Race results or most recent 20 minute test to establish zones?

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    This week I am starting my Level 2 Pace based Marathon training plan for Boston on 4/17/23.
    My last (and only!) marathon was on 8/28/22 in Santa Rosa. I just completed a 12 (actually did 13) maintenance training plan, where I used the results from the Santa Rosa Marathon to establish my zones.
    Today I did the 20 minute time trial, and I Heli be the results show just slightly better fitness (slightly quicker LTP) than the results from the SR marathon.
    My question is:
    Should I use the marathon race results or the more recent 20 minute test to establish my training zones for the 18 week training plan for Boston?
    I do feel like my fitness is pretty good after this maintenance (don’t feel like I’ve lost fitness at least!) But I guess I’m just a little nervous about making my workouts harder over the next 18 weeks. The difference will be small. But it’s really the faster workouts that concern me. I did feel during maintenance training that I was sometimes struggling to hit zone 5 paces, (or maintaining longer zone 4 stretches) and the thought of having even slightly harder (faster) zone 5 targets is sort of scary!
    Hope this makes sense.



    Sorry.. was typing fast…


    12 *week (actually did 13) maintenance training plan.

    I *believe the results show

    ALSO, I just checked and the 20 minute test actually shows a significantly quicker LTP (6:46) than the results from the Marathon (6:59).

    I suppose this means I should update my zones?
    Again, pretty nervous about this.
    Definitely felt like I pushed myself during the test.
    (Hard to believe I could keep a 6:46 pace for an hour!)

    David Warden

    shway, congrats on your BQ time and best of luck in your upcoming training.

    For sure, use the more recent 20-min test. The estimates based on recent race results are just that: estimates. Your 20-minute test is real.

    Regarding your concern on the intervals, keep three things in mind:

    1. You can always target the lowest point of the intensity range.
    2. When using HR, you’re unlikely to reach Zone 5 and even 4 bpm before the end of the interval. Best to use Pace, Power or RPE for Zone 4 and 5.
    3. If you can’t even meet the lowest level of the zone, don’t worry about it. Pick the highest intensity you can hold for the prescribed time. If the workout calls for 8x 1 minutes in Zone 5, and you can’t hold that, do 8×1 minute at the highest you can consistently hold, even if that is Zone 4. The Zones prescribed are ideal, but there is very little difference in benefit between low Zone 5 and mid Zone 4.



    Thanks so much, David!

    My one pushback would be this:
    I essentially ran 3.1 miles for the 20m trial (Garmin clocked it as a 19:59 5K).
    If I plug 20m into the calculator as a RACE result, it gives me a significantly lower LTP (6:55m/M versus the 6:46m/M for the 20m time test).
    I realize that is by design, because the assumption is that I’m going to perform better under race conditions than I would in a self-administered time test.
    However, I did sort of feel like I went quite hard for the time test. Hard to imagine that I could have been that much faster in a race…

    I guess my fundamental concern is getting my actual Lactate Threshold Pace correct. I realize the zone targeting can be a fluid and flexible affair throughout training. But it seems to be there is quite a considerable difference between, say, doing a Threshold Pace run at 6:45m/M vs. 6:55m/M

    Of course, I haven’t yet attempted either for this training cycle, since I literally just started today, and from my recollection, TP segments don’t come till later in the 18 week program.

    But, fit as I might feel, the 6:46 TP does seem rather ambitious to me!

    (BTW I am a soon-to-be 54 year old male.)

    Thanks again!


    David Warden


    9 seconds may seem like a big difference, it’s really not. That’s 2%.

    Particularly when you consider that the difference between 6:46 and 6:55 results in a Zone 2 range of 7:47 to 8:54 or 7:57-9:06. That’s a huge range that both those thresholds share. In other words, those two are only 2% different, but when you add in a zone range the difference becomes even smaller.

    I’d still point you back to points 1 and 3 of my previous post. Even though I still maintain 6:46 or 6:55 is essentially the same, you still have a ton of flexibility to adapt when training.



    Thanks, David. Hear you loud and clear! Just updated my zones with the 20m test results. Fingers crossed! Josh

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