Which cardio training is best – HIIT or LISS

Listen up competing athletes! This one is for you.

For a very long time, a debate between which type of cardiovascular training, commonly referred to as cardio, was best for fat loss flooded (and still continues to flood) the fitness industry. And the main focus of this debate always seems to revolve around whether one should do HIIT (High-Intensity Interval Training) or LISS (Low-Intensity Steady State) cardio when the goal is to get as lean as possible.

With competition season in full swing, here’s something for you to take into consideration when deciding on your cardio choices.

Many coaches are against using LISS in their cardio burning arsenals for their clients, as they feel that LISS is no good for muscle retention. This is due to the fact that it is very non-specific towards weight training and that “hill sprints”, for example, were similar to weight training. On the other hand, just as many coaches feel that HIIT would also negatively affect muscle retention and burn too much muscle as it is very similar to weight training and places a lot of caloric stress on the body. Caloric stress that they believe to be catabolic.

Interestingly, new research actually shows that neither form of cardio is better than the other when it comes to retaining muscle (1).

However, on a minute-to-minute scale, HIIT wins overall. In other words, 25 minutes of HIIT burns a lot more calories versus 25 minutes of LISS cardio. In some cases, it may be argued that 20 minutes if HIIT can burn just as many calories as a 40-minute LISS session. Obviously, this will yield a much greater net fat loss.

Furthermore, HIIT may even result in a 24-hour-energy increase or a day of extra fat burning if you would call it that in simpler terms. Some studies have even shown staggering differences of 50% more fat loss using less than a tenth of the time that Low-Intensity Steady State Cardio would take (2).

So using HIIT would seem like a no brainer winner here right? 

Well, there are two big things to take into consideration when using HIIT (i.e. its downsides):

HIIT may impede recovery and possibly heighten the risk that one has of getting an injury while in a deficit such as a fat loss/contest prep diet.
A lot of people find it excruciatingly taxing on a psychological level. Many people find it much easier to step on a treadmill than have to psych themselves out just before going all in on a bike or up a hill. This can result in a great overall decrease in motivation levels (1).

So now what?

Quite simply, it boils down to whether you can sustain weeks of doing HIIT or, if you have the time, do the monotonous steady state cardio but maintain it during the weeks of your shred.

One thing to keep in mind, and a potential life benefit (as it were) from doing LISS, is that you’re able to listen to podcasts or audiobooks during your LISS cardio session. Whereas doing this during HIIT would be extremely difficult due to the taxing nature of HITT.

For those of you choosing to do HIIT, here’s a sample program that you can use to work from. You can tailor, edit and change it according to what you feel would best suit you and what you’re able to do and sustain:

• Warm up for 5-10 minutes.
• Run intervals as follows:
  • 15-second MAX effort sprint.
  • 90-second low steady movement to rest/recover.
  • Rise, wash, repeat an additional 6 times until you have completed a total of 7 sprints.
• Slow moderate cool down for 5 minutes (3).

Sustainability and consistency

Keep in mind the medium you choose to use when doing HIIT. For example, hopping onto a bike would be a little safer from an injury perspective versus doing track/hill sprints, for example, may result in you pulling your hamstring if you aren’t sufficiently warmed up or have poor running form.

Moving forward, be sure to use what fits into your lifestyle and preference. What’s sustainable and maintainable is what will get you far.

References:

1. L. Norton, PhD, et al. 2018. The Complete Contest Prep Guide.
2. Run sprint interval training improves aerobic performance but not maximal cardiac output. Retrieved 03 Jan, 2018. https://www.ncbi.nlm.gov?pubmed/20473222
3. Pakulski, B, 2014. MI40Xtreme 2.0.