Seiler’s 8-minute intervals (Polarized)

4 x 8 min intervals at 108% with 2 mins rest would be brutal.

Start with the workout Jobs (4 x 6 min intervals at 105% with 2 mins rest), or Jobs-1, and then adjust up from there over time.


Gross, most likely.

Especially if you are not conditioned for, or weak at, VO2 max work.

Personally I would find completing the same time at intensity, in more bouts (i.e 8 x 4 or 6 x 6) and gradually progressing more rewarding and encouraging than falling to bits on 4 x 8.

Granted the initial adaption isn’t going to be quite the same but productivity from blowing up 4 times on the trot has to be evaluated too.

That said I have a reasonable VO2 Max performance and having done mostly SweetSpot work the last 6-8 weeks I found Elwell (one of my favourite go-to’s of the past) to be challenging but managable.

Might be a good place to start and then modify the workout.

Here’s my personal experience with trying to find the best set for me.

  • I started with 5 x 4 minutes with 2 minutes rest at 111% FTP and started failing in the 4th interval. This was too hard.

  • Next time I stepped up the length of the interval to 5 minutes, increased the length and dropped the intensity a little: 4 x 5 minutes with 3 minutes rest at 108% FTP and I got within 1 minute of the end before failing.

  • My third attempt was 4 x 6 minutes with 3 minute rests at 108% FTP which I completed successfully but the last few minutes was hellish.

Between the second and third sessions I had a week where I did a couple of 30/15 intervals.

Here’s what that 3 week period looked like.

Resting up this week but my plan is to continue to combine the two types of intervals and work my way up to the full 4 x 8 minutes duration. It’ll be interesting to see what happens when I re-test my FTP. Good chance I’ll start with 4 minute intervals again an see how many I can do with 3 minute rests.



Two observations.

  1. Putting numbers into Workout Creator and getting an intensity factor reading across the 4 intervals, I don’t believe anyone should be able to do these at more than 105% of threshold.
    This workout expects you to do 32 minutes of work with only 3 2min rests. If you can do that at “108%”, then you probably need to re-test your FTP.
  2. The stated purpose of the Seiler intervals is not to hit a particular power, but to accumulate the maximum time at vo2 max. It’s on another thread but it’s somewhere around 90-92% of max HR you’re shooting for (maybe up towards 95% in the final interval but not before or else you’ll probably blow up soon after).

Edit: I might have got mixed up with my Workout Creator numbers (see below) - I’d now revise this to say that 108% is just about do-able, but completing it at anything above that would suggest a re-test is in order.


I do these from time to time and I find they are doable but very challenging. However, I execute them the way Seiler (and almost every running coach I ever had) specifies, not the “hit the power ERG mode TR approach”. I go anywhere from 102% to 108%. I only know I hit that %FTP after the fact.

Not knocking the TR way of doing intervals. But I find it trying to fit a square peg into a round hole. A nice side effect is that you are learning pacing by feel, maybe less important for cycling than running? Not sure.


My take (from a different thread):

Conclusion: 4 min intervals rock! :metal:


Lols, I struggled with Mount Hope-2 a few days ago which is 4x10mins at 95-99% FTP and 6min recoveries! I was a little fatigued from the weekend of training, but still…I did however really enjoy the workout.

I previously did sustained power build and I am DONE with anything 80-100% FTP. How I even thought that would be of benefit I do not know (I have a Masters Degree in Sport Science). Sweet spot is nothing more than a no-mans-zone intensity that’s too low to create adaptation but high enough to create fatigue.

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Sweet spot and threshold have worked for me. So have VO2max and sprint work. Not everyone responds the same.

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Didn’t think the sustained power had that much sweetspot work. Thought it was more threshold, U/O’s and VO2. My experience with sweetspot (90% ftp) is that it’s hard enough to bring about adaptations but not so hard that you can’t do back to back days. Think it works well for building a base early on in the season. Horses for courses and all that!

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Sounds like the Polarised training thread is where you need to be

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The intensity factor is 1.03 but the workout length is only 38 minutes. I don’t understand why you think that a rider shouldn’t be able to complete that.


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Well, yes, but the subjects were asked to do even pacing across all four of the intervals, so it makes sense that the intervals should all be at the same power. The trick is to decide what power that need to be at to get to the end only just able to complete the last interval. This is were it becomes very individualised.



Maybe you’re right. I think I was mixing up the numbers I put in for 105 and 108.

Though by the time you get past 30 minutes, the power curve is pretty flat. 38 minutes at 103% is a seriously tall order. TT race pace territory.

These intervals are very hard.

It will depend on the specific rider too. My numbers are a percentage of my FTP taken from a ramp test, which I’m pretty sure overestimates my LT2 so the actual percentages could be a little higher.

I’ll be interested to see what happens after my next FTP test.


I just think of those 2x8min tests and trying to hold very close to that with minimal recovery… ouch ouch ouch ouch

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The 8 minute FTP test assumes that your max 8 minute power is ~110% of your FTP, so it would be really surprising if someone could do 4x8 minute at only ~2% below that “max 8 minute” effort, that would be some seriously impressive repeatability.


I think that’s a fair observation, and as it is, I haven’t worked up to the full 4 x 8 minutes yet, and it’s been a while since my last test…

To complete the picture around the different FTP tests:

The 8 minute test is 2 x 8 minutes at 111.1% FTP (100/90) with 10 minutes of rest between. The IF for this is 0.99 for 26 minutes.

The 20 minute test is 1 x 20 minutes at 105.3% FTP (100/95) with a 110% 5 minute effort before that to reduce the anaerobic contribution. The IF for this is 1.01 for 30 minutes.

On reflection I could see the intensity being reduced back a little to get to the full 4 x 8 minutes.


Although many people believe that 95% of 20 minute test overestimates most people’s FTP. Which would - if the ramp test is a better test for FTP - tilt things back towards 1.03 intensity for 38 minutes being just about possible.

Just adding my 2 cents. I was going to try a polarised plan this year but have since changed my mind. However I did try a scaled down version of the 8min intervals, 3 x 8, using Seilers method of let the athlete figure it out. I’m no athlete but I soon figured out I went too hard on the first interval when the 2nd kicked in!

1st was just a smidge under 110% ftp. 2nd was 106% and third 105%. Had I not gone as hard on the 1st interval, I’m fairly sure I could have ridden all three at 107% or just under.

One thing to note, the 2 min recovery intervals are not set in stone. Seiler said that he found most athletes only needed 2 mins before going again. If I were to do these again, I would increase them from 2 mins to 3.