Should some long sessions be distance-based instead of duration-based?

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    I am toward the end of the Ironman Level 2 plan (first “season” I am using the 80/20 and I really like it !!).

    This week, I have (among other sessions) RAe21 as well as a Brick Combo of CAe34 + RAe1.

    1) RAe21

    => 10 minutes Zone 1, 4 x (15 minutes Zone 2/1 minutes Zone 1) 90 minutes Zone 2
    => total of 14mins “Z1” and 2hours30 of IM Race Pace (Z2)

    I am an “OK” runner and my IM Marathon is around 3hours. Such a session will make me run around 37-38kms which seems potentially quite excessive?

    2) CAe34

    => 10 minutes Zone 1, 5 x (30 minutes Zone 2/10 minutes Zone 1) 120 minutes Zone 1
    => Total of 5hours30mins, although a BIG chunk of it is at Z1 power.

    I am also an “OK” cyclist (last IM bike leg was 5hours10mins) and although here a BIG chunk is at Z1, that is still quite a long session.

    Early in the 80/20 for Triathlon book, the authors state they prefer workouts to be “duration-based” rather than “distance-based” (mostly to avoid trying to run/cycle/swim faster in order to finish up the session more quickly) and I am 100% on-board with that philosophy.

    However, for the very long sessions which are also done at an effort close to race pace, shouldn’t the duration be weighted as well as a percentage of estimated race time?

    Thanks for reading me and apologies for the lengthy post!


    Maybe another way of looking at is is to weight it in terms of TSS?

    => A “faster” runner/cyclist would have a race pace/power which is at a higher percentage of their threshold pace/power (for instance, a pro IM Cyclist would do the bike leg at 80% FTP for instance while a slower athlete might do it at closer to 70-75% FTP)

    => X hours of race pace/effort for a faster athlete would result in a higher Training Stress than for a slower athlete

    => Should some of those training sessions (the long ones) take it into account?


    Apologies David – It seems you replied ~6months ago to a similar query

    I’ll shorten a bit the runs & bikes for those long ones.

    David Warden

    Thibaut, thanks for posting and thanks for searching! Most of our questions around this issue are from athletes concerned about not going long enough, but you found the correct response for what do to when concerned about going too long.



    Thanks David – and thanks for all the hard work on the 80/20 – really helped me to get “out” of a plateau issue (obviously linked to always going too hard for too long on every workout) and managed to see great improvements since starting it in Feb!

    Big Kudos!

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