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How I Think of WKO4's mFTP

WKO4 introduced a lot of new metrics and new thinking about old metrics. EN was an early adopter of FTP both from the perspective of how to use FTP to guide training and how to use FTP to guide race planning. Over the years, a lot of people on the team have started looking at other metrics, such as 5-hour power, as useful tools for race planning.

With the introduction of WKO4, Coggan and team 'reset' the way that they use FTP vs the way that the general public used and thought of the term/concept. This create a lot of confusion, discussion and ultimately a better understanding of the concept. There is an ongoing discussion about how to help people understand the Power Duration Curve, mFTP and the other metrics on the WKO4 FB forum. I wanted to re-post some information that I wrote and posted for that forum here so that it is available for the team.

I believe that a lot of the confusion in discussion of about FTP comes about because we are sometimes not clear about the questions we are trying to answer. FTP as a concept has evolved from something that, previously, has been generally understood/misunderstood to something about which WKO4 requires us to have a more specific understanding.

With respect to FTP, I ask myself three questions:

1. What is FTP? 
Coggan defines it as: “The highest power that a rider can maintain in a quasi-steady state without fatiguing.” In other words, if we never got tired, and we were working at our maximal aerobic plus our basal level of anaerobic contribution, that power would be FTP. It is at the point where the PDC makes an inflexion downwards. It is really representing the maximal aerobic power that I produce (plus a little FRC) before it starts to decline from fatigue.

2. How do I estimate FTP?
There are lots of ways to estimate it. Some are better than others. A 20-minute test is one way to estimate FTP. A 60-minute test is another way to estimate FTP. Doing a series of maximal efforts and loading them into WKO4 so that I have a PDC is another way to estimate FTP. From everything that I have seen over the last couple years, WKO4 gives me much more insight, not only into my FTP, but into my ability to perform at different timeframes. But – WKO4 is creating a PDC which is a MODEL of my performance that is optimized to fit my data. Statistically, it is more accurate than any single effort. The PDC can never really be RIGHT or WRONG… it is only OUT OF DATE. If I disagree with it – I go do an effort and feed it more data, then it adjusts.

3. Why do I care what my FTP is?
I care for two reasons: To know how to train better and to plan how to execute races. To some degree, WKO4 with the PDC and iLevels have made FTP less relevant to my training. Now I plan training sessions based on different areas of the PDC whereas in the past I planned training sessions based on percentages of FTP. WKO4 (and the team) have dramatically changed how I think about my training. I believe it is one of the biggest advancements in understanding how to train that I have ever seen.

With respect to race execution, WKO4 and the PDC give pretty good insight into what I can expect on race day. For a long-course triathlon, (5+ hour rides), the PDC is probably not as useful to me as it could be if I had closed courses to train on. The realities of stop signs, towns, etc diminish the value of the data that I am able to put into the model. I use sFTP (which I base on a 20-minute test) and mFTP and 5-hour power and… together to plan race execution.

This was perhaps the biggest hurdle that I had to get over when I started with WKO4… I thought that I was learning how to use a tool. In fact, I was learning a much more specific mindset of how to think about my training and how to impact my fitness.

The picture below helps illustrate the concepts:


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Comments

  • Great stuff Rich,
    So did Coggan redefine FTP and remove the 60 min limit?
    What is PDC ?
  • @tim cronk - PDC is Power Duration Curve. That is the curve that WKO4 fits to all of your mean maximal power data to model your efforts. the MMP (mean maximal power) curve is your actual data, PDC (power duration curve) is the model of that data.

    In fairness (since Coggan invented FTP) - I think that someone else 'defined it' as being 60-minutes. The best I can tell is that there is a lot of physiology work that suggest 'thresholds' occur somewhere between 30-70 minutes. He objects to calling FTP hour-power and says that was someone else's term, not his. Who knows? He gets really sensitive on the subject; seems that he feel everyone took over the terminology without attributing him with the work. 

    Coggan emphasizes that FTP is meant to define a physiological condition and that the 20-minute test, 60-minute test, PDC, etc are all estimating FTP. Within WKO4, mFTP refers to the Modelled FTP and is calculated from that inflection point on the PDC, sFTP refers to Set FTP and is set by the user. sFTP is used to calculate things like CTL, VI, IF... so it seems a lot of people use a 20-minute test (or their best guess) for sFTP.

    When you look at the graph, you can tell that the PDC is decreasing at a decreasing rate... if you didn't fatigue, you could imagine that the curve would level out as an asymptote to mFTP. But then there is an inflection point (fatigue set in) and the PDC starts decreasing at an increasing rate. It looks like a straight line on the PDC chart, but keep in mind that this is a log-scale chart... straight lines on this chart are power curves in linear time.

    In WKO4, mFTP is that power the PDC would level off at if fatigue didn't set in and TTE is the time where mFTP occurs, or the time when one can no longer operate at their max aerobic level.
  • "@Rich Stanbaugh all good stuff here, thanks.
    I was wondering about your actual approach to training that part of your PDC that is less than 10 minutes?
    It seems to me there are at least two different paths.
    Either use the S/W curve to identify the "lowest hanging fruit", then use ilevels that are closest to that minimum; or
    Use the PDC curve and attack those portion(s) where yor actual performance is below the PDC.

    In my case, the S/W curve suggests intervals around 30 secs, whereas the PDC approach suggests intervals of 90 secs.

  • @Peter Greagg I used the PDC curve to identify "lowest hanging fruit" and then attacked them. I used iLevels to determine the recovery time between intervals. For example - looking at my current chart, I would do the following sets:

    • 2x Pmax (10sec sprints, starting from a standing start in the small chain ring) w/ 7+ minutes recovery
    • 30" @ 750w - 7-12' recovery
    • 1' @ 650w - 7-12' recovery
    • 90" @ 500w - 7-12' recovery
    Probably I would not be able to hit high numbers after that, so would finish my legs off with 350w repeats up a hill for as long as I could hold them, each with a substantial recovery. 



    I have not tried the iLevel repeats at 95% that Cusick suggests. The main reasons are:
    1. Time - I typically try to get 3 meaningful bike workouts in each week, not sure where I would fit that workout
    2. Good data: My challenge is to keep the PDC populated with good data. So I will target several intervals in a workout so long as they are substantially using the same energy system.
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