How to interpret a lactate curve

Training
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Hey guys

Can you advise on how to interpret my lactate curve or suggest any resources I can read to understand it. I do have some understanding, just wonder how those with experience of working with and testing lactate would interpret it. I know there are a lot of nuances to it.

I was surprised by how low my lactate values were (I thought I’m quite glycolytic and would see lactate building up quite quickly). However, at 4.3mmol I was at around 90% my max HR and found it hard to continue.

Over the last few months I have done quite a few intervals below or just above my perceived threshold and not much vo2 work. Also the last couple of weeks I haven’t been feeling great (I had some sort of gastro issue, so for about 10 days leading up to the test I wasn’t training fully. 3 days leading up to the test I was able to do a few longer rides with some efforts)

The protocol was 15 min warm up at 145w and then 6 min steps (test on 5th min) starting from 165w up to 360w

Up to 270w the lactate meter kept showing 0.2mml and I thought something was wrong. Then at 290 it was 1.0mml, 315w 1.5mml and 336w 2.6mml and then final step it went straight above 4mml

I know that some use 2mml and 4mml as proxy for LT1 and LT2 which would put my LT1 at 92% of LT2. However, some also say LT1 is where the first increase happens.

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You’ve got a triathlete/ultra-athlete lactate profile. :smiley: It’s not unusual for pro triathletes to have trouble getting blood lactate up to or over that 5mmol range. Your curve looks typical to me…baseline lactate levels are higher than once you get warmed up. I’d say somewhere between 225W and 250W you crossed the 1st lactate threshold. ‘2nd lactate threshold’ is wherever you want to draw…I’m not a big believer that you can find ‘2nd lactate threshold’ on a lactate curve.

I’m a big believer that if you want to find FTP the best way to do it is right there in the name: functionally. Not critical power. Not 4mmol lactate. Just get on the bike and pedal at or around the pace you think you can hold for an hour. Just like Gollnick did, you will find out a lot about what is and isn’t your threshold when you do that. In fact, search this forum for Gollnick and see what you can find…

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The funny thing is I’m not a triathlete though haha I race track and always had a sprinter/pursuiter type power profile. I had a bad crash about a year ago and since recovering I have been predominantly working on my endurance near LT1 to increase my threshold before building my anaerobic power back up.

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Ah! Ok. I should have guessed based on your UserID.

Ok, easy solution! Just use a Critical Power model. For track cycling/rowing/middle distance a three or five point critical power model is probably most appropriate (or so say I). CP is more of a 20 to 30 minute power number.

But, anyhow, I think you’re lactate curve is very typical for an athlete that is doing a lot of triathlon or ultra training. If you start doing a lot of traditional track cycling work, I bet you’ll start to see the right hand side of that curve terminating with a 7-handle. (I mean 7mmol or higher).

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The shape of the curve looks ok, but the values seem low.

What meter was used for lactate? Was there any calibration or control solution used to verify the meter?

In my experience, the curve would be a little more informative if there were another point above 360 watts, or very near failure.

Personally, I would ignore any fixed lactate value estimates from this data. I would only use the shape of the curve to identify where I would do more testing.

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could also be low glycogen or high blood volume.

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I agree with this, mathew hanson recently made a short video that gets the point accross really well matthanso on Instagram: "LACTATE TESTING 🧪👨🏼‍🔬 everyone’s obsessed with the lactate meter right now. and fair enough. it’s easily one of the best tools we have for controlling intensity in endurance training… but the truth is most people are using it wrong. i’ve made the same mistakes. if you want to use lactate testing properly, here’s what actually matters: 🧪 lactate is a reflection, not a target • lactate levels are not fixed zones • 2.0 or 4.0 mmol does not mean the same thing for every athlete • what you are measuring is the balance between lactate production and clearance • and that balance is constantly influenced by:  🍝 glycogen availability  💧 hydration status  ☕ stimulant use  🌡️ temperature and altitude  😴 accumulated fatigue  ⏰ time of day  😮‍💨 stress and sympathetic tone • this is why chasing a single lactate value can be misleading 📈 the trend is what tells the story • when lactate remains stable across a session, you are below your second threshold • this is your maximal lactate steady state (MLSS) • at this point, the aerobic system is working at full capacity without tipping into excess anaerobic stress • it is the most effective intensity for long-term endurance development • you get maximum adaptation with manageable recovery cost 📏 rules of thumb to apply LT2 (second threshold) • lactate should remain within a 1.0 mmol range • if it drifts upward, you are working above MLSS • adjust pace accordingly to stay just under LT1 (first threshold) • lactate should be flat or only slightly elevated from baseline • any upward trend likely means you are moving out of purely aerobic territory • this should feel sustainable, comfortable, and repeatable you do not need to aim for textbook numbers you need to understand your own physiology test multiple times in a session look for stability over time and always combine lactate data with RPE and heart rate that is how you get the most out of lactate testing and the most out of your training"
IMO I would retest

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