Yet another trouble interpretting AeT thread

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  • #34783

    Howdy all – I’m 39 male, and up til about 4 years ago I was pretty active and fit in the mountains, always on skis or in boots, not much of a runner. Was able to do long days (15+ hours) and could hold a normal conversation pretty well on approaches with heavy pack.

    Four years ago, I started having problems with my knees and backed off (ski)mountaineering almost entirely, but kept hiking a good bit and really got into mountain biking which I supplemented with higher intensity training and strength work.

    Anyways, finally got in with a good PT, have started running, and am getting back into shape again with about six months of consistent aerobic work. When I’m hiking outside, I notice I often need to start mouth breathing around 140-145 bpm, so I’ve assumed my AeT is near there, but can’t get my treadmill drift tests to agree with that range.

    Test 1: HR @ 135 for first and second half, i.e. drift = 0
    Test 2: HR @ 140 for first half, 139 for second i.e. negative drift
    Test 3: HR @ 146 for first and second half, i.e. drift = 0
    Test 4: HR @ 151 for first half, 150 for second, i.e. negative drift

    I was pretty fatigued after the last two despite not getting any drift.

    Today, I ran on the treadmill at 2% incline and followed the drift test protocol and ended up with an HR of 157.5 for the first half, and 165 for the second, so right about at 5% drift. I was able to nose breathe almost the entire time.

    Anyways, I understand that AeT will vary some among activity types, but according to these results am I correct in interpretting my AeT (at least for flat running) to be closer to 157-ish? That just seems really high given the four years of higher intensity activities, minimal aerobic training, and a tendency to need to mouth breathe around 140-145 when outside.

    Thanks in advance for any help/thoughts!

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    Anonymous on #34832


    We have found this HR drift test to correlate very well with gas exchange test. But it is not perfect. While the test compares the avg HR of the first and second halves to find the drift it is the starting HR that should be your guide as to AeT HR. The starting HR in a 5% drift test will typically be the AeT.

    What was the starting HR for these tests? How far apart were these tests? Were you in the sate of recovery for each of them.

    If you got quite tired after an hour then either you were above AeT or your AeT and AnT are quite close together. You might want to read this article if you have not.


    DaveB on #34833

    Thanks for the reply, Scott.

    The first three tests were not in a super well rested state and took place about three weeks apart from one another. The fourth and then yesterdays were in a very well rested state. I was not fatigued at the end of the run test yesterday, I felt like I could have gone another hour easily – which makes me think maybe 157 is closer to my AeT (???).

    Thanks for the link to the intensity article, I’d not read that one yet!

    Anonymous on #34889


    A really good measure of where you are staying in the aerobic zone (Z1-2) is: Can you go out tomorrow and to the same workout as you did today and do it again the next day and the next and the next. If this type of work is sustainable by you long term, meaning that you are recovering from it with in 24 hours then it is under your AeT.

    But with such a high AeT as you have I think you need to do an AnT test. You may wont to cut back on Z2.

    Good luck,

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