Is this quick change in AeT rate possible?

  • Creator
  • #66430

    The gist of my question: Can one increase aerobic base this quickly? Read on…
    57 yo female.
    Previously very fit alpine climber, rock climber, trail runner, and gym rat (weights).
    Currently not fit, coming off 2 years of minimal activity.

    1 month ago, started hiking (Zone 1-2) ~ 2-3x/week, trail running (Zone 3) 1-2x/week, weight lifting 2-3x/week again.

    Of note:
    – I’m on keto for health reasons, I’m used to IM fasting 14-16 hours, breakfast at 10-11 am, and I nearly always train in the mornings, so fasted workouts are comfortable for me.
    – All the AeT/AnT zone tests below were done while walking/hiking, and I used the “go as fast as you can *comfortably* w/o opening your mouth to breathe” method (vs. “able to converse in full sentences”).
    – About 3 weeks ago picked TFNA up again, and after a refresher realized that with my low fitness level, I’d better stop with the Zone 3 runs for now. Check.

    I did my first ever AeT test(s) 2 weeks ago: I did two, to compare the “on the trail” version with a more controlled indoor treadmill version, however I did not have a HR monitor for the first one, so… filter as necessary:

    Test 1: Trail hike, varying slope but not steep. No HR monitor, so I measured HR manually every 3 minutes and averaged it: AeT 122.
    Test 2: Bought a Polar chest strap HR monitor two days later and repeated the test (also fasted) on a treadmill, per the book: AeT was 118. Decided to average it, so let’s call my initial AeT 120.

    Note: Moving fwd all my Zone tests are done w/the HR monitor (tangent: small-ribcaged folx, the Polar H10 small strap goes *really* small! I measure 29″ just below the boobs and the small strap is almost too small. And it’s comfy with a good latch that does not self-undo).

    A few days later, did the AnT test per the book (no hard workouts in the 3 days prior; full meal 2 hours prior; small carb-heavy snack 30 min prior): AnT=157.

    AnT 157 and AeT 120 = ~24% difference, clearly ADS (Aerobic Deficiency Syndrome).

    So for the past 2 weeks I’ve been following UA advice for ADS and doing Zone 2 hikes (trying to ride near the top of the zone) of 40 min or longer, with NO Zone 3 runs. I have lots of time to train, therefore many of those hikes were Z2 all uphill, and there was added Zone 1/recovery pace time on the descent; my 3-4x/week trail hikes have averaged about 1 to 2 hours each.

    Also… despite the UA advice for those with ADS to *only* do base aerobic training (ie: no strength training) for the initial 4 weeks to reduce the ADS before going harder, I have continued with ~3x/week weights at the gym (going easy, not to exhaustion).

    Here’s where my question comes in: It’s been 1 mo since I started training again, and 2 weeks since those initial AeT and AnT measurements; yesterday I did another AeT test on a hiking trail — a good night’s sleep, but unlike the first AeT tests, it was *not fasted*, but 1.5 hours after a medium-sized keto breakfast — and I got an AeT HR of solid 140.

    Then I re-did the test this morning on a treadmill exactly the same way as before, but *FASTED*, and, after a shite night’s sleep, and got AeT of 134.

    Either way you slice it, it appears my AeT has come up substantially (from 120 to 134-140) in just 2 weeks. Is this likely? My understanding was that it would take more time to see a measurable difference. My body has always responded quickly to training, but I’m new to Zone training and have no history to go with regarding the numbers and time frame.

    And… I’ll be doing the next AnT test in a few days… very curious to see what it tells me.

    What say you? And thanks!

  • Participant
    mgoat4 on #66465

    Update: I was curious about the fasted/non-fasted results, so I did a repeat on the trail test today, fasted, on a crap night’s sleep (cats…) and got AeT of 140.

    Jane Mackay on #66544

    Hi mgoat4 (mountain goat? Awesome name 😉 )
    Thanks for providing all that detailed information.
    Unfortunately the first HR drift test you did is unusable because you didn’t have a strap and the hiking test must be done on a treadmill or stair machine to ensure a perfectly consistent gradient (and you likely slowed or stopped every three minutes to measure your HR).
    The second test that you did on a treadmill with the H10 strap might be usable. Can you post the link to your results in Training Peaks (you’ll need to make the test public)?
    The AnT test is, as Coach Carolyn says, hard to screw up, so let’s go with that number.
    Now for the tests two weeks later. The first one again is unusable because it was done outside on a trail. (Likewise the one you just did.)
    The second one with the strap on the treadmill and replicating the conditions (fasted) of the previous one, might be valid. Can you post the link?
    It is quite unlikely that your AeT would have risen from 118 to 134 in only two weeks. It could in theory be possible given your background, but it’s still very unlikely. What I would recommend is to do the test one more time, following to the letter the instructions in one of the articles below, depending on whether you decide to do it outside or inside. Make sure you’re well recovered – at least two days since the last hard effort.
    There are many factors that can affect an AeT test and it can take a few tries to get usable results. I did a test last week that I’m throwing out because I chose the wrong type of test to do. I’m coming back from injury and did the running test, but my body wasn’t ready for that much sustained effort and the results are worthless, so next week I’ll do the hiking test on a treadmill.
    A few important points to remember:
    – In the treadmill test you’re keeping a consistent *pace* and *gradient* and letting the HR do its own thing.
    – In the outdoor running test you’re keeping a consistent *heart rate* and letting the pace do its own thing.
    – The outdoor test MUST be done on pretty level (flat) ground, and an out-and-back course will not give you useable results.
    – You cannot stop during the test. The pace (treadmill) or HR (outdoor) MUST be kept as constant as possible for the full hour.
    – Warm up for longer than 15 mins if you need to, but not so long that it then tires you too much. I usually do about a 20-min warmup. (I’m 51.)
    It might be helpful to take notes from the articles below to refer to when you’re out ‘in the field’. It can be hard to remember everything exactly.
    Hope this helps and let us know how the next test goes!
    (ps. I also love the H10!)
    This article has an overview of how to do the test:
    This article explains in detail how to do an accurate test outside:
    And this one explains how to do an accurate test inside:
    Here’s an explanatory video that also shows how to read the results in Training Peaks:

    mgoat4 on #67370

    Hi Jane, I attempted to post a reply twice about a week and a half ago, but it seems the system didn’t accept it. Do you see this reply?

    Jane Mackay on #67393

    That’s odd. There must have been a glitch. I’m sorry you had that trouble. Yes, I see this reply.

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