VO2 Max test - full zone breakdown plus fat/carb burn rates

[TheHeadhunter]

I've posted this elsewhere, but it's probably more relevant for this group.

I did a VO2 Max test on Friday, I know it's the gold standard cardiovascular/cardiorespiratory assessment, but I've never been overly bothered. I've always relied on other metrics, plus 'feel', plus at 53yrs old I wasn't sure how useful it would be, but a friend arranged it and arranged a slight discount (£100) so I went along.


However, it was really insightful! Aside from the VO2 Max figure itself, we all got a report showing exact zone HR thresholds, where we all with from aerobic to anaerobic, fat vs carb fuelling etc. And then a consultation to talk us through it all.

Possibly the best £100 I've spent on my own fitness, definitely recommend if you have any element of geek about your cycling.

We used these guys: https://myvitalmetrics.com. Sites in London and Manchester. Can't recommend them highly enough.

[Voguely]

Interesting stuff, thanks for posting. How did they assess the fat vs carb burn rates in the last graph? Unusual to see that fat burn would go up, then down, then back up again over a range of power ouptuts; you'd expect it to have a linear build, up to the point of switch to pure carb energy system usage.

Did you find the numbers were about where you expected in terms of zones etc?

[TheHeadhunter]

Voguely said:

Interesting stuff, thanks for posting. How did they assess the fat vs carb burn rates in the last graph? Unusual to see that fat burn would go up, then down, then back up again over a range of power ouptuts; you'd expect it to have a linear build, up to the point of switch to pure carb energy system usage.

Did you find the numbers were about where you expected in terms of zones etc?

It's all part of the test. Exactly how, I don't know. It is unusual to have such a flat fat burn (and flat and immediate carb burn). It's not, apparently, unusual for it to drop and pick up again. The others that died the tests all did that with the fat. Mine was a little unusual in having carb burn almost immediately, and such a flat fat burn that extended all the way to the anaerobic level.

I do intermittent fasting though, and they suspected it was a benefit of that.


And yes, the HR zones were roughly where I thought, all very roughly 10% higher.

[Harpoon]

I've never done a test like that before, so maybe a silly question but is it a ramp test to failure at stage 17?

[Dannbodge]

I did one this summer as well.

Signed up to a university study and the first part was the VO2 max study and getting my LT1 and LT2 values

Annoyingly, their bike was terrible and made it really hard to perform. It also read a fair bit lower than my power meter pedals.

[z4RRSchris]

impressive stats,

c260w ftp? @ age 53 but vo2 max of c70? are you tiny kg?

edit: if your threshold is 260w you only managed 90 seconds after that? is that test to failure?

Edited by z4RRSchris on Wednesday 12th November 10:37

[addey]

Don't think FTP is 260? More like 240? Although I think the usual guide is 75% of last minute power, which would put it a bit lower again. Agree that he must be light!

[TheHeadhunter]

Yes it's a ramp test, but just go until you reach max VO2 (when the graph line starts to go down) and the RER figure gets to 1.1, it's not to a set 17 stages. Some get to more, some less. I think 22 is the max.

Start at 55w then goes up in 15w increments. Power isn't really part of it, you reach the inability to breathe enough before your legs give up so it levels the score between different bikes etc. My legs were fine, I wasn't reaching max power for my legs, but I just couldn't breathe, and everyone was the same, a bit like climbing above 2000m. That's what it is testing.

But yes, I am small. c60kg. I've not done an FTP test for a while. Last proper one was 305w in Summer 2024. Zwift calculations say its around 275w.

[mooseracer]

Just twigged who you are, the amount you do on Zwift must be paying off!

[TheHeadhunter]

mooseracer said:

Just twigged who you are, the amount you do on Zwift must be paying off!

Certainly a not inconsiderable factor.