Runners are often driven, goal-oriented, and always looking for that extra edge—so it’s no surprise that one of the most common questions is: How can I get faster? There are countless training methods designed to help runners improve their speed and endurance.
Some runners favor high mileage at very low intensities, while others rely on frequent high-intensity interval sessions, like threshold workouts, to push their limits.
One increasingly popular and research-backed approach is polarized training—a strategy that emphasizes keeping easy runs truly easy, hard workouts truly hard, and minimizing the time spent running in the moderate “gray zone.”
In this guide, we’ll break down what polarized training is, why it works, and how you can apply it to your running routine for smarter, more effective results.
What Is Polarized Training?
Much like the North Pole and the South Pole are on the extreme ends of the planet, polarized training involves splitting your intensity levels for your workouts into two extremes—very easy and very hard.
In other words, if you practice polarized training, you run your easy days easy and your hard days hard. The murky middle is all but eliminated, or at least minimized to nearly nothing.
Runners who engage in polarized training typically use an 80/20 approach, which means that they run 80% of their mileage at an easy, conversational pace (low-intensity training) and 20% of their mileage at a high-intensity.
For example, if you run 20 miles a week, you’d run 16 miles at your easy pace, and 4 miles would be high-intensity training.
Polarized training for endurance athletes emerged about 20 years ago in response to the observation that most elite endurance athletes were inherently practicing this method.
In other words, elite athletes who competed in endurance sports such as running, spent the bulk of their training time doing low-intensity workouts, with some training time at a high intensity and little to no time in the murky middle.1Seiler, K. S., & Kjerland, G. O. (2006). Quantifying training intensity distribution in elite endurance athletes: is there evidence for an “optimal” distribution?. Scandinavian Journal of Medicine and Science in Sports, 16(1), 49–56. https://doi.org/10.1111/j.1600-0838.2004.00418.x
How Does Polarized Training Impact Endurance Performance Compared To Other Training Methods?
Many runners fall into the trap of running roughly the same pace every day, or run their easy runs too hard.
When I first started running, I was guilty of the latter. I was always trying to run faster than I could sustain, struggling to breathe easily, and feeling like my heart was going to burst out of my chest. I was not getting any better this way, as I never recovered.
Many runners simply don’t run their recovery runs easy enough to allow the body to recover fully.
If, for example, a high-intensity session takes you from feeling 100% to 60%, proper recovery doesn’t occur until you’ve bounced back to nearly 100%.
If your recovery run the day after your hard-intensity session is too fast and intense, instead of returning to 90-100% or so, you might recover only about 80-85%.
As a result, when it’s time to do the next hard workout, your body is already starting at a reduced capacity–you only have 80-85% of your effort to give to the workout instead of nearly 100%.
This, in turn, impairs your ability to run as hard or as fast during the training session, reducing your potential performance gains.
In practical terms, if you’re supposed to be running 6 x 800 at your 5K pace but you’re only able to muster about five reps, or you’re falling 5 seconds off your pace for each interval, your body will not receive as potent a training stimulus for inducing positive fitness adaptations.
Proponents of this polarized training model argue that Zone 2 is not sufficiently challenging to trigger the physiological adaptations required for improved performance, nor is it sufficiently easy to facilitate recovery or increase endurance.
Not only does falling into the trap of running at almost the same pace for every run limit your overall progress, but it can also lead to overtraining and overuse injuries, as the same stresses and intensities are placed on the body, stride after stride, run after run.
In contrast, runners who train at drastically different paces—running speed workouts and slow runs—introduce more variability into their stride and the resultant stresses on bones, muscles, and connective tissues.
This can reduce the risk of injury and increase overall strength.
In sum, the main benefits of polarized training for runners include the following:
- Allows you to maximize your potential for performing well in challenging workouts, leading to more rapid and significant performance improvements.
- Improves the ability to recover after workouts.
- Reduces the risk of overuse injuries.
How to Train With the Polarized Running Method
Rather than the five different intensity zones used with the traditional heart rate zone model, the polarized training model divides training intensities into three zones.
Zone 1
Zone 1, the low-intensity zone, involves running at an easy, conversational pace that allows you to talk in complete sentences.
On a physiological level, Zone 1 refers to any effort below your lactate threshold or ventilatory threshold, typically corresponding to a heart rate of 70-75% of your maximum heart rate.
Zone 2
Zone 2, moderate-intensity running, is a “comfortably hard” level, where you can probably speak in short sentences.
This zone corresponds to your threshold power effort, falling between your lactate threshold and critical speed.
In the polarized training framework, Zone 2 corresponds to a heart rate of about 80-85% of your maximum heart rate.
Zone 3
Zone 3, the high-intensity zone, is anything faster or more intense than your critical speed.
When running in Zone 3, you can only utter a couple of words at a time or very choppy sentences.
Your heart rate when running in Zone 3 is above 85% of your maximum heart rate.
With polarized training in its purest form, athletes usually spend about 80% of their training time in Zone 1 and 20% of their training time in Zone 3.
Still, polarized training has evolved to incorporate several different iterations in the distribution of training volume and zones over time.
Some coaches still consider themselves to be practicing polarized training, grouping zones 2 and 3 together; therefore, athletes do 80% of their training in zone 1 and 20% in zones 2 and 3 combined.
Others further refine polarized training by spending 70% of their time in Zone 1, 20% of their mileage in Zone 2, and 10% in Zone 3.
This should be distinguished as pyramidal training, but the term polarized training is still often used.
Does It Work?
Studies have shown that polarized training can be an effective way to improve performance and get faster over time.
For example, one study2Muñoz, I., Seiler, S., Bautista, J., España, J., Larumbe, E., & Esteve-Lanao, J. (2014). Does Polarized Training Improve Performance in Recreational Runners? International Journal of Sports Physiology and Performance, 9(2), 265–272. https://doi.org/10.1123/ijspp.2012-0350 compared the effects of a polarized training program and a more traditional running training program on 10K running performance over the course of 10 weeks.
The researchers divided 30 endurance runners into two groups.
The polarized training group did 77% of their mileage in zone 1 (defined as an intensity below ventilatory threshold), 3% of the mileage was run in zone 2 (defined as an intensity between ventilatory threshold and respiratory compensation threshold), and 20% of the mileage was in Zone 3 (defined as high intensity above respiratory compensation threshold).
The “between thresholds endurance training” group ran nearly the same amount of mileage in Zone 3, but the distribution of training time in zones 1 and 2 was quite different.
This group ran 46% of their workout time in Zone 1, 35% in Zone 2, and 19% in Zone 3.
To quantify and qualify the type and duration spent in each training zone, runners wore heart rate monitors, and their exercise heart rates were compared to their baseline testing, in which their ventilatory threshold and respiratory compensation thresholds, along with associated heart rates, were identified.
After 10 weeks, both groups showed significant improvement in their 10K run times. Although not statistically significant, the polarized training group showed a greater improvement than the more balanced training group.
Runners in the polarized training group improved their performance by 5%, whereas the other group improved by 3.6%.
This difference in improvement between the two groups equated to roughly 41 seconds, meaning that runners who had followed polarized training reduced their 10K run times by an additional 41 seconds compared to the other training group.
Moreover, when the researchers examined which runners in the polarized training group had most dramatically polarized their training, they found that those with the least training time in Zone 2 experienced the most significant performance improvements.
Another study compared the effectiveness of four different training approaches on improvements in aerobic threshold capacity (VO2 max) over nine weeks.
The researchers split 48 highly trained endurance athletes (runners, cyclists, triathletes, and cross-country skiers) into one of four training programs: high-volume training, “threshold-training,” high-intensity interval training (HIIT), or polarized training.
Out of all four approaches, the athletes in the polarized training group demonstrated the most significant increases in VO2 max, time to exhaustion, and peak velocity/power after the nine weeks.
Polarized training increased VO2 max by 11.7%, time to exhaustion by 17.4%, and peak velocity/power by 5.1%.
Not only did polarized training yield significant improvements in endurance performance parameters, but the other training programs were found not to cause improvements in any of the variables measured.
If you find that you aren’t making the improvements you’d hoped for with your current training program, it might be worth following the lead of many elite runners and jumping on the polarized training bandwagon.
As a certified running coach, I use polarized training with most of my athletes, as I have found it provides the best results. It’s hard to stay in that easy recovery zone, but it’s worth the effort in the long run.
Although you don’t have to do away with every moderate-intensity workout strictly, see if you start to feel fitter and faster if you focus on taking your easy days really easy and pushing yourself to the max in your hard workouts.
If you are looking to put together a successful training plan for your next race, check out this next guide on periodization:
