HIIT (High Intensity Interval Training) has become the next big fashion item in the fitness world with Facebook and Instagram celebs singing its praises for its incredible fat burning powers.
Conversely LISS (Low Intensity Steady State) has been almost demonised, with supporters of the long, steady run ridiculed for their naivety and ignorance.
So, who is right?
Is HIIT truly the panacea to all our fat loss problems?
Is LISS really a complete waste of time when it comes to getting lean?
Before we get into whether one is better than the other, let’s first make sure we fully understand what each is.
WHAT IS HIIT AND IS IT A NEW THING?
HIIT is basically a short duration training session (usually 30 minutes or less) which intersperses short bursts of high intensity anaerobic activity with short periods of rest and recovery, with a ratio of somewhere between 1:1 and 1:4.
High Intensity Interval Training is nothing new. Runners have been using a form of HIIT called ‘fartlek’ since it was first developed by Swedish coach Gosta Holmer in 1937. Alternating fast and slow runs throughout the duration of the training session.
Circuit Training is another form of HIIT which has been around for many years, indeed I started doing Circuit Training in the mid 90s, but I believe it was initially developed as a training methodology by Morgan and Adamson at the University of Leeds in the UK in 1957.
HIIT is simply a new-fangled term for something that’s been around for many years.
Out of the HIIT trend there have developed numerous different methodologies such as Tabata which typically last about 4 minutes and is intersperse ultra-high intensity intervals followed by short periods of recovery, and Gibala, which consists of 60 seconds intense work followed by 75 seconds of rest, over 8-12 cycles, among others.
WHAT IS LISS?
LISS is fundamentally the opposite of HIIT.
The intensity of the exercise is much lower and therefore sustainable for longer periods of time. LISS predominantly uses our aerobic energy system, meaning that it needs more oxygen to break down fat as fuel, whereas HIIT is predominantly anaerobic meaning it relies on glycogen stored in the muscle.
Walking, jogging, swimming and cycling, if done at an intensity that means you can still comfortably converse, would be classed as LISS.
Depending on fitness levels one man’s (or woman’s) LISS would be another’s HIIT!
SO WHICH IS BETTER FOR FAT LOSS?
There has been much written in the social media arena of late suggesting that the best and only way to burn fat is through HIIT training. In fact some have even suggested that LISS can cause weight gain! (However most of the articles I found in support of this theory seemed to be written by trainers who focused their business around HIIT protocols.)
Let’s face it, how many fat marathon runners do you see?
So, back to which is better for fat loss.
You may have heard of the ‘afterburn’ effect or EPOC (excess post-exercise oxygen consumption). The afterburn has been ‘bigged up’ as the reason why HIIT training is so effective for fat loss; the idea being that you continue to burn calories for hours and hours after you’ve finished training.
However recent studies suggest that the actual increase in afterburn effect may be significantly lower than some would have you believe.
LISS on the other hand doesn’t provide that same afterburn effect, however it is a great way to expend a high number of calories as it can be performed for longer periods of time.
In terms of fat loss, we need to be in a calorie deficit and both HIIT and LISS can help to create one, assuming that we don’t eat back any deficit gained from the training.
I like to think of it in terms of driving a car. This may not be the most scientific analogy but it makes sense to me.
If I fill my fuel tank and drive from A to B at 70mph and it takes 30 minutes I will use the same amount of fuel as if I drive the same distance at 35mph, it’ll simply take me twice as long.
So from a fat burning point of view either/or will help create a calorie deficit.
WHAT ABOUT THE BENEFITS
If time is at a premium then HIIT is certainly an efficient way to train. You can get a lot done in half an hour and that‘s you done for the day.
A good HIIT session can be done with or without equipment and you don’t need a lot of space. It’s not dependant on the weather so you literally can do it any time, any place, any where!
The disadvantage is that it can be pretty stressful on the joints and if you’re not used to exercise it can lead to a high risk of injury. Ideally you’d build up strength around the joints and allow the muscles to strengthen and adapt and the motor skills to develop, by beginning with a lower intensity combination of cardio and weights.
Building up through the use of MITT (you guessed it… Medium Intensity Interval Training) can give the supporting tissues and joints the chance to strengthen before going all out.
LISS on the other hand can do wonders for your mental health. Many people enjoy the ‘me’ time they get from a long walk or run. It’s good thinking time and can help reduce emotional stress.
LISS eats up calories which is great if you’re wanting to lose weight.
Generally speaking the effect of DOMS (delayed onset muscle soreness) is less with LISS and therefore recovery is quicker, meaning we can do a bit more of it.
On the other hand it is very easy to over estimate how many calories we burn from LISS, and there is a definite tendency to eat to compensate. If you’re looking to lose body fat, you will need to be mindful of not undoing your hard work.
THE BOTTOM LINE
As always it comes down to balance and choice. If you absolutely love HIIT and hate LISS, do HIIT. Conversely if you really enjoy getting out and doing a long run and you’ve got the time to do so, go for it.
If you want to get the best of both, why not incorporate both into your training regimen.
Ultimately the best fat loss results will come from consistency, no matter what you choose. Which is why first and foremost you need to do what you enjoy.
Finally, don’t forget that any form of exercise, whether HIIT, MITT, LISS or resistance training, places physiological stress on the body and therefore it’s imperative that you also include recovery/rest days into your training programme.
Bev Thorogood is owner of Floresco Fitness and Fatloss Coaching