The Nordic method for pushing the limits of endurance: Every detail counts

Norway (population 5.5 million) and Denmark (almost 6 million) are modest Scandinavian nations that nevertheless churn out endurance champions with striking regularity. Whether it is Jakob Ingebrigtsen, Kristian Blummenfelt or Gustav Iden from Norway, or Jonas Vingegaard, Jakob Fuglsang or Helle Frederiksen from Denmark, the list is long—spanning cross‑country skiing, biathlon, cycling, triathlon, running, and more. Let’s try to understand where their “secret” comes from—and above all, whether there truly is one.

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1. An early, structured sports culture

• Physical activity from childhood
  In these countries, movement is second nature: from an early age, children do sport regularly and enjoy at least 45 minutes of mandatory daily activity at school.

• School schedules that help
  In Denmark and Norway, classes often finish around 3 p.m., leaving plenty of free time for club training without sacrificing academics.

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2. Long‑term preparation

A champion is forged over at least ten years: developing motor skills and aerobic capacity early on allows athletes to absorb very high training volumes in adulthood.

For example, Norwegian juniors (ages 17–19) already run 115–145 km per week—a workload that sets the stage for a long, successful career.

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3. An integrated scientific ecosystem

In both Norway and Denmark, the coach is never alone: physiologists, data scientists, nutritionists and physicians collaborate daily to

• measure every parameter precisely (lactate, heart rate, heart‑rate variability, etc.),

• interpret the data collectively,

• adapt the programme rapidly according to fitness, nutrition and recovery status.

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4. Defined training zones and strict intensity control

The famous double threshold is the hallmark of Norwegian training, but it is preceded by extremely tight intensity control. Lactate is used as the metabolic reference to maximise time spent in optimal zones. Hence a consensus has emerged around a unified intensity‑zone model: coaches, athletes and scientists all read from the same playbook when planning, executing, analysing and comparing sessions with rigour and consistency.

Developed by the Norwegian Olympic Federation for endurance sports, this model divides effort into five zones, rests on scientifically recognised physiological thresholds, and provides a universal framework for training design.

Why five zones?

When defining an intensity‑zone model, the goal is to link each zone to precise indicators: % of heart‑rate max, rating of perceived exertion (RPE), muscle‑fiber recruitment, energy substrates used, respiratory parameters, lactate metabolism, muscle oxygenation, and so on.

A three‑zone split (Z1: below the first lactate threshold; Z2: between the two thresholds; Z3: above the second threshold) often lacks the finesse needed to target a specific metabolic process. For instance, distinguishing a low‑intensity outing (Z1) from a Zone 2 session (in a five‑zone model) aimed at improving mitochondrial efficiency is tricky: although both lie in the aerobic domain, heart rate, substrate oxidation, RPE and lactate levels differ markedly. To achieve truly specific training, it is therefore essential to define precise zones and to use rigorous measurement tools during workouts.

To delve deeper into Zone 2, I recommend this article.

Norwegian and Danish coaches and researchers systematically measure lactate during sessions in order to adjust metabolic intensity in real time: depending on duration, targeted speed or power can be lowered to stay within the desired range. This methodological precision sets them apart; they believe that a prescription based solely on a percentage of speed, power, or heart rate is insufficient.

Indeed, athletes with a high blood volume and a large proportion of slow-twitch fibers (low lactate production) will exhibit a lower blood-lactate concentration than others who have more fast-twitch fibers. Without a complete metabolic test, the coach risks miscalibrating the zones by ignoring these inter- and intra-individual variations. For example, Sandbäck illustrates in a recent article how these differences can distort the definition of intensity.

Finally, remember that intensity zones evolve according to the athlete’s adaptation.

When you perform a laboratory test in a well-rested state, using stepwise increases, you obtain values specific to that protocol. However, these can vary depending on training conditions:

• Nutritional and hydration status

• Temperature

• Wind

• Altitude

• Route profile (flat, rolling)

• Terrain surface

• …

Intensity zones defined as a percentage of speed, power or heart rate may then fail to reflect the intended metabolic impact. To compensate for these discrepancies, Norwegian and Danish coaches systematically take lactate samples during sessions, in addition to data from the power meter, GPS or heart-rate monitor. They adjust the intensity at each interval based on the lactate measurement, thereby limiting arbitrariness: the stimulus is prescribed according to the actual internal load, regardless of fluctuations in fitness, wind or altitude.

In practice, you don’t measure after every interval but rather at the end of the 2nd, 4th, 6th repetitions…; if the values remain stable (± 0.3 mmol), you can—for example—skip the 6th and simply check again at the 8th.

Why choose lactate as a metabolic index?

Lactate accurately reflects the metabolic load imposed on the muscle, whereas heart rate or RPE capture only part of it. As both a product, a fuel and an adaptive messenger, it embodies the true internal load better than any other indicator. By placing lactate at the heart of intensity regulation—as Danish and Norwegian coaches do—you can accumulate a high volume of “useful” training time while controlling fatigue. This is the principal lever for sustainably raising your thresholds and, ultimately, improving endurance performance.

Indeed, lactate plays a key role as a muscle “fuel” via the lactate shuttle and acts as a genuine “lactormone,” triggering cellular signaling pathways (PGC-1α, SIRT-1/3, HCAR-1) that enhance mitochondrial biogenesis.

5. Distribution of Training Intensities (DIE)

It was the Norwegian scientist Stephen Seiler who, in 2006, popularized the notion of polarization after analyzing the training logs of Norway’s elite athletes. Since then, there has been a shift toward a “pyramidal” profile within a three-zone model:

• Zone 1 (LIT) – about 85 % of total volume: easy, continuous aerobic work (“easy & steady”)

• Zone 2 (MIT / threshold) – 12–13 %: moderate effort, around the LT1–LT2 lactate thresholds

• Zone 3 (HIT) – ≤ 3 %: high intensity, short and very demanding sessions

Pyramidal profile: predominance of LIT, a controlled amount of threshold work, and a very small proportion of HIT.

In the Norwegian model, triathlon coaches often prioritize threshold sessions (LT1–LT2) on the bike and in running, while reserving high-intensity (HIT) primarily for swimming or cycling, with the aim of injury prevention.

6. Central Role of Threshold Training