Lactate threshold

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  • #19640
    NandaDevi
    Participant

    Before starting the 16 week mountaineering program, I did an AeT in December 2018, which I repeated a few weeks back and the results were pretty similar, i.e. AeT close to 145 bpm, though in the second instance I had to crank up the treadmill from 8% to 10% incline and the pace from 3.0 to 3.3 mi/h) to reach the same results, showing that I had made some progress in my aerobic capacity. I then dug up a lactate threshold test at the University of California, San Francisco’s “Human Performance Center” that I had done in June 2018 (more out of curiosity than anything else). The results are attached here, along with the “training zones” that they recommended.
    The question is ,if my “lactate threshold” was determined to be 169, then do I have ADS? I have not measured my AnT by the treadmill test that I have seen recommended on this site and I have been training at/below my AeT for mountaineering starting in a couple of weeks. I’m also curious about the first inflection point in the curve (at ~ 158 bpm) – is this significant? I initially thought that was my AeT, but (assuming the June results hold for the December assessment) clearly that was not the case. Appreciate any feedback on what this test revealed, whether the format was appropriate, and whether it is worth paying to get a retest for the next training season. Thanks!

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  • Keymaster
    Scott Johnston on #19734

    NandaDevi:

    Good for you for taking the initiative to get tested. Let’s see if I can help you sort out the information the lab gave you. But first thing is to get the semantics sorted out. Exercise science has done no one any favors by not standardizing the nomenclature for many commonly used terms. To wit:

    Aerobic threshold (what we call AeT)is defined differently by different sources. But there is enough commonality to make some good assumptions and to be able to translate between definitions. DEF #1: When the blood lactate level rises 1mMol/L above the base line (meaning lowest. Baseline for well trained endurance athlete (especially in a fasted state where I like to do these tests) will be in the range of 1mMol/L. This is where DEF#2 comes from: 2mMol/L. AeT is also often called First Ventilatory Threshold (VT1) because in a gas exchanges test the rate and depth of respiration takes a jump up here. It is also called the Onset of Blood Lactate Accumulation (OBLA) for obvious reasons. And in some literature and schools AeT is called Lactate Threshold. Crazy, I know but this is where some of your confusion is coming from I think.

    Now back to your test:
    1) Your initial lactate levels were elevated slightly. Were you in a fasted state? Had you have a high carb snack within a couple of hours? Lactates like these, hovering around 2mMol/L in the initial stages would seem to indicate excessive glycolytic involvement for such low intensity work. This could for the reason stated above or because of poor fat adaptation or aerobic deficiency or….

    2) How long of a warmup did you have before starting the test? We recommend a 15 min gradual warm up to get the aerobic system firing on all cylinders.

    3) How long was each intensity stage? If the test protocol ramps you through the aerobic zone too fast your aerobic system can’t respond quickly enough and will be playing catch up. In order to get a good look at how the aerobic system responds to increases in intensity we like to see 3 minute stages which give the metabolism time to stabilize before increasing the intensity.

    4) They’ve set your Z1 upper limit as 123 but your HR never was in Z1 for this test. You started the test at the upper end of what they are calling Z2. I suspect that you are aerobically deficient which would explain why your HR started the test at 147. When you do your personal basic aerobic training what sort of heart rate do you see? Can you train on your steady runs/hike at 125-130.

    Regarding your final question about where your AeT is. I’d recommend doing the bulk of your training at and below that 158 inflection point. I’d also recommend conducting an AnT test.

    I hope this helps,
    Scott

    Participant
    NandaDevi on #19837

    Scott, thanks very much for the detailed feedback. In response to your points:

    1. I don’t quite remember, but I *think* I had a light breakfast on the morning of the test. The weird thing about the data is also that the lactate levels are given in mmol/dL, and one would have to multiply by 10 to get numbers in mmol/L (mM), in which case a baseline level of 20 mM does not make sense! I think it is probably a typo.
    2. There was definitely no 15 minute warm up. I think there was at most 5 minutes of warm up, and at the pace that was used for the test.
    3. Each stage was 4 minutes long.
    4. At the time I would go “jogging” for an hour at what seemed to me “nose-breathing” pace, and my average HR would be in the mid-150s at a pace of about 4.2 mph. Now I am in the 13th week of the 16 week program during which I have been training at/below my AeT as determined by the HR drift test using a treadmill (145 bpm). Yesterday I had a recovery run/hike and used a treadmill. At 4 mph, I had to crank up the treadmill incline to 2.5% to get my HR between 125 & 130! Your program has made a big difference in my aerobic capacity!
    I’m going on my Himalayan expedition in 2 weeks, but after I’m back, I would like to continue the workouts at or below AeT to a)improve my aerobic capacity and b)raise my aerobic threshold
    The question is, how many hours of training at/below AeT would be necessary to accomplish a) and b), or at least a) (depending on time commitment)? I recall seeing a post by you on this forum where I think you recommended at least 8 hours a week?

    Thanks!

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