Why doing exclusively HIIT is NOT great for your heart.

I want to dance at my granddaughter’s wedding.” 

 To this day, the above goal is perhaps one of the greatest I’ve ever heard. It comes from a coach by the name of Dan John, a mentor who I’ve learned a ton from over the years.

I listened to him speak about it years ago, but it didn’t resonate with me quite as much until now. My wife and I are expecting our first child in March. When I recently revisited his work, I was listening with a different set of ears and a changed heart, and now it made sense. 

My goals have shifted away from how much weight I can lift, how lean I get, or how fast I run.

If I plan to age as a strong, mobile and fit person, I need to get ahead of things now. No matter how hard we fight, all these attributes decline with age.


So what does this have to do with HIIT?

For those of you who dont know, HIIT training, if performed correctly (that will be another blog), is short bouts of extremely difficult work paired with a period of full to moderate rest, repeated. 

Our “Get Lean” classes are a form of HIIT prescribed to the best of our ability.  Crossfit, and other intense group fitness classes are other examples.  

Over the last few years, this form of exercise has been touted as “just as effective” as 2x the amount of traditional “steady state” cardio (moderate aerobic activity sustained over a period of time without rest).

Effective for what?

Calories burned? Sure, the lasting effect of HIIT will result in a few extra calories burned throughout the day but not much.

Improvements in aerobic fitness? Yes, but without getting too complicated, only depending on what we measured in the first place


The fitness world ran with this and suddenly every gym focused on heart pounding classes, posting pictures of heart rate red lining for an entire class.

You even started to hear things like “If you strength training properly, your heart rate is elevated, so you don’t need cardio.”

The mistake we’re making is  taking data which supports certain methods for fat loss, elevated metabolism, or better athletic performance and equating that to improved heath. 

These aren’t always the same thing!  There are a lot of great ways to perform better at football, but I don’t think they’re keeping you alive any longer.


So what are we missing?

The heart pumps a certain amount of blood out with each contraction. The more blood we circulate, the more oxygen our body receives which means we’re winning.


So how does it do that?

It’s simple.

Method One: The heart can contract stronger. So you can imagine the harder the heart squeezes, the more blood would come out. We’ll call this CONCENTRIC HEART ACTIVITY.

Method Two:  The heart can STRETCH OUT more. So imagine if every time it filled up it could hold more blood to send out. We’ll call this ECCENTRIC HEART ACTIVITY.

Method Three: It simply beats faster. But there isn’t much we can do to actually change Max HR. 

When we perform a hard set of exercises during strength training our heart rate rises. The same is true during intense interval training.


This is CONCENTRIC HEART activity.


This makes the heart stronger much like strength training for any other muscle. It also can thicken the heart wall slightly. You may have heard of “athlete’s heart” where the heart enlarges a bit. This is rarely a problem but it may decrease the amount of blood in the chamber. 

This isn’t a bad thing, but ONLY doing this could be problematic.

When we include more STEADY STATE cardio, typically in lower heart rate ranges around 60-70% of our max (HIIT is performed at around 85-90%) we are improving the ECCENTRIC HEART, or the stretchiness.

We’re improving how much blood enters with each beat. With more blood per beat, the heart can beat less often and with less forceful contractions.

Steady State cardio as described above is also much better than HIIT at lowering blood pressure, resting heart rate, improving your recovery rate, and a host of other health benefits. It also correlates to lowering stress and improving longevity. 

Think of it as your heart’s “first gear.”  You may be  fit, but if doing almost any task requires you to get above 85% max heart rate, that’s a problem.

This article isn’t meant to scare you. There’s nothing wrong with HIIT training. I prescribe it to most of my clients in some form.

The problem arises when we’re neglecting other areas of “health” for minor benefits in fitness and aesthetics.


So “they” are right.


You don’t NEED cardio to lose body fat. But you sure do need it if you want to improve the length AND quality of your life.


Want to get started?

Grab a heart rate monitor, and perform  120-180 minutes a week of activity that keeps your heart rate between 60-70% of your max.

After a few weeks you’ll notice that you’re getting more work done within the same timeframe

At first you might only go a few miles in an hour but now you’re going further.

Your cardiovascular system is actually becoming more efficient.

Your blood pressure likely went down.

Your sleep likely improved.

I wouldn’t be surprised if due to the reduction in cortisol (stress hormone) levels that you dropped a pound or two either.

This was a long read, so THANK YOU if you made it this far.


If you have any questions don’t hesitate to reply to this post and I’ll be sure to answer.


As always…

Keep Moving Forward,


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