What is Polarized Training?

You’ve heard you should train in zone two or do “low heart rate training.” Or you might have heard your favorite influencer say, “You have to run slow to get fast.”

But if all you’re doing is slow runs, you’re missing the entire point of 80/20 or polarized training. Today, I’m breaking down what polarized training actually is. I’ll tell you why it’s important and how you can finally use it the right way without burning out.

Heart Rate Training Zones Explained

If the heart rate zone model of training seems confusing, don’t worry. Let’s clarify it.

Heart rate zones are individual to you and based on your maximum heart rate. Most heart rate zone models include zones 1-5. Zone 1 is a lower percentage of your max heart rate, and Zone 5 is the highest percentage of your max heart rate. Some zone models also include smaller zones within Zone 5 (usually Zones 5a, b, and 5c). Some heart rate zone models only use three zones: low, moderate, and high. For the sake of simplicity, the examples I use below will use a Zone 1-5 model. 

Your maximum heart rate is dictated by several factors, such as age and genetics. Two factors, duration and intensity, affect the percentage of your max heart rate you use. The higher the intensity, the harder your heart works to pump blood to the working body parts. When your heart works harder, you use a greater percentage of your max heart rate (higher zone).

Here’s where duration comes in.

The higher the intensity, the shorter the duration. The lower the intensity, the longer the duration you can maintain. 

High Intensity-Training Example: 60-meter sprint repeats. (Zone 5).

Low-Intensity Training Example: Long run at a very easy pace for 75 minutes (Zone 1-2).

Low- and high-intensity efforts have their place in a well-structured training program. The polarized training model section below provides more on that.

Heart rates (beats per minute) are specific to each individual, but there are some general percentages of max heart rate that line up with each zone.

Zone 1: <60% of your max heart rate

Zone 2: 60-70% of your max heart rate

Zone 3: 70-80% of your max heart rate

Zone 4: 80 – 90 % of your max heart rate

Zone 5: >90% of your max heart rate

Here are some examples of how this might look for someone like me (a 38-year-old).

An easy way to determine your max heart rate is 220-age, so that would be 182 beats per minute as my max heart rate.

One thing to remember is that this simple formula is often inaccurate, but can serve as a “ballpark” estimate.

Zone 1: <60% of your max heart rate – <108 bpm

Zone 2: 60-70% of your max heart rate – 108-126 bpm

Zone 3: 70-80% of your max heart rate – 126-144 bpm

Zone 4: 80 – 90 % of your max heart rate – 144-162 bpm

Zone 5: >90% of your max heart rate – 162-182 bpm

These are considered target heart rate zones. There’s only one problem.

These numbers are not very realistic for untrained or novice athletes. 

If you’ve trained with a heart rate monitor, you may have been surprised how high your heart rate was at an easy pace. You might go out for a light jog, assuming you are in Zone 2, only to see that your heart rate is in Zone 4.

That’s because you have not built your aerobic base…yet. 

You build your aerobic base by spending A LOT of time working at the lowest possible heart rate. For many beginners, this means walking or jogging at the slowest pace possible.

Before using a heart rate monitor, most people assume their comfortable jogging pace is in Zone 2. This is rarely the case, and this is why so many people give up on low-heart-rate training. It’s too frustrating to put in hours of work for little short-term results.

It’s even more frustrating when an influencer posts a photo of their low heart rate at a blazing pace. Rest assured that over time, your heart rate will drop. Your running economy (how much energy you use at a given pace) will improve.  You’ll even recover faster from harder intervals. But it takes time.

Aerobic vs Anaerobic Explained

Aerobic means “with oxygen.” According to the National Strength and Conditioning Association, 

“Oxygen uptake (or consumption) is a measure of a person’s ability to take in oxygen and deliver it to the working tissues, and the ability of working tissues to use oxygen. During low-intensity exercise with a constant power output, oxygen uptake increases for the first few minutes until a steady state of uptake is reached.”

This type of low-intensity exercise produces necessary adaptations for endurance sports:

• Increased stroke volume (how much blood your heart pumps with each beat)
• Improved blood flow and oxygen delivery
• Improve mitochondrial function
• Lower resting heart rate 
• Lower heart rate during sub-maximal efforts 

Anaerobic means “without oxygen.” The anaerobic system uses glucose to produce adenosine triphosphate (ATP) for energy. Here’s a great explanation of the anaerobic energy system from physio.com. 

“ATP is produced by the breakdown of glucose and glycogen( the storage form of glucose). The muscular stores of ATP is very limited and gets depleted within a seconds after a activity. Normally anaerobic system works from the second of start of exercise till 2 minutes.”

Anaerobic adaptations are also important for endurance athletes. They include:

• Increases anaerobic enzymes
• Improved neural drive (recruiting motor units needed for muscle activation and force protection)
• Increased lactate threshold
• Increased glycogen storage

Athletes of any sport benefit from producing aerobic and anaerobic adaptations. Building the aerobic base first will help athletes produce anaerobic adaptations over time.

Let me explain, boxing is a highly anaerobic sport. But what is the first thing every boxer does in their training program?

Road work, which of course is another name for long, slow distance running. The boxer, just like the runner, spends hours every morning building their aerobic base. They do this with low-intensity work that will enhance their anaerobic conditioning.

A good option for beginners frustrated with their heart rates is using a pacing approach. 

Pacing vs Heart Rate Approach

The body is good at doing the things we tell it not to. Think of any time you forgot to put on deodorant. When you realized your mistake, you thought to yourself, “Please don’t start sweating.”

What does your body do in response?

That’s right. You start sweating.

The same thing can happen with monitoring your heart rate. If you’re checking your watch during your run and thinking, “Please stop going up, please stop going up, ” what do you think your heart rate is going to do?

An approach that can help with obsessive heart rate monitoring is the talk test. If you can carry on a conversation, you are likely in a low heart rate zone.

It looks like this.

Zone 1: Walking or the lightest possible jog. You can carry on a whole conversation out loud. You could get lost in thought and lose track of time.

Zone 2: Easy jog. You could carry on a conversation out loud that might be labored. You can speak, but with a little effort getting the words out.

Zone 3: Moderate pace. You could get short, breathy sentences out, but a full conversation would be a struggle.

Zone 4: Challenging pace: You could get single words out but struggle to say a complete sentence.

Zone 5: Max pace: You cannot speak at this pace.

I like starting my beginner clients with the talk test approach. It allows them to improve without the added mental stress of worrying about heart rate zones. When their fitness improves, I then move them to a heart rate monitor to dial in their pacing.

What is Polarized Training?

Now that we understand heart rate training zones, aerobic and anaerobic adaptations, and pacing alternatives, let’s dive into the polarized model of training.

The bulk of training (about 80%) will occur in the lower heart rate zones (Zone 1-2). Twenty percent of training will occur in the high heart rate zones (4-5), with very little occurring in the moderate zone (Zone 3).

This is the exact opposite of how most amateur athletes train. Most amateurs spend most of their training time in the moderate intensity (Zone 3). 

Exercise scientist Dr. Stephen Seiler popularized polarized training for endurance athletes. Selier advocates what he calls the 80/20 rule for endurance training, which corresponds with the general split between low and high training in the polarized model. 

According to 8020endurance.com, “The single most beneficial thing you can do to improve your performance in endurance racing is to train a lot. The fine print is that in training a lot, you must be sure not to train too much, and you can train more without training too much if you train at low intensity, so what Seiler really means here is that the single most beneficial thing you can do to improve your performance in endurance racing is do a lot of low-intensity training.”

The 80/20 rule allows athletes to achieve the necessary training volume while lowering the risk of injury. Training, especially running, is hard on the body. The more challenging the intensity, the greater the risk for injury. The 80/20 rule allows athletes to increase the training volume without increasing the intensity. 

Sports journalist and 80/20 advocate Matt Fitzgerald often points to the training of professional athletes in Ethiopia as an example of 80/20 effectiveness. 

“The same is true of the not-entirely-easy easy runs the Ethiopians do. The unbreakable rule here is the 80/20 principle, where 80% of total weekly run time is spent at low intensity and 20% is spent at moderate to high intensity. It is a well-established fact that elite endurance athletes (and not just runners but also cyclists, swimmers, and others) train this way, and Ethiopia’s elite runners are no exception. They just distribute intensities a little differently, allowing some of the 20% to bleed into the 80, as it were.” – Matt Fitzgerald https://run.outsideonline.com/people/ethiopian-runners-train-differently-or-do-they/

What Do Amateur Athletes Get Wrong About the Polarized Approach?

Here’s the biggest misunderstanding of 80/20 or polarized training: It doesn’t mean that you only do low-heart-rate work or that all your training sessions are at a single intensity. 

It means that throughout a long-term training plan about 80 percent of your total training time should be at a low heart rate pace and about 20% should be hard to very hard. 

Think of it as training intensity distribution. If you zoom out, the total time spent follows an 80/20 split, even if a workout includes a mix of low-intensity work with high-intensity interval training or threshold training.

That could mean doing an easy 60-minute run with 12 minutes of tempo intervals worked in.

Tools like TrainingPeaks make it easy to program this type of workout. That’s why I use TrainingPeaks for my custom coaching clients and pre-made race plans.

This hill repeats workout from one of my clients’ 10k programs shows spikes of higher intensity mixed with lower intensity periods. One thing a lot of new athletes get wrong with 80/20 is that they end up only doing low-heart-rate work. You still have to do the hard workouts, the 20% that push your anaerobic threshold.

Does Polarized Training Only Apply to Running?

Polarized training can complement any endurance sport, from cross-country skiing to cycling to multi-sport events like triathlon. The activity is different, but the energy systems and road to peak performance are the same.

How Does Strength Training Fit Into Polarized Training?

Strength training works well with polarized training. The focus on low-intensity endurance work allows the athlete to incorporate power-focused workouts without overtaxing the central nervous system. 

Strength training enhances the athlete’s sport performance. However, if both endurance and strength work are done at high intensities, it can inhibit recovery. That’s why it’s important to periodize endurance and strength in a training plan.

Conclusion: What is Polarized Training?

There are many different ways to program endurance training. The polarized model is simply one of them that produces some of the best results for my clients. 

If you feel stuck or your training feels like it’s not going anywhere, polarized training might be a great option. Several of my custom coaching clients have made significant improvements after I switched them to a polarized training plan. 

Check out my coaching page if you want help programming your own polarized training plan.

If you’re interested in doing your own research on polarized training, I recommend reading anything by Matt Fitzgerald. 

Here are a few of my favorites.

80/20 Running

80/20 Triathlon

Run Like a Pro Even if You’re Slow

Remember to subscribe to the Outdoor Muscle YouTube channel. Leave a comment if you want me to explore any other strength and conditioning topics.

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