Hindsight is 80-20… Or Something

We usually talk first about total mileage/training volume when it comes to running programs. There’s good reason, as endurance athletes require high volume training and messing up your the progression can get you in trouble (see previous post on increasing weekly mileage). What about the intensity of the run, though? Does running 5 miles at race pace really count the same as 5 miles at easy pace? Are all runs really created equal???

Let’s define running intensity first, using this figure by Seiler as a guide:

Instead of using exercise physiology terms, I’m going to define them in running terms.

• Zone 1: your easy zone anywhere from 50-74% VO2max, depending on fitness level. You should be able to speak comfortably while running. 
• Zone 2: your threshold zone. This includes both tempo (continuous) and interval (intermittent) running between 83-88% VO2max. This is a “comfortably hard” run where exceeding this pace leads to lactate accumulation. 
• Zone 3: your hard zone running at 95-100% VO2max. You won’t be able to spend much continuous time here, so most work is done in intervals. In a 5-zone model, zone 3 encompasses 3-4-5.

Something you might see commonly in running programs is the “80-20 rule”. Great, another “rule” that’s actually more of a guideline and tricks people into thinking there are a bunch of rules in running. The basic concept of 80-20 is that 80% of the weekly mileage in a program should be spent running easy (zone 1) and 20% should be hard (zone 2 and 3). There’s actually pretty decent evidence behind this one, as a review of running performance studies showed that increasing higher intensity running past ~20% didn’t result in significant physiological changes. One of the issues here is that “high intensity” lumps zone 2 and zone 3 running together, even though there are well-established differences. Enter the different types of distribution:

• Pyramidal: mostly zone 1 running, followed by zone 2, then zone 3. Ex: 71-21-8 distribution 
• Polarized: mostly zone 1 running, more zone 3 than zone 2. Ex: 77-10-13 distribution 
• Threshold: as you would imagine, a generally higher percentage of zone 2 running. Ex: 48-38-14 distribution

The evidence tends to show threshold is less effective than the other two distributions, although there may be some merit to this training for marathon runners. What’s better between pyramidal and polarized, though? Well, that’s a bit more inconclusive. The issue with what we know about optimal performance in elite athletes is that we can’t exactly perform trials on them; their livelihood doesn’t allow it. If they thought for a second that something would decrease their performance, they’d immediately nope out of a trial. As a result, descriptive studies basically guide what we know about elite running performance. There’s some anecdotal nature to it, which obviously makes me uncomfortable if you know me, but unfortunately it’s the best we’ve got right now.

All of this said, we can still use it as a guide. It seems that there’s a place for both pyramidal and polarized distributions depending on the race distance/pace and stage of the training plan. In the early stages, pyramidal might be best to limit excessive stress on the body. For optimal performance during the late stages, a polarized distribution can have its benefits. Does the race distance have a pace that falls closer to zone 2 or zone 3? This can be a factor as well.

The common theme, regardless, is that both pyramidal and polarized training have high (70-80) percentages of easy running. We can’t forget, as endurance athletes, that the most important task is building endurance or "biological durability" (Seiler). Ultimately, 80-20 isn’t a bad rule of thumb for a running plan. It might not hurt to be a little more specific within that 20%, though.

Questions? Please keep at least 70% of them easy for me.

Dr. Jason Tuori, PT, DPT, CSCS

References/cool running readings:

1. Seiler S. What is best practice for training intensity and duration distribution in endurance athletes?. Int J Sports Physiol Perform. 2010; 5(3): 276-91.
2. Daniels J. Daniels’ Running Formula – 3rd Edition. Lower Mitcham, South Australia: Human Kinetics; 2014
3. Kenneally M, Casado A, Santos-concejero J. The Effect of Periodisation and Training Intensity Distribution on Middle- and Long-Distance Running Performance: A Systematic Review. Int J Sports Physiol Perform. 2017; :1-26.
4. Esteve-lanao J, Foster C, Seiler S, Lucia A. Impact of training intensity distribution on performance in endurance athletes. J Strength Cond Res. 2007; 21(3): 943-9.