HR Drift Test Analysis

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  • #46258

    Hello everybody,

    I’m new around here. I’ve read the Uphill Athlete materials and am shifting focus on my runs to include mainly sub-AeT activities. For context, I’ve been running ~15 MPW and have been averaging a heartrate of 155-160 (watch measured), which is higher than conversational pace for me.

    I performed the HR Drift Test to get a baseline for my AeT today on a track in colder/windier than usual conditions (if that matters). I was shooting for a HR of 144 BPM, which my MAF-5 BPM because I’ve recently been getting back into running. This test was the first time using a new chest HR monitor, and I was able the hold my HR surprisingly consistent.

    I have a few questions:
    1. The first half of my run shows a 3.29% drift in Training Peaks, and the second half shows 0.57%. Is This normal?
    2. Analyzing the run as a whole yields a HR drift of 3.45%, which seems like it’s a believable value and I consider it the result of this test. Would others agree?
    3. Assuming a HR drift of 3.45% at a HR of 144, does my MAF value of 149 BPM seem accurate for my AeT? I plan to use that number to limit my HR in future sub-AeT runs.

    I’ve attached screenshots of the various analyses. I did a 10 minute (walk/run) warmup that is shown in the attached activity data, though I did not use that data for HR drift calcs.

    Many TIA,


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    Anonymous on #46277

    Welcome to the Uphill Athlete community. Thanks for writing in with your questions. It looks like you did a good job on the test itself. I suspect the reason for the lower drift in the second half of the test is that the first half served as a better warm up. The aerobic system is very slow to come on line and it this was a cold day you probably needed a longer worm up.

    I’d say that 149 seems like a good place to peg your AeT (top of Z2). The best test will be; can you get up tomorrow and do the same run you did today and then again the next day and the next? If you can recover in 24 hours then you are probably using a a good AeT. As you see improvements in your daily runs (based on perceived exertion, pace etc) you may want to retest in a few (6-8) weeks.


    PC on #46298

    Scott, thanks for the reply. The effort yesterday was certainly “easier” than I’m used to, and no doubt is repeatable every 24 hours. I’ll heed your advice and continue down this path. Thanks again!


    Anonymous on #47820

    One other thing: Was the test done wearing a chest strap? Or with only the wrist-monitor in the watch?

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