Lactate Testing - Data and Results

I was not fasted for either. Both same time of morning after same/similar breakfast with same shoes. As far as training, the first test was in the middle of structured/unstructured mix of bike and run workouts. Following that test I started a few weeks of base/aerobic focused training then three weeks of speed work. This week has been a down week so much easier in terms of intensity.

The strips are/were brand new and I had very few, next to no, issues with drawing blood the time around… So maybe calibration as you noted.

Appreciate the second set of eyes.

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These are serious questions… Were you drunk the night before your January test? Did you not train at all between the two?

Also when the test protocol and RPE are not included with the results, since most of the time I’d throw out the test results if stages are too short for someone’s training status (usually the case) or we can’t corroborate with RPE. Besides, when someone insists I test them, or one of my pros gets decently done testing with the team (not always the case), all it does is confirm what we already know by power and RPE.

General thought: the most irksome things I’ve seen in lactate testing are either when it gets shut down early because the lactate concentration is assumed to be sufficiently high and an inflection point is assumed to have been found, or a concentration is pre-determined. I’ve seen FTPs underestimated by >50w like this, and first threshold overestimated by >50w like this too. This then leads to undertraining or overtraining.


Ha, no, definitely not drunk. Prior to the December test I raced a half ironman in mid-October and then ran NYC Marathon in early Nov… I took about 1.5 weeks off running and biked easy before returning to running. I did about 30ish miles a week for two weeks before I tested.

Following the test, I did three weeks of mostly aerobic focused runs ramping up 40-50 miles. I then started working on speed at the start of this month averaging 60 miles a week for three weeks. This past week was/is a down week so less volume and less intensity.

Maybe it’s worth mentioning, the day before the test was quite possibly one of the most stressful days I have ever had; emotionally/mentally. Still, my diet and sleep were all very much the same as all other days.

As far as RPE goes, it hadn’t occurred to me to document/track but I can say both runs felt ‘fine’. Meaning, not difficult or hard and the effort alligned for the given HR/pace for the given stage. Which were the same for both tests (5 min stages).

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One important factor influencing lactate concentration during exercise (and even at rest, albeit to a lesser degree) are muscle glycogen stores. You therefore need to carefully control both activity and nutritional state/intake to obtain reliable results.


Does higher muscle glycogen reduce or increase lactate concentration?

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Note: This issue is why the Dmax method was originally developed.


Does the Dmax method depend on the last point being at failure?

Dmax is just math. What does it have to do with glycogen stores? Can you share a reference?

Nevermind…found this.

That is the assumption, yes.

Thinking about it just now, though, I’m not sure it would really matter, as long as you went “pretty darn hard”. The higher anchor point would increase in both Y and X and the line connecting to the lower point would be further from the fitted polynomial, but the tangent line would likely intersect the curve at about the same point, or at least close enough that it wouldn’t matter, at least given normal variability.

That’s how I am picturing it in my head at the moment.

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I updated the LT graph to include the values at each point… I also updated the original test and it occurred to me this week’s test was not entirely the same. The difference being I did a number of slower stages in my test from December. This was my first test so I wasn’t sure where to start.

Here’s the original December test with all data points.

Here’s the updated graph of this week’s test compared to Dec’s test… With the values plotted out the delta doesnt look as significant as before without the values. At least not until I got to the 7th step at 6:49 min/mi pace through 6:11 min/mi pace.

My guess is without the additional slower steps I prevented my body from shuttling lactate earlier in the test which caused the ‘higher’ values.

Correction: without the slower steps, you likely produced more lactate (it’s not about “shuttling”).

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Also, it just occurred to me the original comparison chart plotted each test against different axis making the delta appear greater.

I tested a new device for measuring lactate at home for a quick test today. I guess I’ll have to go to a friend again for a full fitness test because something is “too easy” lately…

I’ve been playing around with my lactate meter and did my first step test today. I was specifically looking for the first inflection point (AeT) to help hone in my base training period after a long break off the bike, mostly to ensure I’m not training too hard.

I was afraid of missing the inflection so I decided to do 6-7 minute long steps with an increment of 10 watts. These steps probably turned out to be little too small (or at least I started from a little too low wattage) and I started to run out of time & strips so for the last 2 steps I increased by 15 watts, which brought on the obvious inflection in lactate.

I think a few of the early measurements may have been containmented to the high side, so I started measuring most steps with 2 strips, so my fingers are a state now!


  • Fasted state in the morning, basically straight out of bed
  • Current ramp test FTP: 340 watts
  • 30 minute warmup at 150 watts
  • 6-8 minute steps with 10 watt increase
  • Low readings relative to previous were retaken.

Ideas for next time:

  • Do 15-20 watt steps instead
  • Start steps a little higher than 50% of FTP
  • Wait longer until HR flattens off in each step (except perhaps last few steps past inflection)



Your lactate curve is pretty flat, I’d guess you are pretty well trained! What power do you typically do you endurance training at?

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Thanks @lee82. I had to take 4 months fully off the bike and I’ve returned and just focused on tonnes of volume at or below 250 watts, and the last few weeks I’ve done 1 or double day threshold workout from TR.

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I’ve just done a Lactate test on myself and thought I’d share the results. I did 5 minute steps of 25W with a 25 minute low intensity warm up. I also used the alphaA1 App to see if there was any correlation with the RR/A1 ratio and also the DFAAlpha1 metric.
Interestingly the everything seems to match up for LT1 ( I wasn’t concerned with FTP as I’m reasonably sure its in the 195/200W range).
Alpha1 hit 0.75 on the first rise (0.3) in lactate. RR/A1 also should the first increase there and there was also an inflection in the HR line.
Any comments would be gratefully received.

Screenshot 2024-03-20 at 12.02.23

Not buying in to the DFA stuff** but everything else is textbook. Well done!

Would be interesting next time to have some breath count at the end of each 5 min stage. Not perception or talk test or any of that…but actual counts (so no RPE business…just how many in 15 seconds, multiply by 4). Spoiler, I bet it is linear increase until it isn’t (abruptly). It can be useful to see where that matches up with the other measures.

**I just think there is plenty we don’t know about it yet, so not knocking your exploring it.

I suspect the DFa at .75 = VT1 is a bit like max HR @ 220-age or LT1 @ 2mmol. A population average with wide individual variance. I’ve found that the RR/A1 gives me consistent results except when I’m very fatigued. The VALUE changes when it increases but where it changes is reasonably consistent. I agree about the counting breaths but as soon as I start thinking about my breathing it changes from what I naturally do.

…which you just happen to fall smack dab in the middle of. :grinning: Nice.

On Steve Neal’s old site ppl would comment about that, so seems like it is not uncommon. I definitely had to “train myself” to pay attention but not pay attention, which sort of makes sense and doesn’t make sense at all. LOL.