Testing VT1 and VT2 Using HRV! Find AeT and AnT on a budget?

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  • #9305
    mountain_stoke
    Participant

    I stumbled across this really interesting Masters Thesis paper called “ASSESSMENT OF VENTILATORY THRESHOLDS FROM HEART RATE VARIABILITY IN FIVE INCREMENTAL TREADMILL TESTS IN CROSS
    COUNTRY SKIERS” by Ibai Mendia Iztueta. Link to the pdf is here: https://jyx.jyu.fi/dspace/bitstream/handle/123456789/44123/URN%3aNBN%3afi%3ajyu-201408272673.pdf?sequence=1

    The short version is this: using RMSSD or STDNN (the normal time domain metrics used for tracking heart rate variability or HRV) and LF/HF (normal frequency domain metrics used for tracking heart rate variability) while doing a graded (step) treadmill test can be used to approximate the location of VT1 and VT2 in XC skiers.

    For finding VT1 or AeT, as workload increases during test, the RMSSD or STDNN metrics drop linearly until a point where they stop dropping and either remain the same or start creeping back up slowly. Check out the plots on the screenshot that I attached. The point of this dramatic slope change coincides with the VT1 marker as confirmed in the laboratory test.

    For finding VT2, the process is a bit more involved and uses the frequency domain metrics. I didn’t read much on this one, since I am personally more concerned with finding VT1 without spending $300 each time to go to a lab.

    Anyway, I decided to give the VT1 test a shot the other day. I went to the gym and got on a stepmill with my Polar H7 HR monitor on, and after a 20-minute warmup, did 5 minute increments from intensity levels 1 to 10, where I during the last 2 minutes of each 5 minute increment, recorded my R-R data using HRV+ app on my iPhone.

    What is nice about the app it not only gives you HRV test results in the usual metrics, but also lets you export the raw data to an email address. I took the raw data in excel from each test increment, calculated the RMSSD values (easy google search will reveal calculations – https://www.alancouzens.com/blog/HRV_Calc.html). Then I plotted the RMSSD values vs. HR at each test interval. My resulting plot matched the expected shape like you see in the attached screenshot. The point where the slope leveled off was very distinct, yielding a VT1 about where I expected it to be- not posting plot just yet.

    I am getting a Gas Exchange and Lactate test done at a lab tomorrow and I am going to simultaneously repeat the HRV test with the iPhone to see how its result matches the crossover and lactate threshold points for AeT. Once done, I’ll post the actual results.

    What I am hoping is, this might be an affordable and easy method of doing lab-free AeT and AnT testing. At least if it works, it will be possible to easily do re-tests every couple of months throughout training to objectively check progress.

    Curious to hear what you pros out there think (Scott, Steve, Scott?). Everyone else feel free to chime in too!

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  • Keymaster
    Scott Johnston on #9308

    I have conducted a similar test using real time HRV to determine AeT on XC skiers before. It was 10 years ago and the there was only one watch, a Polar that had the ability to display real time R-R intervals during the rest. We couldn’t record or export the data but we could see where R-R reached its minimum. We didn’t compare to a gas test but to a lactate test and it did correspond to 2mMol/L of blood lactate concentration.

    I have not kept up on the newer watches but this is very interesting as long as the watch is able to record and download the R-R intervals.

    I’ll read the paper you attached to and be interested in hearing your test results

    Thanks for this info,
    Scott

    Keymaster
    Scott Semple on #9310

    Interesting. It’d be great to have a free, accurate way to determine AeT. I bought a lactate meter several years ago, so that’s my go-to method, but it’d be interesting to try this as well.

    I’ll be interested to hear your results after the lab tests.

    Participant
    mountain_stoke on #9324

    Okay, here we go. Please see the attachment. HRV test results (see gray line) are very encouraging as an indicator for the Metabolic Efficiency Point (MEP) or 50/50 Fat/Carb crossover point, not at all as a good indicator of AeT/VT1. Next time I test I will try to take extra data points for HRV to create a more compelling plot. As you can see, I am currently in a state of aerobic deficiency and my MEP/crossover point is much lower than I want it to be – it is way left of my AeT. Also- maybe interesting to note, my nosebreathing limit is around that MEP point, not at my AeT… although I am convinced I have narrow nasal passages.

    I am going to start a new high volume training cycle and incorporate a high fat, clean diet using my new zones in a fasted state. Will focus on uphills in Zone 2 to increase aerobic capacity and all downhills jogging in Zone 1 below MEP to increase MEP. Going to shoot for 65% in Zone 2 (Uphill), 35% Zone 1 (Downhill) for now. The lab test guy thought this sounded reasonable. He said since my fat oxidation rate was very flat up to AeT and didn’t drop off at all before AeT, it would be best to focus on Zone 2 work primarily as opposed to primarily below MEP work.

    Hopefully I can drop 10lbs of my pesky bodybuilder muscle-mass remaining from my misspent youth so I can get faster. I created an app on my Suunto Ambit Peak 3 that will take 1 minute averages of HRV during my workouts, so I can hopefully track these values and see my MEP move upward as the weeks go by.

    I plan to test again in 3 months to make sure my program is having the desired effect on my MEP.

    Would love to hear feedback and what you think of this plan. I will post results here again after my next set of lab tests!

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    Participant
    mountain_stoke on #9327

    I should mention that Scott J told me it would be a good idea to focus more heavily on sub-MEP intensities when starting out because MEP should respond quickly and then I should increase percentage of volume of proper Zone 2 training as I go on. So I plan to adjust my plan accordingly.

    Keymaster
    Scott Semple on #9361

    This is really interesting. It’s great to see these inflection points (ME, VT1, VT2) at these positions. It’s amazing that human physiology is so adaptable.

    As you said, it looks like a great illustration of Aerobic Deficiency Syndrome, in particular, that the MEP point is below your aerobic threshold.

    (As a side note, I’ve seen at least three VO2max tests where the 50/50 crossover happened at anaerobic threshold rather than aerobic threshold. All three subjects were very experienced alpine climbers and they were still burning 10% fat at their maximum heart rate.)

    Out of curiosity, did they happen to take lactate samples during this test? If so, I’d be interested to see what your lactate values were for each marker (MEP, VT1, VT2). This chart makes me wonder if ~2mM was below VT1.

    Thanks for sharing this. Really interesting.

    Participant
    mountain_stoke on #9362

    Thanks Scott! Yes, lactate was tested. See the attached screenshot of the result. Lactate value was at 1.6mM at both MEP the inflection point/ VT1 at Heart Rate of 152bpm since my lactate values were very flat up until VT1. Interestingly enough it occurs exactly at the FatMax inflection point. VT2 occured at 3.7mM lactate at 183 bpm

    To your point about seeing very high MEPs on athletes, I have been reading this book: “Metabolic Efficiency Training” by Bob Seebohar. He has numerous case studies in his book, some of which had MEP values that were off the charts on the left (SEVERE aerobic deficiency) and then some of which had MEP values literally off the charts on the right (INCREDIBLE aerobic efficiency). For both of these situation there is no crossover point on the plots but for totally different reasons.

    Anyway, yeah fixing my own plots is going to take a lot of work, but I’m excited to give it a go.

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    Keymaster
    Scott Semple on #9366

    Interesting! This tells me that I have to learn more about the MEP and what affects it. I don’t see a connection with any of the other variables. It seems like it can position itself anywhere.

    WRT your training, I think a good goal, of which you’re probably aware, is to increase AeT by following what Scott J. said. I wouldn’t be surprised if you can eventually raise AeT to ~165.

    The key is to be patient. Training with friends will be challenging, but it’ll pay off in the end.

    Participant
    Richie on #9453

    @mountain_stoke Thanks very much for this, I learned a lot.

    By the way you can make your processing a lot more easier by using Kubios It is free for an individual license and doesn’t take long to learn (read: this is what I did last night).

    You can then record your complete workout or test with your Ambit and download the .fit file from Movescount (the .fit file can also be used from Garmin too). Just load this into Kubios.

    You can use Kubios to clean out the Artifacts (you really do need to do this).

    The cursor can be set to the interval length you want to look at. (1 min 30 secs was used in the paper). You can then just select the part of the R-R data you want to look at (example the last 90 secs of the stage of the test) and it will out put the averages for you (including Time Domain and Frequency Domain).

    Sorry the explanation is a bit long winded but it will make sense once you use it and I think it will save you a lot of time too.

    I had a lactate test the other week and I recorded the whole workout I will post my findings later.

    Participant
    mountain_stoke on #9456

    @Richie –

    It’s good to hear more about Kubios. I will definitely download that and try it out; thanks for the tip.

    I look forward to seeing your test findings when you post them.

    Participant
    Richie on #9485

    @mountain_stoke

    I recorded the test on a Suunto Ambit2, so I could download the .fit file from Movescount.
    This I processed through Kubios. I first filtered out any artifacts, then selected the last 1min 30secs of each stage. I used the Mean Heart Rate and SDNN data to plot the graph.

    lactate levels for the test:
    154 bpm 1.89 mmol/L
    169 bpm 4.20 mmol/L

    A copy of the test results was posted here previously.

    I was hesitant to post the result because the first part of the graph is effected by an elevated HR in the second stage.
    The second part however, after passing 2 mmol/L mark the SDNN values level off at 2.4ms for the last 3 stages.

    The tester said at the time that my HR looked raised and offered a retest next month. On the day I just thought I might have needed a longer warm up and I have also read that some people experience a higher than usual HR if they are not used to running on treadmills. However, on the next day I wasn’t feeling too great and my son had had a high fever for few days, so that could have really effected things.

    Anyway, I will post the HRV results of the retest here and a hopefully clearer picture.

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    Participant
    mountain_stoke on #9488

    That’s too bad the results weren’t ideal. Thanks for posting anyway and also the process you used for getting the data. I will use your method next time I get the test done.

    Keymaster
    Scott Johnston on #9560

    @Mountain Stoke;

    I finally had time to read the entire (109 page) study you linked to in your first post. The conclusion I draw from the results and from the researchers own comments is that they really could not get consistent correlation between VT1 or VT2 and the time domain and frequency domain HRV methods they were assessing. Some worked for some ski techniques and not others. The worst correlation was for Nordic walk (a XC ski simulation) and running in other studies I looked at.

    There were definitive inflection points in their tests but the problem is that they didn’t line up with the gas exchange test results very well.

    Scott

    Participant
    mountain_stoke on #9564

    @Scott Johnston

    I will go read the results again I guess since my take-away from it when I looked at it was that the VT1 result matched up well for all tests except for the one with double poling – (they were saying that the large rhythmic bodily motions were interfering with what the heart or monitor was doing somehow). Maybe that is the case with running as well. I was hoping that for simply hiking up a steep grade, it would be useful since the kinetics are more subtle than running or double-poling.

    From my result – the inflection point matched my MEP heart rate, so maybe HRV is a better indicator of MEP? Or maybe that was just luck during the one test so far.

    Anyway, so it looks like there is no trusty substitute for a good gas exchange and lactate test!

    Participant
    Richie on #9602

    That’s what interested me too, the correlation with your MEP. As my AeT was a little high for my age in my lactate test I was interested to see what kind of correlation I would have, if any.

    I really enjoyed the research, I have learned so much from this site and finally today I have received a copy of TFNA (took 2 months to get to here).

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