Aerobic threshold – drift test vs DFA alpha 1

  • Creator
  • #65380

    Hi everyone,
    I have used the drift test described on this site to calculate my aerobic threshold. At about 82% of max HR, my drift was around 4% so I am assuming that is probably a good enough estimate.

    I recently learned about the DFA Alpha 1 HRV based test and used the FatMaxxer app to do a test to see if the results confirm. Turns out that my aerobic threshold as determined by an alpha 1 of around 0.75 is closer to 72% of my max HR, which is even lower than the Maffetone formula.

    This seems like a pretty big discrepancy. Has anybody else used the alpha 1 test and gotten confirmation with the HR drift (or other) test?

    Just some background: I have been into endurance sports for about five years now. Over the last winter, I became aware of ADS and have been doing “base training” since November doing runs or cycling between 1.5 to 3 hours. My avg heart rate per session varies with duration. For the shorter ones, I am closer to what I thought was my aerobic threshold heart rate (82% of max HR) but for the longer ones, I usually between 70-75% of max HR. If the alpha 1 test is accurate, then it seems I’ve been overtraining during my base. Thanks for any insights you can provide.

  • Participant
    Dada on #65387

    The DF Alpha test is relying on the test protocol. How did you test it besides using fatmaxxer?

    Participant on #65392

    Hi Dada. Thanks for replying. I don’t know if I understand your question. FatMaxxer calculates alpha 1 in near real time. So I can see when it crosses .75 and what my real time heart rate is. I tried it both in terms of 2 minute ramps and longer steady state 5 minute intervals.

    Participant on #65394

    I downloaded the CSV file and ran a regression of alpha 1 on heart rate while controlling for elapse seconds to control for drift/fatigue etc. I also noticed from Bruce Rogers’s talk that on one of his graphs, he shows aerobic threshold as a range, not a single point. So using my regression parameters, my HR range for alpha 1 between 0.8 and 0.7 is from 119 to 137. A HR between 127 and 128 would put me right at 0.75.

    I do wonder how he arrived at the point estimate of 0.75. It seems that even if we increase the AeT interval by a little bit, you can get quite a large variation in HR that bounds the ends of the interval.

    Al B on #65515

    The authors talk about where the .75 value came from in this paper:

    As near as I can tell, they split the difference between a standard heartbeat at 1 and a random heartbeat at the anaerobic threshold (.5).

    And FWIW, Marco Altini – one of the original proponents of tracking DFA alpha 1 – no longer recommends using it to track your aerobic threshold. (Too variable/ too many individual differences). You can find links to his work on twitter. (@altini-marco)

    I still use it as a rough estimate because I also own a lactate meter and worked out that at .75 I am about 5-8 bpm under my AET during most phases of my training.

    Participant on #65561

    Al B thanks for that info! Very helpful. It’s interesting that altini no longer recommends it. I was a little suspicious in looking at some graphs how much variability there could be.

    alexcombs95 on #65586

    Funny you guys mention the discrepancy of nasal breathing and AeT. My last test resulted in a 147 BPM AeT, and although I am due for a retest, I doubt I have improved past the mid 150’s. I went for a 60 min “fun” run today where my only constraint was nasal breathing, and I found that the last 30 min were consistently above 160 BPM and peaked at 178 BPM. My nasal breathing was labored at the higher HRs, but I was able to stay nasal. I think this just goes to show that it is a poor indicator of AeT.

    Question though, what is ADS in sejadatzinc’s comment?

    Dada on #65614

    @Alexcombs, fyi, nasal breathing as an AeT test is pretty outdated since a long time

    Mariner_9 on #65642

    “what is ADS in sejadatzinc’s comment?”

    Aerobic Deficiency Syndrome – see

Viewing 8 replies - 1 through 8 (of 8 total)
  • You must be logged in to reply to this topic.