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Ramp test with lactate, strange result

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Ramp test with lactate, strange result

Old 03-17-15, 02:19 PM
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CdCf
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Ramp test with lactate, strange result

I've paid for several professional lactate tests (ramp tests) over the years, but I decided earlier this year that with lactate meters being as cheap as they are now, I should get one and do my own testing. Said and done.

After a few weeks of misery when the lancets/blood samplers I first got provided too little blood volume for the test strips, I got a larger model and I finally managed to get enough blood out of my poor fingers to satisfy the thirst of the test strips. The meter has been tested with control solutions and everything looks all right. When I've taken two tests within two minutes of each other, they agree to within one decimal. I.e. 2.4 and 2.5, or 3.6 and 3.5.

Exactly one month ago, I did the first ramp test. Now, testing yourself while pedalling is tricky, but I did it successfully. Everything looks fine, and the lactate curve slopes gently upwards, at an increasing rate.

Here comes the weird part. According to the standard methods of determining lactate threshold, either through absolute values (such as 4 mmol/L) or geometric properties (such as Dmax, which in my case happens to coincide with ~4 mmol/L), my lactate threshold is around 245-250 W. I believe that lactate threshold power should be taken as roughly the average power you can manage for about an hour. Or what most people refer to as FTP. Here's what's weird. I'm able to average much, much more than 245-250 W. At this moment, on the very same bike that I performed the ramp test on, I could probably squeeze out 300 W for an hour. I've done a 289 W average for 60 minutes, and that was at an average heart rate comfortably below my accepted threshold heart rate range. I've also done a 335 W 20-minute max effort. Again on the same bike (a calibrated Monark ergometer). Yet, when I check what my lactate level would be at 290-300 W, I find it to be around 80-85 mmol/L. That is crazy high, and far above any range given for lactate threshold that I've seen.

What do you think? The lactate values are too consistent to indicate measurement error, wouldn't you say? So what's going on?

This is my diagram of the test results. It's in Swedish, and I couldn't be bothered to translate now. Red is heart rate, blue/purple is power, pink circles are lactate measurements (x10 to fit in view, so divide by 10 to get mmol/L) and the pink line is the trend line for the lactate point values. Green is cadence. Heart rate, lactate (x10) and cadence on the left-hand scale, power on the right-hand scale.

BTW, this test was not taken to exhaustion, since I wouldn't be able to test myself at that level of exertion, so I ended it when it became too difficult to handle the strips and the meter.

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Old 03-22-15, 07:28 PM
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"I find it to be around 80-85 mmol/L. That is crazy high..."

Yes, it is. That is an implausible concentration.

You do say it's "lactatex10" earlier in the post, which at least leaves you with 8-8.5 mmol/L, which is a physiologically observable value.

Also, 4 mmol/L is usually referred to as OBLA. LT is 1 mmol/L over baseline, or 2.5 mmol/L (depending on who is using it...)

The FTP value will be more like maximal lactate steady state (MLSS), which is greater than OBLA. So, no real surprise that your FTP would be greater than your power @ OBLA.

8 mmol/L is a high, but possible value for blood lactate concentration at MLSS.

Last edited by tadawdy; 03-22-15 at 08:24 PM.
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Old 03-23-15, 04:34 AM
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I have never read a study where MLSS was at 8 mmol/L. In fact, very few studies MLSS report much above 4 mmol/L.

Where on the curve did your breathing become non-linear and very hard? Looking at the curve, I suspect this transitioncame at around 280W.

You have measurement error. It is either the meter, the controls miscalibrated the meter, or the reagent strips are bad lot.

Do you have another Lot number of reagent strips to try? Or, can you reset the calibration to factory settings? Or try recalibrating using your controls. Lastly, I would call the Mfg before buying new controls.

I love that that chart! I just use pencil and paper but I have found it takes me more than 3 minutes for lactate to stabilize. I have to use 6 minutes when I get closer to MLSS.
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Old 03-23-15, 08:25 AM
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Oh....also, did you clean the sample size with an alcohol swab before taking the blood? Sweat can cause this kind of error.
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Old 03-23-15, 09:29 AM
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Originally Posted by RR3 View Post
I have never read a study where MLSS was at 8 mmol/L. In fact, very few studies MLSS report much above 4 mmol/L.
yeah, 8 is high.

It is possible, though. He could also just have a testing error.

"...MLSSc has been reported to demonstrate a great variability between individuals (from 2-8 mmol/L) in capillary blood..."
(The concept of maximal lactate steady state: a bridge between bioch... - PubMed - NCBI)
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Old 03-26-15, 04:45 PM
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1. Of course I meant 8.0, not 80! I just read off the diagram and forgot to divide by ten before I typed...

2. I don't think there were any errors in the lactate test results. The curve provides a self-correlation of the individual data points, and I've also plotted results from an old test (2011) over the recent one, and found that the lactate curve was practically identical (the same ramp test protocol was used) in the old test. That is, lactate vs power was more or less identical. Power/lactate vs heart rate was not, though. My heart rate levels are significantly lower now, at any given point in the test. And despite lactate levels being the same, the fatigue and endurance limits are far higher now.

3. How and when the breathing pattern changes is a decent marker, and one I both use for my own testing and when I test others. In this test, the noticeable shift (from easy and irregular to more forced and regular) occured at about 22-23 minutes. Or roughly 280 W, yes.

4. I use clean kitchen paper to wipe the fingers clean and dry before both the pricking and the blood sampling. No sweat contaminating the test strips.
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