Is it vo2 max if your power drops below threshold?

Vo2 workouts are definitely the ones I struggle with the most and I’ve experimented with a few approaches - short/shorts, long low (106%) and recently, hard starts.

When I first tried vo2, all I did was try to maintain the power target - typically 120%. Then, on researching it seems like power is just a way to push your oxygen uptake and you should gun for > 90% max HR?

So I’ve been experimenting with hard starts. Go way over the power target and get HR up to > 90% then back off the power and just keep my HR up.

But, this does fatigue my legs and often I’ll end an interval at sweet spot power, although my HR is still > 90%.

Is this still vo2 max training?

I imagine there’s a lot of info in this thread - from memory (it’s a while since I delved into it) there was some quite heated discussion!

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As long as your HR is above 90% of VO2 Max it is. I’m reading the hard start thread and I’m getting that these intervals are based on HR.

Isn’t VO2 Max a measure of HR?

Edited; Isn’t VO2 Max determined by HR? Meaning to know you’re getting the correct stimulus (above 90% VO2 Max) don’t you monitor HR?

  • Nope.

That’s what I took away from that as well - it’s oxygen uptake, but hr is a better proxy for it than power.

I’m not sure if pushing over ftp has some sort of effect on the muscle that’s important as well and dropping below ftp negates that :person_shrugging:

It can be. Here is data proving it…from my thread on the anatomy of a 15 minute Vo2max interval. This is an example where measured O2 consumption stays at or near vo2peak for an extended period of time even though work rate stays (for t he most part) below threshold.



Right. It appears (I’m probably wrong) that the goal is to stay above 90% of VO2 Max at HR. Hence the hard start to spike the HR and slow decline of power to keep HR up but the power decline assists in prolonged time spent within that desired stimulus (above 90% VO2 Max HR).

I’ll keep checking that thread, I’m sure I’m missing something.

And for that reason I find breathing to be the best proxy. Locomotive breath. Breathing like a fish out of water.


This is why I’ve started to shy away from using erg mode. I can let my power dip whilst still doing vo2.

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If you feel like you’re drowning, you’re probably at 95% VO2peak or greater. If you’re not used to it the next day your intercostals will be sore.

If you’re going to attempt these extended hard start VO2max intervals it helps to mentally prepare yourself before you start. It’s gonna feel like you are suffocating. Don’t freak out when that feeling hits you. Relax. Keep pedalling. You can do it.


Locomotive breath is just below drowning. Maybe ~90% VO2max :man_shrugging:

Ok, that’s fair! The best O2 consumption as a percent of VO2peak for training VO2peak remains an open question!

I usually try warming up my lungs before a VO2MAX session or race even, it gives my diaphragm a good awakening too. It’s the same as what windwarrior said with “locomotive breath”. I read somewhere a while ago it’s a good thing to do before some hard intense efforts. It’s supposed to help your body get prepped for those workouts/races, I cant recall the source.


That’s what I’m talking about!

Related question: I struggle to get into VO2 max for my heart rate these days. 90% of max heart rate is 153 for me.
I also wonder if medication has an impact on heart rate. Would blood pressure medication impact my heart rate?

Did Gendarme +5 this week and have a steady heart rate of 146 from interval 3 to the end of the interval block. So 30second intervals with a 20 second break dont get the heart rate going hard enough.

A few weeks ago prior to an FTP increase I had done Mondnock +2 and had over 10minutes over 153. Those were 4 minute intervals.

AT is selecting short intervals and increasing the power on me. I know the next VO2 workout is slated to be Merced so 40 second intervals at 135%FTP.

I feel like I should be selecting different workouts if we are focusing on heart rate. The workouts do have my legs working and feeling it after so I dont find them a complete waste. Thoughts?

91% HRmax is riding at lactate threshold for 20-70 minutes for me. HR isn’t that useful for me. Although my coach uses WKO, he has a lot of athletes and it takes forever to load, so he estimates intensities using a different method. However he still arrives around the same level of intensity for example on a 260+ modeled FTP, WKO puts my max aerobic (FRC/FTP) at 268 to 393W, with 393 at 1:41 (easier to round up to 2-minute interval) and 268W at 19:53 (lets call that a 20-minute interval). Depending on the interval structure, they end up being locomotive breath like a recent 10-min at 290W, or drowning for air like 4-min at 330W. Whatever you do, I suggest turning off erg if being done inside.

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It would be interesting if they also captured and graphed perceived exertion along with the power / vo2 data. I know its fuzzy, but that would be interesting to see how difficult it ‘felt’.


Translation, courtesy of Jethro Tull:

"In the shuffling madness
Of the locomotive breath
Runs the all-time loser
Headlong to his death

Oh, he feels the piston scraping
Steam breaking on his brow
Old Charlie stole the handle
And the train — it won’t stop going
No way to slow down"

With vo2max work you can never win, only argue your limitations :wink: