Threshold intervals for building FTP

If we’re targeting somewhere between 95-105% of FTP for power for each interval, what have you found to be the most effective?

Background: I’ve been happy with a custom Sweet Spot progression by which I’m focusing on building up TiZ through intervals that are no less than 15 minutes in duration. As the progression moves on the interval length increases. Example: 3x15 > 2x25 > 1x45

I’m curious if a diet of intervals similar in nature, but targeting a higher percent (or even above) FTP is the most optimal way to go. I’m looking at a couple of ways to approach this. Either riding longer intervals at or just below FTP or shorter intervals just above FTP.

Example A: @95-100% of FTP: 4x10 > 3x15 > 2x25
Example B: @102-105% of FTP: 4x8 > 3x12 > 4x10

I would do 2x (possibly 3x of example A) of these workouts per week with the remaining workouts/rides at or around LT/VT1 or 65-75% of FTP.


Here is my approach. I do 98% of my rides outside and I live an a mountainous area. So when I do threshold I pick different climbs and the progression is like this:

1 x 35min
1 x 25min + 1 x 35min
1 x 45min
1 x 60min
1 x 60min + 1 x 25min
1 x 70min

All these done at 95%-105%. And it never made sense to me to do shorter intervals. I’m curious to learn what would be the advantage of those over my approach.


Version A. Implementing longer threshold workouts was a big jump for me (not to mention 70W FTP increase since that). Going just below it also helps with recovery and you can go longer (and as a goal you should in my opinion after this progression).


B looks closer to what some studies are finding most effective. Intensity is king is seems.

I like the idea of mixing A and B up to cover any weaknesses.

Yes, with vo2 max and sprints. 105% is not high enough intensity to elicit the same adaptations but you will be destroyed all the time. By going under you can go longer and rip more benefits. And you will be able to supplement it with harder efforts if you want.

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Good question, but don’t we also need to talk about what you do the rest of the days?

I’m doing B - 105% work - but the rest of my week os long z2 work, and together it looks like 1 or 2 interval days and 4-5 endurance days totalling 15-20hrs. I don’t think you can look at it in isolation.

My other question is whether that progression is realistic. Progressing time >FTP is nothing like progressing time at SST. I’d be surprised if you can genuinely progress 105% FTP anything like as fast as that or to that TiZ, IF your FTP is set correct. A jump from 32 to 45 mins TiZ @ 105% is a BIG increase in capability and my own experiences moving from 6-8 min intervals makes me question a shift that big. Maybe people with a far better anaerobic performance will be able to do it, but who knows?

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I have exactly the same question. Iam in a 3 weeks FTP block (2 FTP workouts each week).

1e workout i did 3x10min @ 105% with 8min rest. (After that i thought the rest was a bit to long for the duration of the blocks).
2e workout i did 3x15min @ 97% with 5min rest.
3e workout i did 3x18min @ 97% with 5min rest.

Optimized intervals said 26min 95-100%. But iam now thinking about to do more intensive and less duration than 26min. So for example 3x15 with 100% FTP and 5min rest. But when i need more rest to get 100% FTP i will do more rest…(do you think that is ok?)

For TS it also depends on your goals i think. Iam crit racer so i dont need more than 45-60 TiZ.

Fair points. This is more of a theoretical question asking what is optimal or what has worked well for TR users: building FTP with longer intervals at or just below FTP or shorter intervals slightly above FTP.

I think the durations for B need to be in that 8-15 minute range, for me anything less than 8 min (eg 5x6 @ 105%) falls into that area of not quite hard or long enough. Hence why I started progression B with 4x8 (a Seiler staple)

I included a sample week for both to help add context.

Here’s a little snippet from a Reddit thread (user is Kolie Moore)

“I usually go 10w below 100% ftp for threshold work”, as a percentage of FTP that equates to 97%

I’ve found one VO2 max and one threshold interval session a week and rest low intensity long duration works well.

As to progressing duration of intervals or interval sets. I’ve found adding 10% duration to each subsequent session type works sustainably.

So for threshold that might look like.

3 x 5
3 x 5.5
3 x 6
4 x 5
4 x 5.5


After a recovery week and ftp retest. Hopefully with new higher ftp restart half way along duration, say 3 x 6 in this simplified example. Then progress duration so you’ll be further along at end of next block etc.

Remember FTP is just something for setting training intensity and showing one marker of fitness progression. It’s no good progressing FTP if your events are 5 hours long and you cannot repeat that FTP effort after 4.5 hours of easier effort. So don’t neglect the base endurance.


Those look like very short intervals for Threshold, shorter and less intervals than are common for VO2max sessions. For VO2Max you generally target 20 - 30 minutes TiZ and ^this is less than that.
I would have thought for Threshold you’d want to be targeting 40 - 75 minutes TiZ

What rest between intervals and what % of FTP?

It depends where the OP is starting from. The duration climbs quickly enough. This was just a simple example not a prescription. If you are used to 2 x 45 mins threshold then start there etc.

Ah, got it, not literal. ~+10% rule seems to work out…

With rounding starting with a TiZ of 30minutes…
30 - 2x 15
32 - 2x 16 (could have made this 33 - 2x 16.5)
36 - 2x 18
40 - 2x 20 etc…

You’ve got it. Yeah just round as you see fit. I just used 10% as maths is easy. Whether it is 8% or 12% increase per session doesn’t really matter. Just progress it steadily and it soon builds and sustainably.