From reading the title, “HIIT Vs LISS” I’m sure that unless you have been living on Mars for the past few years you know what HIIT is or at least you could make a decent guess. LISS isn’t so well known outside the professional world. Or, I should say that not many know the term LISS but I know that everyone has been doing it for years.

In this post I’m going to enlighten you about what both HIIT and LISS are and take a look at the pros and cons of both so we can decide who will win:





HIIT Definition

You will have heard of HIIT before but do you know what it actually entails?


“HIIT (High Intensity Interval Training) is the concept where one performs a short burst of high-intensity (or max-intensity) exercise followed by brief low-intensity activity, repeatedly, until too exhausted to continue.”



In other words, you exercise as hard as you can for short intervals between which you get your breath back. These sessions normally only last a few minutes and never longer than about 30 minutes.

A HIIT session that does last longer isn’t truly HIIT as you should be ready to drop after only a few minutes.


But Why Does My Local Gym Offer One-hour HIIT Sessions?

Gyms like to offer one-hour sessions, it’s tradition and our clients like to train for an hour. They like to feel they are getting value for money, plus it takes time to warm up, warm down and give instruction during the class. Some gyms are now offering half hour HIIT sessions but I don’t believe this is long enough to ensure that clients are aware of what is going on and making sure no-one injures themselves.

The intensity that you go at during the short burst should be over 80% and nearing 95%. It really should be at a high intensity.

Although HIIT has been around since the 70s, it has become extremely popular in the last few years for a few reasons.


Why So Popular?

Everyone is pushed for time, all of the time. Clients feel that getting a one-hour HIIT session in, three times per week gives them all the exercise they need to stay healthy. And they feel like they have had a proper workout at the end of it.

As I said, gyms and trainers love to fit sessions into an hour. It’s the way that the industry has worked for years, it’s simple to manage time and it is what the client expects.

It gets results and because of this is actually used by sporting athletes every day. If it’s good enough for them, then I want to do it as well.

We all know that the fitness industry likes a good fad and that is what HIIT has become in the last couple of years. Despite being around for nearly 50 years, it has been captured by fitness celebrities and gyms all around the world and is being sold as the new, sexy exercise that will get you fit and thin in only one hour.

I mean, who wouldn’t want some of that?




LISS Definition

So, I couldn’t find a Wikipedia definition for LISS but I can tell you about it. It stands for Low Intensity Steady State and sometimes people tag a Cardio on the end of it.

It really is what it says. Long periods of low intensity exercise where the heart rate doesn’t really get higher than 50% of its maximum.

If you aren’t sure what your approximate heart rate should be then it’s 220 minus your age. Simple.

A standard LISS workout could consist of walking on a treadmill, cycling, low intensity jogging or swimming. The key here is that you don’t get too out of breath whilst doing it.

Again, this has been around for years, remember the 80’s and the jogging trend? And it’s still really popular with most people that go to gyms on their own. Go into you local Virgin Active and you will see hundreds of people on treadmills, exercise bikes or cross trainers with headphones on watching the TV.

It’s really simple to do as you don’t need any instruction (most of us can walk) and for some it’s a great way to do some exercise as either they physically couldn’t manage anything more intense or they enjoy doing it.

I will let you into a secret. You will sometimes see me in the gym on a spin bike whiling away an hour on a rest day, or even walking the dog down a country path.



HIIT and LISS are as different as chalk and cheese, aren’t they?

One involves running around like a person possessed for short periods and resting and the other calls for a sedate long period of exercise without rest.

To get a little more in-depth though:

The high intensity of HIIT taps different energy systems in the body. Because the body needs energy and right now, it can’t burn fat and instead turns to stored energy in the form of glycogen. It will however need to replenish this store later on.

This causes something called EPOC (Excess Post-Exercise Oxygen Consumption) which is where the body keeps on burning off calories even after you have finished exercising.

I explain this in much more detail in another post called “Weights Vs Cardio” which you can read here.

LISS doesn’t give you that. It maintains a heart rate of about 50% of your maximum which keeps the body in the perfect fat burning zone.

In this magic zone, the body can tap into the fat deposits around your body and use that for fuel. However, this pretty much stops when you step off the treadmill.

If you do HIIT correctly, it will tire your body so much that you will struggle to do more than three sessions per week, whereas LISS can be done every day.


hiit vs liss


What I Really Think

Maybe from reading the first few paragraphs of this post you may think that I don’t really like HIIT. That’s not the case and in fact I love it. I train my clients and myself using HIIT a lot for the very reasons I have already talked about.

What I don’t really like are fads. And unfortunately, the current trend of everyone doing HIIT all the time and not doing anything else isn’t helpful for most people.

LISS is great for people who are on rest days, for people who are new to training, are unable to do HIIT due to disability/injury being overweight or are unfit. It’s really useful training for most people at some point but a fad will eclipse all the good in something to further its own agenda.

Because of that, I feel that the HIIT trend is selling people an untruth.

“All you need is HIIT.”

Trainers have made millions of pounds selling this.

But the truth is, well maybe it’s boring but… the truth is you need an all-round training, nutrition and health regime to see life-altering changes.


Be all you can be




If this has struck a chord with you and I hope it has, then please leave me a comment below.


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