Combined Zones on Weekly Summary

Very basic question I feel.

For context, I’m using (or trying to use) a polarized training method. I have input all of my Run HR & Pace zones (don’t have power) as well as all my Bike HR & Power zones & everything lines up. Kept my threshold numbers right at the start of Z5 as the model seems to group Z3+4 into >=LT1 & <LT2.

I’m using: Run: Time In Zones: Pace, HR, Power; Bike: Time In Zones: Power, HR, Pace.

My question is as follows. For the “Combined Zones” in the weekly summary, does Z1&2 generally come from HR and the higher zones pull from power/pace? For tight intervals, say 30" on / 30" off or 1’/1’, HR doesn’t have time to fall far enough on the recoveries, even though I’m just trotting along at a Z1 effort recovery really. Do the “combined zones” caputure the recovery potion of these tight intervals from pace/ power? Because if it just looked at HR for a limited recovery interval, I’d still be registering in Z3/4+ in terms of HR. Just trying to get a handle on this display as I’m really trying to adhere to the polarized model.

Also happy to start supporting the platform. Genius work!

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A very basic answer:
Polarised training is best done on the number of sessions, i.e. 8/10 are in zone 1, and 2/10 are in zone 3.

Heart rate will drift through all three zones when doing a hard workout, with the rest/recovery in between each interval.
Example: VO2 efforts should as hard as you can sustain across all intervals, 4-6 sets between 3-8 minutes with about a 1:1 work:rest ratio. Recovery is at 40% to ensure you’re mostly recovered to go hard again.

The session is a hard one, even though TIZ shows something completely different. So to adhere to a polarised model, look at sessions and the intent of each session.


Couldn’t agree more :wink:
Polarized is not about TIZ distribution. It’s about 4 sessions easy, one hard. The easy below AeT and the hard above AeT.
It’s very simple and extremely easy to follow up on with just a HR strap.


Drinking the koolaid you are selling. Makes sense. Thanks folks.

Just for interest sake though, i’m still curious how TIZ combined is coded. Ie when each metric (HR/power/pace) takes over as dictating what zone a particular section of a workout is in to give the weekly total.

Without knowing how David encoded it, logic would tell me that if power is missing, eg. all my MTB rides, it would take the TIZ for HR and add to the total I have from all my power based rides.

That can be misleading, as my zone 5 power and zone 5 HR are not equal. I could be doing AC (L6) or NP (L7) work and my HR would stop at Z4. Those efforts are short and all out, but not long enough for the lag in HR.

This is an important discussion - I have been wondering how to monitor if I am doing 80/20 or not - and it seems that youtube coaches are taking a different approach:

  • Joe Friel would surely agree that polarized training should NOT be measured by calculating you weekly distribution hourwise. That is: If you train 10 hours, a full 2 should be above threshold. Instead you measure by number of sessions you train hard/above threshold. So typically you would only need one hard session a week since most of us never get above 5 sessions a week. In that session you are - of course - not only riding/running above threshold but doing hard intervals.
  • Dylan Johnson seems to be implying that you measure by time spend above threshold on a weekly basis (though he would surely agree that you should not do more than one or two interval sessions a week). In this case, you can look at’s weekly calculation to see if you were able to hit the 80/20-target.

Can anyone confirm that there is a different approach here - or if I have misunderstood something?

This is, of course, hugely important since it is almost impossible to hit an 80/20 on a weekly basis if calculated by time spend above threshold (the weekly summary), while it is not only possible but even feeling a bit too easy if you would only spend one day doing intervals.


Think of your training over a mesocycle (3-4 weeks) rather than just 7 days. In early base, I’m not worried about polarising my training, but in the build phase I am. Here’s how I do it.

Two examples, one with the number of sessions, and then one measured over time in zone.
The workouts would be:

  • 3-4 easy sessions - “free” rides in Z1 (heart rate) with no target power;
  • 1x L5 (16, 20 and 25 minutes per week, or 16 & 20 in one block and 20 and 25 in another).
  • 1x L4 (3x8, 4x8 and 5x8 progression) workouts per week (4 weeks cycle). The for 3-week cycle I would do 3 blocks with the 3x8, 4x8 and 5x8 in each block.

This is based on having a max workout time of 90-minutes per day (weekdays) and up to 4 hours on a weekend. Are my easy rides that easy? They should be. I do allow up to 30 minutes in Tempo, as some hills or a head wind can make things a little harder. In Zwift, it’s much easier on a Robo-pacer group ride.

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For each activity the priority of the zones for the sport is used to choose which zones are used for time in zones for the activity. So if you have Power, HR, Pace for riding and don’t have power meter then the HR zones will be used. Pace is never used for riding.

The total for the week just adds up the time in zones for each activity. This works best if your zones are matched up.


Hi everyone,

I’m reposting here as I made the mistake of starting a new thread. Thank you @Morten_Horning_Jense for your response! I essentially have the same question (see below for my original post). My understanding is that TID is determined on a session basis … at least that appears to be how many talk about it (e.g. Dylan Johnson) and, if I am understanding correctly, how it is used to define polarized training in the original Seiler & Kjerland paper. “training was organized after a polarized pattern, with most sessions performed clearly below (about 75%) or with substantial periods above (15-20%) the lactate accommodation zone, which is bounded by VT1 and VT2.”

So then my question becomes, how does one use the TIZ calculations to monitor this? Currently, the training models they are tied to seem to assume that TIZ is what determines polarized/pyramidal/threshold, etc. Would it be possible to have a way of earmarking a sessions as Z1/Z2/Z3 focused, and calculating TID based on these designations? A happy medium between these two would be a calculation that weights the duration of the session, such that a 1h Z3 focused sessions counts as half of a 2 h Z1 focused session (in the Seiler 3 zone model).

Wondering whether you ever figured this out. I’ve been reading 80/20 Running, and it clearly says that the entire interval section of an interval workout, rests included, counts towards the 20% portion.

I can’t figure out how to get to do that calculation for me.