HR Drift – Interesting Findings

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  • #18287

    Today was supposed to be the Metabolic test day in Boulder, however mother nature decided against that. Instead, got on the treadmill to do a 2hr HR drift test (the TP article says people training for distances over 2 hours should use a 2hr AeT test)

    Test performed at 15% Incline..during warm-up:
    2mph working up to 15% over 10min – HR got up to 120-125
    2.2mph x 5min – HR at 126-130
    2.4mph x 5min – HR at 133-136
    2.6mph x 5min – HR at 145
    2.8mph x 5min – HR up to 153-154
    3.0mph x 5min – HR up to 160 (test HR)
    ***3.0mph x 30min – HR avg 164, max 167
    ***3.0mph x 30min – HR avg 164, max 168
    3.2mph x 5min – HR up to 170
    ***3.2mph x 30min – HR avg 173, max 175
    ***3.2mph x 30min – HR avg 177, max 179

    During the first hour, with a starting HR of 160, my average HR remained constant and only 2.5% above the start. Seems like that is definitely within AeT. Since I could tell my HR wasn’t going anywhere from there, I bumped it up to 3.2mph which gave me a HR of 170 after 5min, started 2nd hour at that. Ending HR was consistently 177-178, which is around 4.5% above starting. This would correlate pretty well to AeT being 170.

    The caveat. I did an AnT test on the incline (yes, I know, avg 40% vs 15%, stairs vs no stairs, no exactly direct comparison), avg HR 178. This would mean my AeT is within 5% of AnT, which just seems outrageous to me as I don’t consider myself in that good of shape really compared to the paces my friends can put out. It would also mean I was averaging my AnT HR for the last 30 minutes of a 2hr test, making me think AnT is actually higher that what I tested at.. To give a direct comparison, I know I can do 3.8-4.0mph skate walk/slow jog for 30 minutes at 15% which would be just about maximum. 4.0/3.2 = 1.25.

    Thoughts? Would you say that AeT is probably around 170 based on this test? That’s my gut feeling but I just want to make sure before I start planning out the schedule.

  • Inactive
    Anonymous on #18312

    I suspect that your Anaerobic Threshold test was not accurate. Maybe you were tired??
    Are you collecting the HR data with a chest strap or off a wrist monitor. Wrist monitors are inaccurate and read high.

    Being able to go for an hour at 170 and see less than 5% decoupling would indicate 170 is your aerobic threshold. You’re right that an AeT/Ant difference of 5% is very unusually high.

    This decoupling test has very high reliability. In our use it seems accurate for well over 90% of the people who use it. But it is not the gold standard and you something is strange then a gas exchange test like they do at CU will dispel any questions.


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