Your FTP went down. Six reasons, and only one of them is fitness

You did the same test on the same trainer as last time. You suffered at least as much. The number came out 12 watts lower, and the rest of the evening was spent wondering where the winter went.

Before you rewrite your plan: a lower test result is not the same thing as lost fitness, and in most cases it is not lost fitness. Here are the six explanations in order of how often they turn out to be the answer.

What an FTP test actually measures

A threshold test measures your best sustained effort on that day, in those conditions, under that protocol, with that motivation. Fitness is one input among several. Treating the output as a pure fitness readout is the mistake that turns an ordinary bad day into a crisis of confidence.

The number also has real error bars. Repeat the same test on the same rider across a week and you will not get the same figure — which means a small change between tests may be indistinguishable from noise. FTP explained: how to test it and raise it covers the protocols; this article is about what to do when one disappoints you.

The six causes, most likely first

The test that answers the question

There is a simple way to find out whether the drop is real: look at your ride data instead of your test data.

If your best 20-minute power from actual rides over the last month is as high as it was three months ago, your threshold has not moved and the test was the problem. If those real-world efforts have fallen too, something has genuinely changed and it is worth investigating. This is one of the strongest arguments for a power curve built from every ride rather than from tests — the rides are a much larger sample, and nobody games them.

If it is real, what then

• Check the boring things first. Sleep, food, illness and stress explain most genuine declines in amateur riders, and none of them are solved by training harder. Low energy availability and REDs and iron and ferritin are the two worth ruling out properly.
• Look at what you have actually been doing. If the last eight weeks were long easy rides, a flat threshold is the expected outcome, not a surprise. Add threshold work — over-unders are a good re-entry — and retest in six weeks.
• Check you are not permanently tired. A rider who never comes back to positive form will test badly forever. Recovery is training is the fix, and it is less popular than it should be.
• Accept the seasons. Nobody holds peak threshold for twelve months. A lower number in November is a plan working, not failing — see how to peak twice in one season.

A better relationship with the number

FTP is a useful anchor for setting training zones and a poor scoreboard for your worth as a cyclist. The riders who improve most steadily tend to be the ones who test occasionally, adjust their zones, and then forget about it — rather than the ones who test monthly and ride the emotional wave.

Moveee builds your power curve from every ride you upload rather than from tests alone, so you can see whether a disappointing test is contradicted by your actual riding. Have a look at your power profile — and if your best real efforts are fine, the only thing that went down was one Tuesday evening.