I was listening to this and wondering if it was worthwhile to give it a shot. 2 moderate VO2max TR workouts the same day (morning and evening) instead of a single hard VO2max workout?
From what Iāve heard about double-threshold training in the running world, a lot of athletes are going back to one bigger session per day since high-carb fueling allows it without as many risks of fatigue and injury, which is what prompted the two sessions to begin with. 
Double threshold and double vo2 are not the same thing.
Theyāre both two hard sessions in one day. I think my point applies to both. 
Marinus Petersen is a coach working with Koolie Moore whoās a strong promoter of these double VO2max days. Yes, it is VO2max cycling workouts. The usual format is 3-4 times 5min high cadence low VO2max (around 105% ftp) in the morning and again later in the evening.
It looks daunting but Iād sign for it instead of a singe 5x5 min at 115%ftp single session
Itās two hard sessions yes but the reasons for breaking them up are completely different.
I would listen to some of the podcasts they have done, they explain it quite well.
I havenāt really heard Kolie Moore pushing double VO2max days especially for your average amateur. My guess is that this would be for an elite level athlete needing a strong stimulus.
But give it a shot and see if you can recover.
I recall Sebastian Weber talking about VO2max days during team camps. Theyād do like 5 sessions in a day and do nothing else but eat and lay around the pool all day. I donāt think pro teams are doing this approach anymore or at least I havenāt heard about it lately.
Here is Koolie Moore talking about it. Why itās beneficial is mostly unknown but it looks like empirically demonstrated
Interesting. I donāt think heās talked about double days much on his podcast. Of course, he says he hardly ever uses blocks but everybody was talking about hard start blocks a few years ago.
Give it a go. Note all the caveats he puts out there.
I also thought that it was interesting that he said a starting set might be 3 or 4 x 4 minutes. Only 12 to 16 minutes of work. Lower power on the 2nd session.
This was for runningā¦ but back in 1998-2002 we would do workouts like 60 min tempo @ marathon pace in the morning then come back in the afternoon and do 6 x 300 in the afternoon. But that was early in the season.
I couldnāt imagine doing two VO2 sessions. Those were so hard you would often struggle to jog through the cool down. I guess the morning session is closer to threshold but I donāt think coming back for more in the afternoon would have much value, especially for masters athletes. But of course the bike is different so maybe that changes things?
Marinus is my coach and I can guarantee a couple of things. He is not āworking with Kolie Mooreā, heās got a whole different company called Kilowatt Coaching. Secondly, that āusual formatā is not true ā Marinus never prescribes anything with percentages of ftp. And yeah, he does like vo2max double days. Weāve done several double double days with him ā double vo2max day, then another one tomorrow, then a few days easy riding, then another double double day. Not fun, but really good for performance. I recommend eating lots of carbs off the bike, maybe taking a nap in the afternoon if possible.
I was listening to Steven Seiler talk about double days on Andrew Vontz podcast, particularly about the Norweigan runner. It sounded like his take on them is that unless you have been seriously training for a very long time, 10-15+ years, you can illicit the stress you need to grow without the extra fatigue or injury risk.
For the ultra elite, yeah they may need them. For most people it may not be worth it.
My main issue with double intensity days is sleep after a hard session in the evening. I am afraid that negates any possible benefits of double sessions unfortunately
It works until you are pushing your limits. So late winter, early spring, double days can help me get my load up without getting wrecked. Applying the principle of Progressive Overload soon means that the first vo2 becomes too hard to effectively do another hard session that day.
Iāve tried it cycling/cycling, running/runninf, and cycling/running.
Isnāt the whole point of doing one of these very demanding vo2 blocks to break through a plateau?
You would need to be pushing your limits for it to be worth doing in the first place.
Injury risk though applies to running, not cycling. At worst, in cycling, youāll exhaust yourself and just want to lay on the couch for 3 or 4 days.
Initial thoughts were that this seemed like way too much vo2max, but if its works for his athletes, thatās hard to argue with. Iād assume thereās a minimum weekly TSS requirement to not completely bury yourself.
Napkin math is like 2x90 TSS on each interval day. Plus some Z2 on the days between, and a week of this could hit 600+ TSS easily. Will vary a good bit based on specifics, I just tossed something basic into workout creator for an estimate.
Had said they were doing 3x6m and 6x3m doubles, with long rest between intervals. Not sure if theyāre still doing the 20m rest on the 6x interval workout, they talked more detail on that for the 3x interval workout.
I do wonder how effective this would be if you reduced the TSS a little on each workout, to lower the total daily stress. Could you do 2x6m and 4x3m for example? and would it still be beneficial for lower volume athletes. Feels like I might be able to recover from that, whereas the longer workout sure look like theyād bury me.
Consistency has been highlighted as one the key markers of those who progress the most. No hero workouts or days. Just the boring day in, day out, week in, week out training that builds you up over the long term. The sort of training you can do without getting burnt out. The sort you can do over the long term.
To answer the question are they worth it? You have ask how they would fit in with your maintaining consistency over weeks, months years. If it blows your consistency, probably not worth it. If it does not blow your consistency, maybe.
But you probably already have easier wins in your training.
Consistency is king, and I think this kind of format would reduce consistency in the long run.
I (and I reckon most) athletes find āgoodā VO2max workouts very hard, i. e. they really tend to push myself close to my physical and mental limits, closer than other types of workouts.
If I split them in two, I donāt think Iād be able to dig as deep in at least one of them. Or, alternatively, Iād have to make both a lot easier to avoid burning out.