VO2max Questions

It doesn't exactly say that from what I read "It is also specifically designed to automatically recognize the best data for making the calculation, meaning stops and starts are excluded along with any other interference that occurs along the way." From my experience, the algorithm expects a decent run period on the flat and can be "'confused by gradual hills etc. There are lots of situations that would impact your effort vs HR, such as running on sand, snow, mud which the algorithm cannot "know" about. It needs a number of good runs under "normal" conditions to start estimating Vo2Max and can easily be fooled by a unique condition that caused you to work harder for the same pace. Back in the F3 day a number of us asked to have Vo2Max not calculated for trail runs as these would generally drop your Vo2Max - snowshoe running in winter would drop me from in the 50s to barely 40 in no time. Now I use trail run for most outings and only the run for specific road work.

It doesn't exactly say that from what I read "It is also specifically designed to automatically recognize the best data for making the calculation, meaning stops and starts are excluded along with any other interference that occurs along the way." From my experience, the algorithm expects a decent run period on the flat and can be "'confused by gradual hills etc. There are lots of situations that would impact your effort vs HR, such as running on sand, snow, mud which the algorithm cannot "know" about. It needs a number of good runs under "normal" conditions to start estimating Vo2Max and can easily be fooled by a unique condition that caused you to work harder for the same pace. Back in the F3 day a number of us asked to have Vo2Max not calculated for trail runs as these would generally drop your Vo2Max - snowshoe running in winter would drop me from in the 50s to barely 40 in no time. Now I use trail run for most outings and only the run for specific road work.

Yes, but what I mean is that it still counts warm up, steady run, hills, and variable pace (intervals).
correct?

i can see what you are saying about mud, snow, stop/start, and trail running. I would probably use the trail run activity for that too.

I do a lot of interval runs, and also run at places that have some hills, and just want to make sure it is ok to use the run activity for those types of workouts.

for example, here is my interval workout today...

https://connect.garmin.com/modern/activity/2387381721

My VO2max is currently 37 (good).

thanks,

In the end you are asking a watch with an algorithm to try to figure out something that is best done in a lab. At what point it decides things are too hilly or some other variable is off is a mystery to all but the first beat and Garmin team. Heavy wind can screw it up. Having said that, given enough road runs, it actually closely matched my lab tested value. Then I used Run activity for a trail race and it dropped. Vo2Max does not change quickly, so that is an issue with the way Garmin averages out the value.

My suggestion? Enjoy your training and and just let it settle to a somewhat stable value without worrying about it. The More runs the more stable (which is not the same as accurate). Use Trail for anything out of the usual. You can always use one of the other Vo2max tests or get lit done in a lab.

Thank you.

i dont need it to be dead accurate, just close enough. And as i said, if i am going to run off road i will use the trail run activity.

It is probably better thought of as measuring your running economy, rather than your VO2Max, although in good conditions, the number should approach your VO2Max - Firstbeat estimate the error as within 5% (9% if you don't know your true MHR). Basically comparing your HR with your pace, allowing for hills. Improving your running technique and efficiency will lower your HR at any given pace and improve the number, even if the ability of your body to deliver oxygen to the muscles hasn't changed.

On a loop course, headwind/tailwind, gradual inclines and declines tend to average themselves out, so the overall figure should be reasonable. On one-way courses, this may not hold true.

For intervals, it is going to depend on the length of the interval. If you are doing 10 or 20s sprints, the GPS will struggle to identify the pace changes over such short distances, and even measured accurately, HR is always a lagging indicator of effort (with even greater problems if you are using OHR rather than a chest strap), so the number won't be very reliable. If you are doing longer intervals (eg. 2 minutes), then the number may not be too bad.

I agree with the suggestion of logging things as a trail run if the surface is going to be uneven, if it is really hot, you have a slight illness, or any other reason your HR may be elevated that day. Trail runs still give you training effect and training load, it just doesn't change your VO2Max figure.

VO2max is more complicated then the watch can figure. I had the fenix3. It had my vo2max after 2 years a 54. I was tested in a lab and it was 57. I just got the fenix5. Every run changes. I am down to 46. I am 3 weeks out from a marathon and the last 2 weeks have been the most miles per week. Not really counting on the info the watch gives me till I am 2-3 months into the new watch.

norris,

3 possible factors come to mind from your post:

* You mention you just got the watch - the numbers do tend to be a bit conservative when new - it takes up to 4 weeks for the watch to get to "know" you.
* You are logging your highest miles per week, which means you are probably not recovering fully between runs, and therefore have a higher HR. As you begin your taper and log more recovery time, your HR will decrease and you will likely see the VO2Max figure increase.
* If this is your first time with OHR, be aware that watch positioning and placement matter in terms of HR accuracy. The watch should be on the fleshy part of the arm away from the wrist bone (this is higher than most people typically wear a watch) and the band should be quite snug (I find I have to have the band one notch tighter when accurate measurement while running than I do for 24/7 monitoring). A loose watch can lock onto your cadence rather than your pulse, leading to an overestimated HR (and underestimated VO2Max).

Good luck for your marathon!