns out, there are a lot of crazy people out there. Crazy enough to actually enjoy doing the world’s most insanely tough workout. To like the feeling of being drenched in sweat, of going balls-to-the-wall for a full 45 minutes of muscle-searing exercise. Is INSANITY^® hard? Oh, yeah. It really IS the hardest workout ever put on DVD. It’s totally crazy but it’s going to get you crazy-good results.’

What I love about that statement is it says to people you would have to be crazy to try this, but if you do you’ll get unreal results. This promise is backed up by testimonials from people asserting that they had previously tried ‘everything’ and that INSANITY^® was the only thing that produced results. To compel people to post ‘before’ and ‘after’ shots that demonstrate the effectiveness of the programme, INSANITY^® has come up with a clever marketing strategy that means participants only receive the much-coveted INSANITY^® T-shirt bearing the logo ‘you can’t buy this T-shirt you have to earn it’ if they submit these torso shots for scrutiny by the INSANITY^® team.

The best way to describe the INSANITY^® method, they say, is to compare it to a cycle class, during which you work then recover. In INSANITY^®, however, instead of recovering for a couple of minutes (which is a bit unfair because it suggests a cycle class is an easy option) you only get a few seconds’ recovery (time enough to ‘gulp some air’) in an INSANITY^® session, before it’s time to go again for another three to five rounds.

Is the lack of scientific verification of this method an issue? For me, the answer is no, because I’ve spoken to many very fit people who still say that they can’t keep up with Shaun T. throughout an entire DVD. (Although of course we don’t know for sure whether they actually filmed the workouts in one take or if there were some ‘cuts’.) Either way, though, the workout itself is great fun and certainly gets the heart racing.

Probably the fastest-growing fitness business in the world, it’s not even worth me guessing how many CrossFit™ ‘boxes’ (they call their gyms ‘boxes’) there are out there because they are opening at a phenomenal rate. CrossFit™ isn’t intentionally ‘disruptive’ as an enterprise, but their business model does have similarities with those of two of the biggest companies on the planet: Uber™ and AirBNB™. In case you don’t know, Uber™ is a taxi company that neither owns any cars nor employs any drivers, and AirBNB™, without owning a single hotel, rents out more rooms per night than any of the biggest hotel companies. CrossFit™, meanwhile, runs an affiliate system whereby the ‘box’ owners pay a fee to be able to use the CrossFit™ logo above the door.

Despite this commercial side, CrossFit™ itself is not restricted to a specific workout or venue, and there is nothing to stop you going online and finding the WOD (‘workout of the day’) and doing it at home, for free. A Crossfit workout can consist of almost any credible form of exercise that fits the Crossfit model of challenging yourself on a daily basis, the mode of ‘challenge’ can be eclectix as a Crossfit WOD could involve the gym, the great outdoors or even a swimming pool. However, the exercise routine isn’t the end of the story, and CrossFit™ sees itself as a way of way of life and a philosophy as much as a workout, as expressed by Greg Glassman, the founder and owner of CrossFit™, who sums up the fitness system thus:

‘Eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar. Keep intake to levels that will support exercise but not body fat. Practice and train major lifts: Deadlift, clean, squat, presses, C&J, and snatch. Similarly, master the basics of gymnastics: pull-ups, dips, rope climb, push-ups, sit-ups, presses to handstand, pirouettes, flips, splits, and holds. Bike, run, swim, row, etc., hard and fast. Five or six days per week mix these elements in as many combinations and patterns as creativity will allow. Routine is the enemy. Keep workouts short and intense. Regularly learn and play new sports.’

CrossFit™ abbreviations and common vocabulary

If you do fancy venturing into the world of CrossFit™, then it helps to equip yourself with the some of the language that’s often used (all of which is also available on the CrossFit™ website).

AMRAP – As Many Reps/Rounds As Possible

BP – Bench Press

BS – Back Squat

BW – Body Weight

CLN – Clean

C&J – Clean and Jerk

DL – Deadlift

DUs – Double-unders (When using a jump rope, the rope passes under your feet twice between each jump.)

EMOM – Every Minute On the Minute (So for instance, on the WOD whiteboard one day is written: ‘10 push-ups EMOM for 10 minutes’. This means that you must do 10 push-ups at the top or beginning of every minute for 10 minutes.)

FireBreather – An elite-level CrossFit™ athlete.

FS – Front Squat

Girls – Several classic CrossFit™ benchmark workouts are given female names.

ME – Maximum Effort

MP – Military Press

MU – Muscle-ups (While hanging from rings you do a combination pull-up and dip so you end in an upright support.)

OHS – Overhead Squat (Full-depth squat performed while arms are locked out in a wide-grip press position above (and usually behind) the head.)

PC – Power Clean (barbell)

PP – Push Press (barbell)

PR – Personal Record

PSN – Power Snatch (barbell)

PU – Pull-ups, possibly push-ups depending on the context

Rep – Repetition (One performance of an exercise.)

RM – Repetition Maximum (Your 1RM is your maximum lift for one rep. Your 10 RM is the most you can lift 10 times.)

Set – A number of repetitions

SN – Snatch

SQ – Squat

T2B – Toes to pull-up bar

TGU – Turkish get-up

WOD – Workout of the Day

That it involves 90 days of hard work is all you really need to know about P90X™, the fantastic system that has captured the imagination of millions of people around the world. The star of the regime is Tony Horton, the master of motivation behind P90X™ – the number-one fitness infomercial in America – whose on-screen presence is the perfect mixture of encouragement, humour, discipline and fun. Guys who just shout at people usually have nothing important to say. Tony, by contrast, has a more gentle aura, the kind of power that can stimulate action with nothing more than a glance.

So what is P90X™? Well, it is HIIT, but their USP is what they call ‘Muscle Confusion’, which they explain by saying: ‘By providing an extensive variety of different moves that take time to master, P90X™ is continually challenging the body’s muscles into new growth. The more you confuse the muscle, the harder your body has to work to keep up; the more variety you put into your workout, the better and faster your results will be.’

In basic terms, this is very similar to a method that PTs have been using for some time called PHA (Peripheral Heart Action) but with a little Hollywood sparkle thrown in. The PHA system requires us to design an exercise routine whereby each exercise alternates between focusing predominantly on the upper or lower body, the goal being to make the circulatory system constantly having to work hard to get the required blood/nutrients/oxygen to where they are needed. It is very effective because: 1) the fatigue you generate from one exercise has gone by the time you need to use each major set of muscles the next time around; and 2) while being a very intense session, it feels achievable because you can keep telling yourself that you have almost finished working those exhausted muscles.

For either of these methods, there is very little reference to how many reps you should be doing or optimal speeds. In fact, if detail is your thing then you won’t like P90X™; the goal is far more AMRAP (As Many Reps As Possible) rather than being focused upon technique and form. It expresses an attitude that I have, which is: ‘Do no harm, but rather than stand around discussing what’s optimal just get a move on because if you’re moving you’re improving.’ If you buy P90X™ you’ll receive 12 DVDs, which are designed to be followed as many times a week as you can manage. The entire regime revolves around old-school bodyweight and dumbbell moves. There are also some yoga and t’ai chi-inspired sections to be performed at different points in the 90-day schedule (these are provided to help prevent overuse injuries, because 90 days of working out at this kind of intensity is tough, and beginners need to be given some breathers to ensure that the connective tissues such as ligaments and tendons have enough time to recover/develop).

This programme is named after researcher Jonathan P. Little – whose specialist field of study is exercise and the prevention/cure of diabetes – and is somewhat catchier than its original full title: ‘A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms’. The Little Method it is then.

Published in 2010, the study by Dr Little and his colleagues aimed to measure the effects of HIIT when applied in a ‘more practical model’ (i.e. than that outlined by programmes such as Tabata™ Protocol, which, if done by the book, is a brutal workout). These guys are serious scientists so they would have been looking for optimal results/maximum adaptations rather than the development of a sexy commercial product, and the aim of the study was simply to establish if there is a way of achieving results at lower intensities with less volume than the frequently used Wingate tests (these are lab tests that involve a person performing maximal power-output sprints on an ergometer bike).

Considering how often the Little Method is banded around it was actually a very small trial, but that’s not to say the results aren’t credible. It involved seven men of approximately 21 years of age who performed six training sessions over two weeks. Each session consisted of 8–12 × 60-second intervals at 100 per cent of peak power output elicited during a ramp separated by 75 seconds of recovery. (A ramp session is a test or workout where rather than staying a constant intensity the challenge is continuously increased or ramped up – on a treadmill this would involve increasing both the speed and incline, while on an exercise bike the rider would increase their speed and also add more resistance).

Prior to the experiment, all the men had been active but were not competitive athletes (Dr Little’s goal was to create a system that could be replicated by ordinary people not just conditioned athletes). All of the participants showed an improvement after just two weeks, with their muscle metabolic capacity increasing, which in effect means that their bodies were functioning and processing fuel more effectively. In addition, their functional performance was demonstrated to have improved over the test period simply by the fact that they found the sessions easier to complete.

The testing procedures were done at a cellular level by means of pre- and post-regime biopsies, these demonstrated that after the two-week training regime all the participants were processing protein and glycogen more effectively. If this had been commercially motivated no doubt the results would have been extrapolated to demonstrate reductions in the participants’ body fat levels, however there were no claims made in this area. That said, you can safely assume that if the participants continued at the same level of activity for more than two weeks they would have noticed an increase in lean muscle and a reduction in surface body fat.

These results demonstrated that a low-volume HIIT programme can be effective for improving muscle metabolic capacity and functional performance, and in particular that rationing of recovery isn’t always a prerequisite of successful HIIT sessions.

The Little Method is a low-volume high-intensity interval training system that induces mitochondrial biogenesis (the process where cells increase in size and number) in human skeletal muscle and it works like this:

Perform 60 seconds of high-intensity exercise (any of the exercises listed in this book working at around 100 per cent of your capacity), followed by 75 seconds of absolute recovery, which means you can sit down, lie down or just keep ticking over.
Repeat 8–12 times.

This means that (excluding your warm-up time) the whole thing will be over in 18–27 minutes. This is much longer than the time spent doing the original Tabata™ Protocol method, but without doubt it’s more do-able by people who wouldn’t class themselves as being athletic.

Although this study was very small (only seven participants were involved), the researchers found that this approach to HIIT improved the capacity of the participants as measured during time trials and it is now a commonly used training method.

The fitness dynasty that is the Mills family from New Zealand has an answer for every fitness goal. Want to get stronger? Try Body Pump. Want to improve your core and well-being? Try Body Balance. And so the list goes on, through Body Attack, Body Combat and BodyStep – you name it, they have a workout with the word ‘Body’ in front of it.

Les Mills is, however, probably a name more familiar to group-exercise instructors than the public because their business is the most successful when it comes to the production of what we call in the fitness industry ‘pre-choreographed workouts’. Their package offers a tried-and-tested formula of easy-to-follow pre-formulated sessions that instructors learn by heart, with the music to match the moves and an in-club marketing package for the health-club operator to use to promote the sessions. Access to these materials is via a licence fee (the club pays a fee to use the class content), and the instructors pay a fee to the club to receive and use the choreography and music. This is updated every three months to keep things fresh. So, bearing in mind that Les Mills has either created or been quick to follow every big fitness trend since the start of the 1990s, it’s no surprise they have their version of HIIT. This time, though, there’s no mention of the word ‘Body’ in the title. Instead, it’s a different four-letter word: ‘Grit’.

These Grit sessions are about 30 minutes long and are broken in to five or six tracks (a track is a piece of music that’s mixed with sound effects and a strong beat to set the correct pace), as outlined below:

Track 2: propulsion training during which the heart rate begins to spike to its maximum;

In classic Les Mills’ fashion, in order to ensure ownership of their concepts/methods the actual intervals don’t use any recognisable formats, so they neither follow the Tabata™ 20/10 seconds, nor the Little Method of 60/75 seconds, etc. Some of the intervals are 1 minute followed by a minute’s recovery, while others can be much longer at 3 minutes. Not that this matters, since a Les Mills session is always part science and part exertainment, with the music and attitude of the instructor being a key part of the experience.

Turbulence Training is all about speed. In fact, it’s so fast there isn’t even time to say the entire name, so it always gets referred to as ‘TT’. Craig Ballantyne is the man behind the programme and his magic number is 90 – standing for the 90 minutes’ exercise a week you sign up for when you take on TT. An American PT trainer, Craig doesn’t hold back with his views about the rest of the fitness industry – long, slow cardio is evil and the like – and in the TT videos he looks straight down the lens of the camera and, unlike the mesmerising Tony Horton, he basically tells viewers to go hard or go home (although if you are doing TT then you are probably already at home because the entire programme is sold via the web as a home-workout solution).

In reality, TT doesn’t differ all that much from most of the other HIIT programmes available online. The raw ingredients are the same: weightlifting and bodyweight moves making up the lion’s share of the workout, buffered with cardio components. The timing intervals aren’t remarkably different either, although they are much longer than the likes of Tabata™. TT goes for 8 heavy reps of weightlifting sets followed by 1–2 minutes of cardio, the sessions are a maximum of 45 minutes and the recommended frequency is three times per week. Personally, I think alternate days would work well, but obviously that means the training days change each week.

So if TT isn’t much different from many of the other HIIT programmes available online, why is it so successful? Answer: it’s brilliantly presented. Note I say ‘presented’, not ‘packaged’. This is because everything revolves around the testimonials of people for whom TT has worked (with the obligatory shirt-off before and after photos) as well as countless statements relating to research studies by very respected scientists and universities (it’s worth noting that most of these statements refer to workouts ‘like’ TT or present themselves as if the quote were made specifically about TT, whereas this may not be strictly the case. All this means is that TT has been extensively tried rather than specifically tested. I personally don’t have a problem with that and think if you can motivate yourself to stick to the programme and be prudent with your nutrition then the chances are you’ll also end up on the TT website with your shirt off saying ‘this could be you’.

It’s confession time on this one. Dr Mercola and Phil Campbell are very familiar faces to me since their programme, Sprint 8^® features on the equipment manufactured by Matrix Fitness, one of the global companies to whom I deliver master-trainer and brand-ambassador services. However, all of the Sprint 8^® research and protocols were developed before that relationship began and they received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors to perform the study, so my views on Sprint 8^® are based on their merits alone rather than any commercial bias.

Sprint 8^® is probably the most researched and substantiated exercise system that you’ve never heard of, and I think it is the most universally suitable for ‘real’ people who have limited experience of exercise or are in fact absolute beginners. Phil Campbell is a passionate advocate of using the protocol, which was developed in three medical centres in the USA: King’s Daughters Medical Center, Brookhaven; University of Mississippi Medical Center, Jackson; and Copiah-Lincoln Community College, Wesson.

The Sprint 8^® method has evolved from the concept packaged in book form as Ready, Set, Go! Synergy Fitness for Time-Crunched Adults by Phil Campbell, which was written more than a decade ago. It was shown to fight obesity in both an economical and time-efficient manner by naturally stimulating significant growth hormone (GH) release. GH-serum levels are known to increase substantially after exercise, which is beneficial since the hormone initiates lipolysis (fat breakdown), inhibits the uptake and storage of other lipids, and induces muscle hypertrophy (growth).

The research consisted of an eight-week study of free-living individuals (that’s geek-speak for normal people), who completed eight hours of exercise over an eight-week trial (20 minutes, three days per week), without dieting. The results were awesome: among the 22 participants, growth hormone values increased 603 per cent following the initial bout, and by 426 per cent by the final bout. On completion of the trial, reductions of body fat in some cases had dropped by as much as 27.4 per cent, with no dieting! LDL cholesterol (the undesirable stuff) also dropped, while HDLs (the desirable version of cholesterol) increased by 2.0 per cent.

Sounds great. So how can you do Sprint 8^®? Easy, you can use any cardio equipment (bike, rower, cross trainer, running machine, etc.). If you have access to Matrix Fitness equipment, it may have Sprint 8^® pre-programmed as an option on the menu, which means that you simply select the programme and then you get a ‘hands-free’ workout as the machine will make all the adjustments to incline and resistance for you. All you have to do is go fast. If you don’t have Matrix kit then you’ll have to press the buttons more often, but the long and short of it is you are going to work as hard as you can for 30 seconds and then cruise (recover) for 90 seconds and repeat this eight times. How hard? As hard as you can! The probability is that if you are programming the CV kit yourself then you will most likely go too fast too soon and struggle to complete all eight repetitions. If this happens, don’t think of it as a failure – it just means that you are simply learning how your body functions.

Sprint 8^® stands out as a medically developed programme. It can be used by beginners all the way through to elite athletes, and it can be done using CV equipment, bodyweight moves or strength equipment such as dumbbells and barbells (in fact EVERYTHING that I advocate in the workouts in this book).

•30 seconds of flat-out sprinting (Flat out means that if it you were told to work at that speed for 35 seconds you couldn’t do it);

Repeat this eight times and then rest in the knowledge that your HGH is spiked for at least the next two hours and is chasing down your body fat like a heat-seeking missile.

Founded in 2006, SoulCycle™ is without doubt one of the most financially successful yet disruptive boutique workout models on the planet. In fact, SoulCycle™ is disliked by many group-exercise cycle instructors, but I doubt the disdain of some quarters of the fitness industry is going to cause them to lose too much sleep, especially since their A-list riders include celebrities and social-media heavyweights such as the Beckhams, the Clintons, Lady Gaga, Oprah Winfrey and a loyal, vocal fan-base of some the coolest bloggers on the planet.

So what is it and, more importantly, is it HIIT? Well, the clue is in the name: it’s all about Soul. Instead of focusing upon cycling technique, form and the production of power (watts), they (in their words): ‘Believe that fitness can be joyful. We climb, we jog, we sprint, we dance, we set our intention, and we break through boundaries. The best part? We do it together, as a community.’

Sound cool? Well, it gets better because the instructors range from hippy yoga chicks to snarling, tattooed muscle men who push and pull you through a ride that makes you sweat, smile and maybe even cry for mercy or joy. Oh and did I mention the studio? Well, let’s just say every time I’ve been there I come out smelling of grapefruit because they love to pump its essence into the air while you ride. In other words, the studios are gorgeous, and the music is equally awesome.

But is it HIIT? It should be, but I expect for many of the riders it isn’t, simply because they don’t put enough resistance on the flywheel of the bike to propagate the physical responses within the body that spike HGH. That’s down to rider error, though, rather than the class itself, and since the format of these varies depending upon which instructor you get on the day, they without doubt provide a really fun way to work out.

My first experience of Orangetheory (OT) occurred in California at a session in which the instructor not only wore head-to-toe orange get-up, but also had matching dyed orange hair with the OT logo shaved in. Based on this evidence, I think it’s safe to say that orange is a key part of the corporate fabric of the amazing franchise …

What makes this method unlike the majority of boutique HIIT facilities (apart from the preponderance of the colour orange) is that OT holds itself accountable during every session it ever delivers by means of chest-worn heart-rate monitors. These transmit data back to TV screens mounted high up on the walls of the studio to display not just the heart rate of all the class’ participants but also to translate the different participants’ live pulse into colour-coded zones and calculate the number of calories burned.

The Orange 60 sessions last an hour and roll through bursts of activity and recovery using running machines, rowers and the TRX suspension trainer. During the 60-minute workout, you perform multiple intervals designed to hopefully produce 12–20 minutes of training at at least 84 per cent of your maximum heart rate, or in the ‘Orange Zone’ or ‘Red Zone’, in Orangetheory parlance. This is one of the five zones that lights up next to your name on the screen, allowing you to stay tuned in to intensity but not become obsessed with it. Each of the zones represents the following:

Zone 1 is 50–60 per cent maximum heart rate and makes you glow a miserable grey colour;

Zone 2 is 61–70 per cent maximum heart rate, which is a rather cool/tepid blue;

Zone 3 is 71–83 per cent maximum heart rate, and turns your tile on the screen green (green is good, but orange is awesome);

Zone 5 is all-out effort of 92–100 per cent maximum heart rate and tips you into the red.

According to Barry Jay, his Barry’s Bootcamp venues don’t just do workouts, they do the … Best Workouts in the World^® and they have been doing so since 1998, long before HIIT became popular.

The signature workout at a Barry’s Bootcamp is a super-loud hour-long workout in a dark space that is filled with running machines and steps/benches alongside rubber bands, medicine balls and dumbbells. Every workout is different but should include 25–30 minutes of interval cardiovascular running-machine routines and 25–30 minutes of strength training. Instructors, muscle groups and even workout segments vary throughout the week so that no one class is ever the same. What I like about Barry’s Bootcamp is that while there isn’t a great deal of validation behind the session plan, if the instructor is even vaguely good you should get a great HIIT workout. Each day on the timetable is aimed at invoking a HIIT effect via the running-machine running sections as well as targeted sections for body parts that change daily. For instance, in a week, you may work on the following:

Thursday: hardcore abs (I guess abs features highly on the clients’ ‘wish lists’!)

Friday/Saturday/Sunday: everything they can throw at you, since it’s a full-body workout in every session.

‘Our innovative technique works to “shock” the body in the most efficient and effective way to improve your cardiovascular system, lose weight and build muscle. Our world-class instructors are the best in the business and promote a positive, supportive environment that will help you break past your own personal boundaries. Come discover why Barry’s Bootcamp has been voted “The Best Celebrity Workout” by Allure, Los Angeles Magazine and many others. Regardless of skill level, you can burn 1,000 calories in just one hour. You will see and feel results right away in a thumping music-filled environment where every class feels new, fun and exciting.’