I do Vo2Max, 4x8m @ 106% FTP intervals. I do the first one without any problems, in the following intervals, unfortunately, due to leg pain (not breathlessness), I have to take breaks.
How do you think it is OK? Is it better to reduce the power or shorten the time? Do you leave it as is? Personally, I think I’ll leave it as it is.
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Are you sure your FTP is set correctly?
The fact that the 8m 280W is a record for you, I think it’s not.
106% is the absolute lowest part of the VO2-range. Maybe shorten the intervals.
I’d have to do my fitness tests to be sure 
I have FTP set to 265W. 2 * 20m training on 91% FTP I do without a problem.
I’m going for over 2 hours on 200W (75% FTP) aerobic decoupling I have less than 5%. and average heart rate of 144bpm. When I do a test with HRV with DFA a1, everything is below LT1.
This record is only from this season.
This season I am just starting Vo2Max intervals for 8 minutes doing.
If this is your first time doing VO2 intervals then I would cut the time down. So start at 6x 5min for a week or two, 5x6min then 4x8min.
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Hi,
Here you will find an excelente article about intervals The Magic of Interval Training (HIT or HIIT) - CyclingApps.net | Fastfitness.tips
and this is Tim Cusick “general” take on VO2 max intervals progression:
You’re lucky because your recovery intervals are quite long. 4 minutes instead of the 2 minutes from the workout in Xert 
I hate those 4x8 ! I’ve been doing a lot of VO2max workouts this winter (kind of Ronnestads 3x13x(30s/15) and similar high intensity intervals), and whenever I do a “fitness breakthrough test under pressure” on Xert, Xert estimates my TP so high that I can’t even do 1 interval of those 4x8 at 106% !
So… I’m not sure if those 4x8 should be considered as VO2max workouts. It’s a different specificity.
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Agree.
The most “advertised “ VO2 max workout is the 5x5m.
The desirable rest period is 2m but you can make a progression here too. Starting with 4m than 3 up to 2.
Most individuals can stay at their VO2max for maybe 6 minutes tops.
A good strategy is to actually find out what your VO2max is in the first place, test your Tlim at VO2max, then target something like repeats of 50% Tlim and work your way upwards as you see fit. Or, you can keep the same time interval and bring down your active recovery interval.
Eg.
5 x 50%Tlim w/ 3min active recovery
Progress to
5 x 50%Tlim w/ 90s active recovery
and so on…
As for intensity to target, start with a number mid-way between your proper gas exchange threshold (or CP) and VO2max. If too high. adjust accordingly. If too low, same thing. Adjust accordingly.
There are no cookie cutter methods of training. So you have to assess it for yourself in a n=1 self-study.
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I personally really like doing sets of 15, 30 second intervals at 130% FTP followed by 30 seconds of rest. They’re called Billats. I find them very effective and doable and a good way to collect a lot of time at VO2 max.
Could you explain what is your acronym Tlim ?
I am abosolutely clueless about that acronym !
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Time to exhaustion at your maximum aerobic capacity.
Dr. Veronique Billat would be proud of me using up her acronyms 
It took me a while to understand this, but I think you mean that if you go all out for 5 min @ say 300w, then you start at 2.5 min @ 300 watts and then add 1:1 recovery. That right?
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Yes, and you’d do several repeats of that.
Personally, I think 2.5 mins is a bit too small, I’d start with a minimum of 3 minutes to maximize the time spent at VO2max within each interval too, since the HR takes atleast a minute or two to stabilize.
You can get creative with the recovery duration. As you get fit, you bring down the recovery duration. If you’re not fit, you need some extended time at P < CP to recover reserves and reconstitute W’. Lots of ways to skin the cat and get a good workout.
If this is for cycling, make sure that cadence is nice and high and you’re a few beats from your max HR each interval.
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That reminds me of Thibault’s interval training:
Been doing a lot of these this Winter…
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Start with short/short intervals, to get some “legpower”,
30/30 @120% - 3x10
or 60/60@120% - 3x7
it depends on your abilities to higher powerzones and endurance.
Do one or two trainings on a week for 2 weeks, and the restart with longer intervals on lower Z5 values.
Progression for 4 weeks:
4x6 @106 Rest: 3’
4x7 @106 Rest: 3,5’
5x7 @106 Rest: 4’
4x8 @106 Rest: 4-5’
good luck
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