Norwegian threshold training: My take.

Threshold training has been around since the 80s and is not specific to one training model: It is part of the pyramidal, polarized and Norwegian model. However, it has gotten the most attention through the “Norwegian model” that has produced so many athletic successes: In most recent years most notably in running (e.g. Henrik Ingebrigtsen and Karsten Warholm) and triathlon (Kristian Blummenfelt and Gustav Iden, coached by Olav Aleksander Bu). As I have had the privilege of working with Olav Aleksander Bu for a few years where we have spent countless hours discussing training, I have developed my own understanding of threshold training in the Norwegian model. I am pretty sure my interpretation is just one of many but I tried to make it as generic as possible.

Definition

Although there are more definitions, the most used definition of threshold training is training at or around maximal lactate steady state (MLSS). MLSS is the highest exercise intensity at which lactate production and combustion are balanced, resulting in a stable blood lactate concentration (BLC). At this intensity, lactate does not accumulate (significantly) over time and although lactate (accumulation) is not the direct cause of fatigue, MLSS is also the highest intensity that can be maintained for considerable amounts of time (>~30-90 minutes, depending on the individual)

Threshold training in the Norwegian model

In my understanding, for all but the Norwegian model, the goal of threshold training is to “just” stimulate an adaption at threshold intensity. In the Norwegian model, there is another thought behind it: Threshold intensity is the highest intensity at which a significant training volume can be accumulated without excessive fatigue. Or, put differently, the maximum possible training volume is greatly reduced when training above threshold intensity. Hence, in general, in the Norwegian model, threshold intensity is at or below threshold intensity and definitely not over (although deviations from this exist, for example on “double threshold days” as explained below).

Let me explain this difference by asking you a question: Let’s say we have an athlete with a power at MLSS of 200 Watt while running. What will give her/him the highest training stimulus to increase MLSS: Running a total of 15 minutes at 5 Watt above your threshold, or running 30 minutes at 5 Watt below your threshold? I think most of you will answer the latter (5 Watt below). This is the core of threshold training in the Norwegian model: By making sure you are not exceeding MLSS, you can maximize the volume of your threshold workouts, which will in turn give you the highest training stimulus without causing excessive fatigue.

Double threshold days

When talking about threshold training, inevitably people will mention “double threshold days”. As the name suggests, “double threshold days” are days where 2 threshold workouts are executed, for example in the morning and evening. In general, the intensity in the first session is more traditional (at or below threshold) but the intensity in the second session can be a bit over threshold to give an extra stimulus. Of course this comes with a trade off and that is that the volume (interval duration and/or number of intervals) has to be reduced, but it appears that especially for elite athletes, this tradeoff is worth it. Marius Bakken has written in more detail about these double threshold days in his famous article about the Norwegian model. To be completely honest, I do not yet fully understand the potential benefits of and mechanism behind double threshold days and what makes them different from any other day with 2 workouts or simply splitting a workout in 2. (let me know if you do!)

In practice

In elite environments, controlling this intensity is often done by measuring BLC after intervals, either comparing it to a previously in the lab obtained concentration at MLSS or by just ensuring it is stable across the entire session. In most other environments, measuring BLC in the field is too complex and/or expensive and intensity is controlled based on an in the lab obtained threshold value for speed, heart rate or power. If that’s not available, subjective feeling (RPE) can be used (which works surprisingly well for experienced athletes).

tl;dr

Threshold training in the Norwegian model is not just about training at threshold, but it is about maximizing training volume around threshold intensity.