Agreed on eating before VO2 being risky depending on timing. I’ve had issues from over consuming carbs during the ride too. I start to suffer, so I try to drink more sugar, which then bites me in the stomach. Finally, heat can get to me as well, so when possible, I like to do VO2 in a colder environment.
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Weird, maybe you are getting sick. Either way, if your subsequent attempts yield the same reaction then something is off and you should probably reassess and maybe skip the block. I don’t know, but your body is talking to you.
I thought I had had cereal about 2 hours before the ride, which would seem just fine. Didn’t eat on the bike because I was miserable. Maybe the cereal was bad?
Day 2 went a lot better. Stopped eating “real” food at 11 am (with 6 pm work out). Only ate simple carb snacks in those 7 hours. Drank mix during the work out (carefully) and did a much longer warm up. Going 7 hours without eating real food seems like a bad plan, but it worked 
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Samus, make sure your power duration model is fully seeded with recent max efforts.
FWIW, I’m consistently at 87-90% but I’m 58 years old and fighting declining VO2max. I wonder if they are mostly talking about trained 20 somethings in those videos.
And FWIW, doing more extensive work (tempo / sweetspot) has lead to my largest performance gains.
I also haven’t responded well to VO2max work. I did 5x5min last year, and while the workout was just fine, my legs were sore for a week. This kind of work just fatigues me and then my training load plummets while I try to recover between sessions. I’ll try again in 2025 but I’ll do way less time in zone minutes.
Maybe try something different instead of 5x5?
I’m more of a diesel and feel I get a good response to 4x6’. By not going to hard but still close to VO2max (I do these roughly at 112% of FTP and reach 96-97% of maxHR) I also feel like I’m raising my VO2max without going to anaerobic. I feel these also help improve FTP in a way.
I feel with shorter efforts I’m going to anaerobic and start going to high in Lactate. And thus also improve anaerobic performance over aerobic performance. And considering I’m not racing but aiming for longer Alpine Gran Fondos that is the opposite of my needs.
Just personal experience though, I have no scientific base for all of this, just ‘vibes’.
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I’ve played around with 4x3 and 3x4 and that seems to be a much better dose for me. This has been discussed above. Next time I won’t do a vo2 “block”. I’ll do one vo2 and one threshold workout per week and see how that goes.
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Yeah, I agree. More isn’t necessarily more with VO2max if you over do it.
And all other endurance training, from Z2 to Z4 also (at least) maintains VO2max.
If you’re doing these intervals “max” (like the stuff I’ve talked about all over this thread), 5x5 is crazy. People are obsessed with getting this 18-21 min “at VO2max” for some reason, and that’s where 5x5 comes from (I’ve seen some people advocating for 4x8s as VO2 training for similar reasons…). The truth is, you get plenty of stimulus from doing MAX intervals in things like 6 or 7x3 if the interval structure is good.
5x5 to train VO2max specifically? Nah. Not for me. If you need to improve 5 min power? Maybe. But I’ve trained probably two dozen cyclists to improvements the last three years coaching and I’ll let you guess how many times I’ve given 5x5 VO2s as a workout. I give 4x5 as one of the first steps of my VO2 progressions for people on 3x 3 weeks blocks, most of the time by that fourth interval if they’re doing it right, the work quality is markedly lower. Doing a 5th there would be detrimental. Maybe pros, but that doesn’t mean it’s good for the rest of us.
IMO if you’re doing 5x5, it’s more like suprathreshold work and that’s different/specific. Again, that’s all just my opinion here.
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What kind of results are you seeing with this workout? How do you know it’s working what you intend it to work?
If this is true, pretty good chance VO2max or max aerobic power is your limiter regardless of age. It’s really rare I see that number in any model I’ve coached (as in I don’t think I’ve ever seen it). 
My point to Samus was that maybe percentage of mFTP has to be individualized or maybe Tim Cusick is talking about well training youngsters. At 58, my % of mFTP just doesn’t move much. YMMV!
The strange thing was that I could do the 5x5 workout just fine - around 110%. I just couldn’t believe that it took 5+ days for my legs not to feel sore. Crazy.
I’m lifting weights this winter so maybe that will change the equation next year.
I don’t know if I’ve mentioned it in this topic but I’ve also enjoyed Vaccari ladder intervals. I read about them in an Alex Hutchinson article. I did the on portion, hard start. They are
3 minute interval
2 minute “rest” tempo paced
2 minute interval
80 seconds tempo
1 minute interval
40 seconds tempo
45 seconds interval
30 seconds tempo
30 second interval
repeat the 30/30s until you can’t go anymore. I’ve done like 15-20 minutes in total.
Most of all they feel more fun than traditional longer vo2 intervals. Alex Hutchinson thought they were great (4 free articles at Velo):
Well, what I noticed is pretty steep FTP incline after doing these 4×6’ coming of a bit of unstructured ‘ofseason’ (I still rode for 6-9hrs/wk including some Zwift racing).
I haven’t done these in a block though (I plan to in January probably). But rather in a once every 7-14 days, combined with some threshold/tempo/Zwift racing. As said, not really structured but also not unstructured.
I have done 4 of these now and noticed I my threshold workouts (e.g. 3×17’ today) at a much higher power then I would have expected. Hard to say if it is due to higher VO2max or higher fractional utilization without testing, but my 5min power during Zwift races is also on the highest level for this time of the year compared to previous years.
That said, could it be any other factor … Sure, don’t know.
But I do feel that I can complete these 4×6’ with long segments with HR >90% much better then the shorter ones. With those I either have to go to hard to get HR up during the interval and can’t sustain the power in subsequent intervals and also can’t up the HR in the later intervals. Total time with higher HR and breathing is just much lower with those. For me. I will try some 5×4’s as well at the start of next year to see how it will go too. But loved the 4×6’s for now.
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This is why those workouts are not great for block training. Too much. Great workout for other stuff (like TT training which is why Kristin Armstrong swears by it), but not really gonna move the needle on the things you’re targeting because it’s just way too much load in an individual workout. You’ll get better results doing some consistent/frequent workouts rather than trying to do one huge one that costs you 4-5 days afterwards. Total stimulus vs. individual workout stimulus. This is a tough message to get across to a lot of athletes who think every interval workout should leave them wrecked or they aren’t improving as much as they could be. Again, 5x5 at that level is probably fine for pros.
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There are coaches out there who swear by stuff like 5x5 at 105% on 1 min recovery progressing to 4x8 at 105% on 2min recovery as early season “threshold” work. (Note that their 105% for this prescription is of 60-min power rather than some tested FTP value, so really you end up essentially doing 25-32 min at what most of us would consider “threshold” by feel). Some of those protocols also include a hard-start. I think those workouts can be effective… but also found it interesting that a prominent coach who likes those (one of the guys at Fast Talk) admitted he was finding more utility in TTE extension via SST work now as well, so it shows you what they think they’re targeting with those workouts in my opinion.
Granted I think your 4x6 is higher intensity. If your 5 min power wasn’t better right now, I’d be concerned - of course it should be since you’re basically training it. And that increase in MAP translates to better FTP right now. So, that’s good if that was your goal.
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It is. I’ve been doing target testing based on the duration that wko5 says will have the biggest impact on the model. The real missing piece is efforts longer than 2+ hours, but if I throw in efforts from the past several years, my mFTP will bump up a smidge. I don’t think my mFTP is severely over- or underestimated given my threshold workouts.
This is what I did for Build Block 2 and it went well. I’ve got two weeks of rest & thresh, then it’s back on the horse for another mini-build block surrounding a B (or C?) event.
I’ve bumped up my (trained, wko5 modeled) VO2Max by a good 15% I started doing VO2 work. Half with the first dedicated block, and half with the second mixed block. My (trained, wko5 modeled) FTP has improved by over 20% since the start of Block 1. These are all new gains–I started Block 1 at around my all-time highs from 2022. Maybe the VO2 is revisiting old rugby territory, idk. Both Garmin FirstBeat and Sikto’s formula have modeled a higher VO2Max than wko5; the absolute value is pushing into XC skier territory, so I’m going with wko5’s lowball. Either way, the values are trending up.
87-90% is where I’ve ranged all fall. FTP and VO2max seem to be in lockstep with one another and I can’t separate them further.
I thought my weight might be artificially inflating the score, but tossing in a lower weight raises the %. I’m not sure where these coeffs come from. Perhaps whatever model they use gets wonky at higher weights.
(avg(metric(lookup(weight,now)))*0.007 + 0.0108*(ftp(meanmax(power),90)))/(vo2max(meanmax(power),90))
My operating hypothesis is that I’m extremely slow twitch dominant. How all this slow twitch translates to my high weight room maxes remains a mystery. But I don’t deal with much muscle fatigue from either lifting or VO2. And I’m not skimping on VO2 either (clearly not, given the progress). I can tell when the VO2 stimulus is good because my HR will be elevated for the rest of the day and my RHR will be elevated for 1-3 days thereafter. Also my sleep is affected.
I’ve been treating threshold and VO2 as somewhat of a continuum. I will often push threshold work into VO2 territory (eg, just hammer the last few minutes of an interval). If I don’t have much fast-twitch fatigue to worry about, why not maximize training stimulus? For thresh I string together 10 min intervals with 1 min standing butt break (thank you to @ivegotabike for that suggestion). So like, 4x10 with 1 min break between. Last thresh of the progression of Block 2 was 2x (4x10). The 10 minutes is a real sweet spot for me psychologically. During longer intervals I end up holding on and zoning out. With 10 mins I’m able to focus on emphasizing different aspects of the pedal stroke, leaning into (instead of away from) areas of weakness.
Did you do a 5x5 straight out of the gate? 5x5 is what sits at the end of my VO2 progressions. I think 5x5 & 3x6 were my last VO2 double day.
I’ve seen it, but I can usually move VO2max up pretty well at that point so people don’t hang out there for very long. I think it’s pretty unusual for someone to live at 87-90% “consistently” as he said, so there’s something missing there IMO.
FWIW I think @AJS914 is probably on the right track doing more consistent, shorter, but higher intensity MAP-style work (like 3x4, 4x3) in mixed block periodization. He won’t get a massive shift all at once, but I bet things will push upwards over the course of several months there.
Funny you should say that. Cause I did progress my threshold sessions from 5×5 with 1’ RBI, to 4×8’ to 5×8’ (60-90 sec RBI). But kept those at 95-98%. Definitely not 105%.
But that was more or less just some easing back in to it. Like today was 3×17’ with 2’ RBI and will progress that out.
Though I might keep 6×8’-10’ with (up to) a minute recovery in the loop as well. Those are fun and ‘easy’ to do after a full days work. And keep the longer intervals for mentally fresher days like the weekend. All just below FTP
Edit to add: FYI, I did those 4×6 around 310 watts and the long threshold of today around 265-270 with stable HR. The shorter Thresholds (8’ were around 270-275) to give some numbers and context. At 70kg.
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The difference in those workouts that you did is just probably the 95-98% of what. Most people don’t test 60 min power. Back when I did that protocol to see how it worked and how I liked it, I did a 60 min power test up VenTop on Zwift and then did the workouts at 105% of that value.
If you’re doing 95-98% of a model derived FTP (which usually has a shorter TTE), you’re probably doing the same workout or very close to what they’re shooting for.
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I did a 30 minute time trial at 280w in October. After that I assumed 270 for a while and now upped that to 275 on feel.
I’m due another long form test but feeling it for now
Old time bike internet lore: 5x5 @ 105% got branded way back when as ‘ZeCanon’ intervals by Caley Fretz - supposedly handed to him by some coach. He claimed good success with them.
I think it’s just because we read this stuff on the internet and in ex phys literature (Hickson study 1977) or we hear coaches on podcasts about 5x5. It’s kind of a standard classic now like 2x20 ftp intervals.
I wasn’t even thinking it would crush me. It felt fairly achievable in the moment.
Kolie Moore dropped a nugget in one of his Vo2max episodes. He said something like ‘you probably get 90% of the benefit out of a 2 minute or 3 minute interval’. Then you think - why does anyone do long intervals. He didn’t elaborate further in that episode. I think he talks about shorter intervals in one of the listener question podcasts.
Of course, we have many studies showing long intervals to be the most effective which further confounds us dumb amateurs.
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