Confusion about threshold calculation

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  • #21035
    albiurs
    Participant

    Hi,

    I’m following the 80/20 running plans for about six months. However, I’m still confused about the calculation of the threshold HR and pace. According to the Guidline
    https://www.8020endurance.com/intensity-guidelines-for-8020-running/ , I performed several 20 min time trials to define the threshold pace and HR and used the calculator
    https://www.8020endurance.com/80-20-zone-calculator/ to calculate the training zones.

    The calculation of the lactate threshold heart rate is quite strait forward. I picked LTHR form the method in the calculator and entered the average HR form the last 15 minutes of the 20 min. all-out effort. Threshord Pace:

    Here I’m very confused:

    What kind of method do I have to pick in the calculator if I performed a 20-min-all-out time trial? “Threshold Pace” or “20-minute Test”?

    If “Threshold Pace” is true, what makes sense in my opinion, what is “20-minute Test” for?

    If “20-minute Test” is true, why is there a difference between the pace to be entered (I guess the 20’ all-out average pace) and the calculated threshold pace? Actually I would expect the pace during the 20’ test should match the LTHR above and therefore, I would expect the average pace during the test should be equal and the actual threshold pace.

    Could you please clarify this confusion?

    Thanks,

    Urs

    #21067
    David Warden
    Keymaster

    Urs, thanks for posting in our forums.

    The Threshold Pace option is for those who know their LT Pace already. Maybe a lab test, or the full 30-minute test, or some other method used to identify LT Pace.

    The 20-minute test option is the one you should pick, and enter the FULL average pace for the 20 minutes. The peak 15 of 20 is only applicable to the LTHR test, not the LT Pace test.

    For example, if you run 20 minutes and have a peak 15 HR of 170, put that in the HR calculator with the method LTHR. If your average pace for that 20 minutes was 4:30 per kilometer, put 4:30 in the Pace calculator using the 20-minute method.

    David

    • This reply was modified 1 month, 3 weeks ago by David Warden.
    #21071
    albiurs
    Participant

    Thanks, David for your reply.

    So, then I calculated my threshold and zones all right so far.

    Am I right that the 30′ TT is considered more accurate (but also harder to perform) then the 20′ TT? And is it based on Joe Friel’s 30′ TT protocol as posted at TrainingPeaks:
    https://www.trainingpeaks.com/learn/articles/joe-friel-s-quick-guide-to-setting-zones/ ?

    So, if someone follows the 30′ TT, then the resulting anaerobic threshold, LTHR as well as FTP (pace/power)  is exactly the threshold between the top of zone 3 and the bottom of zone Y?

    And if one follows the 20′ TT, then the FTP is calculated by 95% of the trials 20′ average pace/power respectively, but the LTHR is still the same as in the 30′ TT (=100% of the measured maximum 15 min. average HR), even if the test duration is considerably shorter (15′ in the 20′ TT vs. 20′ in the 30′ TT)?

    I just want to make sure I got it right.

    Thanks, Urs

     

     

    #21073
    David Warden
    Keymaster

    – Yes, we use Joe Friel’s protocol for the 30′ test, and introduced the 20′ for athletes who were struggling with 30 minutes.

    – Yes, it is helpful to understand that you could actually test all 3 intensity types at once. If you capture Pace, Power and HR in the same 30′ test all 3 would be captured. In the 80/20 system, we place LTHR, FTP and Threshold Pace as the top of Zone 3.

    – Correct, the Pace and FTP are 95% of the 20′ TT. LTHR is slightly different for the 20′ in that you take just the peak 15′ of the 20′.

    David

    #21075
    albiurs
    Participant

    Thanks, David for clarifying that.

    Two more things are still unclear to me:

    Firstly, according to the intensity guidelines for 80/20 running, to re-calibrate the FTP based on LTHR, it’s suggested to increase the pace until the HR settles at the LTHR during a zone 3 workout and the current pace would then be the new FTP. However, during the 20′ TT I ran much longer (the full 20′) at a pace which was even 5% faster then top of zone 3. Hence, the new re-calibrated pace must be slower than LTP in my opinion.

    The second thing targets the critical velocity (CV) which is described in the workouts as “Critical Velocity (CV) is the fastest pace a runner can sustain for 30 minutes, which for most falls at the low end of Zone 4.”. If, according to Joe Friel’s 30′ TT (= maximum all-out effort), the LTHR and FTP are exactly at the threshold between zone 3 and zone Y, it cannot be the low end of zone 4 at the same time. Hence, there is a inconsistency. I guess that the low end of zone 4 would rather be “the fastest pace a runner can sustain for 20 minutes” which is the 20′ TT pace.

    Am I wrong?

    Thanks,
    Urs

     

    #21173
    David Warden
    Keymaster

    Urs,

    The “backing-in” method to find FTP from LTHR assumes you have locked down your LTHR. In your case, your getting mixed LTHR results, therefore your LTHR is not known, so the backing-in FTP method won’t be reliable. Further, if you ran 5% faster than top of Zone 3 for 20 minutes, that’s your new LTP. If you perform better in a workout, even if not intending to test threshold but break it anyway, that’s your new threshold. Imagine if I ask you, “how much money do you have in the bank?” and you say, “I know I have $1,ooo” but then I show you a bank statement that says you have $1,500. You would say, “ah, I am mistaken, I have more than I thought.” If you are running 20 minutes at >5% higher than LTP (top of Zone 3), your LTP is higher than you think.

    The other problem is that you’re referencing FTP, LTP, and LTHR but all done in different test settings (FTP back-in, LTP test, separate LTHR test). If you want FTP, LTP and LTHR to align, they all much be done at the same time in the same test, not in separate tests.

    Regarding CV, there is only a 2% difference from the top of Zone 3 to the bottom of Zone 4. I would not call it an inconsistency as much as a normal margin of error. Also note that Matt says, “for most…” I use top of Zone 3 for new athletes, and bottom of Zone 4 for advanced athletes.

    David

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