HIIT classes in the age of AI

I went to an exercise class once, in a backroom upstairs in a fancy hotel in Piccadilly, which was very popular because the USP was that only 3 people could attend. It was as close as possible as you could get to having a personal trainer without paying full whack for one. Because personal trainers are a luxury, aren’t they, Boris Johnson has one and celebs have one but ordinary people generally don’t. Most people just don’t have hundreds of pounds a month to spend on exercise.

But people do spend on exercise. London has seen an explosion of boutique studios over the past 5–10 years, generally charging around £10–20 for a HIIT class. They’re popular because they offer a full body workout, the energy of being part of a class — the music, the collective movement; its like a box of all-round fitness compacted into one hour. But the downside, relative to a personal trainer, is that you don’t get much of a personalised experience. There’s maybe 30–40 people in a class, so there’s little room for giving personal feedback when your form is out. Maybe you get one shout out of motivation if he/she knows your name. There’s a tiny bit of scope for customising the exercises for you — e.g. doing press-ups on knees or feet — but generally everyone is following the same workout.

That’s in-class. Of course outside of class there isn’t anything with HIIT. There is no measure of progress, how you’re coming along week to week, no consultancy or feedback on what areas you should be working on, no diet advice, no reflection on what’s working / not working. Its all basically self-serve in that sense, and the only degree of freedom users have is to choose which class to go to — once you find one you like you stick to it.

So feedback, personalisation and customisation are mostly non-existent with HIIT classes, they are very much just ‘in the moment’ blocks of exercise for a bunch of people with vaguely similar levels of fitness. Well — that’s what you pay a personal trainer for right, to design a custom programme for you, be with you running round the park and keeping you motivated, telling you what the next exercise is that minute to minute, week to week adds up to a programmes that gets you moving as fast as possible towards you personal exercise goals, whatever they might be. Right now these two modalities of fitness instruction (HIIT and Personal Training) are worlds apart.

But this will change, I think, with AI. Steve jobs saw computers are ‘bikes for the mind’, well AI then is like a car for the mind. What’s needed first is a new hardware stack. The primary components are probably a smart mirror, and possibly a smart mat (fitness trackers like fitbit, apple watch are already wide-spread). Imagine doing an exercise class at home using a smart mirror that shows you the instructor and gives you feedback on what you’re doing, in realtime. This isn’t sci-fi, its already here from the company Mirror (acquired by Lulu Lemon):

Hardware start-up Mirror, acquired Lululemon

Now imagine getting custom feedback on your form — for example when you are moving your hips too much when doing press-ups, or not going low enough to the floor. That technology is already here, the most advanced form I have come across deals with musculoskeletal medicine by carefully studying your form using AI image recognition (Kaia Health):

Next-generation MSK care by Kaia Health

So a HIIT class of the future would come with personalised feedback on your form — correcting you if you weren’t going low enough on your push-ups, or your squats were too wide. This could be visually via the mirror, but the real magic would be if using AI synthesis of the instructor’s voice the feedback could be given to you verbally — “lower please Tom!”. That is probably feasible in the next 5 years or so, provided all the inputs are there. You need voice feedback when you’re mid-movement because you’re not always looking at the screen. It also allow the instructors to bring through their own unique style and personality into the experience — that’s very valuable ultimately — the top-end personal trainers don’t make over £1,000 per hour for nothing. My favourite example of this is David Beckham’s video calling for an end to Malaria in nine different languages, all done through AI synthesis:

That’s in-class feedback on form, which currently happens to a very limited degree in HIIT classes. The next level up would be to customise the number of and variant of each exercise for everybody. So when the instructor says ‘do burpees’, it comes with a custom target for me to hit. This target is based on all the times I’ve done burpees on the platform before, at least, and perhaps with some sense for my longer-term exercise goals. Now the class is really pushing me because — just like the best PT — it is finding the edge of your current fitness level and pushing you just through it. There is simply no way an instructor leading dozens of people in a HIIT class could do this, but with ‘personally augmented’ instruction this could happen, and doesn’t seem at all beyond the realm of current AI.

So now you have a new class of HIIT experience, one that blends the best of the ‘analogue’ classes — live, in-person, with pumping music and a format that everyone is following — with ‘augmented personalisation’, so completely personalised feedback on your form and benchmarks for performance.

Where next from there? One of the things you really get from a PT is a custom programme for the next few months, to get you where you want to go in exercise terms. Do you want to lose weight, be able to run further, build muscle? A great PT should be able to turn your aspirations into a fully-tailored plan, that takes account of all your needs and nature — what motivates you, your physical needs and particularities, what kind of schedule you want to work to, how hard you want to push yourself.

The intermediary step to this could be to offer this as a ‘side-service’ alongside HIIT classes. So suppose I sign-up with a studio for £75 per month, which has classes every day and I get use of a smart mirror in my home with this. It wouldn’t be too hard to tack-on a ‘consultancy’ service that gives me e.g. a 1 hour initial consultation, and then on-going feedback of maybe 1/2 hour per month. The beauty of the smart mirror is that it can log everything — all your exercises and movements, so the reports on your progress could be generated automatically; the consultation is just a layer of expert advice on top. The radical thing is that the mirror could also give you feedback on whether you were achieving your goals. Say your goal was to lose weight, could a smart mirror observe this? Could it show you the difference, visually on a screen, between you now and you one month ago? Like the shadow form of you from before. Perhaps it could pick up things imperceptible to the human eye, like your skin health. It could also presumably show you muscle growth, if this was your aim. All of this should be quite possible with current image recognition technology. Not easy, but possible.

So now you are getting realtime and ‘holistic’ feedback on your progress towards your goals — both in-class, and outside the class. The studio of course can point you towards different classes that would be most suited to you and through consultation help you design a personalised programme e.g. legs on tuesday, upper body on thursday, cardio on sunday etc. They help you figure out get the most from the class schedule, viewed at over a timeframe of months. This expert programming I’m not sure could be automated easily, understanding someone’s goals holistically requires a form of thought that AI is not so well suited to yet. The training data would also be much too thin. That’s ok — this is the point of great leverage for humans within all of this, and part of the necessary blend to create the overall experience.

So now you have a custom exercise programme designed with expert consultation, you have in-class feedback of a kind never seen before, and you have in-class and out of class performance feedback that is far beyond what you get could ever dream of getting from a fitness tracker today. You have an experience which is next-level HIIT.

The truly radical evolution though, would be to flip this from HIIT classes — the idea of everyone following along a general class — to a format entirely oriented around the personal trainer. It may, one day, be possible, for a personal trainer to ‘modularise’ all of their different exercises — push-ups, burpees, squats, deadlifts, everything; and then the ‘class’ is not really a class at all. It would be a digital 1:1 class made just for you. The trainer isn’t delivering it to you in-person, the ‘class’ has been programmed automatically by an AI to be exactly the right combination and sequence of exercises to work towards your goals; it is being delivered in a personalised way using voice and video synthesis to emulate the instructor, as if they are there with you — telling you what exercise to do next, giving you feedback mid-movement; it is using visual tracking technology to keep a track of your performance (maybe synced with fitness trackers). The remaining role of the PT is to consult with you about the progress you are making month-to-month, and what if any tweaks might be needed to your schedule and plan. This brings everything back to the limits of the physical world and time, but it seems perfectly possible to imagine a personal trainer having 500 clients, seeing each one of them for 20 minutes a month of consultancy.

Its easy to see PT becoming commoditised in this way, but contrary to that the differentiating factor could well be that intangible element of the ‘style’ of the instructor — the way they speak, motivate, encourage, cajole, these are very finely tuned human social skills, and people have different tastes in what works for them. The AI would afford maximum leverage to these parts of the personal trainers skill set — their ‘personality’ let’s call it, because now their personality can reach not just a few dozen people but hundreds, thousands, and quite possibly hundreds of thousands of people.

There is a long way between there and here. But the pieces are all there. My bet is that now gym studios have been suddenly been thrown into competition with fitness-at-home, which is vastly cheaper, they will have to start competing on value-add services — something special you can’t get at home like pumping music and lights, but also high-end hardware. The introduction of this hardware, combined with the inevitable cost-pressures, could provide the right petri-dish for these various emergent technologies to co-evolve alongside fitness instructors in a way that could completely change how we think about exercise over the next decade.



Data scientist, product junkie, one-time founder. London-based. @tgh44

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Data scientist, product junkie, one-time founder. London-based. @tgh44