Extensive FTP interval progression

I’ve been experimenting with FTP intervals. I’m doing them right at FTP. I did 3x10, 4x10, 3x15 so far.

Completing the workout is relatively easy. I wouldn’t be surprised if I could do much more. I’m not struggling at all during the last interval. (My FTP is well calibrated with a KM long form test.)

The issue I’m having is recovery. After 3x15, my legs felt thrashed for days. Not horribly but sore, tired, mild flu like symptoms for a few days.

Any suggestions?

My ideas:

Do the intervals at 90-95% of FTP.

Instead of doing 45+ minutes every 4-5 days, build up to 2x15 or a 2x20 twice a week.

I think my TTE is actually sufficiently long. WKO5 models it at 41 minutes right now. I bet it’s actually longer. WKO5, of course, only knows about the efforts you have done for it.

How often do you currently schedule them? Once a week? Every second day? Nothing unnormal with having some easy days after a hard day.

If you reduce the intensity to 94% or below I guess you are doing sweet spot intervals instead.

scroll down to Final Considerations and look just above that heading. Specifically look at the note for the 2x20 ftp workout, and then the two workouts above it. Thats what I’ve found to be true and my coach is not with High North.


Although couched in scientific-ese, there is much wrong with that article, especially the commentary about lactate clearance.

ETA (now that I’m not on my phone): this lecture that I used to give to the fellows and post-docs at WUSM explains why:

Or, you can simply ask yourself this: even if you could measure it, why does lactate clearance matter? It’s not a fatiguing metabolite, so who cares?


Yeah I ignore the science-ese in those articles.

All I care about is what has been proven to work, for me. I don’t need science-ese explanations about adaptations yada yada yada.

What I can say is that for me, significantly over/unders are pure gold, and provide me with better bang for the buck than doing straight threshold efforts (which I’ve done quite a bit in the past). Every once in awhile I’ll go out and do a long threshold effort, effectively like a 10-15 mile solo TT effort, and these feel straightforward after doing a block or two that includes some significantly over/unders at 85-90/110-115% or thereabouts, along with some mid-tempo work, like 1x30 or 1x60 or 1x90 around 80-85%.


What’s your nutrition like? Pre, during and post?

I suggest eating like a ravenous horse and riding at 98% (5 or 10 watts below FTP, say)


I’ve recently been doing Cusick’s FTP progression he outlines in his fatigue resistance slide deck that’s floating around on the forum in a couple threads.

Basically 3x10 > 3x15 > 5x10 > 2x25 > 6x10 > 3x20 > 1x60

I’ve been doing them on Tues/Sat and the other days have been roughly 2hr Z2 rides. I made it through the progress to 3x20 this past Saturday. Yesterday I knew there was no way I was going to be able to do 60 mins at FTP, so I tried a 30/20/10 at FTP. Made it through the 30 min interval JUST BARELY, then only 10 mins of the 20 min interval. After that I was SMOKED. My legs are definitely trashed, but up to this point I’ve been accumulating fatigue for sure in my legs, but not so much that I couldn’t do the next workout in the progression.

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Sweet spot intervals are threshold intervals!

That note is exactly what I’m feeling. “we feel these steady-state workouts with lots of time spent right at the lactate threshold are not as effective as the two designs above, and provide a fairly small adaptive response for the level of fatigue they can create”

I don’t think food or fueling is an issue. Basically I’m 57 and don’t recovery quickly from 45 minutes at threshold. When doing the workout, it’s fine, completely achievable, could even do more, etc.

I use WKO and a long form KM style test.

I’m pretty sure I could do a 3x20 today without too much problem. I started at 3x10 and then bumped it up to a 3x15 and it took 4-5 days before my legs were feeling good again.

Maybe one workout every 5 days is just fine?

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  • Yup, for reference find my display of the Zones of interest:

  • image

The typical definition for Threshold is 90-105% of FTP.
TR uses 88-94% of FTP for Sweet Spot, which essentially lives about equally on both sides of the split between Threshold & Tempo.

Main point being that your 90-95% workouts are correctly classified as Threshold by the most common definition. Sweet Spot may be relevant too, since there is clear overlap between them as well.


About the same as if you had done a 3x15 - several days for me.

Are you training indoors?

(Heat sress → decrease in splanchnic blood flow → increase in gut permeability → translocation of gut microbiota across endothelium → increase in LPS.)


Could you elaborate on that? I’m curious to know more

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Sorry, which post? (I’m on my phone.)


Yes, I do those intervals on the trainer but I don’t think I’m experiencing heat stress. The room is air-conditioned to 65F and I have fans. I’m barely working up a sweat by the end of 3x15 at FTP.

A few things that I picked up from the Empirical Cycling podcast regarding threshold blocks:

  1. It’s not advisable to try to do these intervals right at FTP. You’re likely to have some error in your FTP, so you should do them 10W lower than your FTP. Otherwise that fatigue will build real fast.

  2. You might be progressing your duration too fast. If doing an threshold block, typically people can add 5-7 minutes to TTE per week. If you’re not focusing on threshold, then the TTE will increase less than that.

It shouldn’t take you 4-5 days to recover from these workouts. Something’s wrong there. Kolie said he has (high volume) people do 3 threshold workouts a week. So you’re far from the mark.

What does your full week look like? Other training will influence your fatigue and glycogen level replenishment. How about work stress and life stress?

Nutrition! You can’t eat fast enough in the bike to fuel these kinds of workouts. You have to fuel ahead of time, during and after. Your body might need the next day or two to fully replenish. You need a lot of carbs but also protein (off the bike).

Sleep is a factor too. If your body isn’t recovering well it’s not going to improve well either.

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Also, Kolie says once you reach a FTP TTE of 55-60 minutes, you should try focusing on VO2Max to push your FTP up. That will reduce your TTE at the new higher FTP. You can then push out TTE again.

Have you weighed yourself pre and post workout?

Just trying to think of ways of reducing the overall physiological strain without reducing the intensity.


Before and after, yes. During, not really. Given the intensity and duration, muscle glycogen is going to be both the primary source of carbohydrate and the primary source of energy, and ingesting carbohydrate during exercise isn’t going to change that. Indeed, your likely going to be hyperglycemic at least initially even if you do such training after an overnight fast and only drink water during exercise.

ETA: Note that by “before and after”, I am referring to habitual diet. Aside from making sure that your glycogen stores are adequate, pre-exercise carbohydrate ingestion either doesn’t do a lot, or may be harmful if you experienve rebound hypoglycemia. Somewhat along the same lines, the importance of immediate post-exercise carbohydrate (or protein) ingestion has been exaggerated.

Here’s a study (from 1988! I started studying exercise physiology in 1976) in which we had cyclists do repeated 15 min efforts at what would now be termed FTP, interspersed with 15 min periods of pedaling at “upper level 1”, with and without carbohydrate ingestion during exercise. On average, they were able to do 3 repeats at the higher intensity before having to dial it back a bit, and differences in performance due to carbohydrate ingestion only started to emerge after the 4th repeat (so >2 h of exercise).


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While that approach is seemingly logical, you 1) have to be careful that you’re not just being fooled by what I call the “teeter-totter” effect (modeling artifact*), and 2) consider your your competitive goals. If you’re training for a flat TT, for example, I think that it’s better to just keep pushing FTP work until race day.

*Note that when WKO4 was first released, it didn’t report estimates of TTE. That’s because I consider it more of a fitting parameter than a physiological indicator, due to the imprecision involved in both estimating (via modeling) and measuring (by doing a constant intensity trial to failure) it.