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Does HIIT burn muscle?

HIIT cardio vs steady state cardio

On today’s episode of Live Lean TV, we compare steady state cardio vs HIIT and answer a viewer question who asked: does HIIT burn muscle?

This is another episode from our #WayBackWednesday series, where we highlight the best questions from previous episodes of our #AskLiveLeanTV Q&A show.

This question is from #AskLiveLeanTV Ep. 004.

Does HIIT burn muscle?

Here’s today’s viewer question:

Tara D Cooper from Facebook says: my question has to do with steady state cardio vs high intensity. I much prefer doing shorter, high intensity cardio, but I have a friend who recently hired a personal trainer and was told to do steady state cardio to keep her heart rate at a certain level for an HOUR. Otherwise instead of burning fat, she is burning muscle. Does HIIT burn muscle? Would love to hear your thoughts on this! Love you guys! #LiveLeanIsTheBestTeam.

The heart rate target training zones displayed on the cardio equipment at the gym doesn’t tell you the whole picture.

How To Calculate Your HIIT Heart Rate Target Zones

It’s more important to think about overall calorie burning, throughout the day.

Low intensity steady state vs HIIT cardio

For example, a lot of people will complete their cardio workout on a treadmill for an hour, and stay at a low intensity steady pace.

This type of cardio is called low intensity steady state cardio, also known as LISS cardio.

Pros And Cons Of LISS Cardio

Let’s say, on average, this hour long LISS cardio workout burns 400 calories.

Now compare that to completing 20 minutes of high intensity interval training sprints on the treadmill.

Since this 20 minute HIIT workout is comprised of high intensity and low intensity intervals, you may only be doing 6-8 minutes of high intensity sprinting.

Sure, you may not burn as many calories within that 20 minute period as the 60 minute LISS cardio workout.

However, the HIIT workout helps increase your metabolism at a much higher rate when compared to the LISS workout.

Pros And Cons Of HIIT Cardio

HIIT increases EPOC

When you’re huffing and puffing after an intense workout, that oxygen is helping you burn more fat, and increasing your metabolism as your body repairs itself.

This increase in metabolism is referred to as excess post oxygen consumption, i.e. EPOC.

15 minute afterburn effect workout with an agility ladder

We refer to this as the afterburn effect.

You don’t experience as much EPOC during a low intensity steady state cardio workout since your heart rate and breathing is more steady and controlled.

This means your total overall calorie burn for the entire day becomes higher, even though you burned less calories during your workout.

This makes HIIT a more efficient and overall better activity for fat burning.

HIIT Cardio Workout Routine For The Treadmill

Also, since HIIT workouts are more athletic and explosive, it helps recruit more muscle fibers, thus improving strength and muscle building.

Now let’s answer the question: does HIIT cause muscle burning?

Does HIIT cause muscle burning?

Since HIIT workouts take your heart rate outside of the “fat burning zone”, does that mean you’re entering muscle burning mode?


We disagree with that theory, as long as you’re eating enough protein, your muscles should be protected from being burned for energy.

If you’re worried about this, simply supplement with BCAAs or consume protein in your pre-workout meal to ensure your muscle nitrogen levels are high.

Early Morning Pre Workout Meal

This will help prevent muscle breakdown when doing HIIT workouts.

Plus, in most cases, your body will tap into stored sugar for immediate and short-term energy.

As long as you consume enough protein, your body will also tap into stored body fat for energy.

More reasons why we love HIIT workouts

HIIT cardio workout routine for the treadmill

Another reason why we are big supporters of high intensity, short duration workouts is because we make fitness fit into your lifestyle.

In other words, we take a more holistic approach.

We understand that you’re only going to get results based on what you consistently do over the long-term.

Plus there’s more passion in your HIIT workouts when you do them correctly, and hit them hard.

How To Do HIIT Cardio Correctly

Completing a 20 minute HIIT workout makes you feel a lot different than if you go in for a slow hour of boring steady state cardio.

You also get a lot more activity done in a shorter time, so you can get on with your day quicker.

There are so many reasons not only from a physiological standpoint, but also lifestyle related.

HIIT workouts are also more:

  • fun
  • energizing
  • athletic
  • time efficient

Besides, who can stand to be on a treadmill for an hour?

This is just another reason why we rarely do 60 minutes of steady state cardio.

Bottom line on does HIIT burn muscle?

As long as you are eating enough protein, you’ll be fine.

So don’t worry about burning into muscle with your HIIT workouts.

This is not to say that low intensity steady state cardio is wrong.

Give them both a try, but when it comes to your cardio workouts, focus more of your efforts on HIIT.

HIIT cardio works for us and it works for most of our clients.


If you want the best HIIT cardio program designed to destroy body fat, not muscle, check out our Live Lean Sprint 2.0 program.

Live Lean Sprint 2.0

This program will get you lean and athletic, as fast as possible.


Start by taking our FREE Live Lean Body Quiz to get access to the best program specific to your goals, current fitness level, and access to equipment.

Take the Free Live Lean Body Quiz


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Questions For You:

  • What works better for you: high intensity interval training (HIIT) or low intensity steady state (LISS) cardio?

Be sure to share your answers in the comment section below.

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