How HIIT Could Be Wrecking Your Results

When someone first begins working out, it’s only a matter of time before they hear about the magic of High Intensity Interval Training (HIIT).

The notion that you can perform 20 minutes of HIIT and get the same benefits as 60 minutes or more of lower intensity work makes people feel like they’ve found the Holy Grail of Fat Burning.

There is a place for High Intensity Interval Training and it can be especially beneficial for losing body fat.

If this is your primary training method you’ll soon be left wondering how HIIT could be wrecking your results…and your body.

Training volume and intensity aren’t interchangeable. You can’t trade one end of the spectrum for the other and expect the same results.

Human performance is powered by 3 different energy systems with both time and intensity guiding which system is dominant.

Without getting too geeky on the science, this post will review the 3 energy systems, why too much high intensity is counter-productive, and provide you with 2 different training applications so your training doesn’t leave you feeling like you’ve been HIIT by a truck.

What You Need To Know About Energy Systems

If you’re reading this post, you probably want better results from your fitness and don’t care about passing a science test on ATP production.

So my goal is simply to give you you what you should know and leave out the nerdy stuff.

All 3 energy systems are functioning and ready to go. You don’t need a large dose of pre-workout to turn anything on.

Adenosine Triphosphate (ATP) is the currency of our energy systems. Our muscles use one phosphate molecule from ATP we’re left with Adenosine Diphosphate (ADP).

In order to have more energy, we need to turn the ADP back into ATP.

Hang in there, we’re not going too deep on the science!

All 3 energy systems produce ATP but in very different ways and at very different speeds.

Here’s what you should know about each energy system.

Alactic Energy System

This system is high in power and short in duration. Addtionally, the production of ATP is slow for the Alactic System.

Although this system can cover the first 30 seconds of activity, a true maximum effort will deplete this system in about 12 seconds.

The Alactic System uses stored ATP and is like spending the cash in your wallet. This system is anaerobic meaning it can run without oxygen.

Once depleted, it may take anywhere from 3 to 8 minutes for the Alactic System to fully replenish.

Approximately 80% of ATP is replenished after 60 seconds. After 120 seconds, ATP is restored to 88% and then 93% after 180 seconds.

High Intensity Training is typically defined as anything higher than a 90% effort.

If you’re training at true high intensity (90% or more) for more than 15 seconds, your energy systems aren’t able to recover and maintain that level of performance for very long without a significant loss of power.

This is one of the deeply flawed beliefs around HIIT.

This is why powerlifters and world class sprinters take such long breaks between working sets. They’re truly giving a maximum effort which depletes the Alactic Energy System.

Glycolytic Energy System

This system is moderate in power and moderate in duration.

When the Alactic System is depleted, the Glycolytic System kicks in for the next 60 to 90 seconds.

While the Glycolytic System produces more ATP than the Alactic, it also takes longer.

Producing ATP is a little more complicated for this system as the first part is anaerobic (without oxygen) and the second part of the process is aerobic (with oxygen).

The Glycolytic System produces ATP from the stored glycogen in our muscles (from carbohydrates).

Most importantly, of the 3 energy systems, the Glycolytic System is the only system that isn’t chemically balanced in the production of ATP.

Think of the Glycolytic System as energy purchased on credit. When this gets out of balance, you’ll build up Recovery Debt.

The Glycolytic System is often referred to as the Messy Middle because relying on this middle system for too long comes with a relatively high cost of recovery.

Moderate Intensity is the range from 75 to 90% of maximum effort.

Many fitness brands and trainers employ flawed applications of High Intensity Interval Training with minimal rest times which can wreak havoc on your body given the accumulation of lactic acid.

The science behind the Tabata Protocol was for 8 Rounds of 20 seconds of Maximal Effort and 10 seconds of rest for a total of 4 minutes.

Given what we covered about Alactic training, we now recognize this approach would have fully depleted this system and switched to Glycolytic. This was proven to be manageable at the given dose of 4 minutes.

This is where fitness professionals tend to mess things up. To quote legendary strength coach Dan John, “things are going so well, help me screw it up.”

Attempting to maintain this level of intensity with Tabata training for 20 to 30 minutes or more will significantly impact your bodies stress response and require a disproportionate amount of recovery.

For Tabata training, intensity is the key and NOT duration. Don’t make the classic mistake of “if some is good, more must be better”.

When people begin working out, they can become overly reliant on the Glycolytic System because of the satisfaction from a hard workout and the inital fat loss results it can produce.

Too much Glycolytic work will yield negative consequences for your body.

Aerobic Energy System

This system has low power and long duration.

The Aerobic System breaks down our fat cells through a process called lipolysis to create ATP and for this reason, the aerobic system can produce endless amounts of ATP.

The production of ATP from the Aerobic System is a slow process which is why power is low.

Using our currency analogy, the Aerobic System is like spending from your savings account.

This is where the popular Zone 2 Cardio resides.

The intensity associated with Aerobic training is from 60 to 75% of maximum intensity.

Putting It All Together

When we review an athlete’s training intensity, we’re looking to see that at least 75% of their training is Aerobic, 15 to 20% is Glycolytic and between 5 and 10% Alactic.

We recommend Morpheus because this heart rate training system allows you to see if you’re consistently training at the right intensities.

Whether you decide to use a heart rate device or not, here are 2 different ways to maximize the benefits of your energy systems with your conditioning work.

Alactic + Aerobic

I first learned about this training method from StrongFirst as this has a “low cost of adaptation”. The goal of Alactic + Aerobic (A+A) is to build you up without tearing you down.

This is a very simple example and if you’re interested, I highly recommend The Quick and The Dead and Kettlebell Axe: High Speed, Low Drag Alternative to HIIT.

Choose 2 exercises that you can perform explosively such as Kettlebell Swings, Kettlebell Snatches and Push Ups.

Alternate exercises every other round using an On The Minute format with 10 seconds of explosive work followed by 50 seconds of rest.

It’s important NOT to exceed the 10 seconds of explosive work so as not to fully deplete the Alactic System. This application can be performed for 20, 30 or up to 40 minutes (in trained individuals) without fully compromising the explosiveness of the Alactic System.

Perform Heavy Explosive Swings / Snatches for 10 seconds.

Rest for 50 seconds.

Perform Explosive Push Ups for 10 seconds.

Rest for 50 seconds.

When either intensity or form fall off, this is your signal to stop training.

Here is another method you can use to benefit from the Alactic and Aerobic systems.

Going HIIT-LISS

In the world of baseball, going hitless is great for a pitcher and horrible for a batter.

When it comes to your conditioning, Going HIIT-LISS is fantastic!

Begin with 5 to 10 sets of High Intensity Interval Training working for 30 seconds and resting for 30 seconds. You could also use intervals of 20 seconds of maximal work and 40 seconds of rest.

After completing your HIIT sets, you’ll want to rest for 4 to 5 minutes allowing your systems to recover.

Then perform 30 minutes of Low Intensity Steady State (LISS) work such as rowing, biking, SkiErg, brisk walking or jogging.

If you really struggle with doing Low Intensity Steady State work, check out this post on Conditioning for Cardio Haters.

Conclusion

Now that you have a solid understanding of the roles each Energy System plays, you can better manage your conditioning.

Remember the comparisons of your energy systems to spending money.

Alactic is the cash in your wallet, Aerobic is your savings and Glycolytic is spending on credit.

Each of these systems plays a role in supporting a well-rounded conditioning program.

Just like your spending, if your training is out of balance, your recovery will need overdraft protection.

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