Aerobic Test Thread

  • Creator
  • #58738
    Steve House

    Here is the description straight from your training plans:

    The heart rate drift test is used to determine your Aerobic Threshold (AeT). It is more accurate than the nose-breathing test suggested elsewhere on the Uphill Athlete website, especially if you are aerobically deficient( The goal is to do the workout at what you think is aerobic intensity (below your AeT). You must exercise for an extended period—about one hour—and at a steady effort while recording heart rate and GPS data.Here is a video explaining how to do the test:

    Watch this video after you have completed the test to set up your HR zones:


    Outside: On a flat course (running)

    Inside: On a treadmill or stair machine

    Do not do this test on an uphill/downhill out-and-back course. During the first half you will be going uphill and therefore doing more work, meaning the pace-to-heart-rate ratio of the two halves will be very different.


    * A GPS-enabled watch
    * A chest strap heart rate monitor that pairs with your watch or phone (we recommend against using your watch’s built-in wrist heart rate monitor)
    * A TrainingPeaks account, ensuring that your watch is connected and communicating with the account. Uphill Athlete will upgrade your account to Premium to view all the data. The various metrics TrainingPeaks ( provides are invaluable to athletes and coaches, and we gladly pay our fee to them (we receive no price break or kickbacks).


    If you are going to be doing a lot of running in your training, do this test as a run. If you are primarily going to be hiking for your training, do this test as a hike on a treadmill or stair machine.


    This effort should feel easy and relaxed—a conversational pace. In other words, you should be able to carry on a conversation in full sentences.

    1.) Run on a flat course at what feels like an easy aerobic pace. (See above for more detail on the desired effort.) If you have a good idea of what your AeT is, then target that heart rate for the beginning of the test. If you have no idea about your target, then the MAF formula of 180-age is a great place to start.
    2.) Once your heart rate stabilizes for 2–3 minutes after at least a 15-minute warm-up, start the recording feature on your GPS watch.
    3.) Record for 60 minutes while doing your best to keep your heart rate close to that initial heart rate number.
    4.) Upload the data to TrainingPeaks.
    5.) Open the workout in TrainingPeaks and click the “Analyze” button. In the window to the right of your workout graph you will see Pa:Hr X.XX%. This decoupling metric compares the pace-to-heart-rate ratio of the first half of the workout to that of the second half. Note the number and skip ahead to “Reading the Results.”

    1.) Set the treadmill to approximately 3% if using a running gait and 15% if using a power hiking gait. Make sure that the treadmill will not automatically stop after 60min of activity.
    2.) Gradually build speed over the first 15 minutes until your heart rate stabilizes at what you feel is an easy aerobic effort for 2–3 minutes. (See above for more detail on the desired effort.) If you have a good idea of what your AeT is, then target that heart rate for the beginning of the test. Once you’ve dialed in the speed and grade, do not adjust them again during the test.
    3.) Now you are ready to begin the test: Run or hike continuously for 60 minutes at that speed/grade while recording your heart rate.
    4.) Upload the data to TrainingPeaks. Since GPS does not work indoors, the pace part of Pa:Hr will not be accurate. That is why it is so important that you hold the pace and grade constant once you start this test on a treadmill.
    5.) Open the workout in TrainingPeaks and click the “Analyze” button. You will see a graph of your heart rate, pace, and elevation. To calculate heart rate drift, select the first half of the test in the graph and note your average heart rate in the window to the right of the graph. Then do the same for the second half. Compare the two numbers to determine the percentage rise of your average heart rate.


    3–5 percent: You have determined your AeT heart rate, which was your starting heart rate for the test. Set that as the top of Zone 2 in your TrainingPeaks zones. Subtract 10 percent from this and set that as the top of your Zone 1.

    0–3percent: The workout was within your aerobic intensity zones, but you should do the test again at a starting heart rate that is 5 beats per minute (bpm) higher.

    >5 percent: Your initial heart rate/pace was above AeT. Redo the test using a lower starting heart rate. It may take several attempts to nail a decoupling that is slightly less than or equal to 5 percent.


    Keep in mind that your AeT is not fixed. It changes day to day based on your recovery state and overall fitness. The decoupling (heart rate drift) metric is a convenient means of ensuring your workouts are within your aerobic capacity, and it can be used as an occasional spot check on your AeT.

  • Keymaster
    Steve House on #58740

    Here is the video on how to do the test:

    How to Administer and Analyze a Heart Rate Drift Test

    Steve House on #58741

    And here is the deeper dive on our site about all the ways to test your aerobic threshold:

    Aerobic Self-Assessment for Mountain Athletes

    Michal Wegrzynski on #58813

    Thanks for the materials Steve – does it matter whether we do the test fasted?

    Nate Emerson on #58853

    Hi Michal. Don’t worry too much about doing it fasted or not.

    If you target the correct intensity for the test, it’s simply a training session at the upper threshold of Zone 2. You’ll have many Z2 sessions in this program.

    As you begin a program like this, it could be helpful to approach the test the way that you would normally approach a session like this, or are planning to approach sessions like this. If you would normally do a Zone 2 session fasted and in the morning, try to do your test in the same manner. If you would normally do a Zone 2 session fueled/fed and in the late afternoon, try to do your test that way.

    Tim Weber on #58879

    I tend to use a forearm HR monitor strap, and connect that to my Garmin GPS watch as I find it to be much more comfortable than a chest strap. I wholeheartedly agree that the wrist watch HRM are not accurate, but I have found this to be accurate relative to similar runs with a chest strap and this forearm HRM strap. I assume that whatever HRM system we use for the test, we will be using throughout our workouts for the next 3 months, true? That being said, I will use a chest strap if you feel that is much more accurate, but if you feel the above HRM strap is equal, I would prefer to wear it, thoughts? sorry, not trying to cause trouble before I even do my first workout.

    Anna Hern on #58898

    I was hoping to not purchase anymore gadgets. Is the test (this program) worthless with only the watch HR monitor?

    MarkPostle on #58951

    Tim, I havent had great luck with the accuracy of the forearm HRM with my folks (admittedly just a few data points there) but they do seem better than wrist. I would try it if you’ve had good luck and we can see how it looks. Yes you should be using whatever system on a daily basis to monitor anaerobic workouts. (I don’t wear it for strength) That said I am very guilty of just wearing the watch when I’m going out for short z1 outings etc. But I have a good subjective feel of my HR which you may as well.

    MarkPostle on #58952

    Anna- In our experience, none of the wrist based HR systems alone are accurate enough for training monitoring or the drift test. Of course there are folks out there doing the program with the watch only or with no watch at all. I encourage everyone to use the chest strap to get the most out of their training time. Personally, I think one of the worse case scenarios is when people have very inaccurate wrist data and assume its accurate, you would be better off just taking your pulse manually once in a while. I would say the majority of athletes who train by subjective feel without years of HR data beforehand end up going too hard and training primarily in Z3 “death by threshold”

    mattmay3s on #58953

    Garmin Fenix 5 Threshold Value vs AeT calculated above

    Guys – just wondering what the difference is between what garmin auto calculates and the method above?

    Just completed my drift test and TP has emailed me a new Threshold Heart Rate Value of 158 up from 154.

    Ran for hour on flattest course around my hilly area. Average heart rate for the hour was 159 (max 167, min 131) PA:Hr of 4.37% RPE for the run of 3.

    So I use 159 as the upper limit of my Zone 2 now – correct?

    MarkPostle on #58956

    Matt- I 1000% disregard the zone alerts from both Trainingpeaks and Garmin (or any other program), I have never been able to ascertain any correlation between them and reality with any of my athletes, not to mention there is very little if any visibility into exactly how they are calculated. 159 is your average for the time period but not your AeT, Your AeT is the HR that you “started” the test at post warm up. I look for a little lull or stabilized point in the data a few minutes in. If your avg was 159 then you would typically have a starting point of 150-152 (guessing here). 150 for an AeT is definitely at the high end of what we typically see but is certainly possible if you’ve done a solid amount of aerobic training historically and/or have a heart stroke volume on the small side (like I do). Yes that is then the top of your Z2 and the top of your Z1 will be 10% below that. As an aside, most folks that have a very well developed aerobic engine and a fairly high AeT will want to consider doing the majority of their training in Z1 in lieu of Z2 in order to recover well day to day. You will be able to get a feel for this once you do the first 4 weeks of the program and see how you’re holding up.

    mattmay3s on #58957

    Thanks @mark – yep starting point was 152. I always run ‘high’ compared to others. Did 2 marathons and a 50km in a 10 day period a few weeks ago, heart rate was high compared to others throughout but PRE was consistently 2 or 3. I’ve been using UA programs for a few years and feel a I have a fairly strong aerobic base. Noted re Z1 instead of Z2 will give it a try. Thanks for your help.

    Anurag Doshi on #58982

    QQ – In my case, I see Pw:Hr. Is this same as Pa:Hr? For a run I did a week ago, I see Pa:Hr.

    Also, I am on beta-blockers. 5mg daily. Any idea if it would affect my aerobic threshold?

    I did two runs 1 week apart. For the 1st run, my AeT would be like 132. For the second run, I started out little bit harder so my AeT would be like 140? Should this variation be expected?

    Curious as to which one I should pick. I am guessing the lower one?

    p.tenaerts on #58999

    Is there a way to do this test that is easy on the knees? I cannot run and a treadmill at 15% incline is not an option as from experience I know i will be out for weeks due to my knee. Can I use a bicycle or peloton in some way?

    Niv Slama on #59004

    Hi there, I was doing the aerobic threshold test today and then watched the video on how to set the different zones. The only thing that I’m not sure about is how to determine the top number of the anaerobic threshold zone, can you please advise? Also, on Wednesday’s mobility workout the links to the different videos don’t seem to work(for me at least). Thanks for all your help

    bill on #59005

    I did the drift test today after doing a practice trial last week to figure out the protocol. Based on past experience and my current state of fitness, I would have guessed my AeT to be between 125 and 130, but being conservative, I assumed 120 for this run. The difference between the two halves of the test was 3 BPM (120 vs 123) so I guessed low and will run the test again at 125. Three questions from that:

    – Until I run another test, can I assume 125 for my AeT for now?
    – How often is it useful to check for AeT upticks, particularly if one is not expecting
    to see big shifts?
    – When should we do an LT test?

    By the way, I am really happy with this test option. I’ve done blood lactate and gas exchange tests, which may be (marginally) more accurate but are an expensive PITA to arrange and do.

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