21 KM Race plan | 80/20 Endurance

21 KM Race plan

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  • #8524

    Hi David

    Hope it is going well. As previously discussed, I have been following the 21 km program since June after my successful marathon on the 100 km program.

    We organized our own 21 km race and that will happen next Saturday / 19 September.

    I would love your advice on my race pace / race plan. With the marathon I almost ran exactly as your race pace chart predicted. Originally the plan was a sub 84, but due to the efficacy of your plan I think I can go faster.

    I have the following stats that I have used to determine my threshold pace:

    1. 20/08/2020 – I did a flat out 5 km – 17:27 / 3:29 AVG PACE
    2. 29/08/2020 – Did RT 15 – 10 km of 36:55 (inside the 40 min TH run)/ 3:42 AVG
    3. 12/09/2020 (Today) – Had a RT6 this week, instead did the 30 min TT. AVG pace for the 30 min was 3:33.

    I would love to go for a sub 80, 3:47 AVG pace, do you feel that is possible? I was also thinking of a even split approach. Please let me know what you think.


    David Warden


    This is possible. HM racing can take place as fast as low Zone 3, your 3:33 threshold test confirms those are your current zones, and 3:47 falls into low Zone 3.

    It’s a risk/reward decision. <80 minutes is higher risk for your zones, and there is a chance that you will fade and have a poor performance. On the other hand, it does not seem to be a very high risk as it falls within your low Zone 3. I can comfortably confirm your threshold pace (3:33) and that <80 is a reasonable goal.

    As far as an even split, virtually all personal bests (and all world records) are negative splits (second half faster then the first). An "even" split can still be really, really close to a negative split, but I'd aim for perhaps a 3:48 for the first half and then push it to a 3:46 for the second. That's a razor-thin difference, and almost impossible to monitor, but the idea in your head should be that your second 10K should be faster than your first 11.



    Thank you David! Appreciate the advice!



    Hi David, I just wanted to give you an update on my run.

    Ended with a 1:19:10! More than a 8 min PR!

    I have now officially ran PR’s from 1 KM – Marathon on the 80/20 Programs.

    Thank you for the awesome programs and all the sage advice!

    David Warden

    Lindt, we’re very happy, but not surprised, to hear this. Well done, and congratulations on your hard work continuing to pay off.


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