Challenging the validity of an accepted training metric and discussing alternatives.
Editor’s Note: There are topics that, as a cyclist, become tiresome. You have read the many takes, heard the debates ad nauseam, and know that everyone is an expert. Any further mention falls on deaf ears.
FTP (Functional Threshold Power) is one of those topics for me. Now and then, a new voice comes along. One that explains complex details in simple, easily understood terms. Not an expert, per se, but has accumulated a deep knowledge base through experience – trial and error.
A refreshing look at, let’s just say it, a topic that has left us with paralysis by analysis. Our heads are still spinning, hoping to land, by chance, on the definitive answer. Or at least one we can hang our hat on.
Jason Hurst is one of those cyclists. Not a scientist or traditional expert by degree. He isn’t a coach, and I’m not sure he’s ever had one. Jason is a critical thinker. One that knows how to dissect an issue to its core, discarding the unnecessary and presenting it in a handy, helpful package for his fellow cyclists.
Enjoy the first article in a three-part series on the topic of FTP. The first of many articles in which Jason will give new life to tedious cycling topics and bring them back to life. Or at least put them in practical terms we can all understand.
What Does FTP Mean To You?
Given the prevalence of ‘FTP increase’ screenshots in some virtual cycling clubs, it would seem that many people do place a great deal of stock in their Functional Threshold Power (FTP) number.
Some may even let it define their cycling experience. I want to challenge the whole concept of FTP as anything other than a benchmark against which training gains are measured. A benchmark with many caveats, that is.
This series of articles isn’t a training plan or even general advice. It’s an opportunity to express my thoughts on the concept of FTP and what I believe is the over-emphasis in many cycling-related conversations. It’s an opportunity to explore the pros and cons and the impact that FTP has on your training and broader cycling goals.
Maybe it will resonate with you. Perhaps it won’t. Maybe you have no idea what FTP is, or you simply don’t care.
I’m hoping the three articles in this series inform those new to Cycling and generate some healthy discussion.
Who Am I?
I am not a doctor, a coach, or an ex-pro. I’m an average Jason with seven or so years of struggle and graft in my experience bag. The experience derived from efforts to improve my cardiovascular fitness and overall health, overcome injury and muscular imbalances and enjoy my cycling as much as possible.
I read a lot. I listen carefully to subject matter experts in the areas of physiology and fitness. I pay very close attention when I work with a health professional to understand the ‘how and why’ of a recommended course of treatment. I am fascinated by human physiology, especially as it relates to cycling.
What Is FTP?
FTP is short for Functional Threshold Power. The clue is in the name. It is a measurement of the threshold power that you can maintain over a given period. Threshold being typically a (high) zone 4 if measured with a standard 6 tier scale of effort. The idea is that the period is considerably longer than you could sustain a VO2Max (zone 5) or anaerobic (zone 6) effort but shorter than you could sustain recovery (zone 1), endurance (zone 2), or tempo (zone 3) efforts.
A threshold effort is the point at which your lactate levels have risen such that your body is just managing to cope and ward off near-term fatigue by processing the lactate to clear it from your muscles. It feels a bit awful, but you can push on for a while longer. There are more comprehensive and medically accurate descriptions of what constitutes a threshold effort, but I’ve chosen to use my own. Google is a friend of the curious.
FTP is the average power a cyclist can maintain over 60 minutes. Why 60 minutes? It’s probably because someone said it once, and it stuck. It’s also conveniently precisely one hour and sounds sciencey.
60 minute FTP probably falls into the same ‘cycling lore’ bucket as “ball of the foot over pedal spindle” and “knee over pedal spindle” and other bike fitting myths. Easier to package and sell to the consumer. Or maybe that’s my healthy skepticism kicking in.
Some prolific Googling uncovered a 2017 blog post by Mark Tallon, Ph.D., titled “The Myth of Functional Threshold Power (FTP).” The observation by Dr. Andrew Coggan that experts chose 60 minutes because it is the approximate duration of a 40km Time Trial is consistent with other explanations I subsequently uncovered.
For determining FTP, a 40km Time Trial effort was considered representative of a sufficiently challenging threshold effort to establish a reliable measure of an endurance athlete’s performance potential. Like I said because it’s precisely one hour and sounds sciencey.
How Do You Determine Your FTP?
The easiest way to determine your FTP is to do an FTP test. Actually, I tell a lie. It’s not easy. In fact, it is a horrible and exhausting experience if performed correctly. There is no escaping it if you want or need to know your FTP. A typical 20-minute test is definitely not a maximal effort test, though. So you shouldn’t be on your death bed at the end of it.
Many first-timers get their pacing horribly wrong. They finish too strongly, in which case they could have maintained a higher average with better pacing, or they start hard and fade badly in the latter half and produce a lower than expected average. You don’t know how much effort is too much or too little until you have some experience with FTP tests.
Jump on. Have a go. Pay attention and learn from it.
Cyclists should perform FTP tests with Erg mode turned off. Some platforms may turn Erg mode off by default when performing an FTP test, but you should make sure just in case. Erg mode is useful for many workouts as it helps to stabilize your power output and means you are more likely to achieve the target watts for the duration of any given workout segment.
For an FTP test, though, you need to control your effort and cadence and raise or lower your power output based on how you feel. Erg mode will interfere with the control of your effort and produce an unreliable FTP number because you won’t know if the deciding factor was ERG mode or your physiological limitations.
All virtual cycling or training platforms that I am aware of include at least a couple of FTP tests in their list of workouts. Often they are based on a 20-minute‘ test’ that assesses your average threshold power with a warm-up beforehand and cool-down afterward. Some will include VO2Max efforts before the 20-minute test to put some sting into your legs and ideally produce a more realistic FTP number once it is extrapolated over a longer time.
That longer time is usually 60 minutes, so when you see an FTP number, it is often not the actual average of the 20-minute effort but the result of a widely accepted formula to calculate your 60 minute FTP. That formula takes the average of a 20-minute test and multiplies it by 95% to derive 60 minute FTP. For an excellent analysis of the integrity of this formula and the validity of FTP in general, I recommend an article titled “Can you trust the FTP test to give correct threshold power?” by Dr. Martin Bonnevie-Svendsen.
That is why your best 20-minute effort will typically not be the same as your FTP number if recorded across all your rides on a particular platform. Your ‘best effort’ should be higher than your FTP.
Ultimately, FTP can be assessed based on any period you want, representing your typical activity duration, e.g., more than a few minutes and less than many hours. That test duration (and formula if extrapolating over a more extended period) just needs to be stated in association with the FTP number to validate it.
Using a ramp (really a step) test and then applying a formula to determine your FTP is also possible. The resulting FTP number will be a percentage (*75) of the wattage during your last successful (*one minute) ramp. That is the ramp before the one during which you could no longer pedal above a minimum cadence. Pick your poison. None taste pleasant!
*These are the numbers that I encountered when I Googled “ramp test for TP.” Variations may exist.
Are There Alternatives To FTP?
I would argue that knowing your power over a variety of durations is more informative. E.g., 10s, 30s, 1m, 5m, 20m, and perhaps longer depending on the events you prefer. Not isolated ‘best efforts’ either, as you see in the ride summary screen in Zwift. Those numbers should be gathered methodically and throughout a standardized (and repeatable) ride so that you carry some fatigue into each effort.
The 4DP test developed by Sufferfest (now part of the Wahoo SYSTM training app) is one such attempt to provide a more broadly applicable set of training and performance metrics. Then you will have a better understanding of your strengths and weaknesses and a better idea of what you are capable of at any given point in any given ride.
Trainingpeaks WKO4 application introduced new metrics such as Modeled FTP and Time To Exhaustion for optimizing endurance training. It designed these to improve upon the traditional single FTP number as the determinant of workout intensity and the success of trained adaptations. Examining these metrics is beyond the scope of this article, but I strongly encourage you to follow the above link in your own time and settle in for some interesting reading.
What Is FTP Used For?
In the following article in this series, I’ll discuss the typical uses of FTP and what FTP means to me. I’ll also make a case for my dislike of the ‘in ride FTP increase’ notification used in Zwift and some other platforms and why it is misleading.
Just that, what are your thoughts on this approach to the FTP debate so far? Comment below! Your fellow virtual cyclists want to know.
For more great performance-enhancing information like this check out the Training & Performance page on The ZOM!