Garmin fenix 3 HR ~ VO2max estimation

 I have not posted for a while.  I've been busy after thanks giving this year......  Today, I am writing about VO2max estimation on fenix 3 HR.

Display for VO2max on Garmin Connect Mobile

   Recent running watch (GPS watch) from Garmin has a new function to estimate VO2max.  This feature is available Forerunner 235 or higher model.  It is not available on vivosmart HR and vivoactive HR.  It is not available a low end model Forerunner 35.

VO2max

   VO2max is one of good index to show the endurance performance.  Before I got fenix 3 HR, I tried to do “cooper test (12-minutes running)” to get indirect estimate to see my training progress.  However it requires very high intensity running which is almost “all out” to get the number.   Especially right after the injury, it is not easy to do.  Sometime it was a cause of another minor injury in the past.  Now fenix 3 HR has a feature to estimate the VO2max number from daily activates even if not very high intensity training.

Overall result for my case

    I have been using fenix 3 HR around a month and I consistently ran 3 or 4 times a week.  My number is around 38 ~ 42 [ml/min * kg] range, which is probably very similar result from “cooper testing”.   Only one exception is one LSD (Long Slow Distance) training and the result was 36 which is very low comparing the other recent numbers.

    Based on the result, the device probably use “cooper testing and a formula” to estimate the number.  However, “cooper test” requires very high intensity running and it might do some adjustment based on heart rate number during an activity and some past data.   As long as activity is relatively high intensity, my number is somewhere in 40~42 range.  However, if the activity is low intensity, the number becomes somewhere 38 ~ 40 range, slightly lower than the high intensity numbers. 

   I have never measured the actual VO2max number in a lab in the past, therefore I cannot tell what my real VO2max is.  However, if I assume the estimated value by “cooper testing” is reasonably close to the real value, this estimate is very close to the cooper test result.   So as long as the activity is reasonably close to the high intensity (all out), then the estimated value is probably close to my real number.   If the intensity is low, then the accuracy of the estimated number by the device might have bigger offset from the real value. 

   My average value now is 41 [ml/min * kg] which is categorized as "good" in my age group.  I thought my value would be much better something like in "Very Good" category.  But this is what it estimate.  Overall, the value is stable for my recent training result.

Useful?

 VOmax trend last 4 weeks

    I do not see obvious improvement of the number because I only have data for a month.  But I would think this would be useful to see some improvement after some training.   We do not have to have “cooper testing” regular bases and we can collect the data with the daily training.   As long as the intensity is reasonably high, for the heart rate zone 3 ~4, then the number is probably close to the real VO2max value.  I will continue to collect more data to see if it can show some improvement or not.