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The polarized training model is a concept based on complex physiology that boils down to a very simple idea: spend 80 to 90% of your time going slow (and by slow, we mean slow), about 10 to 15% of your time going really hard, and little time in between. That equates to about two, maybe three, interval sessions per week—not two or three interval sessions in swim, bike, and run, but two or three interval sessions, period.
This tiny amount of intensity can be a tough pill to swallow for many triathletes who can fall into the trap of thinking that if you want to get stronger, you need to put in the hard, tongue-hanging out work and the more the better.
However, the original research on polarized training, led by Dr. Stephen Seiler (and which we’ve showcased at Fast Talk Laboratories) shows otherwise. Dr. Seiler has demonstrated that the world’s top endurance athletes often spent more than 90% of their time at low intensities. In fact, the only thing that separated lower-level endurance athletes from the best was that the lower-level athletes spent a much greater (not lesser) percentage of their time doing high-intensity work.
So if your performance has plateaued, the solution might not be that you need to train harder, but that you actually need to train easier. We’ll explore more about why that is below, but this video, Polarize Your Training Stress, provides a good explainer.
More Isn’t Better
Multiple studies have shown that we see our biggest adaptations with two to three intensity sessions per week. Any more than that not only fails to produce bigger gains, but can lead to overreach and even overtraining after as little as four weeks. The fact is that high-intensity work has its limits.
This is not as true for easy training. It has recently been proven that both high-intensity and long, slow training produce their aerobic adaptations through the same biological pathway. In other words, they produce similar gains in your aerobic engine. They just activate that pathway in slightly different ways. High-intensity work appears to produce gains rapidly, but they plateau after about six weeks. Long, slow work produces gains much more slowly but doesn’t have the same plateau—gains can be realized for years. So, if you’ve plateaued, the problem may actually be that you haven’t taken advantage of the greater adaptations from easy training.
To polarize and see those gains, you need to know your three training zones. While there are many different zone models for training, we only have three true physiological zones. These zones are based on our two thresholds. The first threshold most of us are familiar with. It’s often called the anaerobic threshold, lactate threshold, or your FTP (Functional Threshold Power). It’s the heart rate/power/pace you can sustain for 40 to 60 minutes.
But, there’s a second threshold called the aerobic threshold. The only way to truly identify it is in a lab, but as a rough guideline, it is about 75% of your anaerobic threshold, 80% by heart rate. It is a pace or power you can sustain for hours.
It’s All About the Zones
So, to be clear: Zone 1 is below your aerobic threshold, Zone 3 is at or above your anaerobic threshold, and Zone 2 is everything in between. When following a polarized training approach, you’ll spend 80-90% of your time in Zone 1 and most of the rest of your time in Zone 3. It can get complicated calculating percentages, so Dr. Seiler recommends athletes distribute workouts by the purpose of the session, i.e., if you do intervals, the whole session counts as a Zone 3 workout. To maintain an 80/20 split, make two of every 10 workouts Zone 3 workouts. The rest should be steady Zone 1 work. This video, How to Measure Intensity Distribution, helps to explain this concept further.
There are a few particulars to be aware of about polarizing your training as a triathlete. First, keep in mind that threshold intervals are part of that Zone 3 work—even if they sometimes dip into Zone 2. Second, it’s recommended to do a lot of your longer Zone 1 work on the bike to avoid injury. Third, while the adaptations from running and cycling “crossover,” there is little crossover with swimming, which interestingly includes overreach. So, while you should limit yourself to two high intensity sessions each week between running and cycling, you can add a third (and periodically a fourth) high intensity session in the pool with little risk of overtraining.
Want to give polarized training a go? Try some of these tri-specific workouts from coach Ryan Bolton: Polarized Workouts for Triathletes
Trevor Connor has 20 years experience in bike racing and has coached for U.S. and Canadian national performance centers and managed teams. He holds a master’s in nutrition and is the CEO and co-founder of Fast Talk Laboratories.