Lactate test – AeT seems too high

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  • #46519
    vencislav.popov
    Participant

    I just did my first self-administered lactate test using the Lactate Plus device following the protocol and tips described in an article here. I did it on a treadmill , with 1% incline, in 5 min stages, starting with 6km/h and ending with 13km/h, increasing by 0.5km/h for each stage. Between stages, I got off the treadmill , dried my finger with a clean paper towel, cleaned it with an alcohol swipe, dried it again with a new towel, then took the sample. I was careful to remove the first drop, and to place the second drop in the test strip without touching the skin. It took about 60-70 seconds from me getting of the treadmill to when the blood drop was placed in the device. I did the test in the morning in a fasted state.

    The results are attached in a plot.

    If I go by the “2mMol/L” criterion, my AeT would be 179bmp, which seems very high.

    I’m 30, and I’ve been training actively for the past 2 years, but I’m not in that great of a shape, so this seems too high (my marathon PR is 4:00h, which felt right at my limit, back in April). I haven’t been training for the past month because I was recovering from a big event.

    My max HR is ~200, time trial AnT ~177, drift HR test AeT ~ 155-160.

    Can you help me interpret these results? Lactate starts at ~1.4mMol at rest, then stays between 1.3-1.7 during initial easy stages, then suddenly drops to 0.8mMol at peak HR 154 (which was 7min/km with median HR 146 for the last 2 minutes) and steadily increases from there.

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  • Participant
    vencislav.popov on #46521

    PS: I measured HR with a chest strap connected to my watch.

    Participant
    vencislav.popov on #46522

    Interestingly, this manual (in German) from SwissOlympic says that the AeT is the point after which lactate increases by at least 0.3mMol (given that intensity increments aren’t too small). If I use this guideline, then I get an AeT of 156bpm because the lactate increases from 0.9 to 1.4 at the next stage (165bpm), and then continues to rise. This value of 156 is right about what I would expect based on HR drift tests

    https://swissolympic.ch/dam/jcr:b15b191a-eb0d-46e8-b9c0-417b887a440d/Leistungsdiagnostik_Manual_160201_DE.pdf

    Keymaster
    Scott Johnston on #46542

    That looks like a great manual. I wish I could read German 🙁

    As you may have read in some of my writings; If you ask 4 different exercise scientists to define either aerobic or anaerobic threshold you will be 8 different answers. Strangely and unfortunately there is no consensus on these subjects. So, that leaves us to try to sort it out ourselves.

    Two fairly popular interpretations of AeT are 2mMol/L and the HR/pace where the lactate level rises by 1mMol/L above the lowest point. Yours does make a jump from 144 to 150 of .5mMol/L. That’s significant and does indicate the accumulation of lactate that is not being cleared. Based on HR drift and perceived exertion and this test 150-155 is probably a good call for AeT Having to self administer the blood test with 1 min or more to get the sample at these low intensities could affect the results.

    The drop in lactate at the higher HR is usually due to improved economy at this faster pace. I often see this kind of a lactate drop with the athlete hits their typical training pace/HR.

    Scott

    Participant
    vencislav.popov on #46546

    Hi Scott, thanks for the response – your explanation about the drop around 155 makes sense – that’s exactly where I spend the majority of my base runs, (except for recovery runs).

    Participant
    Reed on #46561

    My reading of that graph is that the lactate concentration at 144bpm is about 1.3mmol/L, and at 150bpm is about 1.5mmol/L. The starting point and labeling of the graph axes is a bit confusing. The jump that Scott saw as 0.5mmolL is, I think, actually only 0.2mmol/L.

    That Swiss report is a great document – there’s also a French version, for those who speak French but not German. Check out the graph on page 28. The aerobic threshold is defined there as the point after which lactate rises by 0.4mmol/L. In your case, that looks like it’s about 171bpm (the rise in lactate from 171bpm to 174bpm looks to be about 0.4mmol/L).

    Don’t think too much about your heart rate numbers being high or low – the absolute numbers are pretty variable from person to person. My AeT running heart rate is about 183bpm, anecdotally – similar to yours.

    Moderator
    Scott Semple on #47288

    One other thing to consider is the length of the test. Fourteen 5-minutes stages is a long test. So the low levels of lactate at high HRs could come from some glycogen depletion, especially if you were fasted prior to the test.

    In your next test, I would do a gradual warm-up of ~20′ up to about 145 and then test every 3′ rather than 5′. Up to AeT, lactate usually plateaus after ~2′.

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