What's the difference between sweet spot, tempo and threshold?

That would be nice, but human physiology is a lot squishier than that. FTP is an approximation of a value that fluctuates constantly (power at max lactate steady-state) and each person’s TTE at that power is going to be different.

2 Likes

A few thoughts…

There is a clear definition, its the dividing line between:

  • stable oxygen consumption vs increasing until you hit max oxygen consumption (vo2max)
  • stable heart rate vs increasing to HRmax
  • stable blood lactate generation vs increasing blood lactate

Once you’ve estimated that “line” then you have an estimate for ability to do a “long” effort without explicitly defining “how long.” And using a multiplier of say 65-80% to estimate your lower aerobic threshold (LT1). Then you can do some additional field testing to estimate anaerobic capacity. And now you can also predict how long you can hold an effort above that line / threshold.

Now instead of lab testing, we have mathematical models that only require efforts. Or you can be even more basic, and if you have enough hard efforts from short to long, simply look at your power duration curve to estimate your functional threshold power.

Lets compare two mathematical models that use actual efforts to estimate that dividing line:

Critical Power (CP) mFTP in WKO
protocol: 2-4 max efforts between 2-20 minutes 3 max efforts short/med/long
practically it estimates: best power you can hold 20-40 minutes best power you can hold 30-70 minutes

Notes:

  • critical power info from Dr Skiba’s latest book
  • mFTP info from WKO docs

I’ll also note that some of the more practical sports science studies that report performance improvements use time trials rather than Critical Power. Either way, you can document a performance increase or decrease if the athlete gave a max effort(s).

But how many max efforts are you going to ask someone to do in a study?

Using CP to properly fit your data to a line (linear equation: Power = W’/time + CP) you really need 3 max efforts - the Skiba book has an example with 3-min effort, 5-min effort, and 13-min effort. Over on the HighNorth blog they would like 4 efforts: 3-min, 5-min, 12-min, 20-min.

Using a time trial it is one effort.

What about vo2max estimates? They are a very popular metric in studies. Similar to using TT as performance metric, a vo2max estimate only requires one max effort (a ramp test), which as we know, doesn’t heavily rely on good pacing and therefore is far easier to administer when using untrained study participants.

Lets go back to the clear definition - a dividing line - between stable and unstable:

  • oxygen consumption
  • lactate in blood
  • heart rate

No matter if you pick the functional “long effort” effort (hopefully without 20-min fudge factor), or “the more science-y CP” model, or the “proprietary” mFTP model, you end up with an estimate that can be held for “a range of time” and not a specific duration. There is no 60 minutes.

Clear definition, and then it comes down to the type of participants in the study. Regardless, different athletes will walk away with a CP or FTP (TT or mFTP) that merely estimates what they can hold for “a long time” without a precise estimate of how long. Which brings me back to Coggan’s the best prediction of performance is performance itself, and my own “go long” protocol (adapted from Friel’s 30-min test) which looks just like Kolie Moore’s last protocol in that article on TP blog.

Well before Zwift and TR came along, it was well documented by physiologists that different ramp protocols produce different “FTP estimates” :man_shrugging: and to be more precise they documented different max aerobic powers (MAP) because thats actually what a ramp test is designed to estimate. Applying an exact %, like TR’s 75% (Zwift too?), has also been documented to produce results that may or may not make sense. Because as Coach Chad has explained, and many others explained decades before him, not everyone has the same FTP as % MAP.

4 Likes

windwarrior may or may not be saying this (haven’t read his reply yet), but I AM saying this. And if it matters to you, so does the “sort of grandfather of FTP”.

For example, your power for a 45min max effort and your power for a 55min max effort are actually NOT that different. They are both on the flat part of the curve. Just go all-out for somewhere between 40-60mins and you have a value that is as close as possible to “truth”, and can be useful.

Your ego thinks they are different. In terms of training and racing, you’re good.

5 Likes

@Jolyzara the only time I have good data is from 5 years ago, I’m going to use that to illustrate @tshortt point:

  1. March 15th, before being able to pace all-out for about an hour. Exaggerating power in watts by zooming in to range of powers between 30 and 70 minutes.

8W difference difference between 40 minutes (265W) and 60 minutes (257W).

Also showing modeled FTP two weeks apart - 259W increasing to 262W.

Power at 40 minutes is basically mFTP (+3W), and basically same at 60 minutes (-5W).

  1. April 9th, after I finally pushed pacing of threshold effort out to ~ an hour some ~3 weeks after March 15th:

5W difference difference between 40 minutes (276W) and 60 minutes (271W).

Modeled FTP jumped +15 from 262W to 277W.

My power meter was a Stages gen2, with +/- 2% error margin. At 270W that is +/- 5W.

Going back to auto-scaling, which includes 1-sec power:

Right?! Power curve looks flat in that 40-60 minute region, and as shown above was 8W difference in March and about a month later had a 5W difference.

Same same.

  1. And here is an example from this year, where I cut short a long field test, ended up doing 32-minutes and it was well before what I could have done:

In this case, the power curve doesn’t have any max or near max efforts past 32 minutes which was 276W. Without those hard long efforts, 40-min power is 256W and 60-min power is 225W. The power curve can’t read my mind, it has no clue I felt it possible to push that 276W effort out to 50+ minutes (possibly with a 1 or 3 or 5 watts up/down).

In other words, if you’ve never tried pushing out power past 20 or 30 minutes, you have no idea what’s possible, and you may think your power curve is telling you a long effort is not possible.

However that said, WKO provided a mFTP of 269W for 32-min at 276W, versus point #2 above where WKO gave mFTP of 277W from a single effort with actual 40-min was 276W and 60-min at 271W (part of the difference is curve fitting that must include the impact of short sprint power, and different 90-day actual short power between April 2017 and January 2022).

1 Like

When I think about Sweet Spot and what it trains, I think of these two charts. The first explains the relationship to zones & its training effect. The second also shows the training effect of each zone but with more detail.

image

4 Likes

My response sounded over the top in a way I didn’t intend. My point was just that FTP gets really confused, whatever Coggin originally intended it to mean. If FTP = 60 min max effort, that’s something we can all understand and talk about. If you start to introduce concepts like TTE as a qualifier, then it gets muddy.

Sure. The problem is that it’s an incorrect definition. Human physiology doesn’t recognise 3,600 seconds as some sort of yardstick.

3 Likes

At least for you that seems to prove the point that FTP is actually what you can hold for 60min, or not? Or could you also hold it for e.g. 80min?

1 Like

What is this 60 minutes? :rofl:

Long efforts at threshold? Big mental component. And pacing. And strength endurance. Some days I could go for 35 minutes and then mentally and physically blow up. Pacing or mental, who knows.

30-70 minutes I say. For me on a road bike, Merckx class, it’s a little more than a 10 mile TT and just under a 40km TT.

Some of the ftp confusion imho stems from conflating the threshold phenomenon itself with a method of estimating it. FTP tries to bridge the two but it sometimes seems it is too alluring to get tangled up on numbers (time or power).

The way I see it, a 60 or so min test is just a means to an end, a tool for identifying a threshold intensity above which one fatigues a lot quicker than below it. So, to me the mean maximal power of an ftp test puts one into the ballpark, but the more important thing is to perceive the threshold in action during the final 1/3rd of the test or so. By my experience continuous riding against one’s limit plus the cumulative fatigue of the effort ensure that a wattage one cannot sustainably surpass for a long time emerges. And that’s what ftp is supposed to be about.

At least in my case the test MMP also aligns quite well with this threshold intensity.

Fwiw, I think the empirical cycling ftp test variants are a very good platform for teasing this wattage out. They also helped drive home the kind of understanding of the issue described above.

2 Likes

right, I think its more important to learn how it feels. Some days I went too hard and blew up. Learned from it. Some days I went too easy and could have gone harder. Learned from it. It took about 4 months to learn to pace and get mentally tough to do a long effort at threshold.

For anyone that doubts their ability to train and push out threshold to close to an hour, search the forum for “PD Gollnick” or “Gollnick” and there are a couple threads discussing a 1973 study (“Effect of Training on Enzyme Activity and Fiber Composition”).

I think this is an important point. I firmly believe that any savvy racer can feel when they hit threshold or gone a bit above it. The power (or for me as a runner, the pace) might be different day to day, but I bet my own estimate just based on how I feel would line up pretty well with a lab test.

1 Like

True. But per posts above FTP is not a lab test. So if you aren’t measuring lactate or some other metric… and it’s not a “60 minute” test, what is it?

FTP is a proxy for lab tested MLSS, there are many ways of attempting to determine it outside the lab, some more accurate than others.

1 Like

Coggan did say once that FTP “roughly” would correspond to your max hour (hence the confusion). But he explains more here - that it relates to lactate threshold: What Is Functional Threshold Power? | TrainingPeaks

But getting back to the original question…

It’s pretty straightforward. Tempo is moderate. Threshold is medium-hard. Frank Overton of Fascat coaching first gave the name “sweet spot” to that tiny range at the very top end of tempo, just below threshold because it is right where you want to be to nudge up your FTP. Trainerroad, and most zone breakdowns these days treat SS as its own separate zone. The list of physiological benefits of each are pretty clear in that TR link.

1 Like

It’s a rough proxy for aerobic endurance, useful for setting training zones for work at or below threshold.

That’s about it, I reckon.

1 Like

my take on the OP’s question:

as you move from tempo to SS to threshold, the exercise requires greater input from fast twitch fibres to help the slow twitch fibres, in producing ATP. these fast twitch fibres require carbs and results in lactate production. the higher the power, the more lactate results. the slow twitch fibres can use this lactate but as they become saturated, this spills in the blood and acidity increases. we can cope with a certain amount of lactate and can train this buffering ability. there is no pin point % because we are all unique. of course we can fatigue at tempo, SS or threshold, so not everyone can do 3 hrs at tempo, or 60 mins at threshold. that’s why we train to endure.

1 Like

For me is very much tied in RPE and how they feel as time progresses. It’s easy to get lost in the weeds with this stuff, looking for precise numbers, rather than ranges and good enough.

4 Likes

Coggan also acknowledged Sweet Spot (4a) in his recent intro of iLevels.

That article is a good read to understand deeper the differences between different intensities.

1 Like

I think most forget FTP is a proxy for OBLA. It was never a set time. It’s a concentration of blood lactate which happens at different times/intensities for different people. Training affects the delay of OBLA. Since the vast majority of people can’t test blood lactate FTP was invented to give the us amateurs a way to verify the training we are doing is working. Or not.

Best I can tell the right mix (assuming there is) of z2 through to threshold is very much dependent on what genetic mix of fiber type makeup one has. As @tshortt wrote protocol is important. If you are going to use TR ramp, 20 min, 1 hour the point is to be consistent to see change over time.

1 Like