How does Apple fitness Calculate Vo2MAX? It’s quite innacurate.

Why does it matter?

Just curious. I’d think it’d be more accurate considering the data is for the most part.

The equipment that's used to measure this in lab costs about $30,000 and involves a computer and a calibrated pulmonary gas exchange unit. I guess it is not real surprising that a ~$400 smartwatch gives a rough estimate at best.

Because it’s really giving you a VDOT estimate not your actual vo2max. It can’t know that from your pace and hr.

Relevant thread from a decade ago

https://www.letsrun.com/forum/flat_read.php?thread=3802725

If it’s not corresponding to your vdot value either as you seem to mention, idk. My gfs Apple Watch estimate matches her garmin watch which matches her realistic ability

Right in the health app, right under the data about your estimated VO2max, it has an explanation that might answer your question. It states that it only estimates from 14-60. Maybe because you are "off the scale"? Maybe you don't wear the Apple Watch on all of your runs, on the workouts? Anyway, you can check that out for starters.

Walmslord wrote:

Because it’s really giving you a VDOT estimate not your actual vo2max. It can’t know that from your pace and hr.

No, it is not the VDOT estimate, if it does anything like the Garmin V02max estimate. For example, one with 20min 5k fitness has a VDOT of 49.8, but Garmin will not atypically arrive at a V02max for that person of anywhere from 53 (male) to 55 (female).

This appears to be a very poor estimate. My Garmin's VO2max estimate is more in-line (somewhat above*) my VDOT. For example, at ~20:15min 5k fitness, corresponding to a VDOT of 49.1, it will show my VO2max to be 53.

*We can expect the VO2max value to be higher than the VDOT, since the latter is a resultant 'aerobic power' metric from the combination of one's VO2max and 'running economy'.

However, I think Garmin's VO2max estimate (and 'race predictor') fall short somewhat, in that it estimates these values by (I think?) an average of the last five run activities. If those runs were performed over poor (slow terrain), in slow shoes, with excess clothing, etc., then it is going to arrive at a lower VO2max estimate (and race prediction), than if all of the five most recent runs were in optimal conditions (i.e., on a flat race track in good weather).

Out of curiosity, here is the first 1.5 mile VO2max estimator I found:

As a comparison, it predicts one with 20min 5k fitness, possessing a VDOT of 49.8, with an equivalent 1.5mile time or 9'08", to have a VO2max of 56.4. It is probably looking at tables of population averages. Theoretically, Garmin (at least some of their fitness watches) may be doing something a little more sophisticated than that using FirstBeat's algorithms evaluating Heart Rate Variability.

That makes sense. I often don’t record my interval workouts, as the track I typically do intervals on tracks as .27 of a mile, so it gives me inaccurate readings, so that could exclude a big chunk of my fitness.

The odd thing is that I’ll run a 3-4 mile tempo at 5:30-5:45 pace, keeping at an HR of 175-185, when my max HR is around 205. According to those same 1.5 mile and 2 mile tests, I shouldn’t even be able to hold that pace for an all out effort at those distances.

Of course Apple isn’t using the same method to calculate Vo2MAX, but I still find it ironic.

I’m not much of a believer in Vo2Max being the main predictor of mid d and distance running, as apparently Kipchoge has a Vo2MAX of 70ish, and he’d absolutely annihilate me at anything over 600m, but I still think it’s interesting that Apple fitness could be THAT wrong consistently.

CopperRunner wrote:

The odd thing is that I’ll run a 3-4 mile tempo at 5:30-5:45 pace, keeping at an HR of 175-185, when my max HR is around 205. According to those same 1.5 mile and 2 mile tests, I shouldn’t even be able to hold that pace for an all out effort at those distances.

I don't follow, because I'm not sure what "those same 1.5 mile and 2 mile tests" you are referring to. Just plug a recent race time in to the Jack Daniels Calculator, and it will give you a pretty good idea on a 1.5mile or 2 mile race time.

Of course Apple isn’t using the same method to calculate Vo2MAX, but I still find it ironic.

I’m not much of a believer in Vo2Max being the main predictor of mid d and distance running, as apparently Kipchoge has a Vo2MAX of 70ish, and he’d absolutely annihilate me at anything over 600m, but I still think it’s interesting that Apple fitness could be THAT wrong consistently.[/quote]

Kipchoge's current VDOT is ~82. If his Vo2MAX is only 70ish, that means he has a much higher running economy than the 'average' (over a population of runner's tests) worked into the VDOT calculation.

I don't follow, because I'm not sure what "those same 1.5 mile and 2 mile tests" you are referring to. Just plug a recent race time in to the Jack Daniels Calculator, and it will give you a pretty good idea (prediction) of your 1.5mile or 2 mile race time.

Kipchoge's current VDOT is ~82. If his Vo2MAX is only 70ish, that means he has a much higher running economy than the 'average' (over a population of runner's tests) worked into the VDOT calculation.

Jack Daniels Calculator wrote:

CopperRunner wrote:

The odd thing is that I’ll run a 3-4 mile tempo at 5:30-5:45 pace, keeping at an HR of 175-185, when my max HR is around 205. According to those same 1.5 mile and 2 mile tests, I shouldn’t even be able to hold that pace for an all out effort at those distances.

I don't follow, because I'm not sure what "those same 1.5 mile and 2 mile tests" you are referring to. Just plug a recent race time in to the Jack Daniels Calculator, and it will give you a pretty good idea (prediction) of your 1.5mile or 2 mile race time.

Even without a race time, you could still use the JDCalculator to estimate your 1.5mile or 2mile race times, knowing your tempo (threshold) pace. You are running your tempos right up to 90% HRmax, so assume that is threshold pace, and then iteratively guess race times that eventually give you a VDOT with a corresponding threshold training pace of 5:30. A 9:50 2mile race time corresponds to a VDOT of 65.5, with a threshold training pace of 5:30. You can repeat the exercise to determine the VDOT (and its race equivalents) for a 5:45 threshold pace.

apple must have a terrible formula. I think the garmins actually do a pretty good job, though not perfect on a day to day basis.

I will be around 57-58 with my garmin when I am running tempos at 6:30 to 6:40

Jack Daniels Calculator wrote:

Jack Daniels Calculator wrote:

I don't follow, because I'm not sure what "those same 1.5 mile and 2 mile tests" you are referring to. Just plug a recent race time in to the Jack Daniels Calculator, and it will give you a pretty good idea (prediction) of your 1.5mile or 2 mile race time.

Even without a race time, you could still use the JDCalculator to estimate your 1.5mile or 2mile race times, knowing your tempo (threshold) pace. You are running your tempos right up to 90% HRmax, so assume that is threshold pace, and then iteratively guess race times that eventually give you a VDOT with a corresponding threshold training pace of 5:30. A 9:50 2mile race time corresponds to a VDOT of 65.5, with a threshold training pace of 5:30. You can repeat the exercise to determine the VDOT (and its race equivalents) for a 5:45 threshold pace.

I believe OP has recently run something around a 9:30 for 2 miles

high school xc coach wrote:

I believe OP has recently run something around a 9:30 for 2 miles

Which corresponds to a VDOT of 68, being pretty darn close to his lab test. Per the Jack Daniels Calculator, he should be doing his 20min threshold runs (or Cruise Intervals) at 5:20, particularly if done on the track, but if over somewhat irregular terrain, he might be going slower and achieving the same intensity. That is Jack Daniels recommended threshold pace that should take an athlete with a 68 VDOT to 88-90% HRmax. Of course, there are views that one does not have to train right up to JD's threshold pace to improve endurance.

Did no one read my post?

The Apple Watch VO2max ONLY GOES TO 60! If you're running VDOT 68 paces and/or testing on a genuine VO2max test at 70, the Apple Watch can't help you. You are off the charts, so to speak.

Coach Jeff ROC wrote:

Did no one read my post?

The Apple Watch VO2max ONLY GOES TO 60! If you're running VDOT 68 paces and/or testing on a genuine VO2max test at 70, the Apple Watch can't help you. You are off the charts, so to speak.

Yeah, that's good info to know, if one has a VDOT that high. Regardless, I think I prefer my Garmin (with buttons) over an Apple Watch for training purposes.

CopperRunner wrote:

I decided to get my Vo2Max tested, and as it turns out, I’m sitting at about 70.

My Apple fitness Vo2Max always sits between 57-58.5 though, so this came as a very pleasant surprise for me.

I decided to look up all of the easy ways of estimating Vo2Max online like 1.5-2 mile runs, resting HR compared to max HR, etc, and all of those tests estimate 68-71 for me.

So why does my watch/ Apple fitness data get it so wrong? My HR monitor isn’t completely accurate but it’s usually pretty close.

If anyone knows why or has any similar experiences I’d love to know.

What is the "resting HR compared to max HR" estimate all about? Is there a formula or something? A bit curious about it.

Btw, tried your "magic" 400s CV workouts from another post and they felt fantastic! Thanks a lot for that.

I’m happy they went well for you!!! I think it’s an awesome workout for people that dislike tempo runs or just wanna shake things up.

I don’t have the exact calculations, but a theory is that you can get a somewhat close estimate of Vo2Max comparing your resting HR to your Max HR. It’s obviously not gonna be too accurate, but I think when I calculated it, I put in a resting HR of 45, and a max HR of 203. This resulted in a Vo2Max estimate of about 71, or you could use my real Vo2Max of 70.3. I can’t seem to find the equation again, but using those 3 data points you could probably reverse engineer the equation.