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Does Functional Threshold Power Matter? [GCN Video and Discussion]
Here's the video...would love to hear your discussions on the topic before I chime in!!!
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Here's the video...would love to hear your discussions on the topic before I chime in!!!
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When I watched the video, it simply reinforced in my mind that 5 hour power is what matters for Ironman. It also suggests that if you focused intensively on sprint power, it's not going to help too much for long course racing. But since the test was based on two ends of the ability spectrum, I would think that FTP is still a valuable guide for overall training, especially for those that like to race all distances.
Just reinforced what I kinda already knew.
Sufferfest moved to a less than traditional FTP test which incorporates an "FTP" for sprints, climbs, attacks, etc. I think that makes a lot of sense for a traditional road racer, but less sense for us nerdy triathletes.
Personally, I stopped doing FTP tests many years ago and I don't think has impacted my ability to get faster at all. I know what my FTP is give or take 5 points. However, I recently did the Ramp Test on TrainerRoad, which said my FTP was 175. Either I failed miserably at the test (likely) or their test isn't that accurate because my FTP is more like 200. That was about 4 weeks ago and now I'm ready to increase my FTP to 205.
I love Sufferfest workouts on TrainerRoad and use The Wretched and There is No Try as my 2 main workouts during the offseason.
To me FTP is great measure of progress. What is it today compared to a month ago? I also think that you can improve FTP by training all the other metrics from sprint power to 5 hour power and that in doing so it will inform you of your strengths and areas you should work on. FTP also gives us starting points to inform our training and racing so we know what we might attempt on a given training session. Can I ride .68 of my FTP for 5 hours or how does it feel if I go to .72? In different parts of the training cycle we can focus on different skill areas. For example my one minute and 5 minute power are very low in percentile ranking compared to my FTP amid my peers... so it makes sense to me to spend some effort improving those areas even though I never intend to move up in any race I do as a result of my sprinting. As I get closer to a HIM or IM event I would be very focused on dialing in my 5 hour power and understanding that number regardless of my FTP. But clearly we all have strengths and weaknesses. We should understand how we can deploy them on race day to our best advantage.
YES it does matter , But, What doesnt matter is what you call it.
What does matter is that you know your data for all time frames, from max power in seconds all the way to 5hr power and beyond , so that you can find any weakness timeframes , work on your distance race, or focus on what is important to you. The correlations from one time frame to the other will be relevant but individually different.
The video does a great job of proving two cyclists having very different correlations when comparing max sprint to FTP to 30" intervals. My problem with the video was after explaining to us that FTP was 1hr power, they then go on to "estimate" FTP with a 20' test for the comparisons. The comparisons would still be the same but they just should have used 20 minute power in place of the estimated FTP. It would also stand to reason based on the data and comparisons they were proving that the differential would have been even greater if using 60' power.
The big guy with 247FTP/20' power was able to produce 5.87 times FTP for max power and 2.02 times FTP for 30" intervals.
The little guy with 342FTP/20' power was able to produce 3.14 times FTP for max power and 1.6 times FTP for 30" intervals.
I went on Zwiftpower to get some real people ,real data, from real (ok virtual races) comparisons. Using the 90day power curve we can get good data comps for 20' and 45' . I'm not using 60' because lack of 60' race data in most of the power curves. Besides myself, I chose the people below because I know they race a lot and the data should be accurate depiction of their true abilities.
@Coach Patrick 45' power is 90% of 20' power
@Tim Sullivan 45' power is 91% of 20' power
@Teri Cashmore 45' power is 97% of 20' power
@Tim Cronk 45' power is 95% of 20' power
NOTE: every single person above has an FTP listed as higher than their 45' power.
So as you can see very different correlations for each individual, but some good generalizations of larger more powerful riders vs. smaller less powerful riders. I would expect as you increased the length of race data to 1hr and beyond the differential would increase but not quite as much since the drop from 45' to 60' should be less.
Back to the original question of does it matter? Who cares what you call it. I like speaking in terms of power for a specific timeframe and the w/kg of that rider for that time frame. Those are real data , not estimates, no debate.
If you train , like we all do, you should know your power per time frame that you are interested in. 20'-40' is good for short to long sprints, 60'-90' great for OLY , 2.5-3hr HIM, 5-6hr IM.
20' Power is a good test to track improvement and set some efforts for intervals close to FTP like FTP and sweet spot and below. Whether it is a good predictor of 1 hour power is a separate debate. The point of the video that I got was that it is a poor predictor for prescriptive zones for training short intervals VO2 30 sec or 1 min length. We all know that the 20' power and the IF based on that number that we plan to ride our IM or HIM must be proven in a RR or repeated workouts before we can have confidence that X IF is the goal effort for our race. No one should assume that everyone should race IM at .xx of a 20 minute test power for 5-6 hours and they will be able to run just fine.
Its a number and a good number. It just isn't the only number. We need to test at shorter distances (easily done on the zwift cruise and crush rides or races) to see what our shorter power zones are and then do our intervals at somewhere near but below those(90-95%?).
I fall pretty much in line with almost everybody who has already chimed in.
I think FTP is a great number to guide training to gain fitness and get stronger on the bike. It is particularly useful for athletes that are newer to power. The great thing about it is that it provides a nice simple gauge and who doesn't want to keep it simple? The standard EN test (or most FTP tests) is hard, but reasonably repeatable. Then the number generated "FTP" is a really good guide to structure workouts over periods of time (like the OS). Lather, rinse, repeat. It's also nice because it is easily measurable and you can watch fitness entering the body (i.e. over the course of the OS as your FTP goes up). And it is easily used to measure other gains in body comp and strength to weight ratios (W/Kg) and allows us to set goals and work towards them. So as long as we are using it as a tool to structure training and measure progress, I think it is a fantastic measurement for time-strapped, hard working Age Group Triathletes!
I think some of the failings are caught up in semantics and comparisons... FTP (the way we test it, and from the video) is simply an "estimate" of maximum average power that can be sustained for an hour. Some people will be better at taking tests than others. Some power meters will be calibrated differently than others. We can argue until we're blue in the face whether it's true or not, but in my opinion doesn't matter as long as the thing we are measuring is accurate and repeatable (within reason) and can be used to guide our training and measure our progress.
If we blindly follow certain metrics without variations for individuals (i.e. VO2 is 120% of FTP, or race IM at 70% of FTP), we will still gain fitness, but maybe not optimally for each individuals' needs.
So I do think FTP is important. But I also think looking at our power curves are also important. And if the curve is too flat in the front end (instead of downward sloping), we can still likely benefit from doing more VO2 work (or short Zwift racing). Inside of EN, we start with a 70% of FTP for an initial starting point for IM racing, but test and refine this with our Race Rehearsals. Over the years, I have become more of a believer in 5hr Power as a better metric for setting Ironman race efforts and have focused much of my long IM training on pushing that number as high as possible, but that's partly just adding the "Far" under the "Fast" I tried to develop in the OS (Where have I heard that before???)
Once we're 3 or 4 or 8 years in this sport as a power athlete, we can argue over all kinds of minutiae to try and eek out ever shrinking marginal gains to our fitness. Sometimes simply changing exactly what we've been doing will provide the right stimulus (i.e. more Zwift racing this yr, or more VO2 work, or more longer 85" efforts, etc).
So FTP might not be the "End all/Be All" for Bicycle Racers. Some bike racers are Sprinters and others are climbers and others yet are ride all day near threshold guys. But most people reading this aren't bicycle racers at all, and I don't know if I've ever seen a single Professional Bicycle Racer as a member of EN (even though we would welcome them)... But as time crunched AG triathletes, I think FTP might be one of the easiest and most effective tools to use in our bike training toolbox.
[re:posted]
FTP (defined as the max power I can hold for 60', then collapsing) is a number I find very useful for training, and tangentially for racing.
First, how do I determine FTP? I actually do Zwift races which last in the 60' +/- 10' range, and use the NP from them to hone in on an FTP. I also do a fair number of Olympic distance triathlons, and call the bike leg 0.9-0.92 of an FTP. Then there are the estimates I get from Zwift, Strava, and WKO 4. Stir it all together, and I have a good idea of that arbitrary number, without ever really doing a "test" (races are the real test, and the biggest contribution to my calculus) of any length or nature.
So, I've got a number, how do I find it useful for training? At various times in my season, I will be focusing on "intervals" - work efforts punctuated by short relaxation periods - of varying lengths, depending on what distance triathlon I'm racing, and where I am in the training cycle. Rather than worry about specific wattage numbers, I just rely on IF - percentages of that FTP - to guide my efforts. The longer the interval, the lower the IF. EG 2 hours = 0.83, 3 hours = 0.78.5, 10-20' = 100%, etc.
I'm a triathlete, and like all distances from 20k thru 112 k bike leg TTs. I pay no attention to recommendations coming out of the bike racing world - they are in a different sport, and have different training needs than I do, even Time Trial specialists.
I agree 100% with @John Withrow : every year, it's imperative to do a mental reset regarding my goals and capabilities. And also during the course of a year/season, further reflection is needed to determine what to be working on for the next 3-6 weeks. Repeating what worked last training cycle is a set-up for (at my age) going backwards, not forward. I've got to continually ask, "Where am I weakest" and "What does my next big race require?" The FTP/IF number is a good anchor to work from as I decide where to go next.
@tim cronk -we've had this discussion a few times. I know you are of the belief, that FTP is supposed to be what your power is for one hour. that is the LITERAL definition and I know you seem stuck on it as shown in a recent group me post.
for me, it comes down to, what am i using it for? I really don't care what my 1 hour power is unless I am doing an OLY and I have ridden hilly OLYs at .95 of my "FTP." I care about what # do I need to use to do intervals, that will allow me to increase my threshold power for long periods of time and then build endurance onto that construct to have the best 5 1/2 hour power number I can have to execute an Ironman. The way FTP is defined for this purpose is the way the coaching community has co-opted "FTP" for their own uses.
So while FTP as used from a 2x20(2) or other test may not be a true measure of "1 hour power," to me it the measured number that my training intervals are set on and then my FTP which as @Robert Sabo points out above needs to be validated in test rides, gives me a good guide for how to execute my Ironman, I am fine with it.
I WAS WRONG WRONG WRONG.... Got your attention?Sorry its long ... But I was wrong :-)
Why this thread was started - In groupme there was a discussion about "Can you earn more than 100TSS per hour" I quoted the article and Coach P started this thread.
The Article - I tried to keep within the context of the article in that if FTP is the amount of power one can produce in a semi quasi state for one hour, and there are huge differences between individuals sprints/longer term power , then it is reasonable to assume the same huge differences in those same individual's 20' and 60' power and therefore an FTP derived from a 20' test is NOT a predictor of 60' power...
Powercurve's- By reviewing many powercurve's on zwiftpower, an FTP test derived from a 20' test is not even a good predictor of 45' power. Out of all the powercurve's I looked at I only found two that had 45' power equivalent to there FTP @Sabra Gonzalez and @Shaughn Simmons .
I WAS WRONG AND ANDY COGGAN IS RIGHT
Here is where it gets interesting to me.
The old FTP definition - “FTP is the highest power that a rider can maintain in a quasi-steady state without fatiguing for approximately one hour.” I'd like to add that he used to have the word repeatable in his descriptions of FTP as well.
The new FTP definition -" the highest power a rider can maintain in a quasi-steady state without fatiguing" As you can see the approximately one hour time frame has been removed.
The OLD TSS description/understanding - read bullet point #2... From Joe Friel on TP
The NEW TSS definition and Andy Coggans clarification -"the total workload of a ride as a function of duration and intensity" Andy's response to a discussion on ST clarifying bullet point #2 "The 2nd bullet point is wrong. "
So there you have it - FTP is no longer 1hr and YES you can earn more than 100tss per hour.
How long is your FTP? - look no further your hero bar in WKO4... The definition of TTE - " the maximum duration for which a power equal to FTP can be maintained" Does anyone have an FTP/TTE that is 45' or longer???
Some interesting article threads on the subject. As indicated by most of the responses to this thread, all of us at EN were still speaking in terms of the understanding that FTP is still your 1hr power as well as the article and discussions listed below. But Andy has set everyone straight.
http://marktallonphd.com/the-myth-of-functional-threshold-power-ftp/
https://forum.trainerroad.com/t/the-myth-of-ftp/5623
https://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Strength_Training_and_TSS_P6195594/
Final Thoughts and Takeaways - Never understood the 20' test as the entirety of that test is performed at V02 while estimating threshold? The 2 x 20' always made more sense in that its performed at threshold... Both are irrelevant in estimating 1hr power but are great wko's and ways to track fitness. I never needed a FTP/1hr number to get my intervals or race power numbers, they always work themselves out after a couple wko's and RR's. I still cant wrap my head around the fact we can earn more than 100TSS per hour, this seems like it should be a finite amount... refrain from comparing FTP, TSS, PMC, numbers to anyone but yourself which has always been the case but even more so now in this cloudy environment. If you read the above articles there is lots of data even debunking the relationship of LT and V02 to said FTP/threshold numbers making it even more confusing.
I still say we should simply talk in the terms of what is real. IOW my 20' power is this xxx and my w/kg for that 20' is this xxx..... End of story, real facts ...
Wait till I start a thread on STRYD Critical Power :-)
confused. 10 posts and no consideration / mention of lactate breakpoint. lots of discussion of whether the system has internal logic and consistency.
@Dave Tallo
Lactate threshold and FTP
One of the main studies cited as supportive of the 60minute FTP test as being reflective of lactate threshold and a pragmatic approach to non-lab based testing is that by Coyle et al. [3] In this study 14 male endurance athletes where used. The cycling lactate threshold test was based on testing at 5 different intensities and looked for a 1mmol (a blood measure of lactate) change on blood lactate above baseline as representing the balance between lactate production and use.
The performance test was cycling until fatigue at 88% of maximum (Vo2max). The study split the group into 2. One group (HL) that could work at a higher % of the maximum at lactate threshold (72-86%) and one at lower level (LL) (59-71%). The results in terms of time to fatigue for the LL group (working at 34% above threshold) and the HL (3% below threshold) was as follows.
Time to fatigue in the HL group was 60mins and the LL was 29mins.
Therefore, how can was state that a 60 minute FTP performance test can be related to this study and lactate threshold when the LL group did not work at lactate threshold but 34% above it. Similarly, the HL group although lasting on average 60mins, when we look at individual subjects we have one lasting 75minutes and another only 51minutes be fatigue. That’s a possible variation of 24Minutes between subjects? As such we cannot base any type of assumption that the FTP test is reflective of any type of late threshold based on the results of this study.
Given that subjects during the test where not aware of the elapsed time this perhaps speaks of the inherent variability and weakness of the FTP test i.e. how motivated are you to perform? When the real question is when does lactate threshold occur.
Therefore, I am not convinced that a 60minute test can predict accurately where the lactate threshold is or power at lactate threshold (or at least not without possible significant variability). Although there is no doubt a relationship between Lactate threshold and time to exhaustion that does not mean that time to exhaustion or max power produced over 60 minutes is an accurate value to determine training zones.
Great stuff @tim cronk
now let’s be practical about all this.
Three hour and 5 hour we train and trial with and then choose our goal race watts and IF.
What about our interval workouts? Do we still do “FTP” work at .95 of our 20 minute power? Should we be doing an all out 5 minute test to get our VO2 and use that number for VO2 work? And speaking of VO2 work are we ignoring the importance of short rest intervals to maximize the VO2 work response? Max power with long rest intervals is max power so no pre tested measurement needed. I forgot sweet spot which is supposed to be about 85% ftp. Is that of our .95 20’ min power or a different number ?
TSS is interesting to follow and brag about but not not the be all or end all. I want to maximize my work efficiency and train smart. Just racing Zwift May be fun and build a better bike racer but I hope there is data out there that most effectively helps us know some ways to best build a better triathlon bike leg. For us older folks we easily break down if we do too much so we need to be a little careful.
@Robert Sabo Yes practical I like it. A couple RR's for any distance race will provide race specific power targets.
I would love so have @Coach Patrick chime in here soon , specifically to hear his thoughts on FTP definition, FTP testing, TTE , and TSS accumulation (since I have called him out earning more than 100 per hour) and the structure of various intervals.
I would argue that any time frame interval sorts itself out after a few intervals or attempts. IOW its a good power number if I can barely finish the interval, but I can repeat it after the appropriate rest, and more importantly repeat it again the following week. Its practical and not rocket science. I think the real question regarding interval power target and time frame is based on weakness in the power curve of the athlete and the athletes desired area of improvement.
TSS and FTP bragging - this is funny cause everyone wants to say my FTP is xxx (high as possible) and at the same time everyone wants to say my CTL is xxx (high as possible) but it doesnt work that way, the higher the FTP the lower the TSS the lower the CTL.... We could just have 2 models :-) I'm joking.... In the end they don't hand out trophies to those with the highest FTP, w/kg, or CTL :-).... But this conversation is important to remember when you are looking at somebodies PMC.
Two comments to side issues @tim cronk raised:
• "Does anyone have a TTE greater than 45'?" I have been above that level *at times* during my training. Last winter, when I was doing all-out Zwift races for 60' +/-, I had ramped my TTE up to the 57-59' range. Also, in the summer when I was doing a bunch of Olympic tris, I reached the same plateau. This was WKO4 using the "sFTP" I had put in, which was a bit lower than the "MFTP" it calculates. I briefly tried to find a WKO4 chart which shows the TTE over time to document this, but I've got to leave for the dentist, and can't dive more deeply into it right now.
• "TSS > 100 for an hour"? I think it is possible, but not via a "quasi-steady state" effort. I'm not a math guy, nor a statistician, but I suspect that the way the algorithm for calculating TSS is written allows for it. If one does a series of intervals at a very high IF (say 1.2-1.5 range) with a high enough resting interval between, it might be possible. Like, say, 10 x 4' @ 1.25 with 2' rest @ 0.75 between? Of course, that would be real hard work, but then, it is a very high TSS/Time ratio, no?
@tim cronk ...
“Therefore, how can was state that a 60 minute FTP performance test can be related to this study and lactate threshold when the LL group did not work at lactate threshold but 34% above it.”
I might be reading the study wrong, but what I understood the summary to say was that there is variability across subjects at different % of max (which the study based on vo2), when compared to LT. So, i getting that FTP was a separate test (as well as treated like a fixed input variable), where the different findings were driven by vo2 manipulations. But maybe I’m just misreading it that way to support my bias that there’s weak correlation between vo2 and FTP.
Or am I totally missing the point?
@Dave Tallo Honestly I was good when FTP was 1 hour and max TSS possibly earned was 100 in 1hour. Most of this has gone way over my head/pay grade. I like to keep it simple. But my takeaway is the same as yours, I do believe there are correlations between all vo2, FTP, LT , but believe them to be very different bewtween individual... At this point When somebody says FTP I will have no idea what exactly they mean!
I'm all for keeping it simple. And, as others have noted in the thread, keeping it *specific* to what we do as long course triathletes. From the more recent Coggan / FTP threads (even though they went way off in other directions), I have taken away at least this being reinforced:
-LT matters for the type of training and racing that we do
-research continues to reinforce the validity of FTP as a proxy of LT (even if the definition of FTP slithers a little bit)
-vo2 is not LT
-there is not a strong correlation of FTP and vo2max
So I think there's consensus on ^these^ ... right? I'm asking, if only to work out what Rich used to call the 'signal to noise' ratio.
(I tried to find the Murias study that Passfield talked about in the GTC video, but his recent pubmed activity broke my internet. Prolific!)
To beat a dead horse. Below is a link to the Running with Power Primer for WKO4, applicable to cycling in the power references.
I still dont know what FTP is. Here is the vague new definition. Ya gotta just love "perhaps" , "might be" , and he 30-75 minute range.
FTP was originally defined as “the highest power that a runner can maintain in a quasi-steady state for approximately one hour without fatiguing.” The “approximately one hour” component of the definition has since been clarified to range between perhaps 30-75 minutes, depending on the individual. Thus the correct definition might be amended to “the highest power that a runner can maintain in a quasi-steady state without fatiguing for a duration ranging from 30-70 minutes depending on the individual.”
Below is a great summation of what matters (I dont believe the semantics/definition of FTP matter to be able to apply the below) but I believe it would be more appropriate to have a standard of 20', 30' , 40' power or something more definitive than perhaps maybe 30-75' power.
FTP enables the stratification of training zones. As coach Alex Simmons put it in his blog, FTP “enables a [runner] to define and measure intensities of [running] (or power levels) relative to their own current level of fitness, expressed in a manner that relates to the primary physiological adaptation that occurs at each intensity (power) level. This is very useful for guiding training and making sure that the mix of intensity and duration during a workout or training cycle is appropriate for gaining the specific fitness required for a [runner’s] target events.”
BTW I have always loved Alex Simmons blog which is referenced in the primer . But yet again the contradictions continue as it is dated and using "OLD" definitions. Highly recommend reading the blog anyway with lots of good stuff in it.
https://wattmatters.blog/home/2008/05/the-seven-deadly-sins.html
I DO love this conversation. I think at the end of the day it matters how your training program is written to work with the number you have. It really comes down to, what am I using the number for? I am not interested in having the highest "FTP" number. I am interested in a measurable number that i can repeat a test for that then becomes the basis of my training intervals that are devised to recruit more slowtwitch muscle fibers to in turn increase that number at my next test. Then I want to be able to take a % of that number and use it for determining what effort I should be applying to the bike/ run in my OLY/HIM or IM race.
FTP as we've defined it via either the 5/20 or 2x20 test, seems to do the trick, call it FTP, call it the fakeFTP factor, call it whatever you want, it works for me.
If the goal is to become a stronger cyclist, then FTP/kg absolutely matters. As does VO2. And Stamina. And...
I think these conversations are "muddied" sometimes because we all use these words with different understandings of what they mean and different applications in mind. This is amplified since the guy that invented the term (Coggan) has evolved his understanding and his description of the concept over time.
FTP is describing a metabolic capacity/strength/ability of humans and Coggan has been perfecting the ability to use a power meter on the bike to "estimate" FTP for years. He has come up with a umber of different ways to do that. The "20-minute test," the "60-minute test," the "2x20-minute test" ... are all just ways of estimating FTP. When WKO4 came out, Coggan presented a new model, the Power Duration Curve, that is based on (I think) a least-squares fit of maximal data to a 4th-order polynomial. He has demonstrated that this new model can consistently provide a statistically better estimate of FTP than the previous tests/models, provided that the model is build upon enough "maximal" efforts over a range of different durations.
Some confusion comes because various people have referred to FTP as hour-power, or 95% of 20-minute power. Those terms have come about as convenient ways to describe FTP... but they are not FTP. They are really just referring to various test protocols that have been used to estimate FTP.
I made the picture below a while back to visualize the WKO4 terms that Coggan introduced.
The red line is the Power Duration Curve (PDC). This line is model of my bike performance (sometime in 2017). Each point of the curve of that model is an estimate of the maximum power (y-axis) that I could sustain for a given duration (plotted as log(time) on the x-axis). My raw data (not shown) was equal to, more or less than the red line. The model is a least-squares fit, or an "estimator" of my performance across all durations.
If you start at 1 second (Pmax) and trace the red line to the right, my body used different metabolic processes to product the power. The green line, called the FTP Curve, represents (mostly) my aerobic contribution to the PDC for a given maximal effort at a given time. The blue line, called the FRC Curve, represents (mostly) the anaerobic contribution to the PDC for a given maximal effort at a given time. The FTP Curve + the FRC Curve = the PDC curve. In other words, your anaerobic power contribution (blue) + your aerobic power contribution (green) = your maximal effort (red)
((I say "mostly" in both cases because there is some subtlety in Coggan's model where the FTP does not contain 100% of the aerobic contribution and FRC is not 100% anaerobic... for simplicity sake, it is useful to think of FRC as anaerobic power and FTP as aerobic power. Just remember that's not exactly accurate.))
Metabolically, starting at 1 second up until 15 seconds or so, these maximal efforts are powered primarily by neuromuscular power (ATP), After that, Glycolysis (anaerobic processing of sugars) is the main contributor of maximal efforts... but the aerobic system is always contributing and, as duration increases, it becomes the primary contributor of energy to our maximal efforts. The picture below helps show this.
There are a couple really important concepts here:
Looking at the PDC again (red line in the top picture), starting at 1 second and moving to the right, the curve is first dominated by FRC (anaerobic). After a 1-2 minutes, FTP (aerobic) becomes the dominant contributor. And soon,≈40 minutes, the PDC (red line) starts to flatten out. It looks like it is becoming an asymptote and would be flat forever... but it doesn't. It drops again. The point where it drops is Coggan's estimate of FTP.
As @tim cronk mentions above, Coggan describes FTP as "the highest power a rider can maintain in a quasi steady-state without fatiguing." Or, on my picture, if you can imagine the asymptote that the PDC (red) line is approaching before it drops, this is the point where the model estimates FTP.
The time where that drop (fatigue) occurs is what Coggan calls Total Time to Exhaustion (TTE). When we log a new maximal effort, the model may calculate a new (higher) FTP. When this happens, the TTE moves to the left (shorter duration), many times in the 35-45minute range. As training progresses and there are rides longer than TTE at very high IFs, the TTE will extend to longer durations. If the TTE reaches 65-70 minutes, that is a good indication that one is ready to start doing some harder efforts below 20 minutes to increase the left side of the PDC and the FTP (my TTE was 64+ minutes in the chart above). Raising the FTP will make it easier to ride at higher powers for longer durations (2, 3, 4, 5+ hours).
The reason that FTP matters is because FTP represents a part of how our body's metabolism produces energy. It isn't the only thing that matters... but it is something that we can estimate / measure with a power meter (versus having to go to a lab and pay for a Dr to do a test), we can use that estimate of FTP to plan our training or to help plan the execution of a race and then we can measure improvement from day-to-day so that we new training targets that stretch farther.
One of the HUGE advantages of WKO4 is that it is possible to "feed" the PDC model during the course of normal training. It requires maximal efforts at different durations. If maximal efforts are incorporated into training, the model updates daily, so that each day one has precise, individual workout power prescriptions. The downside of WKO4, is that it requires a pretty solid commitment understanding the data and and model.
FTP is not the only thing that matters. FRC matters too. The graphic above shows that FRC represents the amount of work that can be done above the FTP Curve. In that chart, my FRC was 17.4kJ and my FTP was 256w and TTE (the time my FTP occurred) was 1h4m25s.
In other words, at time = 1h4m25s, the PDC = 256w = FTP contribution + FRC contribution. Since the FRC is 17.4kJ, we know that 17,400J ÷ 1h4m25s ≈ 4.5w of FRC (anaerobic) contribution at threshold and 251.5w of FTP (aerobic) contribution.
Looking at data (mine + lots of other people), even at 5 hours the anaerobic contribution to the PDC is still ≈ 0.75w. That means that on a 5hr ride, ≈13.5kJ of FRC is burned (5hr x 3,600 sec/hr * 0.75w). This does not happen by pressing over hills... it happens during the natural course of producing energy for the bike. If one burns 13.5 kJ of FRC on the bike leg of an Ironman... one had better hope their FRC (their anaerobic energy reserves) is higher than 13.5kJ. Otherwise, the run is going to be very very flat, because there isn't going to be much FRC left to support the run. If you've ever ridden a very appropriate IM bike followed by a run that was very flat but steady with no "pop" at all in your legs... that is a good sign that your FRC was low going into that race and, even though you rode a very steady and conservative bike leg, you had exhausted your FRC.
So - my understanding - not only does FTP matter, but FRC matters too. I could go into a similar explanation for VO2... but I am out of energy (low FRC)!
10/10, @Rich Stanbaugh .
@Rich Stanbaugh amazing post, only about 20% sunk in , the rest is way above my head , thank you for your thoughtful time consuming insight very helpful.
@Rich Stanbaugh Serious question. Since nobody really knows exactly what FTP is or how to estimate it anymore, I would propose some kind of standardization of the "FTP setting" My first thought, since FTP is now supposed to be 30-75 minutes depending on individual I thought about applying a 30' test and using that number, after all that would be the minimum amount of time one is supposed to be able to hold FTP right? But that is still an estimate of a variable number depending on the individual. Then I thought why not just use mFTP? Now I do not know the definition of modeledFTP , I do know its a real thing calculated with Coggan MATH, and all you have to do is hard efforts and then read your HERO bar in WKO4. At least that would be standardized for all. So when you say mFTP I know what you mean and where you got it as opposed to FTP. What do you think of that?
@tim cronk my mFTP (WKO4 estimated FTP) is out of whack a lot of times. For example, I may spend a few weeks focusing on the far left side of my PDC, trying to achieve new maximals at all times under 5 minutes. This will cause the PDC to underestimate my FTP compared to what I know that I can achieve for 20, 30, 60 or even 90 minutes. So I never use the mFTP to track thing like TSS points.
However, I use the PDC to give myself targets for my workouts. Sometimes, my bike training schedule follows a pattern like the following:
Mon: Easy
Tue: FRC
Wed: Easy
Thu: VO2
Fri: Easy
Sat: Long w/ FTP
Sun: Tempo or Easy
I may skip the easy days or maybe only ride 20-30 minutes, depending on fatigue. I try to always hit the FRC, VO2 and Long / FTP days.
Before the workout, I look at my PDC to figure out the workout. If it is an FRC workout, I will find a set of specific interval times/powers between 10 seconds and 3 minutes. I will take a full 5-15 minute recovery (5-10x interval length) between those intervals because the purpose is to jam the Neuromuscular/ATP/Glycolysis systems as hard as I can. I don't want any kind of aerobic fatigue to impact the interval, because that is not the system that is being developed. I will focus on trying to use gears to hit high (100+ rpm) cadences during these workouts because that helps the neuromuscular development (according to research).
On the VO2 days I will look at the PDC to come up with a set of intervals in the 5-20' range. The goal will be to accumulate a minimum of 12-15 minutes of efforts above 95% of my Power @ VO2 (as estimated/measured by WKO4). These will have a shorter recovery (1-2x interval length) because I am targeting aerobic systems, lactose clearing etc). Same process for the FTP intervals that I work into longer rides.
But - I always use an FTP estimate of 95% of 20-minute maximum for all my TSS calculations. I do this because it makes TSS more meaningful and easier to compare to previous year's level of work.
My goal /purpose for TSS is to measure work load / stress. My goal for the workout is to specifically target weaknesses in my ability to produce power. For me, using different estimates/measures of FTP works best.
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One other thought on the question 'does FTP matter?' After writing the previous post, I thought of an analogy that may be useful.
Do x-rays matter? Do MRIs Matter? x-rays and MRIs are models giving us an understanding of what is going on inside out bodies. FTP, FRC, VO2, Stamina, TTE are also models giving us an understanding of what is going on inside our bodies.
Granted, x-rays and MRIs are more accurate models and can easily be verified. But, they also have a margin of error and do not show everything. Sometimes you do them with contrast. Sometimes you look at views that highlight bone and other times you look at views that highlight soft tissue. No one model works for all purposes.
Coggan has invented a system of using a power meter to give us a view into our bodies. We can use that for training. Sometimes we look at our aerobic system. Sometimes we look at our anaerobic system. Sometimes we use one way to estimate FTP and sometimes we use another... it just depends on what we are trying to achieve.
@Rich Stanbaugh OK so you just keep your FTP set at 95% of 20 min power? Since this has been a long accepted practice, and the fact that we no longer have to think of this number as something we should be able to hold for 1hr it probably makes the most sense to use as a standard model for PMC/TSS numbers.
Most of the FTP methods have always been within a few percent anyway. I'm just hung up on the "new vague definitions" of something that used to make perfect sense of 1hr power and 100tss max. I pretty much know my "FTP" line in the sand by feel within a few minutes on that day anyway , IOW I can tell "above this number" I wont last long , "below this number" I can hang on for much longer.
FRC Intervals? I found the WKO4 charts to prescribe these and found them to be pretty big windows. Pmax/FRC was 15-45 seconds of 465-327 watts, Interval/FRC was 45"seconds to 2.75 minutes at 322-237 watts, and FRC/FTP was 2:30-37minutes 250-199... My question is not so much how much power to target but what time frame to target ?
Moving mFTP is very similar to moving CP , I did one WKO last week with 10 x 15" second sprints, setting new power highs for the 5-30 second range and my mFTP dropped 3 watts :-)
@tim cronk that is exactly how I think of if...
95% of 20' maximal power is an FTP estimate that I use for measuring TSS, Fatigue, etc and comparing to other seasons.
mFTP, iLevels and the PDC residual errors are estimates that I user for planning power targets in workouts.
Stamina, 2hr, 3hr, 4hr & 5hr power are estimates of aerobic fitness that I use for planning race rehearsals and races.
When we first started using power meters, there wasn't really a concept of how to use it. Dr. Coggan came up with FTP and a method of estimating it, so we created power zones like we had previously done with heart rate zones and used our power meters to train.
Now the models have evolved. There are several more metrics. These metrics give us different insights into our fitness and we can use them for planning training - both micro and macro planning. We can use them for race & recovery planning.
The biggest challenge is figuring out how we can apply them to help us without having to get a PhD in sports metabolism!
I think I have a hold on FTP/TTE 95% etc. But now this FRC is confusing me. If we raise FRC by doing short intervals, does that pull the curve to the left or just the new higher FTP at a shorter TTE? What does working on FRC actually do for us as long course triathletes? Thanks for great questions Tim :) and great answers Rich.
@Robert Sabo Effects of a workout on the PDC
The Power Duration model is calculated by doing a "least-squares fit" to a sigmoidal function over a fixed duration of time (the Hero Bar metrics are calculated over a rolling 60-day window). So, each time you add more data to the calculation, the curve will change to reflect the new data you have added.
If you achieve some new maximal data to the left of the mFTP / TTE, (FRC / VO2 work), this will cause the PDC to calculate a new least squares fit for data. This the mFTP to lower and the TTE to move to the left.
This doesn't mean your FTP is lower. It means that the model's estimate of your FTP is lower. If you look at the residuals and the standard error of the PDC (something you can look at in WKO4), you will likely see that the model is a better estimate in the FRC / VO2 regions and that there is more error in the FTP region.
New Maximals in the 1s - 10min range means you need to chase new maximals in the 10min - 30min range to improve the overall accuracy of the model.
This is why I am trying to emphasize using "the right tool for the job." When you order MRIs, you request the T1 or the T2 depending upon what you need to see... I use the 95% of 20-minutes when I am thinking about fatigue/TSS etc because it is a decent approximation and is day-to-day stable and I use the PDC/MMP curves when I am targeting intervals because they show me exactly where my actual data is below the modeled data. This allows me to target a very specific power within a zone and it motivates me to go net a new personal best for the month or year or all-time.
@Robert Sabo - "What does working on FRC actually do for us as long course triathletes?"
Short answer: It will make you stronger and faster at all durations.
Longer answer... I am certain that I will over simplify and get some of the physiology wrong here, but will do my best.
First reason: Our bodies are always, simultaneously, utilizing different energy sources. Our cells are aerobic (oxidative) and they are anaerobic (glycolysis). In the aggregate, our bodies are never 100% aerobic or 100% anaerobic. So, even when you are riding your bike at 70% of FTP, you are burning some of your anaerobic stores. I did the math above to show that on a 5hr ride, a person burning 0.75w of anaerobic energy will do ≈13.5kJ of anaerobic work / FRC (5hr x 3,600 sec/hr * 0.75w). 0.75w seems to be a reasonable estimate based on research I've read and data I've observed.
We also burn FRC when we run. So, if you burn 13.5kJ on the bike, but your personal FRC is 10.0kJ, you could reasonable expect that your run will be flat.
Where I've personally experienced most often is on the bike. I will go for a long training ride and absolutely hammer the first two hours. For the remainder of the ride, I can ride along at ≈IF 0.70. But, if there is even a slight rise in the road, I am dropped because there is no FRC left to push up the hill. Later in the season, my FRC climbs up around 18kJ.
Second reason: When we develop the ability to have super high Pmax, 30sec power, 1min power, 3min power, etc. , there is a lot more physical adaption than muscular strength. There is neuromuscular development, our cells become more proficient at clearing anaerobic metabolites, etc. The human ability to generate power seems to be the result of a complicated, interwoven process rather than individual processes that work in isolation. This leads to us achieving higher VO2 which leads to higher FTPs, and so on. To be clear: When I refer to VO2, I am referring to our measured ability to process oxygen, not the theoretical maximum that we could attain. I don't know anyone that cannot improve their demonstrated maximum oxygen uptake. When this improves, performance improves.
Third reason: I've tried it and it works. I have helped others target their intervals and it has worked. I'm not suggesting that it is the only thing that works... but I am suggesting that by purposefully targeting FRC and VO2 development, and designing workouts with the correct power targets and recovery intervals, I have observed material FTP improvements (over 10%) happen pretty quickly (six weeks) in myself and others.
@Robert Sabo From what I am gathering and experiencing first hand in my Hero Bar, the math for mFTP is similar to CP in that, if you increase the shorter harder FRC/V02 intervals you will actually lower the mFTP. You can play with that in any Critical Power Calculator like the one in STRYD , simply put in your 3' and 9' power tests , get your CP calc, then change the 3' up and down to see the results. At first its not what you'd think but starts to make sense and explains the difference between different athletes that have a bigger spread between those 2 numbers vs. athletes with a tighter spread.
@Rich Stanbaugh So how do you go about choosing the duration for FRC intervals? And what does a baby FRC of 7.8 mean for a guy like me who does ride an IM at .75?