Downhill – High HR but low RR?

  • Creator
    Topic
  • #31454
    TerryLui
    Participant

    Hey everyone,
    I’m wondering how come when going downhill (running), my HR gets fairly high (into Z3) but my RR, Respiratory Rate, is well within comfortable nose breathing (presumably AET)?

    Logic would dictate that…
    -Going downhill = less work = lower RR but…the Z3 HR is what’s puzzling me…???

    Thanks!

  • Participant
    OwenFW on #31455

    I’ve noticed the same thing, up into Z4 if I push much at all. I wondered if it had something to do with transitioning from a hard Z4 uphill with no breather before heading back down. Following.

    Participant
    doughywilson on #31457

    If you’re using a wrist-based heart rate monitor, it’s likely that your foot strike cadence is fooling the sensor. Wrist based sensors work by shinning a light onto your skin, and as your heart pumps, a small amount of light is reflected/absorbed based on the heart stroke. When you’re running downhill, you swing your arms much harder, and light can creep in. When that happens, it causes significant errors in the heart rate tracking and will likely show something that correlates with your fast footsteps rather than your heart rate.

    This can also happen with heart rate sensor straps that go around the chest if they are not tight enough, even though they work off electrical conduction through your skin rather than light.

    Participant
    TerryLui on #31481

    doughywilson:
    I’m using a chest strap HRM…not 100% familiar with the technology but if the strap is tight enough on flat/uphill to get accurate readings, how would going downhill change the accuracy?
    I wear my strap tight enough to leave depressions of the contact patches on my skin…???

    Thanks! 😀

    Participant
    doughywilson on #31482

    The impact forces going downhill are much higher than uphill, but if you have the strap tight enough, it might be working just fine. In that case, I don’t know why you would see a higher heart rate on the downhills.

    Participant
    Jan on #31484

    I would guess that a high HR going downhill has something to do with the risk of falling at a rather fast pace and the stress that this implies. You also have to concentrate more on foot placement. Scott Semple just recently posted that HR is not a measure of training intensity, but a measure of stress.
    So rather psychological reasons. But I could be wrong here.

    • This reply was modified 10 months, 2 weeks ago by Jan.
    Moderator
    Alison Naney on #31525

    My bet is it’s an efficiency thing. You could be using more muscle fibers than necessary, so the heart rate reflects that. Here are some tips for downhill technique: https://www.uphillathlete.com/downhill-running-technique/

    Participant
    TerryLui on #31549

    Thanks everyone! Very helpful thoughts/info 🙂

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