How low is reasonable for AeT?

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May 30, 2019 at 3:06 pm #22721

johnnylo245
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Hello UA!

I am relatively new to endurance training. I grew up doing (probably) a lot of anaerobic training for team sports like Soccer and Lacrosse and I am fairly confident that I am aerobically deficient despite a couple years of consistent ski touring and ski mountaineering.

I have been trying to get a value for my AeT using the heart rate drift test. The first time I ran for an hour on a flat road at a heart rate of 120 BPM and received and PA:HR of 12% from Training Peaks. This made sense because I was breathing relatively heavily out of my mouth. I recently tried the test again at a HR of 110 BPM and received a PA:HR of 13%… I am confused because jogging at 110 felt pretty easy and at times I felt like I was barely breathing.

Should I be suspicious of these results? Or is it entirely reasonable for a newbie to have an AeT somewhere below 110 BPM? Should I just keep jumping down in HR until I get to that 5% mark…?

By the way, I am using a chest strap heart rate monitor (garmin-dual) so I am fairly confident in the accuracy of my HR data.

Thanks in advance!!
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Posted In: General Training Discussion

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Anonymous on May 30, 2019 at 3:47 pm #22723

That’s impossible to answer. Heart rates are like fingerprints; they’re unique to the person and irrelevant for everyone else.

One person’s AeT may be 110, and another’s may be 180. Someone who starts at 110 probably has a lower maximum and will never be able to get to 180. But absolute heart rates have nothing to do with fitness, so how high a heart rate is at a given intensity doesn’t mean much. An athlete’s changes in heart rate relative to their own history are what’s important.

However, based on your description of the effort relative to the pace and PA:HR, it does sound like you have ADS.

You could try another test at a lower heart rate (even if you have to walk). Or you could do a treadmill test at a constant speed and manually calculate the PA:HR. To do so:

* Pick a speed on the treadmill slower than your first two tests;
* Stay on the treadmill for at least 30′-60′ (the longer, the more reliable the test);
* Record the workout, pressing the lap button halfway through;
* When you’re done, divide the average heart rate of the second half by the average heart rate of the first;
* Lastly, subtract one and multiply by 100 to get the percentage HR drift.

For example, if (2nd_half_HR) / (1st_half_HR) = 1.091, then the drift was 9.1%.

With that info, start doing all of your aerobic training at whatever pace elicits a drift of less than 5%.

Participant

todd.struble on May 31, 2019 at 8:08 am #22753

I agree with Scott that maybe you should try a different method or test. I wouldn’t just use that TrainingPeaks Pa:HR number as the be-all-end-all of measuring your heartrate drift. There should be some level of analysis of your workout data to confirm what you experienced during your workout or test. Steve’s video on using the PMC helped me think about how to read my data a bit better. @ 6 minutes in Steve goes through looking at the data and the decoupling that happens over a much longer workout. Note how it’s sort of obvious when the athlete’s pace and HR start seriously moving away from each other.

When you look at the data from your AeT test, is your pace dropping significantly like that in the second half of your workout or does it stay largely in step with your HR? This is sort of what the Pa:HR number is getting at, but in my experience it can get fooled easily by elevation gain/loss or bad data. Doing a manual calculation like Scott described will take out those possibilities.

I’ve gotten some wonky Pa:HR numbers, and it’s been either because the road I thought was flat had a bit of a slope, and/or my GPS/HR monitor wasn’t working right. To get into the weeds, I had a problem with noise in the speed channel which messes with how TrainingPeaks calculates the Pa:HR number. I solved the slope issue by doing the test at a local school track, and the noise issue by picking up a GPS watch (I previously used my phone and the Wahoo app to record, which sampled data excessively often, creating the noise in the speed channel).

Participant

Rachel on June 1, 2019 at 2:23 pm #22782

You might also try calculating your MAF heart rate, it’s usually a very conservative starting number. Basically 180 – age but there are a few modifiers too, like if you take meds. 180 formula

Participant

allan.xperia on June 3, 2019 at 12:59 am #22840

Don’t trust that Pa:Hr number from TP over a doorstep if you changed your pace during the workout!

As far as I know, it is based on Joe Friel’s method, and this method assumes that your speed is proportional to your heart rate, which it quite likely isn’t. If you run at constant speed (and slope), this error will not have any influence. But if you run at constant heart rate and instead change your speed during the workout, the result will be wrong.

In my own case, my speed is proportional to my heart rate minus 70-80 BPM. Which makes sense, because my heart rate while standing is 70-80 BPM. So the extra heart beats for running come on top of that.

Participant

jakob.melchior on June 3, 2019 at 9:09 am #22845

the way I read it I think the error is including the warm-up in the Pa:Hr number from trainingspeaks. Try recording the first 20 minutes of the run as a separate activity and then start the “test” as a new one. Also pick a relatively flat route and run for 40-60 Minutes at a constant pace which feels relatively easy for you (the description of the 110 one sounds about right).

Keymaster

Steve House on June 3, 2019 at 11:43 am #22858

For those of you using the Pa:HR calculation, remember that the route has to be FLAT. When I have coached athletes do this test I ask them to run around a track for 60 minutes at a pace they feel they can sustain for that timeframe. Boring, but it works.

Participant

madanyang on June 3, 2019 at 12:53 pm #22868

Steve, I think you mean flat when doing the test outside. Because according to the Heart Rate Drift article

TREADMILL: Set treadmill to 10% and begin hiking slowly. If training for flatter runs set treadmill to 3% and run. Gradually build speed over the first 10-15 min until HR stabilizes at what you FEEL is an easy aerobic effort. If you have a good idea of what your Aerobic Threshold HR is then target that HR for the beginning of the test. NOW YOU ARE READY TO BEGIN THE TEST.

Participant

johnnylo245 on June 4, 2019 at 1:33 pm #22920

Thank you all for your replies!

I decided to try the test again with a longer warmup and running on a flat track. My target HR was 110 and the duration was 60 minutes.

For the warmup, I jogged slowly for about 20 minutes shooting for a HR of 100 BPM. The warmup was on gently rolling terrain near the track. This felt very easy. (See first image)

For the test, I started at an 11:40 pace with my HR pretty consistent at 110. I was able to keep this pace for about 2 miles (22 minutes) before my pace began to slow in order to hold my HR at 110. My pace gently declined for the rest of the workout and my PA:HR for the test was 10%. This test certainly looks more like classic decoupling than my previous attempts. Given these cleaner looking results it seems my AeT is indeed somewhere below 110 and I’ll try the test a little slower in the near future.

One point of confusion:
Some of you had mentioned that the test could be performed between 40 and 60 minutes. If I had stopped the test at 40 minutes my PA:HR would have been more like 6%. I’m going off of the number for 60 minutes, but does the duration at which you cross the 5% threshold come into your analysis at all?

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Shashi on January 28, 2020 at 12:20 pm #37034

Just came across your post as I am trying to validate my own AeT test.

Not sure if you have seen this topic –

HR Max

There is some discussion around different drift rate based on when you record the test that you might find helpful. Not sure if it answers your question –

Some of you had mentioned that the test could be performed between 40 and 60 minutes. If I had stopped the test at 40 minutes my PA:HR would have been more like 6%. I’m going off of the number for 60 minutes, but does the duration at which you cross the 5% threshold come into your analysis at all?

In my gym max. duration on treadmill is 60 mins, so I do a 15 min warm-up and then have to restart the run to go for 60 mins. It takes around 5-10 mins to get the HR stabilized and as result my AeT test run is 50-55 mins (I compare two 25/27.5 min laps for drift calculation ). I am assuming this is okay.

Maybe Scott S or someone else can confirm.

Inactive

Anonymous on January 29, 2020 at 3:01 pm #37078

It takes around 5-10 mins to get the HR stabilized and as result my AeT test run is 50-55 mins (I compare two 25/27.5 min laps for drift calculation ). I am assuming this is okay.

Yep, no problem.

Participant

Shashi on January 29, 2020 at 3:27 pm #37082

Thank you Scott.