Double day…
Couldn’t quite get 4x6 done for a second time - only 4 mins in the final interval. Plenty of time breathing like a fish - actually got a bit panicked at one point and had to turn off the Vacmaster that blows into my face, as I felt like I couldn’t breathe. Good times 
Big drop off in time spent around 93-94% HR max - no doubt a symptom of a 2nd workout 7.25 hours after the 1st one.
I was about ready to die after my block, where I never had more than 8 5-minute intervals in a 24-hour period. And here you are with almost 8 6-minute intervals in <8 hours? 
Nice work!
Let’s see how the block goes before getting too excited! I was in good shape in December - lots of Z2 (loads of 4+ hour rides) and SST - working up to 1x120 had me feeling pretty robust. Also I’m a big diesel, so recovery from efforts tends to be decent. So I’m probably overdue to try and raise the roof again.
Since I’ve had VO2 blocks not work out for me in the past, I decided to go the nuclear option. Will play it by ear whether I do the same in forthcoming weeks.
Reporting back on day 2’s 5x5. Off to a strong start with the first interval being 11w below my all time PR, and then fading off a bit. That’s 3 VO2 max workouts completed in 29 hours. I’m not sure if I have the mental fortitude to do the same again next week - let’s see… But I am grateful that the week’s work is done in just 2 days 
22.47 over 90% max and ~10 mins over 95%
Anyway I won’t continue with the blow-by-blow account, but thought I’d just share some experience as I haven’t seen much on 2-a-days. I might check in down the line with results…
I admire your fortitude. I’m sticking to 1 day VO2, 1 day recovery, 1 day VO2, 1 day recovery, 1 day VO2.
By the way did you do your intervals with erg? Or do you have such great intensity control?
Resistance mode - set to an appropriate resistance that lets me crush and be able to recover to low wattage using the gears (that’s 24%-ish for me on the Neo). However I usually switch to ERG in the recoveries, as it bottoms out 10-20w higher than I’d want to.
During the intervals you can see the power step down as I shift gears on the bike when I can no longer hold the power/cadence at current level. Ideally I’d maybe use the resistance button in the TR app for a finer resolution of power control mid-interval, but I use the mobile app, and it’s too small/finicky when you’re dying on the bike 
I’m glad the cadence looks good - that’s the aim. 110RPM+ or nothing!! 
Caveat: not sure how much smoothing of charts the Neo does
Week 2 was somewhat less successful - layering on work stuff, and decorating on top of last week’s fatigue.
I had a false start on Tuesday (abandoned 4 mins into the first interval), but tried again on Wednesday, while knowing a 2-a-day absolutely wasn’t happening.
In fact the planned 5x5 didn’t happen, but a 4x5 including an all time 5 min PR was definitely good enough.
Thursday I went again - 6x4 - absolutely on the limit
Friday - went in aiming for 6x4 again, but pulled the plug on interval 1 after 3 mins. So 7x3 it was… I mentally cracked on the attempted 3rd interval, but as I spun the legs I resolved to try once more to salvage the workout… and somehow did. I even knocked out a 4-minuter as the light at the end of the tunnel approached. That was character building!
After week 2 I’m pulling the plug. 6 VO2s in 11 days was more densely periodised than last year’s successful block, and had a good bit more continuous interval time.
So in conclusion, I “f*cked around”, now time to chill for a while and find out.
Nice!
Can you post a pic of your calendar to better see how this was laid out?
The week before was recovering from a cold, and then a 30/30 “prep” workout (Cypress) at the weekend. As I mentioned above the Denali workout on week 2 (16 Jan) was abandoned after a few mins. Also to clarify, workouts were done in resistance mode. The TR workouts just privided the desired template.
Have also just finished a VO2 block which covered 11 VO2 workouts in 20 days and finished on Thursday, abandoned that workout after the 2nd internal which confirmed I was ready for some recovery!
Started immediately after a Threshold block with Red Lake +3 on the 29th and the final successful workout was Elephants -2 on the 16th, after struggling through that one I tried it again on Thursday and pulled the plug when it became clear it wasn’t happening! 
This seems like an appropriate enough place to ask: are people using resistance or standard mode for their VO2max intervals? I’m starting a block and endeavoring to leave behind the bosom of erg and grinding my reps. Day 1 was tough to keep the cadence and power up. My outdoor VO2s have all been on hills, too.
Edit: Kickr V5
Generally I find it easier to keep a steady power in resistance mode vs. ERG, which is somewhat attributed to my trainer (Suito). The micro-bursts it does to adjust for power gets to me at top end of VO2
Outside mode, the equivalent inside is slope or free/sim.
I actually do both.
Sometimes I do the first few intervals on ERG mode, I try to keep my cadance high as possible. Then the second half I do on resistance, maybe I can go a little on a good day, or a little lower on a not so good day.
I find intervals between 1 and 4 minutes work pretty good in ERG. Shorter (30’s or 45’s) are better in resistance (go as hard as possible), and longer then 4 minutes are also better in resistance because there is time to adjust according to feel.
Sometimes I do everything in simulation, 5% or something, pick the right gear and go.
So try what works best for you, general consesus is resistance/simulation as far as I have seen though.
Perhaps I was unclear in my initial question. I’m not asking about erg vs. no erg. In TR, there are three modes available with my Kickr: erg, resistance, and standard. My setup is to use my Garmin Edge to have the structure of the workout (ie, the timers and rough wattage goals) and to have to TR control the trainer while running a free ride workout of the duration I want. My question is whether people have experienced an appreciable difference between resistance and standard mode and if so, which is preferred.
I do not have Zwift so I can’t use sim mode.
Personally, I just use my Garmin to control the trainer. I connect my trainer and put use “free ride” mode where you can adjust the virtual gradient. Then I put it on 0 and just ride like normal. I think the speed and inertial feel ends up close enough to a virtual flat ground.
Sorry I haven’t messed around with the TR modes enough to know which is which.
Standard mode is better, a description here:
You can also use Wahoo app to set the mode.
Would there be a big difference in doing a VO2 max block over say 15 days, compared to doing it over 3 weeks or 4 weeks? Assume same number of workouts.
It would probably be better, assuming workout quality can be maintained. Use the time “saved” afterwards to ride easy for an extra week or so.
