AeT Heart Rate Drift Test - Negative Result | Uphill Athlete

AeT Heart Rate Drift Test – Negative Result

  • Creator
  • #49270
    Tyler Johnson

    Went out and tried to do the AeT Heart Rate Drift Test. Walked for a few minutes and then ran for 1:13. For the last hour of the run, my Pa:Hr ended up at -5.90% with an average heart rate of 131.

    This obviously isn’t accurate for my AeT, but before I go out and try again at a higher HR I wanted to mention that my previous “longest run” was around 45 minutes. I was running really slowly to keep my HR at 130-135 and a few times during the run I had to walk in order to bring my HR back down and my speed actually increased.

    I’m not sure if run/walking is allowed during the test or not.

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  • Participant
    Shashi on #49293


    I think the run-walk combination led to negative heart rate drift. As you suggested, you can do the test again at higher HR and see if you can maintain a steady pace for one hour. Another alternative is to do the test on a treadmill where you can set the incline and pace for the duration of the test.

    Reed on #49309

    Oh man, More Mesa! What a great spot…

    What’s leading you to target 135bpm? Can you elaborate on what you mentioned about your longest run being 45 minutes?

    Tyler Johnson on #49313

    In the past, I’d done C25K a few times and played various sports, but running was always in the <=30min range. For the last few months (prior to TFTNA) I had been pushing from 5k -> 10k but my runs were still only around 45 minutes.

    Yesterday, re-reading parts of the book and thinking about this post and how I was going to retake the AeT, I realized that I wasn’t sure why I picked 130-135. Mostly because it felt safe, maybe? Without thinking about it I think I ran the AeT test as a Z1 workout.

    On the plus side, I didn’t injure myself, so at least it was a good (if very slow) run.

    Reed on #49333

    Looking at the other thread you posted, it looks like you’re fitting in a couple of days of running per week. You might find value in (slowly) ramping up to running 5+ days per week. If you can recover from an easy 3-mile jog quickly enough to do it again the next morning, and the next – that’d suggest that your pace is nice and aerobic. Kelly Starrett’s book “Ready to Run” is a helpful guide if you’re getting started with running. Or Pose running, Chi running… Good running form, sufficient strength and mobility, and patience are important. Avoid injury at all costs!

    Tyler Johnson on #49621


    I re-ran the test again today and tried to target the number from the MAF formula.

    15 minute warm up followed by a 1 hr jog. Ended up with an avg HR of 146 and a Pa:Hr of 0.53%

    Rachel on #49622

    That test looks good, the drift is of course quite low still. I’d try low to mid 150s, maybe aim for 155?

    Tyler Johnson on #49638

    Do you think it makes sense to use 151 as a good estimate until I can run the next test?

    Z1: 122-137
    Z2: 137-151

    Shashi on #49640

    Given the low drift from your last test, I think you are safe with your Z1/Z2 estimates.

    Anonymous on #49701

    Agreed. 150 is probably a reasonable estimate for the upper limit of Z2.

    One thing: think of HR as a rough measure. “151” sounds awfully precise for something that can’t be. I usually default to 5-BPM “buckets” for HR targets.

    brettmama on #51643

    Can you confirm what is most important about the test? Pace or HR being consistent?? I feel like every article I read says something different. The data for first 30 minutes comes out with a P:hr of 4.27% with avg HR 138 and max 144. The data for second 30 minutes is a P:hr of -4.025 with avg HR 139, and max 144. I made it public, but the link doesn’t seem to be working to share. Was my HR too low??? This is frustratingly confusing for me. I am not an elite athlete, I just want to train well for an August climb. This feels like a really hard class in school and it is discouraging since I can’t even understand day 1. Any help would be appreciated.

    Shashi on #51647

    When you are doing an outdoor test, the goal is to try and maintain HR around the target HR while your pace changes. But if the pace changes significantly (run to jog/walk pace) then you might not get an accurate Pa:Hr. I believe this is what happened in your outdoor test. You can try to do the outdoor test again with a higher target HR or do an indoor test.

    I have provided additional comments in response to your original post.

    AeT confusion. Help!!!!!

    russes011 on #51678

    Perhaps I am missing something, but for the AeT HR test to be valid your PACE has to be held constant, not HR. You warm-up and achieve what you believe may be your AeT HR–ie the HR you want to test. Once you’re warmed up and at a pace that maintains this HR–you then maintain that pace for 60min (there is never a reason to look at your HR during the test itself, because doing so may confound the results). If your HR drift is 3.5-5% then this is your AeT HR (and AeT pace when the environment and terrain are held constant). Any corrections or comments appreciated.

    Shashi on #51680


    This article has all the information to conduct both outdoor and indoor heart rate drift test.

    From the article, instruction for outdoor test –

    3. Record for 60 minutes while doing your best to keep your heart rate close to that initial heart rate number.

    Hope this is helpful.

    Tyler Johnson on #51681

    Hi Steve,

    I think the confusion here is that there are two ways to run the AeT test – outdoors or on a treadmill. On the treadmill you want to keep your pace constant and you measure the drift of your HR over the hour. Outdoors you want to keep your HR constant and you measure the drift of your pace – i.e. your Pa:HR ratio.

    Hope that helps

    russes011 on #51683

    Thanks for the posts.

    I guess what I’m trying to say is that the original post may be wrong, or perhaps have a typo (this may explain the confusion out there?). I think for both indoor and outdoor tests to be valid the pace has to be kept constant once the HR that you want to test is achieved and stable. For example, regarding the outdoor test, how can an analysis of HR drift be valid if you just adjust your HR (by changing your pace) to keep the HR constant–if this was the case then its just testing ones ability to maintain a goal heart rate, more or less any HR up to ones ANAEROBIC threshold for 60min.

    I apologize if I’m wrong and just confusing myself and others out there by posting this, but this is how I make sense of it.


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