How Are VO2 Max Sessions Supposed to Feel?

I’m interested in understanding more about this, first learned about it with Xert and now reviewing post-ride in Golden Cheetah.

After a ride I can see W’bal “running on empty” at the end of hard efforts where I’ve got nothing left to give. Is there any benefit from analyzing W’bal impact of different VO2max/Anaerobic workouts? Yesterday I did Bluebell VO2Max workout which is 3 sets of 6x1-minute intervals at 120% FTP:

W’bal in red. I haven’t done anything in Golden Cheetah to setup the model, not sure of accuracy. Anecdotally, it wasn’t hard to complete that workout, unlike what I feel on outdoor race efforts when I see W’bal dip to zero (or go slightly negative).

Just trying to understand if W’bal is simply an interesting confirmation of what I felt out on the road during race efforts, or if it can help with customizing a training plan.

This is such a Pandora’s Box…for me, anyway.
I don’t mix this super-granular stuff with doing low-hanging fruit workouts, I just find it very interesting.

My new question: what are the physiological characteristics of finding long VO2 intervals relatively “easy” (e.g. 3-4min @120%)? Fast kinetics? Higher than average VO2max ceiling? More anaerobically trained (vs. aerobically trained)? :man_shrugging:

Big thanks to all who have the knowledge bomb! :brain::bomb:

From an absolute value perspective, W’Bal is valid, but as soon as you are dealing with “recharge rate”, it is no longer scientifically valid. This is why WKO4 has FRC but doesn’t have a W’Bal concept since they’ve said they can break any recharge rate model so therefore they don’t include it.

In otherwise, we can accurately predict how big the bullet is, but we can’t figure out how long it actually takes for you to be ready to fire another one of the same size.

I put W’Bal in the category of “interesting second order metric” that I wouldn’t base any of your training off of. Training to increase W’ or FRC is a more valuable pursuit.

That is what I meant, as during the year I had Xert I’ve seen W’ slowly increase and decrease. I’m assuming recharge rate can be shortened, by working on repeatability of above threshold hard efforts which is part of build and speciality TR plans. Or perhaps it ends up increasing W’ so you can go longer on hard efforts. In any case, my conclusion after using Xert is that W’ and W’bal are interesting second order or maybe even third order metrics. As I said above, its kinda fun looking at W’bal to confirm what I felt on the road but beyond that I haven’t seen a use for it - and yes I can display it live on my Garmin head unit but why? (when I’m going all out the last thing I need is a head unit distraction, particularly one that is telling me I’m about to run out of gas)

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Exactly. Especially because it’s as likely to be wrong as it is right.

The thing about all of these models is that they are all “descriptive” with varying degrees of accuracy. They know what you’ve shown and can tell you what it knows based on that info, but they are not predictive in any way shape or form.

I suppose it can be useful to review after hard TR VO2max/anaerobic workouts, if it felt like I emptied the tank and W’bal says otherwise. That might tell me the reason for workout feeling really hard was more likely due to other factors like cumulative training stress, work stress, lack of sleep, etc. A semi-interesting data point, but not a primary metric.