Many athletes who are new to polarized training struggle with how to measure the time they spend in the different zones. Most training software packages allow you to graph the time spent in each heart rate or power zone over the course of a week, but even that doesn’t always indicate whether your training is truly polarized.
For example, if you do a high-intensity workout with 10–20-second efforts, your heart rate may never go above your anaerobic threshold. So, even though this is clearly a zone 3 workout, a heart rate distribution curve will show that nearly all of the work was done in zone 2.
This is why Dr. Seiler recommends that athletes focus on the session goal or purpose. If you did high-intensity intervals in a session, then the entire session can be counted as a zone 3 workout. To achieve an 80/20 distribution of intensity, plan on one of every five workouts being hard and the rest easy.
If you are using a power meter for cycling, running, or rowing and you want to see the distribution of your power, keep in mind that with a polarized approach to training your time in zone 1 could be as high as 90 percent. Case in point, if that high-intensity session with 10–20-second efforts is an hour in length, only about 12 minutes will be accounted for as zone 3 power. The rest will be zone 1.