And Why Feeling “Good” Can Be Misleading
The long run is often treated as the most honest workout in marathon training.
If you can run long, you must be ready. If the distance is covered without crisis, the preparation is working.
This belief is comforting.
And incomplete.
The long run rarely lies outright.
It simply answers a different question than the one most runners think they are asking.
Running long in controlled conditions builds durability. It teaches the body to stay in motion for hours. It strengthens connective tissue, reinforces aerobic efficiency, and makes the idea of covering marathon distance feel normal.
All of this matters.
But none of it guarantees that the body knows how to function when the cost of movement starts to rise.
The long run, when always performed in comfort, confirms endurance — not resistance.
Most long runs end before they become structurally demanding. The pace is managed. The effort is kept under control. Fatigue is present, but never threatening. You finish tired, satisfied, and reassured.
And that reassurance is exactly the problem.
Because the most difficult part of the marathon is not the distance.
It is the condition in which the distance must be covered.
The final kilometers are not simply “more of the same.” They are run with compromised mechanics, reduced elasticity, and accumulated muscle damage. The body you train early in a long run is not the body that finishes the race.
If the long run never exposes this difference, it never prepares the runner for it.
This is why many athletes can complete long runs of thirty kilometers or more and still struggle badly late in the marathon. The training was not wrong. It was simply incomplete.
The long run taught them how to stop before the problem appeared.
When the race removes that option, the system has no reference point.
This does not mean that long runs should become mini-races.
It does not mean pushing to exhaustion every weekend.
And it certainly does not mean chasing suffering as proof of commitment.
What it means is that duration alone is not a sufficient stimulus.
Adaptation depends on how fatigue is introduced, not just how long it is sustained.
A long run that always feels “good” may be doing its job perfectly — for the wrong objective.
It builds confidence.
It builds routine.
It builds consistency.
What it does not automatically build is the ability to stay functional when comfort disappears.
And that ability is exactly what the marathon demands.
This is why runners often reach a point late in the race where nothing feels dramatically wrong, yet nothing works the way it did before. The pace is suddenly expensive. Form degrades quietly. Effort rises without explanation.
The long run did not fail.
It simply never trained this scenario.
In Fino al km 38 andava tutto bene, the long run is reframed not as a test of distance, but as a test of behavior under fatigue. The book explores why long runs that always end cleanly can create a false sense of readiness — and how subtle changes in training exposure shape what happens when the race no longer allows control.
The long run does not predict the marathon.
It predicts the conditions it prepared you for.
You can find the book here:
https://a.co/d/678Qvyn