Acute versus chronic load calculator

The load of the last seven days is divided by the weekly average of the last four. If the result is 1.0, this week you have done exactly what you had been doing. If it is 1.5, you have done 50 % more than your average.

The underlying idea is sound and predates any formula: overuse injuries are associated more with the jump than with the volume. A cyclist used to 15 hours a week tolerates an 18-hour week; someone coming from 5 hours does not. What the ratio tries to capture is that jump, normalised, so it can be compared between people and between weeks.

Why this is not a traffic light

This is where this calculator departs from almost every other one that computes the same thing. The original formulation popularised a “sweet spot” around 0.8 to 1.3 and a risk zone above 1.5, and those figures were repeated for years as if they were clinical thresholds. They are not.

Since 2019 there has been serious published methodological criticism of that model: the specific thresholds do not hold, the quotient carries statistical problems — it shares its numerator with its denominator — and the relationship with injury is much weaker than the original figure suggested. It has even been shown that a randomly generated chronic load produces a similar association, which says a good deal about how much signal is really there.

So why keep it? Because the magnitude of the jump is still useful information even when the exact threshold is not. Knowing that you have gone 45 % above your average matters. Believing that 1.49 is safe and 1.51 is dangerous does not.

Where it stops working

• It needs four weeks of real history. If you are coming back from injury or from a holiday, the denominator is artificially low and any normal week will spike the quotient without it meaning anything.
• It does not distinguish the type of load. Ten hours of easy riding and ten hours with three interval sessions give the same number and do not ask the same of the body.
• It knows nothing about the rest of your life. Sleeping five hours, an intense week at work or a recent illness weigh as much as the load and do not enter the calculation.
• A sharp drop is not free either. Coming down a long way at once loses adaptations, and that is the other half of the reading that is almost never mentioned.