Super Slow High Intensity Training: Is 15 minutes of Strength Training A Week Enough?

If I told you that you could boost your metabolism, reduce body fat levels, increase strength, increase longevity, improve fitness oh and look darn good naked – all by doing 15minutes of exercise in a week, would you believe me?

No? Well you should.

This isn’t a sales pitch for a new exercise machine, nor is it a sales page with a ‘buy now’ button at the bottom. Instead it’s a closer look a very unique type of strength training. Something that goes against conventional wisdom and everything that I had learnt as a Personal Trainer and athlete.

What is this training system? It’s called High Intensity Training or HIT (note, this is different to High Intensity Interval Training training aka HIIT). Superslow training is another term used for the HIT modality of training.

Super Slow High Intensity Training: Is 15 minutes of Strength Training A Week Enough?

What is HIT Training?

HIT is a very short, very intense, 1 set to failure resistance training protocol. A typical session lasts 10-20minutes, and typically involves 3-5 sets. That’s it.

Oh, and you only perform it once a week, at most once every 5 days.

Again, I’m not making this up, it’s a short sharp strength training protocol that you do once a week.

The particular program that I followed in my 9-month experiment based on the book ‘Body By Science’ authored by the very knowledgeable Dr Doug McGuff. Note – if you already know all about HIT training and just want to see my results from this 9 month period, be sure to check out this article - Body By Science High Intensity Training Review: My 9 Month Experiment.

HIT was popularised in the 1970s by Arthur Jones, the founder of Nautilus and MedX. Wikipedia defines HIT as:

The training focuses on performing quality weight training repetitions to the point of momentary muscular failure. The training takes into account the number of repetitions, the amount of weight, and the amount of time the muscle is exposed to tension in order to maximize the amount of muscle fiber recruitment.[1]

So what makes the HIT/Superslow/Body By Science protocol so effective yet so different to conventional strength training? Well just like your standard strength training, you load a muscle with resistance (weight) and work that muscle until failure.

However, one key point of difference with HIT training is constant tension. You see, you take the muscle to failure by not letting the muscle rest during the set. What do I mean exactly by this? Well think of a pushup. When doing a conventional push up you start with your arms straight, the joints locked out, bone on bone. You move your chest down to the floor by bending the elbows and rotating the shoulders and then return back to that starting position.

That is one rep.

However, in HIT training you remove the ‘arms locked’ component of lifting. This means that when you ‘push up’ from the ground rather than locking out your arms completely at the top, you would stop short of straightening the arms and instead turn around and start heading down again.

Any bodybuilder who has done time under tension training or non-lockout type training would be familiar with this type of training.

Constant tension on the muscle. And yes - it hurts.

Note – I should mention that pushups aren’t the best exercise for HIT training due to the resistance load on the primary movers not being constant throughout the lift. But more on this later.



Slow it Down – Super Slow

Constant tension isn’t the only difference between HIT training and conventional training. You see a key fundamental to the effectiveness of HIT training is the ‘super slow’ lifting.

So rather than a 2 second concentric phase (I.e. muscle contracting to lift the bar), and a few seconds on the eccentric phase (negative), HIT slows things right down… you’re aiming for around 6-10 seconds on BOTH the concentric and eccentric phase….

Yes that means 1 single repetition may take 20 seconds (or even longer).

Think about how many rep’s you would usually do in a 20second period.

So now you have a SUPER slow tempo, combined with constant tension (no rest or pausing during the lift). But that’s not all, there is one final component to a successful HIT workout, and that is isolating the muscle.



Targeting The Muscle – A Win for Machine Based Training

Anyone that has worked with me in the gym will know how I prefer big compound movements over machine/isolated exercises. Even as a bodybuilder the bulk of my training was done using compound lifts like rows, squats and deadlifts. This helped create muscle thickness and density that machine based training couldn’t produce (especially as an all natural lifter).

Quads of Your's Truley - The Product of LOTS of heavy squats!

 So to find that a true HIT protocol involves primarily using machines irked me a little at first. But after learning the reasons behind it I was soon converted.

The idea behind HIT training is to take a particular muscle and stress it to the point of absolute failure – so that every muscle fibre within the muscle has been recruited and then fatigued. As you avoid lock out and keep constant tension on the muscle the fibre is ‘always on’, and has no time to rest (even a brief second rest period at lockout may be enough time for some slow twitch muscle fibres to recover).

Combine this with the ‘super slow tempo’ and you now have muscle fibres that are not only actively recruited, but that are recruited at all parts of the lift. There is no ‘bounce’, no speed to help push through weak points, instead is it a slow grind where the fibres have to work at all points of the lift. You cannot cheat a lift if you’re lifting it with a tempo of 6-10 seconds. Nor can you use momentum to push through a weak point.

Now this is all well and good, and the idea behind taking to the muscle to absolute failure should hopefully now make sense.

Quick sidenote – initially when you lift a weight you will recruit your slow twitch muscle fibres, when they fatigue then you recruit your intermediate & some fast fibres, when they fatigue – and only under extreme circumstances – your body will then recruit the remaining fibres in the muscle, at which point when THEY fatigue then there is literally nothing else the body can do to move the weight. Now in contrast, if you were doing a standard set of 12 reps of pushups, every time you lock out your slow twitch muscle fibres get a brief opportunity to recover. Sure you will still hit a fatigue point, but that fatigue may not come as a result of total muscle fibre fatigue.


But this is where machine isolation training trumps compound free weight training.


With a compound movement like a squat, sure you’re working the quads to move the weight, but you’re also recruiting your glutes, hamstrings, calves and torso. And there are parts of the lift where the load on the quads is high, and parts where it’s lower. This is all well and good for overall strength, but if you’re trying to fatigue every single muscle fibre in the quad, you soon realise that a compound lift isn’t such as the squat, may not be the best tool for the job if you want to apply the HIT method of training. Again, any experienced bodybuilder will understand this.


 You can see in this EMG activity report how the Quad & Hamstring activation varies at different angles during a squat. Source -

For this reason, a machine that has been designed to target one specific muscle for the entire lift is the perfect way to ensure that you’re keeping constant tension (and constant recruitment) on all the targeted muscle.

If all this seems to confusing, think of it this way – the idea is to fatigue a particular muscle. Machine based training allows you to work a particular muscle through the full joint range, minimising other muscles that could potentially act as support.


3 Fundamentals to HIT

So there we go – we now know the 3 fundamentals to HIT training: 

  1. Constant Tension – don’t let the muscle rest at any time during the set.
  2. Super slow – slow tempo (6-10 seconds) means there is even force applied without relying on speed/momentum
  3. Machine training – to allow a targeted approach, keeping constant tension on the muscle.

Note: For more of the science behind the science behind the why and the how as Doug McGuff has done an amazing job of detailing it all in his book Body By Science. I highly recommend this book to anyone interested in exercise training.


A Sample Workout

So what would a sample workout look like? Simple, here is a full (yes the entire) full body routine by the man himself – Doug McGuff.



The idea behind the routine is to keep load on the muscle of 90secs- 3 minutes. Finding the right weight can be tricky on your first session, but you know you hit the sweet spot when you’re failing in that 90sec-3minute window. If you’re going beyond 3 minutes, no worries, take the muscle to failure and next time increase the weight.

If you’re falling short of 90secs before failing, the weight is probably too heavy.

 Remember, you only do 1 set to failure. So even if you get the weight wrong the first time, there is no point doing another set a few minutes (or even a few days) later. This type of training requires a decent amount of recovery (for the muscle itself, but also for the CNS that controls the motor units). Doug McGuff recommends only do this workout once every 7 days – sometimes with a greater gap between sessions if you are not recovering adequately (you can measure this by simply tracking your performance, if it’s not improving then you’re not recovered).


Benefits of Super Slow / HIT 

Now that you have an idea as to how this type of training works, you may want to learn about the benefits of HIT training, and also – how effective it really is?

1. Time

The first key benefit is time. An entire workout lasts only 10-20minutes. You typically only do 3-5 exercises, each one (ideally) lasting 90seconds – 3minutes. And you don’t rest between exercises, you need to move straight to the next exercise. Warmups are not required as they are built into the lift. You can be in and out of the gym in 30minutes.

2. Safety

HIT Training is great for rehab or even as a tool for injury prevention. Using machines that target a particular muscle means we can still load a muscle whilst avoiding an injured muscle for instance.

HIT training also reaps all the benefits of strength training that is accessible to anyone who can get to a gym. This means the elderly can now load a joint effectively that they may not be able to do otherwise.

Finally, and this is a huge benefit to HIT training, it’s a rather injury proof type of training. To fatigue the muscle with conventional training you often require a huge load. With higher loads there are increased forces and stresses on the body – greater chance of something going wrong. However, with HIT training the loads are a lot less, and due to the super slow speed of the lift, there is no sudden directional change under load. Plus, the more fatigued you become, the safer the lift gets (as you can’t apply the same amount of force on the load).

3. Ease of Use

It is a really simple way to train. You don’t need to learn complex lifts. As you are using machines most of the technique side of lifting is taken care of. It’s not perfect, and yes you still need to pay attention to your technique, but if you keep the force on the target muscle then you’re most likely lifting with solid technique. This makes it an appealing way to train for those who cannot afford a coach or PT.

4. Cardio Benefits

In the book Body By Science, Doug does an amazing job of explaining how strength training down properly has a cardiovascular benefit on the body. By doing a 100% effort HIT session, you are improving your cardio function.


It’s important to note, that ‘cardio failure’ is often not because of a limitation in the heart or the lungs, instead it’s the muscle itself that cannot continue under the load. Through HIT strength training you not only increase the power output of a muscle, but you significantly boost your cardio function. Sure, you may not be able to go and race in the Tour De France, but you will still have a solid fitness baseline. And for individuals who simply want to look and feeling amazing, this may be sufficient.


5. Effectiveness

The most important benefit of all – does this style of training – all 15minutes a week - actually work?

If you look at the scientific evidence you will see that there is a lot of proof to the efficacy of the HIT / Super slow / Body By science style of training. Not only that, many top bodybuilders utilised a similar style of training with amazing results. Mike Mentzer and Dorian Yates have both called their training system HIT. Mentzer even believed that no more than one set to muscular failure per body part was all that was required. And finally, I have my own n=1 success story which can be read in this article - Less Is More: How Slowly Down Improved Health & Performance. Also, have a read of my article Body By Science High Intensity Training Review: My 9 Month Experiment.


The perfect Training protocol?

Like everything in the health and fitness world – the answer is ‘It Depends’. If you are a time poor individual who wants to reap the health and aesthetic benefits of strength training then yes it very well maybe.

The science is strong, my n=1 experiment produced amazing results, my coaching clients who utilize this protocol also achieve great results and there are a ton of individuals on the interweb who report similar stories.

Sure there are issues and limitations with HIT – all of which I cover in my 9 month HIT review post, and whether it’s the ‘best’ way to train or just a ‘fad’, I think that’s up to you to decide. But like many things in life, don’t bag it until you’ve tried it.

On that note, hopefully I have provided enough information so that you can give HIT a session a go, even if it’s just for one session. Just remember – 6-10 second tempos, non-lock out, 1 set to failure using isolation exercises.

 If you have any questions please leave them below, alternatively if you really want to dig into this type of training please check out the Body By Science book, or visit Doug McGuffs website or check out the amazing content and courses over at

And if you'd rather follow a more conventional training plan, be sure to check out my Size & Strength training program.


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This blog post was written by Alex Fergus. Alex is an ISSN Sports Nutrition Specialist, Fitness Professional and certified Superhuman Coach who continues to expand his knowledge base and help people across the world with their health and wellness. Alex is recognized as the National Record Holder in Powerlifting and Indoor Rowing and has earned the title of the Australian National Natural Bodybuilding Champion. Having worked as a health coach and personal trainer for over a decade, Alex now researches all things health and wellness and shares his findings on this blog. Learn more about Alex's Credentials HERE.

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