Should the AeT test feel this HARD?

  • Creator
  • #53199
    Tyler Johnson

    Last week during a Z3 run I noticed something interesting – towards the end of the run, I could maintain a HR of 174 entirely through nose breathing! My current AeT was 155 but it had been about six weeks since my last AeT drift test. Still, 174 seemed HIGH and the run was hard. I remember thinking “I can make it maybe five more minutes” for the better part of an hour.

    Today I decided to re-test, aiming for the still wildly optimistic goal of 170 HR. After a 15-20 minute warm up period, my Pa:Hr is exactly 5.0% for a avg HR of 171!

    This run was HARD. Slightly easier than “I can make it maybe five more minutes” but none of the normal sub-AeT “this is my all day pace” feeling. I normally run until I get back to my car – today I stopped EXACTLY at 1hr 15min when the test concluded.

    Is that just the nature of the beast? Just because your aerobic threshold is higher it doesn’t mean you aren’t working harder – or did I figure out a way to do this wrong?

  • Participant
    Shashi on #53205


    Can you share the link to your AeT test? What is your AnT?

    tom.1990 on #53214

    Hey Tyler,

    I’ve had a similar situation. What it came down to for me was that nose breathing is generally only a good indicator in highly trained athletes and that HR drift testing can show low pa:hr percents at anaerobic threshold for some reason.

    Have you done an AnT test to find your anaerobic threshold, as the hr drift test may have just been testing that.

    I’d recommend trying a pa:hr drift test at a lower HR, say 150 and check those and then another a few days later if it was too low.

    Tyler Johnson on #53217

    Hi Shashi,

    Here is the TCX file for the run (warm up removed). I don’t have a TP trial account anymore and have been using the AeT calculator referenced in another thread –

    edit: You’ll need to rename the file to add the .tcx extension. It wouldn’t let me upload it otherwise.

    Tyler Johnson on #53219

    Weird. Let me try that again. The link to download is here:

    I couldn’t upload the TCX file and the edit post option failed?

    AshRick on #53240

    Tyler…I had the exact same result after a long Z1-building cycle. Initially, it took focus to keep HR down that low. Pace was excruciatingly slow.

    Six months later — I just “cruise” at that Z1 HR. Pace is now where I used to be at top of Z2.

    Now — Z2 running is hard! I’m breathing just fine and feel comfortable, but local fatigue in the legs starts coming on much sooner than I expected. And, it should because I’m running faster. Z2 pace is now where I used to be right up against AnT. Half marathon pace, basically. I recently did a 10 mile Z2 run to test things out; a long AeT test, basically. I ran that 10 miles at about my half marathon PR pace from a few years ago, with a HR 15 beats below where I ran the Half (145 vs 160). Entirely within my aerobic zone, but my legs got pretty tired. Local fatigue. Which can be trained.

    It sounds like you’re ready for some fast interval sessions to let the “chassis” catch up to the “engine.” Strides or hard 2-3 minute intervals.

    Shashi on #53241


    I uploaded your workout in TP and it gives me a Pa:Hr of 5.95% (screenshot attached).

    Here are my suggestions –

    – Do the AnT test to get an estimate of your AnT
    – Do the AeT test at a 5 bpm increment (160 for your next test) and check the heart rate drift

    This will help you establish whether you still have ADS and determine the right training intensity (zones).

    As your AeT improves, you might want to consider doing a lab test. Check this link for additional discussion on high AeT (170+) –

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    Tyler Johnson on #53246

    @AshRick The feeling of progress is really amazing. Nice work on your results! I’ve noticed similar things. I find myself running at what used to be my Z1/Z2 pace and finding my HR dropping into the 120s!

    @Shashi That’s really interesting! The AeT calculator I used shows 4.2% for that same tcx file. Some deviation makes sense, but that’s a pretty drastic difference.

    I’m going to take your advice and try some lower target AeT tests. If the ~170 is accurate, than those tests should pretty conclusively give me a very low or negative Pa:Hr. Seems easy to test.

    I need to take the AnT test too. I’ve been putting it off because it always throws off my training schedule for the week. With a low AeT I knew I had ADS so up until now it didn’t really seem that important.

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    Anonymous on #55240

    As Shashi suggested, you need to do an AnT test to be really sure about your AeT test, especially when the BPM values get close.

    * AeT HR doesn’t rise, but it could;
    * AnT HR doesn’t rise because it can’t.

    So it’s possible to go too hard, see little drift (at AnT), and then conclude that it’s your AeT. Training under that assumption will be too intense and won’t end well.

    Once you have your AnT HR, then it’ll help interpret your AeT tests.

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