Seiler’s 8-minute intervals (Polarized)

possibly, so far the results suggest the opposite, but its early days

TBH ive never been good at grinding, always been a peaky repeated VO2 rider, so im embracing that this year and focusing on crit/CX type efforts and races

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Agree! For fysiological adaptations I would aim for accumalated time in high heart rate(>90%hr max). Maybe start interval at high % FTP to ramp oxygen demand and reducing power output to grind 6-8min. No ERG mode, no pwr target, focus on high hr and heavy burn. Rest between intervals could be extended just to be able to reach and maintain that high hr.
I tried to get that kind of workout done with TR Workout creator, but there seems to be problem refreshing and uploading workouts.

Interesting - my experience well into a second month of POL training is the opposite; I can go harder when I have to. This is because, I suspect, I am not mentally fatigued from brutal intervals (at an excessive FTP from the ramp test, but that’s a side issue) 3x/week. Instead, when I know I have 1 really hard session for the week/3 in 2 weeks, I find it easier to empty the tank and really dig in, which has resulted in power and HR PRs from 5 minutes and up.


One of my mates has been spinning away merrily at 110rpm on a set of rollers all winter. We did our first proper hills (5-12%) today and he said he didn’t know what had hit him!

me too - been spinning 110rpm on the rollers for months, but at 115-140% FTP for loads of it the last couple of months, and already matching my PBs on the local hills :smiley:


Just thought I’d follow up with a bit of N=1 anecdotal evidence. After 4 weeks of doing these 2 VO2Max workouts with the rest almost all Z1 for a total volume of around 6 to 6.5 hours a week, I tested this morning → FTP down 8W. There are loads of confounding factors of course so only so much I can learn from this.

A few months ago I followed SSBMV1 (Threshold distribution with 1 base/recovery week at the end), it was a bit of a drop in TSS from what I’d been doing before but hoped to more or less maintain FTP at least but it went down 25W!

In between I did Zwifts 4-week FTP booster (spread out over 5 weeks), which resulted in a pyramidal distribution with max efforts over various durations thrown in and that got me a 13W FTP increase.

As I say only so much this can be generalised even for me never mind anyone else but I think it’s going to be Pyramidal for me now.

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Zwift’s 4-week FTP booster has been the most effective training plan I’ve ever followed and never felt too much or too hard. Used it a few years ago 3x back to back and bumped FTP by 10W each time around.


Only time I tried that booster on Zwift I failed it!

Think I went into it with a lot of fatigue from summer riding though. But the experience put me off. Might try it again sometime when fresh and see.

You were doing 4x8 twice a week and lost FTP?

Sorry haven’t read whole thread.

Did you have a few recovery days before you retested your FTP? You’ve got to have the recovery days / weeks throughout the year if you are going to give your body time to adapt.

I’ve been doing 2 VO2 Max workouts, the first building to 4x8@105% and the other 3x13 30/15 micro-intervals. The FTP drop may be due to residual fatigue as suggested as I tested after a recovery day rather than a week. In my experience, things don’t improve for me after a week of recovery though. I’m going to retest after a few more days of recovery or Z1 work and will report back if anything does!


Turns out a recovery week did help. Fancy that :wink:

Did another Ramp Test today, +11W from last week and +3W from 5 weeks ago at the start of the polarised block. Not that significant a gain but at least not a very significant loss!

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where does this 8min come from? Why not 7min? 9min? 10min? 6,9min?

4min is the mother of all interval lengths

4, 8, 16min

6, 7, 9 or 10 would mess up the number series :slight_smile:


I don’t think there’s anything magic about 4x8 necessarily. In my case I built from 4x6 to 4x7 to 4x8 and will likely experiment with other Train Now prescribed workouts to keep things interesting and progressive.

4x8 mins has just worked well in some studies e.g. Adaptations to aerobic interval training: interactive effects of exercise intensity and total work duration - PubMed

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4, 8 & 16m intervals were used in a study by Seiler - 8m produced the best results in that study so have now become the ‘new 2x20’ :wink:

Point being, more time at slightly lower intensity than the 4m vo2 sessions proved more effective, but going even longer at an even lower intensity also proved less effective. You could call it a ‘sweetspot’ if some people hadn’t already appropriated that term :rofl:


hmm… avg Hr for the intervals; 85%, 88%, 89%, 91% (power 105-106%, last one 108%). I think this was fine for first 4x8 session.

So if i did 108% on the last one, does it mean i did too easy for the first three? I have underestimated my ftp? Or i just had good legs? hmm…

No it means you don’t fully recover between intervals which is as it should be.

Your first ones look like they might have been a little on the easy side and/or your FTP might be improving. 107% is the floor I’ve used for two seasons now after taking a ramp test. As you work through a cycle you should be able to bump up the intensity and maintain a similar HR each week. On average about a 1% bump in intensity per week has worked well. Sometimes 1.5% depending on other stressors. (This is when doing 5 x 8’s)

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I post it here, just came across it: