Realistic conversion between VO2 and FTP

larkim

I'm primarily a runner, and there's a really strong correlation for me (and most other runners) between race times and VO2Max. It's not perfect, but broadly it works, and isnt hugely affected by height / weight etc.

Having jumped onto a bike more recently and riding FTP tests via Zwift etc, I'm a million miles away from other riders who would have similar VO2Max profiles when I compare FTP. Now I'm not imagining I become a powerful cyclist overnight, but if I have a VO2Max of about 52-55 and weigh 73kg, is there a "calc" of an FTP that I should be looking towards as something of a benchmark to give me confidence that I'm reaching the sorts of levels of cycling fitness that my VO2Max might imply? As of now Zwift is saying I'm at about FTP of 235w, but I get the impression that I ought to be closer to 300w, but that's just a sense of things without much logic!

fenix

Go with Zwift. Base your training sessions on that FTP and you'll see that you progress over the weeks.

You could use your guess I suppose but you shouldn't be able to finish any of the harder training sessions. If you can then your guess was correct.

It's impossible for us to know what your FTP is as we have no idea how much cycling you do or how intensely.

larkim

Thanks - but with respect, that wasn't quite what I was asking!

Given I can run a 5k in about 18:30 or 10 miles in about 64mins I have a good handle on what my VO2Max is so "fitness" is well measured in terms of what sort of intensity I can sustain for decet durations.

But is FTP far more a function of both that VO2Max and muscular strength (and efficiency too, I'd have thought), rather than just VO2Max alone, particularly when compared to running where (broadly) VO2Max is almost the sole reliable guide to capability. I don't need to train my aerobic side any more - so is it just strength I need?

I know how to max out effort levels and sustain a high level of work because I do that when I run. But as a cyclist I'm a long way behind others that I can run with - e.g. up the Alpe on Zwift I managed about 1hr20 - I think I could push that to 1hr15 if I was going all out at the moment. But other similar runners with similar VO2Max and similar lack of cycling experience are up there in under an hour.

bobmcstuff

Power at VO2 max is usually around 120% of your FTP (although it varies). How that correlates to an actual VO2 max I don't really know...

A previous thread on here: https://forum.bikeradar.com/discussion/12633254/relationship-between-vo2-max-and-ftp with some contributions from Alex Simmons (i.e., an actual coach) who seems to suggest 55ish is about ballpark for good level club riders.

https://blog.trainerroad.com/how-vo2-max-work-makes-you-fast-the-science-behind-it-all/ - your FTP is usually between 78 and 85% of your power at VO2 Max which is quite a wide range - bigger than the difference between my highest-ever and lowest-ever FTP test results in fact.

One of the things you are trying to achieve with training is to lift your FTP as a % of your VO2 max.

So trying to guess your FTP based on a VO2 max figure is a very inaccurate way of estimating your FTP, although it could give you some kind of theoretical maximum. I think the risk with doing that though is you could end up constantly beating yourself up about not being able to reach those power numbers.

However in cycling the actual VO2 max number is not really used much, since FTP and FTP/kg are more closely related to performance day-to-day. The Coggan power profile chart is possibly more helpful:


Your FTP is around 3.2 w/kg, which is in the "Moderate" bracket. I think the limit of what you can say based on what you have said above is that your potential FTP is likely to be some way above that.

So congratulations, you've got something to train for

maryka

In the lab studies I've done, relatively fit/trained cyclists' FTP is about 75-80% of their power at VO2max. Using this calculator with your figures, https://www.michael-konczer.com/en/training/calculators/calculate-vo2max your power at VO2max is going to be around 310w, so that puts your FTP somewhere between 230w and 250w. So Zwift isn't that far off.

An FTP of 300w at 73kg is over 4w/kg, which is going to require more like 60-65ml/kg/min VO2max.

singleton

Interesting reading - thanks to those who have shared.
I used to do triathlons and have always been a better cyclist (relative to the rest of the field) than swimmer or runner.

Ben6899

Is there any point in saying that pedalling efficiency plays a part as well? If you're wasting effort then your power output will be reduced.

ugo.santalucia

One of the problems is that you CAN measure FTP on a trainer, but you CAN'T measure VO2 max outside a lab. VO2 max is the amount of oxygen you burn per minute per kg of body mass. To measure it, you need your breath analysed whilst you are cycling. Any other number is just an estimate, which is often as good as a guess. Estimates can give wild results, which you are then using to draw conclusions, which makes very little sense.
If you are interested in VO2 max, get it tested in a lab, otherwise don't bother with it.

maryka

Efficiency does play a role. Interesting article here about that here, https://www.outsideonline.com/2398524/highest-ever-vo2max-cyclist-oskar-svendsen

larkim

@ugo - I'm sure you're right in general about lab tests being the only real way to test, but over the years there's been a lot of validation for runners that VO2Max is well correlated with actual running performance. It's not 100% accurate, but it is as good a rule of thumb as most of the others, hence people like Jack Daniels base their entire training and race prediction philospophy on it.

Thus for me coming from a running background, I'm just looking for something to hang my hat on, a similar rule of thumb. It clearly isn't as straightforward for cycling, and it surprises me how far out of line my cycling appears to be compared to other runners that I can compete with. But presumably with some dedicated focus I'd leverage the decent areobic state I have built as a runner and convert it quickly into improvements as a cyclist, even if there isn't a hard and fast rule about how high I should aim!

ugo.santalucia

Yes, but what do you need it for? All training methods are based on FTP, which can be measured, so you don't really need to have an approximated VO2 max, just measure your FTP instead

joeyhalloran

Efficiency counts for a LOT of both running and cycling. It could be the other runners are just naturally quicker at developing efficiency.

The other thing is, are you all measuring power accurately? Power meters are notorious for reading differently, especially any single sided ones.

bobmcstuff

maryka said:

Efficiency does play a role. Interesting article here about that here, https://www.outsideonline.com/2398524/highest-ever-vo2max-cyclist-oskar-svendsen

Is that specifically pedalling efficiency (which the previous poster was referring to) or the efficiency in turning all that oxygen uptake into power (which is more physiological, isn't it?).

My understanding regards pedalling efficiency specifically is that you can't really make huge gains there, not like with running where you can make big running economy gains. You can see this with pro cyclists: they all have quite different cadence and pedalling styles.

bobmcstuff

larkim said:

@ugo - I'm sure you're right in general about lab tests being the only real way to test, but over the years there's been a lot of validation for runners that VO2Max is well correlated with actual running performance. It's not 100% accurate, but it is as good a rule of thumb as most of the others, hence people like Jack Daniels base their entire training and race prediction philospophy on it.

Thus for me coming from a running background, I'm just looking for something to hang my hat on, a similar rule of thumb. It clearly isn't as straightforward for cycling, and it surprises me how far out of line my cycling appears to be compared to other runners that I can compete with. But presumably with some dedicated focus I'd leverage the decent areobic state I have built as a runner and convert it quickly into improvements as a cyclist, even if there isn't a hard and fast rule about how high I should aim!

Yeah I think it's unreasonable to expect to change sports and immediately be the same level as you were in the first sport (otherwise my running would be less terrible, not that I am a particularly good cyclist either ).

The other thing which hasn't been mentioned is you learn how to test after a few goes - FTP tests are generally unpleasant and I think a lot of people see some improvements in the test result just from practice at testing.

Ben6899

bobmcstuff said:

maryka said:

Efficiency does play a role. Interesting article here about that here, https://www.outsideonline.com/2398524/highest-ever-vo2max-cyclist-oskar-svendsen

Is that specifically pedalling efficiency (which the previous poster was referring to) or the efficiency in turning all that oxygen uptake into power (which is more physiological, isn't it?).

My understanding regards pedalling efficiency specifically is that you can't really make huge gains there, not like with running where you can make big running economy gains. You can see this with pro cyclists: they all have quite different cadence and pedalling styles.

You can make huge gains from a beginner's pedal stroke to something which works for you and is efficient.

True that pros have varying pedal strokes (high cadence, low cadence, drop heel, point toes), but you'll find they're all pretty good at using the whole of the pedal stroke rather than just pushing down from 12oclock to 3oclock... for example.

bobmcstuff

Ben6899 said:

bobmcstuff said:

maryka said:

Efficiency does play a role. Interesting article here about that here, https://www.outsideonline.com/2398524/highest-ever-vo2max-cyclist-oskar-svendsen

Is that specifically pedalling efficiency (which the previous poster was referring to) or the efficiency in turning all that oxygen uptake into power (which is more physiological, isn't it?).

My understanding regards pedalling efficiency specifically is that you can't really make huge gains there, not like with running where you can make big running economy gains. You can see this with pro cyclists: they all have quite different cadence and pedalling styles.

You can make huge gains from a beginner's pedal stroke to something which works for you and is efficient.

True that pros have varying pedal strokes (high cadence, low cadence, drop heel, point toes), but you'll find they're all pretty good at using the whole of the pedal stroke rather than just pushing down from 12oclock to 3oclock... for example.

I mean, I don't think the evidence really supports that, but sure, probably if you take your average completely untrained rider who might be rocking around, bobbing, wearing flexible trainers, no clips, then you might see some difference.

Pulling up on the pedals actually reduces efficiency: https://www.researchgate.net/publication/6290447_Effect_of_Pedaling_Technique_on_Mechanical_Effectiveness_and_Efficiency_in_Cyclists

imposter2.0

Ben6899 said:

True that pros have varying pedal strokes (high cadence, low cadence, drop heel, point toes), but you'll find they're all pretty good at using the whole of the pedal stroke rather than just pushing down from 12oclock to 3oclock... for example.

Bob is right - the evidence doesn't support that. There have been tests - there are links on here somewhere - which demonstrate that highly-trained riders (eg pros) have a pedalling style which is not really any different to anyone else, in as much as the vast majority of their power is made on the downstroke. What they are able to do though, when compared to others, is push harder for longer.

N0bodyOfTheGoat

Just bare in mind that it usually takes a number of FTP tests to actually judge what you can sustain for 20mins.

It also takes time for your body to heat adapt to riding to similar Watt levels indoors compared to outdoors and if you are heat adapted, this recent heat wave will cripple your efforts. For me, it typically takes ~3 weeks to heat adapt, doing 3+ turbo sessions a week above outdoor z3 for 20mins+. Once you stop doing frequent hard efforts on the turbo, it doesn't take long to lose that heat adaption, ~2 weeks for me and then I'm back to square one.

larkim

I'm sure that that's true, but I'd also expect that someone who is reasonably competitive as a road runner (OK, not setting the world alight, but trains effectively and delivers on the training) is capable of getting reasonably close to max sustained effort quicker than someone coming to cycling without a parallel background.

Good points about the heat though - though my judgement about how carp I am at cycling is formed as much through experience out in the real world where I get dropped by others with comparable general fitness. Zwift comparisons do seem to reflect that reasonably well though.

cruff

maryka said:

In the lab studies I've done, relatively fit/trained cyclists' FTP is about 75-80% of their power at VO2max. Using this calculator with your figures, https://www.michael-konczer.com/en/training/calculators/calculate-vo2max your power at VO2max is going to be around 310w, so that puts your FTP somewhere between 230w and 250w. So Zwift isn't that far off.

An FTP of 300w at 73kg is over 4w/kg, which is going to require more like 60-65ml/kg/min VO2max.

That's about right for me and the riders I work with. My FTP is 325 at 77kg, last Vo2 max test I did came out as 62ml/kg/min. Two of the riders I do training plans for are at 285 at 68kg and 273 at 64kg, which puts all three of us in the 'good' 3rd cat/'poor' 2nd cat - borne out by race results 😁

Neither of the other two have done a proper lab Vo2 max test but I'd bet big money they're around the same as me, maybe a little higher as they're twelve and eighteen years younger respectively (which means they have more potential than a useless fat old lump like me 😢)

Ben6899

imposter2.0 said:

Ben6899 said:

True that pros have varying pedal strokes (high cadence, low cadence, drop heel, point toes), but you'll find they're all pretty good at using the whole of the pedal stroke rather than just pushing down from 12oclock to 3oclock... for example.

Bob is right - the evidence doesn't support that. There have been tests - there are links on here somewhere - which demonstrate that highly-trained riders (eg pros) have a pedalling style which is not really any different to anyone else, in as much as the vast majority of their power is made on the downstroke. What they are able to do though, when compared to others, is push harder for longer.

Fair enough. Happy to learn. 👍

mpatts

I can only talk about my experience. High tested VO2 max, I don't run but when I do I am relatively quick (sub 19 5k, sub 90 half for example). My FTP is 262, I', 63kg. its been a bit higher but not much.

Ben6899

mpatts said:

I can only talk about my experience. High tested VO2 max, I don't run but when I do I am relatively quick (sub 19 5k, sub 90 half for example). My FTP is 262, I', 63kg. its been a bit higher but not much.

That's a decent FTP for your weight. 👍

My VO2 max - estimated from results as alluded to above - is 53 (~20min 5k, ~40min 10k examples). FTP is also 262. However I weigh 70kg...

😊

larkim

So Zwift uprated me to 259 last night (need to validate this, as the race seemed too easy, relatively), so with VO2Max in the same ballpark (running-wise) as above (18:30 5k, 38min 10k, 86min half) but 73kg it looks as if I'm closer to the range that I ought to expect to be in. Still room for improvement!!

bobmcstuff

larkim said:

So Zwift uprated me to 259 last night (need to validate this, as the race seemed too easy, relatively), so with VO2Max in the same ballpark (running-wise) as above (18:30 5k, 38min 10k, 86min half) but 73kg it looks as if I'm closer to the range that I ought to expect to be in. Still room for improvement!!

I don't trust the Zwift FTP algorithm for general riding whatsoever - it seems to be exclusively using a weighting based on peak 1 minute power (if not one minute, another very short period), which is reasonable enough in a ramp test but not in a "race" which could be really easy followed by a peak 1 minute effort.

Case in point I averaged 259 watts up the Alpe back around Easter (58:30 or something I think) which is a pretty good proxy for my FTP. My last TrainerRoad ramp test was 262 (not long after the Alpe), and I've subsequently completed a whole build block using that figure so am confident it is accurate. Zwift algorithm still reckons my FTP is 247. If I used the Zwift number, I would be training in completely the wrong zones. I just ignore it completely and overwrite it with a tested result (I'm also not at all confident in the Zwift ramp test because it seems to use fixed wattage increments and they aren't at all transparent about it - the TR one uses % intervals and they are reasonably transparent about the bell curve which relates that to FTP - including advice on how to adjust it if you are one side or the other of the bell curve).

bobmcstuff

That's not to p*ss on your chips by the way - in my example my actual FTP is significantly more than what Zwift thinks - although I think a good way to get Zwift to give you an unrealistically high FTP is to do a race, ride fairly easy and then smash the finale.

larkim

The added complication is that I'm riding a dumb trainer with a speed / cadence sensor. It's a well known trainer (Crono Fluid) but clearly limited in terms of how accurate power data from that can be.

The 259w yesterday was based on a 20min average in the race at about 272w, but as you say that 20min average would include a minute of smashing out a lot more w. That was the first race I'd done though, and even in the mid section (only a 11 mile race anyway) I was riding at well above what I thought my FTP was (I think I averaged about 260 before any sense of a finale arrived) so 95% of 260 would put it around 247 which is still a decent jump up.

So far I've only done a ramp test, maybe time to do something a little more painful and see what numbers pop out of that.

bobmcstuff

Ramp tests are totally usable for estimating FTP so long as you are aware of the limitations (I understand it can reward athletes with really good anaerobic capacity and give them a higher FTP estimate for example, and vice-versa - https://gccoaching.fit/2019/04/17/ramp-testing-yea-or-nay/ ). When TR brought in theirs I did one close after the older 2x8 so I know that for me the TR ramp test produces nearly identical results (and backed up by longer efforts I've done), but obviously everyone's different. https://blog.trainerroad.com/new-ramp-test-makes-ftp-testing-more-efficient-and-less-stressful/

The thing with the Zwift one is I just don't know much about it, their workouts and training plans are a bit haphazard in general compared to TR and I trust TR because of the amount of explanation they give.

An 11 mile Zwift race is going to be balls out throughout (btw: if you set Zwift to km you will accumulate XP slightly quicker... about 7%... ), but the usual pattern is incredibly hard for ~5 min, settling down a bit, then incredibly hard again at the end followed by a sprint. I normally try to be doing 350-400 watts off the line and hold 300+ as long as I can to try and stay in the front group. Bearing mind my FTP is similar ballpark to yours. Then hope that I can hold a slightly sub-threshold effort until near the line... Good for setting power PBs but not necessarily what you might want for an FTP test!

Have a go at one of the TTs in Zwift... Tempus Fugit or something. That should be a reasonably steady 20 minute effort, if you do a proper warmup that should be a decent estimate. (Bologna probably not the best due to the profile).

Also if you do some workouts with plenty of VO2 max intervals in them you'll quickly find out if your FTP is set wrongly: you simply won't be able to complete the workouts............

kevin_stephens

Isn't this just about max heart rate? If your maximum effort when cycling gives a lower heart rate then when running, then its not cardio fitness (VO2 max) that's holding back your FTP but cycling specific muscles?

bobmcstuff

No. Cycling will always see a lower max heart rate than a weight bearing exercise like running.

larkim

Simply put Kevin! My inclination having Zwifted and not run for the last 4-5 weeks or so is that you’re largely right. I’m definitely now getting FTP numbers closer to what I might have expected. Another bump tonight (269 after a ramp test), and whether it’s “right” or not in a very precise sense it’s more satisfying than the 219 I was reporting just a few weeks ago. My legs have just learned how to ride a bit better.