When VO2max turns Anaerobic 💥

Yes much better all round.
Yesterday legs were just too lactic / acidic / etc and were shutting down. Got tonight’s about spot on.

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I’m basically doing a three week block. VO2 hard start sessions 3 x each week, 1-2hr endurance ride, and a 3 hr bunch ride. I’m hoping the VO2 focus for three weeks will help break through a bit of a mental block. I’ve just finished session 6, and it’s going well so far.

Let us know how you get along with 3 VO2 sessions per week.

How long should you be able to hold anaerobic interval though? - I struggle with inside/outside ration - and when i do the subscribed vo2 sessions outside for 4x4m lets say - i rarely look at power meter, and im just going to go as hard as i can - since i know 4x4m vo2 max have me clinching for those last seconds each set. But outside i can do 375w, and inside im more in the 320 ish. Just took an FTP test outside 2x8m - and came out with 2x at 368//364w - was that too anaerobic or vo2 though? Am i failing to get any vo2 session done outside basically ? And should i try to focus more on holding abit back? (alltought i think its hard to just keep at a number wiht uneven roaads.

My FTP inside (took on a ramp test) was at 288 three weeks ago

You cannot doo too hard vo2 max work. Especially with longer sessions like 4min and 8min. If you go as hard as you can you are burning your anaerobic contributions and go into higher percentages of vo2 max - so maximal aerobic. Especially when recoveries between intervals are short.

When you are doing intermittent intervals like 30/15s or 40/20s you recharge your anaerobic contribution and these become a more anaerobic workout. With longer intervals, you go as hard as you can and you always end working aerobically.

Here’s the energy demand contribution for better illustration

Or simplified:


I just go as hard as I can manage. As above you’re not going to get much anaerobic contribution on the longer periods.

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I think I’m in the V02max range when i can no longer decide when to stop breathing in. My body decides. It’s like there is a valve which suddenly clamps shut even when I know I need to get more air in.

I’ve done two weeks, 1 week left. Week 2 was better than week 1 so feel confident I will get through week 3 and earn a rest week.

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High North has a good workout based on this study. 5 x 6 min decreasing power intervals, 3 min between reps. I barely made it through four today, and I missed the power targets on the fourth. 4-90 sec steps @ ~ 120%, 112%, 109%, and 103%. WKO had me at 12:15 at VO2 max intensity in 24 min of work. I probably could have achieved more with a higher cadence.

FWIW I did a three week session, “polarized” either VO2max effort or Z2.

Did 3-2-3 workouts per week and didn’t have issues. Took about 10 days to fully recover and about 6 weeks to reap the full benefits: 3% FTP gain in what felt like overnight.


I’ve done 3 workouts in a row in the first week of the block.
First one was messy (went a bit hard).
Second one was 5 x 3mins indoor with 15s hard start. This was satisfying but painful.
Third one was outdoor on hills of 5 mins. Felt good and mentally much easier.

Overall I’m pleased as I was not sure I’d be able to get the intensity. 90g carbs in each 90 mins session and high carb during the day.

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Clarifying my post: I didn’t do any of them back-to-back. My schedule was:
M: VO2
T: Easy
W: VO2
R: Off
F: VO2
Sa: Long and easy
Su: Off

The second week I made the W VO2 an easy day because I felt terrible. Otherwise, no issues and the block reaped tangible (like, WHOA) benefits about six weeks later. I’m 43 and I haven’t played much with training density on myself yet. Maybe next block I’ll double or triple up some of these and then just take multiple easy/off days after before another round.


I’ll defer to someone who knows the physiology here (because I may be dead wrong) but I think there is some value in getting away from constant-pace VO2 intervals and getting more intermittent-spiky, going into zone 6. I don’t mean 30-15 or 40-20, but :30-:60 second efforts with :05 second rests. I’m more of a slow-twitcher, and the “whip it back up” restarts after the short :05 soft pedals kill me – I can hold better power on a constant interval than I can on these.

If I’m having a hard time hitting the wattage target and I feel like I’m locking up on the start of each short segment, I’m guessing that means that stuff like this is working a weak point.

This was last night’s set of 4 x 4min intermittent intervals on my fixed gear trainer setup, done after 15k on the rowing ergometer (because it’s what you can do when you’re tired that counts, right? Or maybe dead wrong!). I aimed for a 350w average for 4min, including the short soft pedals where the wattage would drop by 5-10w each time. I did 4 x 4 at 370 the other day while doing constant pace intervals with fresh legs. These felt much worse.

4 x 4 spiky

I wonder if they feel worse because those microrests have you briefly pushing high torque at low cadence, therefore load the type ii fibres a bit more

Also, what you can at the end of a race matters but I doubt there’s a physiological reason that high intensity work done, during training, when fatigued is preferable.

This was the first time I’ve done an interval set after an erg session. Since the muscle load on the erg is higher, I’d rather make sure I do that with good technique, even if it’s a low intensity session. It wasn’t a matter of planning or ideal adaptations, but more how the cookie crumbled that day.

By chance do you know if there’s a TR workout with that sort of structure? I had a quick look but didn’t see it. I’ll have a deeper look soon.

I don’t, I’m sorry.

Look at the MTB XCO specialty. Not perfectly close but has intermittent Vo2s.

Two weeks of 3 x per week Vo2 sessions.
I must say I found the recovery between sessions easier than i thought and the power of the intervals was about 10-15w higher in the last couple of session compared to the first.
Week after I was nailed (still am).
I’m hoping this week I can do 1 x Vo2 session this week and be good for race on weekend.
Not tested FTP as yet


Which TR training. Plan are you guys following for the vo2max workouts?