Vo2 block periodization

That’s a serious first week!

See Chads recommendation on a vo2 intensive period here.

Yes, to be honest, I’m a little scared. Taken individually, each workout is productive, but stacked up like this is terrifying. But that’s the goal, right?

I’ve tried this before, but short intervals have always been easy for me. That’s why placed longer intervals at the beginning of the week and shorter ones at the end, when motivation starts to drop.

I did a 3 week block this spring with great results. In short:

  • In total, 11 or 12 workouts and races
  • abt. 25 hours of volume per week
  • took me about a month to recover fully
  • great improvements in aerobic fitness all-around

Anything specific you want to know?

I once did Hickson intervals on an ergometer in the lab 3 d/wk for 18 wk. Does that count as a “VO2 block”?


25 hours a week is amazing, I’m lucky to get 10-12

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What was the outcome of that 18 week “block”?

If it helps, I can quarantee you that it gets pretty boring pretty fast - especially indoors. It might take a month to recover from physically but probably a year mentally :sweat_smile:

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Myocardial fibrosis?

I hit the same limit for VO2max (i.e., 5.4 L/min) as I have achieved training other way. OTOH, my sustainable power (‘FTP’) was disappointing.

Specificity, specificity, specificity, specificity, specificity.

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I did something similar this year, 3 weeks of focus on vo2 (2-3x) per week. Then recovery week and
following that two weeks with high volume with 1x over under and 1x vo2 workout.

To be fair in the final week I was too cooked anyway and cut the vo2 and only did (poorly) the over under session.

I should have probably ended the vo2 sessions after the first block.

Anyhow, result? Meh :face_with_raised_eyebrow:
I think for me it might be more beneficial a mixed approach with a vo2 and thr/SS.

It ha been taking me a while to get power back while doing threshold and it has not really improved over last year.

Other info: I’ve been training for 5 years on average of 12-15 hours pw.

This year I also upped the volume hitting regularly 15 hours plus but somehow I fear my recovery weeks were also too easy (6-8 hours due to weather commitments etc).

Putting aside that somewhat less desirable outcome of myocardial fibrosis for a moment…

Did you reach that VO2max limit only after the full 18 weeks, or were you banging along at pretty much that level from earlier in the block?

If it was sooner than 18 weeks, was it quicker / slower at getting you there than the other way training you mention?

I only measured my VO2max at the end. However, based on my power:HR ratio (surrogate for O2 pulse), I was probably very close to my limit after only about 6 wk.

I can’t really answer your second question. I’ve trained a lot of different ways that led to essentially the same result, but except for that one experiment, don’t really have any good time-course data.

(I will say this: I was always a diligent off-season trainer, and would be flying about 6 wk after introducing intensity on a regular basis. But, 6 wk to ice the cake isn’t the same as baking the cake in the first place.)


What workouts did you progress for vo2?

I was lazy and did just one workout over and over trying to execute it as well as I could :smile: So no real progression in terms of TiZ and likewise the power didn’t really improve due to accumulating fatigue.

The workout was pretty much hard start intervals with high cadence and a slight “bumb” in the middle to increase heart rate even higher. Intervals were on the longer side, decending in length towards the end (6min, 2x5min, 4min and 3min).

I noticed first improvements in the fitness after about two weeks after the block. And once I fully got rid of the fatigue I managed to break my previous power pr’s in pretty much everything over 1 minute in length. You really have to give your body enough time to recover fully and not to rush to get back to grinding trough workouts.


I was able to handle vo2 70 sec efforts this week, followed the next day by a race and then 3 days later another race.

I have a race in 2 weeks after that week I will dial in a big vo2 block.

Due on-call duty (night calls and such), actually completed VO2max week became:

VO2max is hard as always, but overall it was easier than I feared. Probably because decreased usual weekly load considerably (20h/900TSS → 7h/500TSS). Recovered quite well for each workout, no heavy legs or improved sufficiently over warmup. According to Garmin, HRV did not change at all during this time. Usually when I do once a week 5x5, it is lower next day. Right now it feels I can return to usual weekly structure (Tue Z5 5x5min, Sat Z4 2x30-40min, other days low Z2)

Biggest bang for a buck per interval type (Z5+ HR vs power):

  1. 3x12x30/30 at 150%: 15:50 (87%)
  2. 5x5min at 114%: 10min (40%) ← this is also my usual weekly progression
  3. 12x2min at 120%: 9:13 (38%)
  4. 3x3x3min at 120%: 9:20 (34%)

With that, next time plan would be something like:

  • Tue/Wed Z5 5x5min
  • Thu SS90 3x20-30min
  • Fri Z1 1h
  • Sat Z6 3x12x30/30sec
  • Sun Z5 5x5min
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So the question is, what are you using to tell you whether or not this block was actually effective?

I hope to lower my Z2 HR. Currently HR Z2 top (~80% of threshold HR) is around ~60-63% of FTP and haven’t changed since last summer when I first started thinking about it.

But even if it does not help, I’m probably still going periodically do such blocks – it is just more convenient with work schedule, when I have to be on-call for a week and really can’t do long Z2 rides.

How will you know whether the lower Z2 HR is due to training or simply due to fatigue?

IMO, “even if it doesn’t work I’ll do it anyway” isn’t an effective training strategy. Point here being, this just looks like you did a bunch of stuff, but you’re not really sure what’s effective and what’s not. 30/30s usually aren’t very good for VO2max/Aerobic training. 5x5s can be, if they’re done right, but IMO targeting a certain strict % of FTP isn’t that. And then you’re doing a massive load of intensity over the course of 5 days.

I would be surprised if your Zone 2 HR isn’t a lot lower this week because of fatigue, so be careful that you’re not confusing causation here.


Yes, this time simply tried various things to learn and scale my expectations for future :slight_smile:

Listened Watts Doc podcast about VO2max and 30/30 vs long intervals some time ago. That’s why my usual weekly progression has been 5x5. And I am not fixed at specific % of FTP, 114% is just my current frontier, trying to push it higher every week. Once I hit real limit, then will try extend intervals to 6min and possibly beyond. Reason for adding 30/30 on Saturday, is because this is somewhat easy for me and helps to keep motivation through weekend.

i ride long distances for my own pleasure (8-24h), no racing, no need to peak or anything. So, if I am chained for a week indoors, then VO2max block sounds good enough. Definitely don’t want to spend 3-8h+ on trainer over that period.

Or if you have suggestion for better approach, I’d be glad to hear it. For now I have tried to schedule recovery week for on-call period but even that is somewhat unpleasant. VO2max definitely feels better.

intervals.icu shows long-term EF for Z2. Of course, I’ll ignore it during week immediately after block, will check in 2-3 weeks. And whether it really helps hopefully will show in couple months or so.

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I’d encourage you to do more sets of less time overall (e.g. 4x5s rather than 5x5s), and execute the intervals differently. With your volume and tolerance for training, you could be a candidate for a structure like 2-a-days. Also, keep the focus solely on the VO2max work and scrap the sweet spot stuff which is just adding fatigue and restricting how hard you can go on the sets that matter. Same with the 30/30s.

If you’re time limited for a week or two, there’s nothing wrong with really ramping up your training density, but IMO it’s quite a bit more effective to target one specific thing when doing that (endurance, VO2max, even back-to-back FTP sets). Otherwise, you’re probably not doing any of it well.

So instead of 3 sets of 5x5s in a single week with some other stuff, either do 4-5 sets of 4x5s of high-cadence VO2max work in a week, or do 6-9+ sets over the course of 2-3 weeks and then keep everything else lighter intensity (maintaining volume if you can).

You can parse through some of the other VO2max threads here where we’ve gone in-depth about specific workout execution and doing the interval sets in the manner “originally” (it probably wasn’t his idea either) prescribed by Dean Golich, et.al.

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