Wednesday, November 4, 2015

VO2Max: Indirect Measurement

Imagine that you are on a treadmill working hard, being pushed to the limit in fact. Not only that, but you have a face-mask and air-tube hookup so that all of the gases going through your lungs are being measured. When you are about ready to conk out, you hear the welcome, "Okay, you can stop." This is how to determine one's VO2 Max directly.

It is both costly and invasive. At least, I wouldn't do it if I didn't have to. But it is the gold standard for determining fitness. The higher the score, the more fit you are. A top athlete may have a VO2 Max in the 70's or even 80's Lance Armstrong sported one of 85. Miguel Indurain may have had one as high as 95. A very fit 70 year old male would have one in the 40's, as would an average-age male of average fitness.

Okay, now suppose you could get the same result by lying on a bed for five minutes relaxing. The same result! (Okay, maybe a couple of percent one way or the other. At my age, I'm not competing on my bike) Wouldn't it be a no brainer?

Well, it is possible. In fact there are several such indirect measurements. But I was intrigued by Polar's "OwnIndex" which is their term for their indirect measurement of VO2 Max. Polar uses the same units so 45 VO2 Max units are the same as 45 OwnIndex points. For a discussion of the units see Wiki's article here.

Here is Polar's description of how to perform the test and (below) a table for interpreting the results. Here are the reliability results offered by Polar. In particular,

"Validity of a test means that the test measures what it is supposed to measure and not something else. The Polar Fitness Test was originally developed on 305 healthy Finnish men and women in a study, where VO2max prediction was developed using artificial neural network analysis. The correlation coefficient between the laboratory measured VO2max and the neural network prediction value was 0.97 and the mean error in the VO2max prediction was 6.5 % which is good compared to any other predictive tests of VO2max."

I'm partial to Polar's OwnIndex because it takes into account HRV (Heart Rate Variability) as one of the predicting factors. But there are a variety of indirect VO2 Max predictors, as it turns out.

One of them (use this link) has a predictor which uses only your resting heart rate! I've tried it and it is not too bad. Polar shows my OwnIndex as of today as 41. The first test on this site returns 36 for me. 1/3 of my current heart rate of 66 is 22. Enter that and 36 is returned. But other factors such as age, weight, HRV or previous level of aerobic activity are obviously not taken into account, so I would go with Polar's. (Aside from the fact that is is higher and therefore better.)

Others from that site use more exercise-intensive tests. The second has you walk a mile, then key in your age, weight, time and pulse rate. At some point I will try this one and compare it to Polar's.

There is a 3-minute step test, but you need to find 16.5 in steps. I'd bet that you could do this on a StairMaster

BTW the site has expanded VO2 Max Fitness tables as well. (Polar doesn't include 70 year olds on the tables I've seen.). Click here to view the expanded tables.

With a score of 41, I'm right on the cusp between "Excellent" and "Superior" for males between 70-79. Or, looking at it another way, with a score of 41, I have a comparable VO2 Max to men 50-59 in "Good" condition (38-42). Or 20 years younger.

Anyway, I'd like to think so. Unless and until getting on a treadmill to do a direct VO2 Max test,  don't hold your breath!

1 comment:

  1. The above posting stands, but I wanted to post a follow up while the memory is fresh. Polar directs that the OwnIndex test be taken "after recovery." I.e, not on an exercise day. Part of the reason, I'm pretty sure, is because one's heart rate is still slightly elevated on the exercise day. The day after, the heart rate is discernibly less. Well, I should have waited a day to do the test I described above. My pulse was 66 yesterday. Normally, resting, it is in the 50's, about 10 beats less. The lower the heart rate, the higher the OwnIndex score. So today my OwnIndex came out to 43. So the 41 yesterday is conservative.