Figuring out Aerobic Threshold

  • Creator
  • #20382
    Sofia Wahaj

    Hello. I purchased the 16 week Mountaineering Program, the book and the training log book. I am trying to determine my Aerobic Threshold HR. I have done the test twice on the treadmill and these were my results:

    Monday (well rested from vacation)
    Incline 2%, Pace 6.2 mi/hr
    HR: 170/155=9.9% drift

    Thursday (kinda sore, not well rested)
    Incline 2%, Pace 5.3 mi/hr
    HR: 158/147=7.9% drift

    My question is:

    1) Do I need to repeat the test again? If so, should I try initial HR of 135? If I do not need to repeat the test, what should I use for my Aerobic Threshold?

    I am sure this info is somewhere in these forums, but I am having a hard time digesting all the info and would like to find my starting point. Thanks for any help!


  • Participant
    madanyang on #20393


    Based on the following article Heart Rate Drift your HR drift is above 5% hence the pulse you start the test with; is not your AeT pulse in my opinion.

    I don’t know how you found the initial HR of 135 for another test, but in my case I used MAF calculation as the starting point for the test (180 minus your age) as I had Aerobic Deficiency. This number may or may not be your AeT HR but it helped me to minimize the number of tests (although AeT HR is not fix and can change from day to day and will move upwards with training so the need to repeat the test in the upcoming weeks is a necessity also).

    My take is to take another test with a lower starting pulse (definitely lower than 147) and try to stay under 5% drift

    More experienced participants may have other tips as well, hope this helps

    Rachel on #20394

    I was thinking along the same lines as madanyang. I’d try somewhere between 130 and 135. You may have to slow to a walk and raise the incline

    If you want to find out your Maffetone HR, you could calculate it here: Maffetone 180 formula. It might be lower than your AeT but it most likely won’t be higher. It worked pretty well for me to start but I also live at altitude (and AeT lowers with altitude.) At sea level it would have been 10 beats too low for me. As it was my starting AeT from a drift test was 133 bpm, and my MAF HR is 129.

    Also I think if you do the test well rested you’ll have better results than if you are tired. good luck!

    Sofia Wahaj on #20397

    Thanks guys. I wish I had known to use MAF as a starting point in the first place. That article was helpful. I will redo the test once more at a much lower HR. And more rested. Thanks guys!

    Anonymous on #20400

    Thanks for writing in and thanks to the other posters for helping her sort this out. I don’t have much to offer other than this:

    This HR drift test is “iterative” in that you may need to redo it a few times to get a drift under and close to 5%. Clearly your 2 starting tests used too high of a starting HR.

    Good luck,


    Sofia Wahaj on #20453

    I redid it again, this time walking on the treadmill at 10% incline. Initial HR of 130 and drift of 5.3%. So now I will put 130 at the top of zone 2. And the bulk of my training should be in zone 2. I hope that is right….

    Anonymous on #20471

    Sounds exactly right. And yes you should probably focus virtually all your aerobic base training in the 125-130 range.


    Vic Sheldon on #20577

    First off, I’m incredibly impressed with this site. I’m also interested in one of the training programs and have been skimming some of the Forum threads. Out of curiosity, I conducted the AeT today on the treadmill. Here’s how I did it. Not sure my results are accurate, but welcome feedback on how I executed the test or if I should re-do.
    Background: I’m 42, 5’11’’, 185lbs and have not worked out consistently for over 3 years. I have previous triathlon experience/training background and competed as a swimmer in college. I am a weekend hiker/MTB rider and occasional climber. 15-18 yrs ago, I routinely climbed in the Cascades while living in Seattle. Summited Rainier several times, Mt. Baker, Shuksan, etc. I have 3 kids and work 70+ hours a week. Finding time to work out is difficult, but I’m looking to carve out time to maintain my health.
    I was in a fasted state (hadn’t eaten in 7 hours) and used a Garmin Instinct watch with wrist HR (pretty sure this is what made the results inaccurate.
    Treadmill at 10% incline for 10 min at 2.8 HR pretty steady at 105
    For next 5 min (10-15 min total) I increased the speed to 3.0 – HR remained at 105-106.
    I breathed through the nose for the entire test.
    For next 15 min (15-30 min total), I increased .1-.2 mph every 3 min. HR rose steadily to about 130-131. At which point I was at 4.1 mph and breathing was noisy and uncomfortable. I slowed to 3.9 mph and the HR shot up 154 and then fluctuated between 148-154 as I maintained 3.9 mph for the next 12-13 min (42-43 min total).
    Should I use 150 at the upper end of Zone 2? That would be a little high I think as the MAF calc would be 138 (180-age).


    Participant on #20582

    Hm. I wrote a lengthy reply. It was visible. Then I corrected spelling mistake – which made it disappear.

    I am not going to type it all again, so here is the short version:
    Don’t use the OHR in your Garmin watch for such testing. It has a tendency to lock on to a heart rate range and ignore readings which indicate that you may have moved out of this range. When it finally accepts that your heart rate has changed, it will make a sudden jump.

    Get a chest strap. Or an OHR arm strap.

    Anonymous on #20583


    Thanks for writing in with your question. To be sure that someone catches your inquiry It’ll be best to start your own thread. Otherwise your post might get buried down here.

    You must use a HR monitor with a chest strap for any exercise HR monitoring. We work with many athletes sponsored by the big HR monitor/GPS watch companies. These athletes get the latest and most expensive products to test. To date, NONE of the wrist based monitors work well enough to use for exercise. This includes the $800 models with option for both wrist and chest.

    Without good HR data you can’t do this HR drift test.

    Vic Sheldon on #20614

    Thanks for the quick replies! Got it. Need chest strap. Thought so. I’ll re-do.

    Rachel on #20619

    Yes the wrist monitor sucks. The last few days I was convinced my Suunto Smart Sensor strap was broken because of the erratic readings (it kept saying I hit 200 bpm, which is above my max, and I was doing a Z2 workout!)

    It turns out the battery died, and my watch was using the optical sensor. Ooops. Btw, I find the Suunto smart sensor more comfortable than the Polar H10 but really both are great straps. The only time I trust the wrist HR is at night for overnight HR averages (and that’s because it shows a trend over time).

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