You can turn them into VO2max eliciting workouts, you just need to do them a lot harder.
That’s why the original Tabata protocol was so devastatingly hard.
[edit: the common mistake is prescribing ‘170% FTP’…the original protocol was based on 170% VO2max, which works out to something like >200% FTP. ]
Probably still not fast enough. 
That’s intense! Full gas means full gas when the Big Cat says it!!
And if you heard the Seiler interview (on VeloNews or Fascat-I forgot which), he says 4x4 or 8x8 are “you figure it out” intervals—as hard as you can sustain. No prescription besides that.
Right. I’m experimenting with a Seiler 80/20 block right now and I cap my Z3 HR at the Seiler ceiling ~92% HRmax, even though my hard start power is a lot more than what TR says to do. Remember, make your hard days harrrrd!
Is the 80-20 model really suited for volume of 10+ hours? I’ve been a 6-8 hr/week guy For years but feeling like I need to bump volume to get to whatever my next level is. Being 51… FTP is growing, anaerobic decline hopefully minimized, etc. hoping to keep racing age group and improve in that cohort.
I don’t have a scientific answer for that. I just know what seems to work for me.
Seiler says:
I found the following article a very useful summary:
That’s laid out very well, thanks for sharing!
Indoor or outdoor? If you’re doing your workout outside, they’re all pretty easy.
I was wondering about this very thing. I have always felt it easier to hit higher power numbers outdoors, but if you account for this variation (indoor v. outdoor ftp) I think you could potentially get an even better workout outdoors as long as 90% + HR is achieved?
I have a cycling track that is public (very lucky) and I’m going to try some VO2 max intervals outdoors. I have to think it has the potential to be even more productive for me personally.
1min @ 120% is easy.
I tried Kaiser outside today. Unfortunately our hills here in the south part of Sweden is anything but great for 360W sustained efforts. 
I did Acrodectes -1 last night, 3 sets of 15 minute 60/60 blocks @115-125%.
I generally hate most V02max work and I kind of enjoy 60/60’s, so that should tell you how easy the 1 minute stuff is.
I’m not really training for anything right now, mostly just focused on base and figured I should try to do some structured intensity once a week. I keep hearing voices like Chad and Friel telling me I need some Vo2max work mixed in to prevent decline (particularly since I’m in my 50’s).
So, if the 60/60 stuff isn’t enough to stimulate Vo2max, any recommendations on a v02 max workout that strikes a balance between Vo2 stimulus and effort that can be repeated weekly without burnout?
I’m with the OP; I’ve done a few Spencer type workouts and find them easy compared to typical threshold intervals. I think this is down to physiology - strengths and weaknesses - and the fact that the interval targets are calibrated to FTP.
Having done a VO2 max test (more money than talent or sense) I know that my 4 minute power is pretty strong when expressed as a % of my maximum power on the test but that my threshold power and ‘all day’ power were average and poor respectively. Therefore if I do a VO2 max session with a power target calculated as a standard 120% of my threshold power it will obviously seem easy.
If I use the numbers from the test it suggests that I should do V02 max intervals at 129% threshold, which reflects my personal physiology. No wonder then that something like Spencer seems easy.
I would say try a few of the standard V02 sessions like Spencer and increase the interval targets if you find them easy. Don’t forget however that everything is fluid and as your fitness goes up and down that may need to change. I’m guessing that the elite guys do CPET tests in the lab with the same frequency we might do a ramp test.
It can be, but you have to do it at higher power than the prescribed 115-125%. Also, 8x1min blocks might not be long enough to sustain the target HR. Maybe search for 60/30s or 3x 12x1min workouts and just go as hard as you need to for your HR to hit >90%.
Give Rattlesnake a try.
Yup. For 60/60 and repeatability I did some trial and error back in Feb:
for me, about 150-160% is repeatable and will elicit max oxygen uptake by 3rd or 4th interval. Would take a bunch of sets of say 8x1-min to rack up 12-20 minutes at max oxygen uptake.
In terms of when to use that type of workout - like in SSB2 I’d use it more as an easy on-ramp to vo2max work. Or perhaps an opportunity to work on higher power repeatability (vs power for 3-5 min vo2 intervals) - more like long speed intervals aka extended accelerations to chase down a gap into a headwind.
From what I know you should be doing at least 3 mins of that intensity with 3mins recovery … I think there is every little science backing that formula up in my opinion … 3min to 5min should be" flat out" sessions already focusing on vo2max
I am really not sure why that was prescribed … I see many sessions are really just keeping athletes busy these days …
Interesting to say the least
I think this “intervals” is wasting your time. Find some more stimulus
Intervals have :
Can we talk 120% intervals for a bit? I saw Spencer +2 in my calendar after an FTP increase following Ramp Test. Spencer +2 is 6 x 3min @120% FTP. I knew I didn’t have it in me, so I did Givens -1 with 1% reduction in intensity, which is effectively 6 x 2.5min @120% FTP. I barely made it. Spencer +2 does not seem achievable now. I have passed this workout in the past, but at lower FTP.
I am on a bespoke low-volume plan where each week I do 1hr VO2max, 1hr threshold, and 1.5 hrs under/overs. Each week I want to do a VO2max workout that gets me closer to managing Spencer +2. Any thoughts on how to progress? Should I do 6 x 3mins @ 118% FTP or keep at 120% but perhaps try to add 15 seconds to each interval? Or should I be happy with being able to do 6 x 2.5 mins @120% and move on to other VO2max objectives for the weekly VO2max ride?