VO2 max - why didn't it activate after my first run with FR235?

The FR235's built-in optical HR monitor is sufficient for providing data needed to calculate VO2Max. Give it a few more runs before panicking. I don't remember seeing an “achievement” of a new VO2Max value after a run until several tracked runs in (after a factory reset).

Did the HRM get a lock before you started? In other words did the little heart symbol stop flashing? That's the key to solid HR data. If it's still flashing while you start running you get unreliable data.

You spent a lot of time in zone 5 (too much?) maybe is threw off the reading.

I definitely got a reading with my first run.

Did the HRM get a lock before you started? In other words did the little heart symbol stop flashing? That's the key to solid HR data. If it's still flashing while you start running you get unreliable data.

You spent a lot of time in zone 5 (too much?) maybe is threw off the reading.

I definitely got a reading with my first run.

Thanks Caferey - that's an interesting question. I'll go for another run tomorrow and double check that re: solid heart rate.

From everything I've read, seems like it should've given me a reading after first run.

I'm not sure about the point re too much time in zone 5 - it was just my normal run. I certainly try to run as hard as I can for the 4kms.

IMO your max heart rate is set at 190, and in your run your HR went up to 194, that's the reason why your VO2max wasn't calculated.

I'm not sure about the point re too much time in zone 5 - it was just my normal run. I certainly try to run as hard as I can for the 4kms.

Why, though? You'll be able to run further/longer if you slow down. It's counterproductive to run every run at maximum effort. :confused:

The manual says to expect a few runs.

Thanks Caferey - that's an interesting question. I'll go for another run tomorrow and double check that re: solid heart rate.

From everything I've read, seems like it should've given me a reading after first run.

From the the manual?

"The device requires a few runs to learn about your running performance." (found via google search for "garmin forerunner 235 v02 max"

I think it took mine about 2 weeks to show up - at that point I was running ~5X a week.

If you go to the Firstbeat Technologies (the people to did the VO2 max and related software) you'll find they need a STEADY STATE period of undefined length to determine the VO2 max. If you look at your heart rate and pace during your run you'll see that you weren't running at a constant pace for the entire run. In fact it appears you started out at a very fast pace for the first 4 minutes and then slowed down. In addition I can tell just by looking at your heart rate trace that your 235 didn't get an actual "lock" on the heart rate until the 7 minute mark. Yeah, I've been there, done that, and have seen that particular Jump in the heart rate. It's one reason why I use a Chest Monitor, because I just LOATHE having to stand around waiting for a heart rate lock when I want to get moving.

Tips, first make sure you have a heart rate lock before you start running. BTW, my experience is this can take as long as 5 minutes if you are imitating a manikin, longer if you are moving around. Second, you really need to do your best to hold to a constant pace. I'm guessing a bit but what the Firstbeat software looks for is the point where your heart rate settles into a steady BPM for the particular pace you are working at. Until that happens you won't get a good VO2 Max reading. Third, consider getting a Chest Monitor. Because my experience with the 235 is it can be overly sensitive to Cadence Lock. I've had so many "flakeouts" with my 235 during a high activity exercise that the only thing I trust the wrist monitor to track accurately is my resting heart rate or when I am mostly idle.

Thanks all - greatly appreciate the feedback and tips.

I went for a second run and can confirm I have a vo2 score!

I did a flatter route and tried to keep pace constant.

But I think the key was waiting for the heart rate to lock - I'm surprised that is made clearer in instructions (unless I missed something). It took about 3 or 4 minutes as I walked to the start of my run. This does seem a bit painful.

Here's the results of my second run - https://connect.garmin.com/modern/activity/1513695355?share_unique_id=2

I'm not sure if heart rate tracking had problens at start or not - seems unusual on chart, but certainly not as unusual as first run.

Perhaps external HR straps are better options!

Thanks again

You really don't need an external HRM unless you're totally OCD about heart rate.

I've found the FR235 HRM to work well, and far better runners than me (including a 1:14 half marathon runner) swear by it.

The VO2Max is just an estimate and will get thrown by all the usual factors that can affect heart rate/effort, e.g. weather (high temperature/humidity), terrain (hills), illness/infection, etc.