interpreting strange heart rate drift test results

  • Creator
    Topic
  • #78916
    OliverL
    Participant

    Hi all, looking for some info or experience in interpreting these results. I did the AeT heart rate drift test on a running track. After trying at my MAF estimate previously (~150 bpm) and failing around 36 minutes with a heart rate of 180 bpm, I decided a much more conservative estimate of around 130 bpm. I did over an hour of running trying to keep my heart rate between 130 – 135 bpm, which was surprisingly tricky. Even thinking about a trad climb or when a RATM song came on I would start going a bit faster without noticing. Overall I think I did well, I was able to nose breathe the entire time and kept my heart rate at a 134 bpm average, and felt like I could have kept going for another hour if I had to. However when I look at my Pa:Hr drift %, I got 6.8% for the entire run (Pic 1). Curiously, almost all the change was in the first half (Pic 2) with 8.2% drift, and almost none in the second half (pic 3), with only 0.8% drift. The second half having such a low drift % even with the same Hr average as the first half is confusing to me and not something I’ve read about happening. Was I right at, above, or below my AeT?
    Do I need to re-do the test? Or can I just assume my AeT is ~140 bpm based or perceived effort and go from there?

    Thanks!

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Posted In: Mountain Running

  • Participant
    OliverL on #78920

    This was all recorded with a chest strap HRM (Garmin dual)

    Keymaster
    Jane Mackay on #78921

    Hi Oliver, that seems really odd. One thing that jumps out at me is that the duration of the first half (in the screenshot) is 23 min, while the second half is 32 min. Could you try selecting again so they’re more equal? It might not make any difference, but it we might as well start with equal halves.

    Participant
    OliverL on #78922

    Thanks for the quick reply Jane. I’ve made both halves 30 minutes starting and ending near the same small peak in HR. The Pa:Hr difference is still strange, 8.6% vs 1.1%

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    Keymaster
    Jane Mackay on #78935

    Yes, that didn’t make any difference.

    I sent the screenshots to Coach Pedro Carvalho. Here’s what he advises:

    1. Do the test again.
    2. Don’t listen to music 🙂
    3. Warm up and start the recording once your HR stablises.
    4. Be assiduous in maintaining a steady HR. When I do this test I tend to look at my watch every few seconds. It’s tedious, but it’s worth it. And at least it gives your mind something to concentrate on.

    He also noted the great variation in your pace. You can see that it frequently drops and spikes as much as 2-3km/hr. Attached is a screenshot of a test done on a track by one of Pedro’s coaching clients, so you can see how even the HR and pace lines are in the graph.

    Try again and let us know how it goes!

    Jane

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    Participant
    OliverL on #78937

    Thank you! The reason my pace drops and spikes so much is because I was watching my HR on my watch. Trying to keep my HR at around 130 bpm requires me to do a weird bounding shuffle, like when you are told to run in place. It feels slower than walking speed and its very tricky to find an even pace. Because it felt so unnatural my pace and my HR would creep upwards so I would slow down to let it drop. Pedro’s client is maintaining an HR of 150 bpm and a pace of 5:30/km which is proper running speed and gait, which unfortunately is above my AeT threshold. I will try the test again but I have a feeling the results, or at least the variability in pace, will be similar to this test.

    Keymaster
    Jane Mackay on #78938

    In that case, let’s do it the other way around. Warm up until you feel like your body’s “in gear”, then settle into the slowest pace that feels natural and sustainable and maintain that pace for an hour. You’ll have to be really attentive not to speed up. Don’t worry about your HR; you’ll look at that when you see the results. In this version, you are maintaining a steady pace.

    Participant
    OliverL on #78962

    Hi Jane, re-did the test focusing on pace. Much better results, Pa:Hr of 4%, starting heart rate of about 140 bpm where pace and heart rate stabilize. I’m including the picture in case you think they stabilize at a different point. If I’m understanding Scott’s instruction video correctly that is roughly my AeT threshold.

    Thanks for all of your help!

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    Keymaster
    Jane Mackay on #78965

    That’s much better! I agree that you can take 140 as your AeT.

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