Unreasonably large jump in VO2max

toddsdn 7 days ago

I recently used my FR245 over three nights to get my resting heart rate while sleeping and it is 50 bpm. However, I have always used my "awake" resting heart rate of 75 bpm to calculate my heart rate zones using %reserve. So I changed that to 60bpm (sort of splitting the difference between 50 and 75). Then, on my most recent 5K run, using my older FR630, my VO2max jumped up from 43.56 to 45.49 - that's about 2 full points!

The run was definitely my hardest effort of the year and PB for the year. I am kind of an aerobic base junky. Also, it was about 15 F cooler than my previous runs. Figure hard effort and much cooler weather would give me a little vo2max boost, but not 2 points.

So question is what made such a huge VO2max jump?

Different watch? The 45.49 was from the FR630 which I rarely use anymore.

Hardest run of the year? My typical 5K's are about 10:45 pace but this last one I pushed to 9:20.

Much cooler weather? Recent runs have been in 70's and 80's, this last one was in upper 50's.

Different resting heart rate used for zone calculations? Went from 75 to 60 for resting heart rate to calculate zones base on HRR.

A combination of some or all of the above?

I have been running since 2017 and have never seen a VO2max jump even close to 2 points.

0 flowstate 6 days ago in reply to toddsdn

Pace is time / distance (e.g. minutes per mile), so your formula is equivalent to distance ^ 2 / (avg hr * time).

I think you mean something more like pace / avg hr or speed / avg hr [higher is better].

Nonetheless, this is actually close to what the activity VO2 Max is supposed to be. Except I think both activity and user VO2 Max are some kind of rolling average, so neither of those numbers can really be associated with only 1 specific activity afaict.

However, I think runalyze's own calculated VO2 Max (not "VO2 Max from file") is truly per-activity (you can kind of see this with how it can vary wildly from activity to activity, as opposed to how both of Garmin's VO2 Max numbers - activity and user - stay fairly stable).

So if you really want to measure your "relative performance" between runs, you could look at the runalyze VO2 Max.

Or you could look at runalyze's aerobic efficiency (for pace), which is defined as 47 * speed [m/s] / heart rate.

Or if you're more interested in how hard you tried, you could use the Strava relative effort data field:

https://apps.garmin.com/apps/6b53eedd-bf67-4c18-a2d6-af1d59518357

People don't seem to like this data field much tho. It seems to produce different data than Strava itself, and people are complaining about bugs in the reviews.

But maybe it would be better if you forgot about all this stuff and just try to have fun with your runs.

0 toddsdn 3 days ago in reply to flowstate

Sorry man, I don't want to forget about all this stuff. I like it. I just do.

As for running, I wouldn't call it fun really. Its kind of a chore about half the time. But after a lot of boring consistency, you have those break out days where you surprise yourself by running faster / farther / both without even planning for it. I train a lot of slow burn runs. But every now and then, when feeling really good, I push myself a bit. But always get a sense of accomplishment no matter how my runs turn out. No doubt, some runs are fun, but if that was my only motivation, I don't think I would last.

I have definitely been looking at the Runalyze metrics too. Their own VO2 max is clearly individual run effort based and it is all over the place. Also track the efficiency metric, which is also kind of scattershot, but it has a smoothing average tracking up.

This is probably similar to what I came up with [length of run] * [speed] / [avg HR]. I used to actually export my garmin data to a csv file and do the calculation. But pace / average HR doesn't take into account the length of the run. Metrics that take into account all 3 in one go are what I am interested in.

Runalyze aerobic efficency is AE (Pace) = 47 * Speed [m/s] / Heart rate [bpm], so not quite there.