What Is Lactate Testing and How Is It Used?

When Jakob Ingebrigtsen wins another global final, most people see talent. What they don't see is the finger prick.

For more than a decade, the best distance runners in Norway have been guided less by how a session feels and more by a single number taken from a drop of blood: lactate. They measure it in the middle of a workout, adjust the pace on the spot, then stack up huge volumes of controlled quality work on the back of it. The results speak for themselves.

That approach did not begin with the Ingebrigtsen brothers. Much of it was mapped out years earlier by a Norwegian 5000m runner named Marius Bakken, who took blood lactate from an occasional lab number and turned it into a daily training instrument.

For anyone who knows me, none of this is a surprise. I am a huge fan of Olav Bu and the Norwegian triathlon group around Kristian Blummenfelt, Gustav Iden and Casper Stornes. What that group has pulled off is a big part of how I fell down the lactate rabbit hole in the first place. Olympic gold, Ironman world titles and a sub-seven-hour Ironman, all built on relentless lactate and metabolic data, made it impossible to write this off as lab theory. Bu measures everything and treats lactate as one of the most honest readouts he has of what an athlete is truly doing. The results speak for themselves. That is the lens I bring to it: lactate is not a science-fair number, it is a performance tool.

Lactate testing is one of the tools I lean on most as a Sport Scientist, so in this article I want to explain what it actually is, what the test tells you and why the Norwegian way of using it looks nothing like the one-off ramp test most people imagine.

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Who this is for: runners, triathletes, cyclists and any endurance athlete who keeps hearing about "threshold" and lactate and wants to know what the test really measures and how the best in the world actually use it.

Quick answer. A lactate test measures how much lactate builds up in your blood at different intensities. Two points matter most: LT1, where lactate first drifts above its resting level, which marks the top of genuinely easy training and LT2, where it starts to climb steeply and you can no longer hold steady, which is your sustainable ceiling. The familiar version is a one-off lab ramp test that hands you training zones. The Norwegian version, shaped by Marius Bakken, treats lactate as a live dial: you measure it during the session and cap the intensity, so you can pack in far more quality work without tipping over the edge.

Here is the line worth remembering, because it reframes the whole topic. Lactate is not the waste product it was painted as for decades. It is a fuel your muscles make and reuse constantly and its level in your blood is simply a window into how hard you are working relative to how fast you can clear it.

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What lactate actually is and what it is not

For a long time lactate was the villain of endurance sport. It was blamed for the burn in your legs, for muscle soreness, for fatigue itself. Almost none of that holds up.

Your body produces lactate all the time, even at rest, as a normal part of breaking down carbohydrate for energy. At easy intensities you clear it as fast as you make it, so the level in your blood stays low. As you work harder, production climbs faster than clearance and lactate starts to accumulate. That accumulation is a signal, not the cause of your suffering. The acidic burn actually comes from hydrogen ions building up as you split ATP for energy faster than your muscles can clear them, which your nerve endings then sense. Lactate rises right alongside it. Producing lactate even mops up some of those hydrogen ions, which is part of why it makes such a clean marker: it tracks the effort without being the thing that hurts you.

The bigger shift in understanding came from decades of work on what is now called the lactate shuttle, summarised in a major 2018 review by the physiologist George Brooks. Lactate is actively transported between muscle fibres, the heart, the liver and the brain, where it is burned as a fast, convenient fuel. It is also a signalling molecule that helps drive adaptation. So when we measure blood lactate, we are not measuring a poison. We are reading a real-time gauge of your metabolism under load.

That distinction matters, because it changes what the test is for. You are not hunting for the point where something goes wrong. You are finding the intensities where your physiology changes gear.

What a lactate test measures

A test works by sampling a tiny drop of blood, usually from a fingertip or earlobe, while you ride or run at a series of increasing intensities. Each stage gets a lactate reading and those readings plot a curve. Two turn points on that curve do most of the useful work. The idea that endurance has both an aerobic and an anaerobic threshold goes back decades, to work like Kindermann and colleagues in 1979.

Marker	What it is	Typical blood lactate	What it means for your training
Baseline	Rest and very easy work	about 0.8 to 1.5 mmol/L	Recovery and easy aerobic running or riding
LT1 (aerobic threshold)	First clear rise above baseline	often around 1.5 to 2.0 mmol/L	The ceiling of truly easy training and the base of your endurance
The band between	Your "threshold" range	roughly 2.0 to 4.0 mmol/L	Controlled tempo and threshold work, the Norwegian playground
LT2 (anaerobic threshold)	Steep, sustained rise	often near 4.0 mmol/L but individual	The hardest effort you can hold roughly steady, near race pace for long events
Above LT2	Lactate accumulates quickly	climbing past 4 to 6+ mmol/L	VO₂max and finishing efforts, used in small, deliberate doses

A quick warning about that 4.0 mmol/L number. It became famous as a fixed "anaerobic threshold" in the 1980s, anchored by work like Sjödin and Jacobs in 1981 and Heck and colleagues in 1985, because one round number was easy to standardise around. It was never meant to be true for everyone. Your real second threshold, the highest intensity at which lactate stops rising and holds steady, often called the maximal lactate steady state, is individual. Some athletes sit well below 4.0, some above. A 2009 review of lactate threshold concepts found there is no single universally valid method and that the thresholds worth training off are individual ones, which is why setting your zones from a generic number rather than your own curve is one of the most common mistakes in the sport.

The old way: the ramp test

The test most people picture is a graded lab protocol. You start easy and step up the pace or power every few minutes, give a blood sample at each stage and keep going until you cannot hold the next step. The lab fits a curve, marks your thresholds and converts them into pace, power or heart rate zones.

This is genuinely useful. A good ramp test gives you real, individual zones instead of guesswork and repeating it every couple of months shows whether your engine is actually changing.

But it has a limit that is easy to miss. It is a single snapshot taken on a single day and the curve shifts with things like how much carbohydrate you have eaten, how rested you are and the exact protocol used. Treat it as a map drawn on Tuesday, not a live readout of where you are on Saturday. It tells you where the lines roughly sit. It does not watch you cross them.

The Norwegian shift: lactate as a daily dial

This is where Marius Bakken changed the conversation.

Bakken was a world-class Norwegian 5000m runner with a personal best of 13:06, a two-time Olympian who later trained as a doctor. As his own career went on he kept circling a simple question: if lactate tells you how hard you are truly working, why only measure it twice a year in a lab? Why not measure it during training and use it to control the session in real time? He ended up running more than five thousand of his own lactate tests chasing the answer.

Out of that came what is now loosely called the Norwegian model. The core ideas are worth spelling out, because they run against how most amateurs train.

• Lactate is the governor, not pace or feel. During a threshold session the athlete stops every few reps for a finger prick. If lactate creeps too high, they ease back. The aim is to hold a controlled level, often around 2.0 to 3.0 mmol/L, deliberately short of the steep second threshold rather than out at the ragged edge.
• Controlled, not maximal. The intervals run at an honest, repeatable intensity that keeps lactate capped. It should feel strong but sustainable, never like a time trial.
• Double threshold. Because each session is controlled rather than maximal, an athlete can run two threshold sessions in a single day, usually six to eight hours apart. That stacks up an enormous weekly volume of quality work that would bury someone hammering each session to exhaustion.

The payoff is volume of quality. By refusing to let any single session drift too hard, the Norwegian approach lets an athlete absorb far more threshold work across a week, month and year, with less of the deep fatigue that forces easy days and missed sessions. A 2021 review of how the world's best 800m and 1500m runners train points to exactly this kind of controlled, lactate-guided threshold work as a signature of the Norwegian approach.

Bakken documented and shared this framework in detail and it became one of the clearest influences on modern Norwegian distance running. Its most visible expression is the Ingebrigtsen brothers, coached by their father Gjert. The method has since spread well beyond Norway.

Put simply: the ramp test asks "where are my thresholds?" The Norwegian method asks "am I on the right side of my threshold right now?" and answers it mid-session, every session.

How blood lactate testing has evolved

None of this appeared overnight. Blood lactate went from a research curiosity to a pocket-sized training tool over about fifty years.

Era	What changed
1970s to 1980s	The threshold concept takes shape. Researchers describe an aerobic and an anaerobic threshold and link lactate to endurance performance.
1980s	The fixed 4.0 mmol/L "OBLA" threshold becomes popular because it is simple and repeatable, even though it ignores individual variation.
1980s to 2000s	The lactate shuttle reframes lactate as a fuel and signal rather than a waste product, slowly changing what the test is understood to mean.
1990s to 2000s	Portable analysers move testing out of the lab. Individual methods, like the maximal lactate steady state and curve-based markers, start to replace the one-size 4.0 number.
2000s to today	The Norwegian model, shaped by Marius Bakken and made famous by the Ingebrigtsens, uses cheap handheld meters to control intensity inside the session itself. Lactate becomes a daily instrument, not an annual checkup.

The technology made the method possible. A modern handheld analyser gives a reading from one drop of blood in under a minute, for a few dollars a strip. The expensive, lab-bound test that used to happen twice a year can now happen between reps on a track on a wet Tuesday morning. That is the quiet revolution behind the headlines.

What this means for you

You do not have to be an Olympian to use any of this. The principles scale down cleanly.

First, get your zones from your own curve, not a generic chart. A single good test sets a real LT1 and LT2, which immediately makes your easy days easy enough and your hard days honest. Most amateurs train their easy runs slightly too hard and their threshold work slightly too cautiously. A test fixes both.

Second, if you want to borrow the Norwegian idea, you can. Controlling threshold sessions so they stay genuinely repeatable, rather than turning every one into a test of courage, is the single most useful habit an age-group endurance athlete can copy. You do not need to prick your finger every rep to do it. You need to know what controlled actually feels like and a test calibrates that feel.

Third, respect the caveats. Lactate readings shift with diet, hydration, caffeine, glycogen and even the sampling site, so the conditions need to be kept consistent for the numbers to mean anything. The value is in the trend and the individual lines, not in chasing a single magic number.

Your zones, once they are set, live in the Be app, so every session you do is prescribed against your real numbers rather than a guess.

Key takeaways

• Lactate is a fuel and a signal, not a waste product. A lactate test reads how hard you are working relative to how fast you clear it.
• The two points that matter are LT1, the top of easy training and LT2, the hardest effort you can hold steady.
• The 4.0 mmol/L threshold is a convenient convention, not a universal truth. Your real thresholds are individual.
• A ramp test is a snapshot that sets your zones. The Norwegian model, shaped by Marius Bakken, uses lactate as a live dial to control intensity during the session.
• Controlling intensity by lactate lets athletes do more quality work, including double threshold days, without the deep fatigue that breaks a training block.
• Cheap handheld analysers turned a twice-a-year lab test into a daily training instrument, which is what made the Norwegian approach possible.

Used well, a lactate test stops being a number on a page. It becomes the dial that keeps every session honest.

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Putting it to work

Lactate testing and physiological profiling is one of the specialist tools I offer at Be Sports Science Consulting. I run the test, fit your individual thresholds rather than dropping you onto a generic 4.0 mmol/L number, then build your training around the lines that are actually yours. If you want your zones set from real physiology and a plan that uses them, that is exactly what one on one sports science coaching is built for. Book a consultation and we'll start with a proper profile.

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References

1. Brooks GA. The Science and Translation of Lactate Shuttle Theory. Cell Metabolism. 2018;27(4):757–785. https://doi.org/10.1016/j.cmet.2018.03.008
2. Robergs RA, Ghiasvand F, Parker D. Biochemistry of exercise-induced metabolic acidosis. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2004;287(3):R502–R516. https://doi.org/10.1152/ajpregu.00114.2004
3. Allen DG, Lamb GD, Westerblad H. Skeletal muscle fatigue: cellular mechanisms. Physiological Reviews. 2008;88(1):287–332. https://doi.org/10.1152/physrev.00015.2007
4. Pollak KA, Swenson JD, Vanhaitsma TA, Hughen RW, Jo D, Light KC, Schweinhardt P, Amann M, Light AR. Exogenously applied muscle metabolites synergistically evoke sensations of muscle fatigue and pain in human subjects. Experimental Physiology. 2014;99(2):368–380. https://doi.org/10.1113/expphysiol.2013.075812
5. Kindermann W, Simon G, Keul J. The significance of the aerobic-anaerobic transition for the determination of work load intensities during endurance training. European Journal of Applied Physiology and Occupational Physiology. 1979;42(1):25–34. https://doi.org/10.1007/BF00421101
6. Sjödin B, Jacobs I. Onset of blood lactate accumulation and marathon running performance. International Journal of Sports Medicine. 1981;2(1):23–26. https://doi.org/10.1055/s-2008-1034579
7. Heck H, Mader A, Hess G, Mücke S, Müller R, Hollmann W. Justification of the 4 mmol/l lactate threshold. International Journal of Sports Medicine. 1985;6(3):117–130. https://doi.org/10.1055/s-2008-1025824
8. Faude O, Kindermann W, Meyer T. Lactate threshold concepts: how valid are they? Sports Medicine. 2009;39(6):469–490. https://doi.org/10.2165/00007256-200939060-00003
9. Beneke R, Leithäuser RM, Ochentel O. Blood lactate diagnostics in exercise testing and training. International Journal of Sports Physiology and Performance. 2011;6(1):8–24. https://doi.org/10.1123/ijspp.6.1.8
10. Haugen T, Sandbakk Ø, Enoksen E, Seiler S, Tønnessen E. Crossing the golden training divide: the science and practice of training world-class 800- and 1500-m runners. Sports Medicine. 2021;51(9):1835–1854. https://doi.org/10.1007/s40279-021-01481-2
11. Casado A, González-Mohíno F, González-Ravé JM, Foster C. Training periodization, methods, intensity distribution, and volume in highly trained and elite distance runners: a systematic review. International Journal of Sports Physiology and Performance. 2022;17(6):820–833. https://doi.org/10.1123/ijspp.2021-0435
12. Tjelta LI. The training of international level distance runners. International Journal of Sports Science & Coaching. 2016;11(1):122–134. https://doi.org/10.1177/1747954115624813
13. Bakken M. The Norwegian model of lactate threshold training and the lactate-controlled approach to training. mariusbakken.com. https://www.mariusbakken.com/the-norwegian-model.html

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Written by Brendon Villanueva, ESSA-accredited Sport Scientist at Be Sports Science Consulting (BExSpSc). This article is general information rather than individual medical or training advice. Check with a qualified professional before making big changes to your training.