LISS vs. HIIT. Which one is the best? (En)


For sure many of you have heard about HIIT since recently It is becoming very popular within the gym environment. But I’m also sure that you haven’t heard about LISS, or at least you don’t recognize it. No worries, in this post I’m going to talk about LISS vs. HIIT defining and explaining the adaptations that they produce in our bodies. So keep reading because I’m sure you will be surprised!

Benefits of cardiovascular training

Before to go into the main topic of this post, I wanted to list out the benefits that any cardiovascular training offers us:

  • Improvement of the cardio respiratory system.
  • Reduction of cardiovascular disease. It decreases LDL-C (bad cholesterol) and increases HDL-C (good cholesterol).
  • Decreases in blood pressure.
  • Increases sensibility to insulin.
  • Improvement of the VO2.
  • Reduce our resting heart rate.

So, it does not really matter whether we use HIIT or LISS, we will get all these benefits from a cardiovascular training.

So what should we do? LISS or HIIT? Let’s go to see it!


Low Intensity Steady State or LISS is a low intensity training where we keep a constant pace for long time (usually between 30 and 60 mins). This type of workout allows us to burn fat during the time of the session (well, not from the very beginning but from after the first 20 mins). It has a very little metabolic impact, which means that you will ONLY burn fat during the duration of the session but not after.

In order to perform this type of training, we need to maintain a constant heart rate between 50% and 70% of our maximum heart rate.

The main characteristics of LISS are:

  • Everybody can do it.
  • We can do it almost on daily basis.


High Intensity Interval Training or HIIT is characterized for alternating high intensity effort peaks (85%, 90% or higher) with low intensity (around 60%) or absolute resting periods (1).

This type of workout has many benefits such as:

  • Increases of the muscle mass.
  • Improve the aerobic and anaerobic systems.
  • You need less time to have the same benefits than with LISS
  • You burn more fat than with LISS (we will see later why).
  • Improvement of the glucose metabolism.
  • More metabolic activation.

It has been demonstrated that, with HIIT, you need less sessions and a lower training volume (so you also decrease the risk of injury) for obtaining the maximum benefits of this cardiovascular exercise.

Main Metabolic Difference: EPOC

When you start a training session, the oxygen that you consume isn’t enough for the metabolic requirements, so the metabolism is progressively adapting the consumption of oxygen to the intensity of the exercise until it reaches a steady state. To reach this state will depend on 2 things:

  • your fitness state and
  • the intensity of the exercise.

Once it is reached, it will remain the same at least the intensity of the exercise changes.

When you complete the session, there is a oxygen descent called: Excess Post Oxygen Consumption (EPOC), which is the additional oxygen that must be taken into the body after the exercise is complete in order to restore all systems to their normal states.

EPOC has two phases:

  1. Phase 1 (alactic): the ATP and PCr (phosphocreatine) are re-synthesized.
  2. Phase 2 (lactic): the lactic acid is removed and transported to the liver where, lately, will be converted to glucose.

So, being said that, the EPOC is higher after a high intensity training session (HIIT session) than a low intensity one. And this is based on the next 3 points (2): Higher

  1. heat gains.
  2. depletion of the PCr stores.
  3. concentration of adrenaline and noradrenaline.

So, those calories that we need due to the high energy demand, come from the oxidation of the free fatty acids. It means that we will continue burning fat even for the next 48 hours after we have complete a HIIT session.


Due to what we have already commented, HIIT is the perfect protocol to burn body fat. But, can we use it on daily basis? My answer is no. HIIT is a high demanding protocol that must be used with high intensity. If we practice it on daily basis, we will not only not be able to work within the intensity required, but also we will have a higher risk of burning out, and the increase of injury risk .

The optimal frequency is 1/2 times per week for those who wants to initiate in it and no more than 3 per week for those who has a higher training background.

A very good plan is to mix it along with LISS, so we can get the benefits from the both of them, reducing any risk. Always keep in mind 2 things:

  • Planification is the key and
  • you won’t be the best training the hardest, you will be the best training the longest.

Timing within the session

There are many different protocols to work HIIT, but we can group them by:

AIT (Aerobic Interval Training)

  • Extensive method
  • 4-6 sets
  • 4 mins working
  • 3, 4 mins resting
  • 85% – 90% of the Vo2 Max

The adaptations that it produces are:

  • More capillarization
  • Glycolysis and increase of glycogen stores within the ST (slow twitch) fibers.
  • Higher heart hypertrophy.

SIT (Sprint Interval Training)

  • Intensive method
  • 4-6 sets
  • 30 seconds working
  • 3, 4 mins resting

SIT produces:

  • Production of lactic in the bloodstream
  • Implication of the fast twitch fibers
  • Glycogen stores depletion

If our goal is to burn body fat, the evidences show that between 1:2 and 1:4 (1 min working and between 2 and 4 resting) is the optimal pace.

If we want to increase our Vo2 Max (although for the most of people this is not a useful parameter), the preferible protocol will be SIT (7).

How many calories we burn

Obviously, after everything that has been said, HIIT will burn more calories per minute than LISS. Approximately, for a 25 mins session, a male with 70 kg and an intensity of 90% will require between 520 and 600 kcals. This is the same calories that we can burn in 1 hour of LISS.

How can I do HIIT?

There are different ways of doing HIIT:

  • Running
  • Swimming
  • Rowing
  • Cycling
  • Elliptical machine (not recommended because of the spine rotation that it provokes)

The best one to do it is running. But we should not abuse of it due to the impact that it has in our knees and lower back. A good recommendation is alternate it with cycling or swimming.

Also, we cannot mix HIIT with HIPT (high intensive Power Training), which is the one used in some disciplines such us Crossfit. Basically, HIPT is a variation of HIIT but oriented to strength sports.

Is HIIT up for everybody?

The answer is clear: YES. Of course, with the correct progression and professional supervision but yes, HIIT can be use by any type of person.


I’ve been mainly talking about HIIT since it is not as known as LISS (although not everybody knows what LISS stands for). In my personal opinion, to mix both protocols is the best approach that we can follow. HIIT is very demanding and can be hard to introduce in the routine of certain group of people (obese and older groups). However, as I said in the paragraph above, with the correct progression and supervision it is a very good protocol to implement.

Also, it has been demonstrated the effectivity of HIIT on people with diabetes type II, increasing the insulin sensitivity(4, 8, 10, 12), metabolic syndrome(8, 9), and reducing obesity in young and adult population (8, 9, 10, 12).

In summary, to mix up both methods is an excellent option since we will favor a constant body fat loss, preserving our muscle mass and increasing the recover time.

Don’t forget to leave me a comment if you found this article interesting or any questions that you can have! And see you in the next one!


  1. Benito Peinado, P.J. (2013). High Intensity Interval Training (HIIT) y su aplicación a la pérdida de peso. Gym Factory Magazine. Entrenadores, nº53.
  2. Lopez-Chicharro y Fernandez-Vaquero, 2006. Fisiología del ejercicio.
  3. David Marchante (Powerexplosive). Entrenamiento eficiente.
  4. High-Intensity Intermittent Exercise and Fat Loss, 2010, Stephen H. Boutcher (diabetes type 2 and insulin sensitivity).
  5. Ainsworth, B. E., Haskell, W. L., Whitt, M. C., Irwin, M. L., Swartz, A. M., Strath, S. J., y col. (2000). Compendium of physical activities: an update of activity codes and MET intensities. Med Sci Sports Exerc, 32(9 Suppl), S498-504.
  6. Talanian, J. L., Galloway, S. D., Heigenhauser, G. J., Bonen, A. & Spriet, L. L. (2007). Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women
  7. Block periodization of high-intensity aerobic intervals provides superior training effects in trained cyclists. Rønnestad BR1, Hansen J, Ellefsen S.
  8. Clinical benefits of high intensity interval training. Tim Shiraev, Gabriella Barclay.
  9. Cardiometabolic risk markers, adipocyte fatty acid binding protein (aFABP) and the impact of high-intensity interval training (HIIT) in obese adolescents. Blüher, Käpplinger, Herget, Reichardt, Böttcher, Grimm, Kratzsch, Petroff.
  10. Impact of long-term high-intensity interval and moderate-intensity continuous training on subclinical inflammation in overweight/obese adults. Gerosa-Neto, Antunes, Campos, Rodrigues, Ferrari, Rosa Neto, Bueno CR Junior, Lira.
  12. High intensity interval training improves liver and adipose tissue insulin sensitivity. Marcinko, Sikkema  Samaan, Kemp, Fullerton, Steinberg.

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