HIIT Cardio vs LISS Cardio

I was recently asked by a client about HIIT and LISS cardio methods. Here is my explanation:

To be blunt, they each have their place for different reasons. I recommend using both. I'm going to explain my reasoning for using each method.

Just like a properly performed HIIT session, I want to get this explanation finished quickly and effectively.
While performing HIIT, you're essentially spiking your heart rate to a near max rate and following that spike with a recovery period, which serves the purpose of preparing you for your next spike. You're literally working your heart, as it is a muscle, and it should be exercised beyond its normal daily drone the resting heart beat.

Working your heart beyond average workload is one benefit of a solid HIIT session. Working = strengthening, and this shows over time as you'll find that your heart will become more efficient at handling larger cardio workloads.

A second benefit of a solid session of HIIT is the metabolic effect. No matter how large or small of an effect HIIT has on the rise of your metabolism, you should be happy to take what you can get. A small overall effect can add up over a week's time. If you are cutting, this is beneficial as it allows you to lose fat more efficiently when paired with a proper diet.

When training a client in on LISS and HIIT, I will always perform the LISS first. HIIT training elevates the heart rate for extended periods and skews their numbers for their LISS training if performed first.

The fat burning effects of HIIT do not come during the actual workout. They come from the afterburn effects. This can throw some people off at first, but it's just the way it is.

As an overall rule, the majority of the workouts you perform do not induce change during the time you are performing them. They create a stimulus which causes the body to change while recovering from that workout.

In terms of LISS, the effects come about from different means. LISS revolves around the body's multiple mechanisms for creating energy. The body will use the highest percentage of fat for energy while at complete rest. The body will use the lowest percentage of fat for energy while at complete work.

LISS attempts to maximize fat loss during the actual workout by avoiding a complete work environment. When performing LISS, you will peform enough work to bring your heart rate to 60-70% of your max heart rate. This keeps things simple and attempts to burn a fair percentage of fat for energy to perform the workout.

LISS is straight forward. Perform work, but perform it in a manner that is low intensity in order to keep fat burning at play.

LISS is also less demanding on the nervous system, allowing you to perform it frequently without mental burnout, which can be detrimental to your resistance training workouts.

I recommend a regular rotation of HIIT and LISS, depending on your goals. Everyone is different, and your current goal will dictate just how you should rotate the two.

The timing of the workouts will vary from individual to individual as well, which is why I did not go into that aspect of the routines.