What do you think the accuracy of performance metrics in the Forerunner 245 is?

Hi,

while of course the calculation of the metrics may be sometimes inaccurate due to the quality of the measured data and also bugs in the algorithms, overall to me it seems ok.

Regarding your examples: One single fast run will nearly never be directly have impact on your VO2Max and that is ok - if you know how that is defined. The best way to improve it is improving your overall stamina with extensive runs in low pulse and tempo runs.

You can find more information about VO2Max here:
support.garmin.com/.../

I’d contact first beat directly on social media(even though it’s part of Garmin now)

Some things to keep in mind, VO2 max is genetically. We could all go to Iten, run about 140km a week for three months and we wouldn’t see huge jumps in VO2. We would probably get considerably faster and leaner. 

You don’t mention how you’re training is different. You’ll see huge difference if you run 45km a week or about 75km. 

If you slowly increase your weekly volume and add a weekly faster run while becoming leaner you should see huge fitness gains and faster times. Remember Rome wasn’t built in a day, changes take months, more than weeks. 

caferey said:

Some things to keep in mind, VO2 max is genetically. We could all go to Iten, run about 140km a week for three months and we wouldn’t see huge jumps in VO2. We would probably get considerably faster and leaner. 

I don't agree with this 100%, as VO2 Max (as determined by Garmin/Firstbeat) is basically calculated based on pace vs. heart rate (assuming a linear relationship, and taking into account your max HR.) In a nutshell, if you can run faster than yesterday at the same heart rate, the VO2 Max that Garmin reports will increase.

Sure, there's probably a VO2 Max ceiling for each individual that's genetically determined. And your VO2 Max results in a lab might not vary as much as what the device reports. But there's also the concept of trainability vs. talent - some people are more trainable than others, which leads to seeing greater improvement for the same amount of training.

Personally, my VO2 Max has gone up and down within a roughly 13-point range, depending on how fit or out of shape I've been.

Since August, my VO2 Max has gone up by 9 points (although it's still not at my all-time high.) Does that mean I'm actually that much fitter? That's the real question which is tough to answer, unless I go out and do a race or a max effort time trial.

In the past, I've definitely seen my VO2 Max go up by 1 point per week for short periods of time, when my fitness is improving. And I've seen it go down quickly when I stop training.

A_Valens said:

I still enjoy the device and running quite a lot, but I guess understanding how those metrics are calculated would help me get over the disappointment I sometimes feel.

Honestly I wouldn't take the metrics too seriously, especially the absolute values. The trends can be useful.

In your case, are you running at max effort all the time? You could be overtraining (despite seeing real improvement). 80% of your runs should be very slow and easy (as boring as this can be). It's entirely possible that if you added more slow runs to your regimen, you might see the increase in training metrics that you're looking for.

I don't know if he still posts here, but HermanB is a FirstBeat employee who has a lot of insight into this stuff.

I would also take a lot of pride in the progress you've made already! Being able to run farther and faster than ever before is an objective accomplishment that nobody can take away from you. You don't really need your watch to validate that achievement, imo. And not to sound cliche, but the most important thing is to have fun.

WillNorthYork said:

Honestly I wouldn't take the metrics too seriously, especially the absolute values. The trends can be useful.

Agree with this totally.

Try Runalyze.com for a much more realistic approximation of your VO2max value.

Edit to add the following:

Also as per V.O2 app 10K of 1h 10m would give VO2max of between 26.5 to 27, which I feel is more realistic.

AtulN said:

Also as per V.O2 app 10K of 1h 10m would give VO2max of between 26.5 to 27, which I feel is more realistic

It depends on whether that’s a maximal/race effort or not (and whether OP’s max heart rate is set correctly.)

But yeah, your number is pretty close to the VO2 Max / Race predictor table that Garmin used to use before they changed the race predictor to be more than just a simple table lookup based on VO2 Max:

https://cicerunner.wordpress.com/2014/07/11/garmin-fr620-race-times-from-vo2-max/

(My predicted 5K time, on a current-gen Forerunner, is still pretty close to the value in this table. I’m guessing Garmin just does an adjustment for the higher mileage races, based on training volume.)

Runalyze is great because not only does it estimate your VO2 Max, it also adjusts its estimates based on your actual race results. (The caveat being that you have to tag your races manually.) For those who don’t know, runalyze.com is free and it syncs with your garmin connect account. The downsides are that there’s no app, the website isn’t very mobile-friendly, and overall the user experience isn’t great. But there’s a lot of data, including recovery heart rate (even for some watches where this number is hidden from Garmin Connect, but recorded by the watch.)

I also like that it shows the Garmin VO2 Max value with 2 decimal places, so you can see why Garmin says your VO2 Max is increasing or decreasing even when the rounded number stays the same.

Are you using a Garmin chest strap for HR data or the wrist based HR?  Your metrics might be based off of inaccurate HR data.  I'm 42 and started a year ago with the FOrerunner 245 in a similar progression as yours and I felt the VO2Max increase (and crash after a stressful detraining period) was pretty accurate.  I went from 47 up to 53 peak from 10k into a half marathon completion.  

Which coach did you use?  I used coach Greg and treated my Stride repeats basically as HIIT and didn't full on sprints for anaerobic increase.  I felt a lot of my VO2 Max increase was attributed to this in addition to the long slower Zone 2 type runs.

Also are you on version 9.0 of the firmware now?

I found the opposite.

Doing faster interval/tempo runs from the 5k training plan improved my v02max from 52 to 54.

I then switched to slower easy runs and half marathons, and my v02max dropped back to 52/53. 

That still sounds consistent with me, it just points to me sprinting as hard as possible in the stride repeat workout probably being more responsible for the VO2Max increases and why I haven’t seen one yet on week 4/13 on my current plan.  I’ve only had one stride workout so far and didn’t go all out.

It’s also possible you may have peaked your value at 53 and then from 53/52 was just a temp fluctuation?  Have you been using a strap too?

I just used the watch (245M). 

Yes, I cannot rule out temperature, but I have gone back and looked at my monthly v02max charts, and this is what I see:

Sep - 51 (mostly easy 5k runs)

Oct - 52 (started 5k 22min training plan)

Nov - 53

Dec - 54

Jan - 54 (end of 5k 22min training plan)

Feb - 53 (easy runs / long runs / half marathon)

Mar - 52 (easy runs / fast parkruns)

Apr - 53

Seems like the fast stuff pushes up my v02max. I run between 5 - 40km per week,100km per month.