Whether you’re new to riding with power or highly versed in the ways of watts, FTP assessment is one of the most important—yet most poorly performed—aspect of power-based training.
You can see how under-utilized assessment is in the world of cycling by quickly skimming the backlog of 20-minute & 8-minute tests in TrainerRoad, where you’ll see workout after workout missing the steady-state objective by blowing up early, finishing too strongly, continuous upward-ramping effort, or riding so steadily that it’s clear it wasn’t a maximal effort. The goal of an FTP assessment is to serve as a useful & accurate estimate of Functional Threshold Power; however, these errors illustrate that athletes are missing the goal of assessment.
The point of this article is not to be critical or blame one aspect or another; rather, we’re interested in helping riders of all experience levels make the most of their test workouts to get the most value from all workouts following their test. Keep in mind that all of your TrainerRoad workouts will be based off your FTP test, thus emphasizing the importance of proper assessment.
What is FTP?
I’d venture to say that most riders understand that FTP assessment is about deriving their FTP. But what does FTP really measure?
Your Functional Threshold Power, or FTP, is the foundation upon which all of your power-based workouts are built. In essence, it’s the measure of your highest sustainable power. This doesn’t mean much unless we talk about FTP in relation to goal duration which, in this case, is upwards of 20 minutes.
And while FTP goes by many names, it’s basically a measure of your ability to maintain a high—but manageable—workload for a somewhat lengthy duration, one where your lactate production has risen, leveled off, and then closely matches your lactate removal and just barely keeps that flooding at bay.
Trying to sustain high effort for durations of this length pushes you into that grey area between power you can sustain all day and the fleeting power you can only tolerate for a couple of minutes.
This is a very trainable physiological response and a useful measure of fitness, one in which a structured, progressive training plan tempered with adequate recovery can bring consistent and lasting increases.
Let’s move on to the ‘why’ of assessing FTP. Then, we’ll discuss the ‘how’.
When creating workouts, we have to anchor our power zones onto something, so we your measure of FTP. Here’s why: a lot of fitness scientists and researchers who are smarter than us have done the legwork and applied it to generations of endurance athletes, providing us all with the benefit of their findings without retracing their steps.
So because we use this measure of fitness as your anchor and the basis for all of your training, it’s important that this number estimates your actual sustainable-power threshold as closely as possible.
By riding as hard as you can, relative to the 8- or 20-minute durations, we can extrapolate the point at which your muscles are successfully walking that lactic tightrope and maintaining the balance between hard work and too-hard work.
This is what we’re trying to find (regardless of your selected testing format) and it’s what we use over time in order to track changes in your fitness.
How to Assess Your FTP
When it comes to testing your FTP it’s important to keep your focus in order to overcome a few challenges athletes commonly face along the way.
Challenge 1: Don’t Go Out Too Hard
This is the heart of the ‘how’ of FTP assessment. It really boils down to what I just mentioned above: walking the tightrope between hard work and too-hard work.
The biggest challenge you’ll face is finding your balance early enough in the assessment so that you don’t waste the early minutes with effort that’s too low, nor sabotage the final minutes with early effort that’s too high.
After all, the goal is a steady-state effort—one that sees minimal fluctuations in power output and limits the unavoidable zigs & zags to a tight range close to that not-too-easy/not-too-hard power figure. This is best achieved with fresh legs and a fair amount of practice. Unfortunately, riders assessing for their first time don’t have the luxury of the latter.
So the advice is simple: don’t go out too hard. At the same time, you don’t want to go out too easy. But with no informed idea of either, you can only guess where to start things off. The best way to do this is by holding back a little bit at first.
So, go hard but know that you’ve got a little room to grow.
Challenge 2: Pace Yourself
The next biggest challenge is pacing yourself throughout the test. This is best accomplished with subtle increases and decreases in effort every couple of minutes during intervals. In the case of the 20-minute test, we prompt you to evaluate your effort every five minutes. In the 8-minute test, these reminders happen every two minutes; however, you can do them at any interval that suits your level of concentration, focus and motivation.
As you evaluate yourself, keep your subsequent changes small. Something along the lines of a 2-3% change is all it should take to either clear muscles that are starting to load up or push a little harder without loading them up.
For example, a rider powering along at 220 watts might ease off or pick things up by 4-6 watts — not much at all.
Challenge 3: Don’t Save It For The End
The final challenge is avoiding the temptation to surge to the line and skew your FTP-estimate with a big dose of anaerobically-driven power at the end. This is a tactic you can use anywhere else but not during an FTP assessment. Use it at the end of an interval, at the end of a race, at the end of a group ride — but not at the end of an assessment.
Surging to the line not only inaccurately inflates your average power, but it also suggests that you held back too much during the bulk of your assessment.
Here’s to hoping this advice proves useful and saves you the misery or repeating your assessment workout or mistrusting the results of one you might be questioning. Good luck!
For more answers to your cycling training questions, listen to our podcast Ask a Cycling Coach — the only podcast dedicated to making you a faster cyclist. New episodes are released weekly.
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