Episode 283 FTP proxies

Listening to the recent potluck discussion, something caught my attention during the discussion about using proxies such as 60 min NP as a means to determine FTP. Of particular interest was the comment at ~23 minutes in, where it was noted people frequently do significantly higher NP for 45 minutes to an hour or more during races than their FTP would indicate as possible.

Before deciding that this would mean one’s FTP is higher than previously estimated, first we should keep in mind Coggan’s original definition, “FTP stands for Functional Threshold Power, defined as the highest power that you can maintain in a quasi-steady state, without fatiguing, for approximately one hour.” Two critical points: 1) quasi-steady state, and 2) without fatiguing. Neither of those situations exist in race scenarios.

From the perspective of wanting to know one’s FTP, in so far as it represents a physiological state roughly equating to MLSS, and thus provides utility in setting training zones for aerobic training, I would think that trying to estimate a ‘steady-state’ value based on decidedly non-steady state normalized power should be avoided.

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From one of Andy Coggan’s post to the old Wattage List on Topica ~15+ years ago:

…er, ways of determining your functional threshold power (roughly in order of increasing certainty):

  1. from inspection of a ride file.
  2. from power distribution profile from multiple rides.
  3. from blood lactate measurements (better or worse, depending on how it is done).
  4. based on normalized power from a hard ~1 h race.
  5. using critical power testing and analysis.
  6. from the power that you can routinely generate during long intervals done in training.
  7. from the average power during a ~1 h TT (the best predictor of performance is performance itself).
    BTW, another method that could be added to this list would be to do an incremental exercise test to determine ‘MAP’, then estimate functional threshold power as being ~75% (range 72-77%, using Ric Stern’s guidelines) of this value. You could then use this estimate as is, or if necessary/desired, further refine it using one of the methods described above (e.g., by doing a TT).

BTW, the reason this approach works is because in trained cyclists, LT falls within a fairly narrow range as a percentage of VO2max, and there is tendency for those with the highest LTs to have the lowest anaerobic capacities (and therefore a slightly lower MAP relative to power at VO2max), and vice-versa. In any case, at the very least knowing your MAP will help ‘bracket’ what could be considered a reasonable range into which you expect your threshold power to fall.

I’ve seen that info before, and have heard AC talk about it on various podcasts. Here’s why I still wouldn’t do it.

Regardless of the race profile and the competitors you’re facing, unless you’re the one driving the break, if you’re an experienced cyclist you’re trying to minimize power output whenever possible. Can’t speak for the assembled masses, but if my NP after a crit, even a really hard crit, isn’t significantly lower than my FTP, I feel like I screwed up my tactics/racecraft. I’ve seen similar results from mid-to-long road races, too. If I’m deliberately metering out my power output to maximize race results, NP will skew below FTP, not above. If you’re spiking your power so high and so frequently as to result in a ‘NP Buster’, then it may be that one’s racecraft is lacking.

@Mudge @dkrenik great insights! For what it’s worth, I’ve gotten into the habit of sticking to the deep science in the main episodes and use the Potlucks to discuss “quasi-science” questions that I’ve heard coaches and athletes discuss. Seems more in the spirit of the potlucks.

In the case of the 1 hour normalized power, I find it an interesting anomaly but agree that I personally wouldn’t use it as a reliable estimate of an athletes threshold power.

@Mudge @trevor I couldn’t agree more. At 62+ years old, I’ve been able to record “NP busters” for almost 20 years. I find them interesting to look at and that’s about it. Anymore I think that they’re more of an artifact of the workout structure or course profile.

I did a 30/15 workout on Zwift once, up the Alpe du Zwift climb, and surprisingly did my fastest ascent ever of the climb. Looking at my NP after the fact, it turned out to be a few % points above my mFTP, which I found interesting. Though I’ve heard people suggest they might try such an approach to racing a TT, I’m not convinced it would be faster than a more conventional pacing strategy.

I’ve seen that periodically doing time trial as well. It’s interesting to see, but, I think I’m still going to stick to more traditional pacing strategies.

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