What is better HIIT vs. Low Intensity Steady State (LISS) cardio?

Edited by: Danielle Abel

In order to determine if HIIT or LISS is better for you & your health, fitness, or athletic goals, we first need to understand what each one is, along with the benefits you can expect to see from each. 

What is LISS anyway?

LISS stands for Low Intensity Steady State and simply refers to exercise performed in a low-intensity heart rate zone. When we exercise in a low-intensity zone, it's considered aerobic because we use a larger amount of oxygen to metabolize the fuel necessary to continue the movements. 

For example, running for durations of greater than 3 minutes at a heart rate of less than 75% of your maximum heart rate (MHR) would be considered LISS. Some other examples of low-intensity exercise include:

• Incline walk
• Light jog
• Spin bike or cycling

The key here is that while performing these movements, you would purposefully aim for an easy pace, something where you could carry on a conversation without feeling out of breath. Keep in mind that all of the exercises listed above could also be performed at higher intensities, but with LISS, we're intentionally keeping the intensity submaximal. 

What are the benefits of LISS?

Because we're keeping the heart rate below the lactate threshold (at and above 75% of your MHR), you're able to minimize fatigue accumulation on the body, which can sometimes leave you feeling burnt out if you've typically always exercised at intensities that felt kind of hard. 

If you're concerned about cardio interfering with strength training, performing LISS can help mitigate the interference effect, decreasing the chances of losing strength gains. 

From a health perspective, LISS cardio can help increase your heart chamber size, which allows you to pump more blood with each beat. You can also expect to see an upregulation in aerobic enzymes that help increase your endurance, delivering more oxygen to your muscles and other tissues of the body. 

Lastly, low-intensity training helps build your cardiovascular economy. Economy simply refers to how efficient your body is at aerobic exercise and is influenced by things like your VO2 max, demographics, biomechanics, and even the footwear you wear. 

What are the drawbacks to LISS?

One of the main drawbacks to LISS is that it can be time-consuming. What we mean by it being time-consuming is that in order to elicit the same adaptations as higher intensities, we need to perform much more low-intensity exercise. For some athletes or clients who are really crunched on time, LISS might not be the most efficient choice. 

If you're looking to improve anaerobic training adaptations, aerobic LISS training won't benefit higher-intensity performance. People with anaerobic goals might be individuals who want to spring faster for example. 

What is HIIT anyway?

High-intensity interval training simply means the individual performs repeated bouts of effort followed by various recovery times. This might look like sprints or bike sprints for 10-15 seconds with about 3 minutes of rest before the next set. 

HIIT sessions often last 10-20 minutes. Keep in mind that over time, or with athletes who are customized to HIIT, a longer amount of time may be needed to continue improving aerobic and anaerobic adaptations. 

What are the benefits of HIIT?

A main benefit of HIIT is that it's extremely time efficient. So for athletes with extremely busy schedules, 20-30 minutes of HIIT may be easier than 40-60 minutes of LISS.

HIIT can also help increase your work capacity (how much exercise you can handle) at maximal or near-maximal ranges. For athletes who must perform maximally for short or repeated bouts, HIIT offers a lot of benefits. 

Probably one of the most known benefits of HIIT is that it burns a lot of calories in a small amount of time. So for athletes who are pressed for time and are looking to reduce their body fat levels, this could be a good choice for them. 

What are the drawbacks of HIIT?

Since high-intensity interval training is performed at high heart rate intensities of greater than 75%, where lactate accumulates, it can be very fatiguing on the body. Additionally, because you need to push yourself to near-maximal levels, some people may not enjoy this. As a result, it might be more difficult for them to adhere to HIIT sessions regularly.

For individuals who enjoy walking at an incline on the treadmill or going outside for a hike, LISS might be a better choice for them because they personally enjoy it, so therefore it's easier for them to get it done.  

We also need to keep in mind that the amount of HIIT we can tolerate is limited, because eventually it may interfere with other types of training. Doing HIIT for 10-20 minutes once or twice per week is probably pretty recoverable for most people. 

So what's the best approach?

The answer is a bit more gray than just choosing one approach over the other. More often than not, most people can probably benefit from both LISS and HIIT in their weekly exercise or training schedules. 

One good way to incorporate LISS without much thought at all is to simply add a 5-10 minute warm-up before your training. Another approach would be to add a 10-20 minute cool-down after training. This could be time spent walking on an incline, using a spin bike, rower, or even elliptical while keeping your heart rate below 70% of your MHR to minimize fatigue. You could also just go for a walk while trying to get your heart rate near 60-70% of your MHR could also be an option. 

If you're looking for an easy way to add HIIT to your week, is to make it truly high intensity, and to limit the sessions to 1 maybe 2 sessions each week. If you have a conditioning day already, you might be able to add in some HIIT to what you're already doing. 

If you don't have a dedicated conditioning day, then you might consider adding it on after your strength training. 

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