FTP - Functional (I'll come back to this) Threshold Power.
I love FTP. What a metric. It took us out of the labs and onto the trails and roads to do our testing. We could do it any time, at our own convenience, we could check it regularly without having to count the cost of another trip to the nearest good sports lab to find out our lactate thresholds, and no one was going to stab holes in us and take our blood while we were testing for it.
That's my perspective, it's skewed by bias of having to do it "old school" in order to identify an anchor point(s) in which to construct my training and get the desired outcomes from all the work I was putting in. I realise that this si not the same for a couple of generations who have come along since. Power is established and here to stay, and all the introductory pathways (Strava, Trainer Road, etc) and assorted internet "gurus" bang on about FTP long and hard.
As such it's become a bit of a problem for a great many athlete. Here's my perspective, I see some of the problem. Maybe I can help? Here are some of the common pitfalls with FTP that I find make this a tricky or sticky point for many individuals.
1) It's not a badge of honour. This is perhaps the most important point to make. Lots of people get distracted by the size of the number. They set weird goals (for instance getting over 300w - like 299w is going to produce any different an outcome in a race) that are mostly irrelavant and of very little use in the real world. I see this all the time: "I just need to get over XXw and XX will happen to my cycling ability" sorry never seen it happen! Forget the number, and forget any notion of the number being a guarantee of anything.
2) Setting it too high/using a dubious test protocol and then not applying very obvious common sense to the situation. I won't hit you with quotes, or what FTP "is" or "isn't" all I want to offer here is what actually works out in the real world, and what Ive seen time and time again lead to zero results or zero physical improvement:
If the test protocol is too short then we all get an elevated number that doesn't equate to any race scenario.
Short ramp test? = Don't bother...
8 minutes? = Don't bother!
Seriously, just make it up, and save yourself the time testing.
20 minute power minus 5% doesn't work for most individuals, but does at least start to get closer. I've only seen it equate anywhere near this for very well conditioned pros or time trial racers who also regulalry perform as hard as they can in 25 and 50 miles time trials. For everyone else it's somewhere between 20 minute power minus 10% to 30%.
If you choose 20 minutes start with minus 5% and then see how you can perform in training. Most often people struggle on anything threshold based, particularly a session like 2 x 20 in zone 4. If this is the case just apply common sense (subtract another 5-10% until the sessions are actually possible) or do a longer test.
1 hour... mmm... This is actually very diffeicult to do unless you are in a race or super committed and fit. Fitness is a factor. For this reason I always roll with the 20 minute test with most athletes but then keep tabs on RPE, heart rate and just how motivated or fearful they become of tempo and threshold work. If you struggle then FTP is set too high. It should be hard, but not hanging on for dear life every minute of the effort...
Which brings me to point 3...
3) Going too hard in a test. This is actually a thing. We are testing for maximum aerobic power. We are not testing for max power we can suatain whilst constantly going anaerobic and barely recovering. If you fear the FTP test then I'd suggest you are just going too hard into it. It's not a quest for a PB. It's clarity on where to pitch the rest of your training by creating training zones based on the FTP number. Horrible pukey, death FTP tesing is only about 10w higher than challenging but totally doable again in a dy or two FTP testing.
If death testing creates 300w, and Attainable testing creates 290w then the difference in training zones is next to nothing:
Zone 1: 0-162w
Zone 2: 163-220w
Zone 3: 221-263w
Zone 4: 264-307w
Zone 5: 308-350w
Zone 6: >351w
Zone 1: 0-167w
Zone 2: 168-227w
Zone 3: 228-272w
Zone 4: 273-317w
Zone 5: 318-362w
Zone 6: >363w
Given that the best bang for your buck in any training session is to aim for the middle of the training zone or lower, there's absolutely no reason on earth to flog yourself to death going too hard in a 20 minute test. It makes no difference other than to your enjoyment of testing and the reluctance you'll develop to do the next test(s) to stay on track.
4) Applying all of the above logic and advice yet still setting FTP too high, or seeing the number has gone down and "forgetting" to update your FTP in the software.
Don't do it!
It's a complete waste of time training, following a training plan, trusting any of the charts in software like TrainingPeaks, if you FTP is set too high. What about too low? Well, the charts might be out, but the chances of overtraining go down considerable. The chances you'll train like a pro go up considerably. If I ask an amateur with the aformentioned 290w FTP to ride train in zone 2 (163-220w) and they will nearly always shoot for 219w. Ask a pro with the same numbers to train in zone 2 and more times than not they are going to shoot for 174w. There's a reason they all end faster than any of us. This is abig part of it. FTP set too high makes this situation even more profound because now riding at the top of zone 2 and probably not getting all the desired adaptations turns into riding entirely in zone 3 and getting even less of the desired adaptation. Set FTP realistically and train in the middle of the zones.
5) Ignoring Function (I said I'd come back to it)
FTP where F = Function.
Function changes with illness. With stress. With Dehydration. With Fatigue. With (endless list... choose one!)
When it comes to training well for endurance we always want to consider that we are biological and constantly in flux. Heart rate is still a valid measure of performance even when we own a power meter. RPE is still a valid counter-balance to the tech. If power is constant and heart rate starts to climb then function is changing. If it feels harder than the numbers suggest then it probably is. Some days it's better to come home with lower power numbers but the desired physiological stress than to come home with a nice even power. Training is not a test or a race, it's not about a performance metric. Speed is not the benchmark. Accuracy of training is the benchmark of well performed training and to do this well we have to balance more than just the wattage number on a screen. How do I feel today? How are my legs? Is it easier/tougher than usual? What imy heart rate doing for this power return? Stay human and understand function and it's role in your training.
FTP. It's a beautiful thing. It's a tool. Learn to use. Learn to use it well and it will always serve you well in return.