Heart rate drift confusion

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November 12, 2019 at 8:29 pm #31819

MMK
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I’ve read the blog post and a number of posts here but I’m still confused about how it works, especially the idea of decoupling. In the post, it says to

> find a pace that brings your heart rate up into what you feel is your aerobic zone. Hold that pace for an hour or so and notice if your heart rate begins to climb. If your heart rate climbs less than 5 percent over the course of the workout, that heart rate was within your aerobic intensity zones.

This suggests that as long as the drift is under 5%, you’re still under the AeT. However, if I look at a recent half marathon race (1:29), my heart rate stays mostly consistent the entire time (average 172, 173) and the pace only varies slightly. So technically the heart rate drift would be under 5%, even though I think it’s safe to assume this is way above my AeT.
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Posted In: Mountain Running

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Anonymous on November 13, 2019 at 10:47 am #31913

Good question. Heart rate drift will also be limited on the high-end, which is what the half-marathon reveals. Once you’re near your maximum for a given duration, there isn’t much room to increase. Judging by some generic formulas (which are never perfect), an average HR for a half-marathon around ~1h30′ is typically ~95% of anaerobic threshold. So your AnT HR might be around 180.

But the aerobic threshold drift test is on the lower end of the spectrum. It’s a place where there is lots of possible room to increase, but due to the intensity being within your aerobic capacity, it doesn’t.

In between the two is Zone 3, where there is room for HR to increase, and it does. Right up until it reaches AnT (or a little higher than your half-marathon HR).

Does that make sense? In the AnT case, HR has no room to move (at that duration and intensity), so it doesn’t. For AeT, there is room to move, but the load isn’t enough to make it happen. Your aerobic capacity can comfortably deal with it.

Participant

MMK on November 13, 2019 at 11:09 am #31915

Thanks, that’s very informative. I haven’t managed to get out and do an AeT test yet, but it seems that, like many, I have severe ADS——or perhaps have just done a poor job estimating my AeT. I try to train at a lower heart rate (less than 150) based on the MAF method, and often than means running 10min miles for Z1 or Z2 (which is a *big* gap between there and the 6:52min pace during the half). Either I have a long way to go in boosting that AeT speed, or need to determine if my AeT heart rate is actually substantially higher than that.

Thanks too for the incredible amount of support and time you all put into this.

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Anonymous on November 14, 2019 at 12:28 pm #31991

MAF is a good starting point, but a drift test is better.

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Heart rate drift confusion