How Slow is TOO Slow?

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  • #21729

    I’ve tagged my AeT at about 140 (HR drift test).

    My question is: how much below that is TOO far below that?

    I understand there’s a penalty for being above AeT and working the anaerobic pathway.

    Sometimes I settle in nicely at a pace at around 125 or 130 where I feel I could go on forever.

    If I get closer to 140, I feel like I could go on for hours and hours, but not forever.
    I don’t notice any major ventilatory changes.


    PS – Absolutely loving the training plan + Training Peaks. Thank you guys so much for these plans and these forums!

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    Anonymous on #21782

    Questions of speed have to be balanced with duration.

    IMO, you’ll still get benefits at 50-70% of AeT. (The low end of that will probably be fast walking; the faster end, super easy jogging.) Shorter durations will be a recovery workout, and longer, multi-hour durations will be a low-capacity workout. Those speeds won’t help you go faster, but they’ll support faster work later on.

    todd.struble on #21794

    Scott, what do you mean by 50%-70% of AeT? Does it matter if you are well-trained or not? For example, AeT at 140, 50%-70% of that is 70-98, which is basically standing around the house (for me anyway). I imagine a well-trained athlete might have their AeT closer to 160 or 170+ and maybe if their resting heart rate is in the 40’s that a brisk walk is getting closer to that 50% mark.

    But are you suggesting that if floresrm has tagged their AeT at 140, they’re getting a benefit if they’re walking at pace that keeps their hr at 70-98 if the duration is long enough? or am I misunderstanding the 50% piece?

    I’m sort of curious because I have gone on walks with friends and promised “you can’t go too slow for me” only to find that… walking really slow barely gets the HR to 100 and also wondered about the training effect.

    Anonymous on #21804

    Good questions. I should have been clearer.

    The estimates I made are for someone with a long training history. The key, regardless of training history, is to stay below AeT when building aerobic capacity. The closer you can get to AeT, without exceeding it, the more effective the training will be. (But just because something feels too easy, doesn’t mean it isn’t beneficial.)

    Note that, on its own, the bpm of someone’s AeT is never a measure of fitness. Higher bpm thresholds don’t indicate better fitness on their own, and they’re uncomparable between people.

    Anonymous on #21805


    It depends on your aerobic status. If AeT is more than 10% below Ant/LT then do most of your training in the 130-140 range. I that spread is less than 10% the cut way back on Z2 volume and do aerobic base work in Z1. Add Z3-4 workouts into the plan.
    Read this for more info:


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