Trail run – too high intensity?

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  • #44648

    Among my regular trail runs is a ~7 mile run with 1200 feet of vertical gain/loss over pretty rough terrain. Takes ~90 minutes, so not a blistering pace. While my average heart rate is top of Z2, obviously that means I spend almost 50% in Z3 and, in the steepest sections, I am in Z4 and Z5 at times. I never stop running throughout, although my pace obvious varies in extremely steep areas (and some places where I am going through streams or fallen trees).

    Despite having read the book, I am not sure how to think about this. Does this still count as capacity training or is this a utilization exercise? If capacity training, is the intensity too high even if I, on average, am at the top of Z2?

    I do other, lower intensity runs as well where I am in Z1 and Z2 exclusively.



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    Anonymous on #44651

    Average HR is misleading for exactly what you’re finding: the average might be at the top of zone 2, but it doesn’t reflect the true stress on your body. For an effort to be capacity building, the max heart rate should be the top of zone 2, or as close to that as possible. If you have 50+% of your run above zone 2, you’ll take longer to see the gains of aerobic training. It will take several weeks, but if you’re diligent, you’ll see gains.

    caperton.flood on #44754


    Very helpful and I suspected that was the answer. Do you have a view on a limit on the time above Zone 2 in a run before it impacts the capacity building meaningfully? I can always do easier trail runs but the reality is at times HR goes up (as it does down). Less that 20%? Or perhaps it is just a 1:1 match with time above Zone 2 (e.g., 20% of time in Z3+ = 20% less capacity building impact). Thanks


    Anonymous on #44956

    Keep time above Z2 to 5% or less.

    This is the problem:

    I never stop running throughout…

    You need to hike the uphill sections.

    Set an HR alert for five beats below your AeT HR. When the alarm goes off, slow down.

    Anonymous on #44957

    And actually, that 5% or less should be for the whole week, not just an individual session if building aerobic capacity is the priority.

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