Treadmill inclination and VO2Max on my FR255

i don't think Garmin will make VO2 measurements from treadmill activities anyway. It needs outdoor GPS runs.

I don't think it is correct to say that Garmin will make VO2Max "measurements" from outdoor GPS runs. Based on what VO2Max actually is, Garmin can't do that. Whether indoor or outdoor, it will have to be estimates.

The difference is important, because the discussion then becomes what level of (in)accuracy we are willing to accept.

I don't see any reason why a treadmill run, done at a known inclination, at a known and constant speed over a known distance, couldn't provide this estimate just as well as an outdoor run where you are going to... stop at traffic lights, go up the hills, experience momentary losses of GPS signal and other artefacts that will jam with the accuracy of the estimate.

I believe my questions are relevant.

If you choose to call it estimates, then Garmin will only make estimates from outdoor GPS runs/walks, not treadmill activities. If you go a long time without such estimates, the watch will eventually start to make adjustments (not estimates) up or down to your VO2Max on any type of activities, based on if you are training well or not.

In theory it would be possible to use other types of activities to estimate VO2Max with extra information given to the watch, but that is not currently implemented.

I'm sorry ovekvam but that is incorrect and Garmin does provide me with VO2Max estimates on my indoor activities, including treadmill activities. These estimates go up, and down. For example, yesterday after my run I recalibrated the distance as calculated by the watch it was too high, and Garmin adjusted my VO2Max downward a little bit, as you can see.

Below log for your reference. These are all indoor. Adjustements every other day.

The way I understand it, those VO2Max-adjustments are incremental, and different from outdoor estimates.In the winter time I get such adjustments even for strength sessions where the watch has no idea about what I have been doing. It just looks at aerobic and anaerobic benefit. In the summer, when I do regular GPS running, I get no such adjustments, but actual estimates.

Yes, I agree, these adjustments appear to be incremental (as discussed not long ago !), and I am fine with this: as you can see from my initial post, I am interested in the direction of the VO2Max, not it's absolute value.

Let me explain why I am fine with this: early April (so 6 weeks ago) I did a proper treadmill test at my cardiologist and on that day, VO2Max was 46.73. As you can see from my log, Garmin estimates is 47.69 as of this morning. For me, Garmins' estimate is close enough, and what I am inquiring about is the direction of these adjustments.

Again, I believe my questions to be relevant - and let me add this: to what I am trying to achieve.

I don't think the watch will look at your running speed or distance when making these adjustments, only the heart rate. If you run slow uphill or fast with no incline will not matter, I think.

JRKingOfBeer said:

Is this correct ?

Yes, it is correct.

I would say  to decline your TM not to 0 but to 1.5%. It is a realistic value to model a flat run.

About all calculating/estimating and so on:

You are completely free to consider that VO2Max also counts on the treadmill. But if we look at the fistbit(aka Garmin) documentation, we will see that the results are valid (with an accuracy of 5%) only for the described measurement conditions. There is no treadmill there. So, in principle, there is nothing to discuss. Your suggestion will only work if you can calibrate the treadmill and set a realistic incline level, everything else will just be unmeasurable guesswork.

Once again - if you want to use such assumptions - I don't see a problem. Although personally, I would go out the door and go for a run :)

global_local said:

I would say  to decline your TM not to 0 but to 1.5%. It is a realistic value to model a flat run.

I can do that. You have mentioned that before, may I ask why the suggestion ? As in, why does an incline on the treadmill simulate flat outdoor ?

Going jogging outside is no longer possible here (too hot and too humid), and also I have some concerns about injuring my knee, I'd rather jog on the treadmill for now.

I am not worried about getting a correct VO2Max number from Garmin anymore. The one I get from the cardiologist is - probably - more accurate. But I can't refresh it very often, it's not cheap.

The incline compensates for lack of aero drag. 1 percent for slow jogging, 1.5 percent for running, and 2 percent for fast running.