TL;DR: Western endurance training, French or otherwise, was built around a shared model that prized effort and fatigue as proof of progress. Modern physiology has not rejected that model, but refined it: controlling intensity density and working just below critical boundaries leads to more repeatable training and better long-term gains.

In a previous article, we explored the tectonic shift occurring in modern endurance training. Building on those concepts, this piece examines why the language we use to describe performance has become the final bottleneck for progress.

If you grew up running in the US, the UK, Australia, or most of the English-speaking world, you probably assume that endurance training has always been fragmented. Different coaches. Different models. Different definitions of threshold, tempo, or speed.

That assumption is understandable. It is also incomplete.

In France, distance running has operated for decades with something that most English-speaking countries never really had: a shared national training language. In the thousands of clubs affiliated with the Fédération Française d'Athlétisme (FFA), you will often hear the same terms, regardless of the region:

These are not casual labels. They represent a codified system, taught through coaching education and tradition. Most club runners broadly agree on what each session is for, where it fits in the week, and how it should feel. For many readers, this alone is surprising.

But here is the more important point: France did not invent a unique way of training. It formalized what most of the Western endurance world was already doing.

When people refer to "the French system", it is often with the assumption that France developed a uniquely rigid or idiosyncratic way of training endurance athletes. In reality, the opposite is closer to the truth.

From the late 1970s through the early 2000s, endurance programmes across France, the US, the UK, Australia, and much of Europe shared the same underlying structure:

The labels differed; the logic did not. France called this VMA + seuil. The US talked about intervals and tempo. The UK spoke of speedwork and threshold.

France’s real contribution was not inventing a new model, but making the existing one explicit and scalable. Clear terms allowed thousands of recreational runners to train with a shared understanding of intent. Group training became easier to organise. Expectations were clear. For its time, this was a genuine strength.

It is important to be fair: the traditional Western model worked, and worked well, for decades. It was simple and intuitive. It matched the tools runners had available: a stopwatch, a track, perhaps a heart-rate monitor. Hard sessions felt hard, easy sessions felt easy, and progress was easy to explain.

For recreational runners, it provided structure and motivation. For competitive athletes, it produced high aerobic capacities and mental toughness. Crucially, it offered a form of psychological validation: in an era without precise metabolic monitoring, feeling "shattered" was the most reliable proof of a productive session. Visible, undeniable effort became the primary proxy for future results. It also aligned with how success was measured at the time: race results and the sheer capacity to suffer. In short, it did what it was designed to do.

But success can hide limitations.

Over time, patterns began to emerge. Many runners trained hard, often very hard, yet struggled to improve consistently. Injuries became common and fatigue accumulated. Training weeks became a cycle of big efforts followed by compromised recovery.

The problem was not intensity itself: it was intensity density. This density was created by two primary factors: the unmanaged accumulation of time spent in the "inter-threshold" space (the middle ground between the first and second metabolic boundaries, often entered unintentionally through pace drift and group dynamics), and, more critically, an excessive volume of work performed above the second threshold (Zone 4 and Zone 5).

While drifting into the middle ground is a common inefficiency, the real systemic failure often came from over-prescribing high-intensity intervals that exceeded the body's ability to clear metabolic by-products. The traditional model often prioritised near-maximal effort in every hard session. This meant threshold sessions frequently drifted upward into race-pace efforts, and VO2 max sessions were performed at an intensity that stunted subsequent recovery.

The Norwegian model eventually turned this concept on its head: instead of avoiding the inter-threshold space or red-lining every interval, they made this middle ground deliberately powerful through a highly controlled threshold focus. By keeping "hard" efforts strictly anchored below the second threshold (LT2), they were able to accumulate far more total volume without the systemic "crash" associated with the older club models.

At the recreational level, the lack of control showed up as stagnation or burnout. Fatigue became normalised and even celebrated as a marker of commitment. At the time, there was no clear language to describe the issue. The default explanation was often psychological rather than physiological: not tough enough, not committed enough, not disciplined enough.

The training model itself was shared across countries. The reaction to its limitations was not.

In English-speaking coaching cultures, questioning established practice has long been part of the ecosystem. Coaches write books, publish blogs, host podcasts, and debate ideas publicly. There is no single authority or national curriculum. As endurance science evolved, these cracks were challenged out loud.

This is why figures such as Steve Magness have spoken openly about how the way they trained as young runners contributed to stagnation in US distance running through the 1990s and early 2000s. The issue was not effort, but how that effort was distributed and recovered from.

In France, debate is just as vibrant and endless. However, the difference lies in the institutional anchor: the FFA. While freelance coaches and social groups in France frequently "do their own thing," the official coaching certification pathways and club structures create a formalized baseline that the English-speaking world lacks.

But this can also create a form of "knowledge debt," where official manuals may lag five to ten years behind what elite practitioners or independent coaches are already doing. In a centralized system, updating a national curriculum requires bureaucratic consensus and long-term administrative cycles. This means that while an elite coach at the INSEP (the National Institute of Sport) may be using the latest lactate-shuttle science, the volunteer coach at a local club is still following the 2015 manual. Consequently, official language often stays fixed even as day-to-day practice evolves underneath it to match modern evidence..

One reason this debate can feel confusing is that elite training has rarely matched simplified club language. Elite runners, regardless of nationality, have long managed intensity carefully. Lactate was controlled. Easy days were genuinely easy. Hard days had ceilings. Large volumes of sub-threshold work were accumulated without constant exhaustion.

What changed over the last decade was not elite behaviour, but visibility. Better data, better measurement tools, and better communication made these practices easier to see, explain, and eventually adopt outside the elite bubble.

Modern endurance science has not overturned the foundations of training. Zone 2 remains non-negotiable. Aerobic volume still underpins everything. Threshold still matters. High-intensity work still has a place. What has changed is how these elements are used, and how they are controlled.

A key development has been a better understanding of lactate. Rather than viewing lactate simply as a waste product or a marker of suffering, it is now understood as a normal by-product of aerobic metabolism and a useful signal of internal load.

At intensities below the critical boundary, lactate production and clearance remain in balance. This is often associated with the Aerobic Threshold (LT1), typically observed around 2.0 mmol/L of blood lactate (though individual values vary). Above it, lactate accumulates rapidly and fatigue accelerates. This upper boundary is commonly associated with the Anaerobic Threshold or maximal lactate steady state (LT2 or MLSS), often cited around 4.0 mmol/L. This boundary matters far more for training adaptation than any single race pace.

In laboratory settings, lactate measurements help identify this line. In daily training, however, we need a practical, repeatable proxy. This is where Critical Speed (CS) comes in.

CS acts as an external output marker for that internal metabolic boundary. It tells us, in pace terms, where sustainable aerobic work ends and non-sustainable effort begins. For context, Critical Speed typically sits at roughly 88% to 92% of VO2 max velocity for most trained runners, making it a far more stable anchor for aerobic development than maximal-speed metrics. For recreational athletes, the effective ceiling is often lower than expected; running slightly slower than instinctively feels "right" is often more specific for aerobic development.

By working just below CS, athletes accumulate large amounts of high-quality aerobic work while keeping lactate stable and recovery manageable. Threshold, in this framework, is no longer a target to attack but a ceiling to respect. VO2 max work remains useful, but it is applied sparingly. Large volumes of training now sit just under the lactate tipping point, where efficiency improves without excessive systemic stress.

The words did not change as quickly as the practice. Terms like seuil, tempo, or threshold began to cover too much ground. They described everything from controlled aerobic work to near-maximal efforts, depending on context.

Even within France, the language is beginning to fray. Many social groups and freelance coaches have pivoted away from the formal VMA scripts, opting instead for labels like fractionné court or fractionné long (short and long intervals). This shift toward more descriptive labels is often a reaction to the difficulty of implementing precise metrics like VMA in a group setting.

Furthermore, the rising divide between road and trail running has added a new layer of complexity. While road groups might focus purely on pace-based metrics for 10k or marathon training, trail groups incorporate hill sessions and varying terrain that don't always fit neatly into a standardized pace-based language. This fragmentation is a sign of a system trying to find a more flexible vocabulary for the modern runner.

The result for many runners is a paradox: training feels easier, yet performance improves. Fatigue decreases, yet consistency increases. This was not because they were doing less: it was because the signal-to-stress ratio improved.

Most club structures will remain familiar. Easy runs, long runs, threshold sessions, and faster work are not disappearing. What will change is execution. Threshold will become calmer. High-intensity work will become shorter and more deliberate. Easy running will become easier. Progress will be measured in weeks and months, not in how shattered a single session feels.

Language will lag. Physiology will not.

This is not a story about France versus Norway, or tradition versus science. It is a story about a shared European and Western endurance model reaching the limits of its original language.

The goal remains unchanged: to get faster. The method has evolved. Repeatability has replaced exhaustion as the marker of effective training. And that shift is not national. It is generational.