The Real vs Smart VO2
Do you own a smart watch? Most of these devices have a lot of calculated scores including the most popular Longevity metric, VO2 max. This is a relatively new metric that is useful in gauging your fitness level and health.
Calculated vs Measured VO2
On a regular basis, we get asked while performing a direct or actual VO2 test, what's the difference between my watch VO2 score and the test we are doing in the lab? To be honest, there is a big difference! We are not just saying this to promote our in-person test but more-so to explain the information gap that is missing. An actual VO2 test measures a person's cardio-respiratory fitness at several different intensities as these are important pieces of your training status. From Zone 1 to Zone 6, which we also refer to as "everything under the curve."
| Measured VO2 (lab) | Watch VO2 (calculated) | |
| VO2 max | Yes | Yes |
| Ventilation and Breath rates | Yes | No |
| Training Zones | Yes (Zones 1-6) | No, (only Zone 6) |
| Fat Burning Zones | Yes, % in each Zone | No, (predicted only) |
| Glycogen / Carb Burn | Yes, Calories in each Zone | No |
The calculated VO2 watch score just measures your VO2 from a series of calculations in an algorithm that involves your age, body weight, heart rate and speed of your workouts. The more data a person records, the better the predicted score. Speed has been correlated with a VO2 score which has been validated by thousands of tests done by labs over several decades. Some of you may have done the infamous "beep test" in school or with a team. The faster you run, the higher your VO2 score. However, it is just Zone 6. There are no training zones or information such as ventilation rate, fat burning efficiency and carbohydrate burn rate.
Why does my VO2 score change?
Since your VO2 is associated with speed and intensity, if you do not perform regular hard workouts, your score will be affected and decrease. This is not the best formula as training programs often require periods of low intensity to develop different areas of your physiology. i.e. your aerobic base. Training in Zone 1-2 actually increases your VO2 by allowing for adaptations such as increased capillary growth (blood vessels) and mitochondria development (the powerhouses of your cells). You should not be concerned if your VO2 drops due to your Zone 1-2 workouts. Our advice is to take the smart watch score with a "Grain of Salt." Some days it will be high, some low depending on how active you are and type of training.
How do you use your VO2 score?
On average, we find that about 50% of the smart watch scores are in line with the actually measured Lab VO2 scores. We know you can't get a weekly VO2 test but this is what we recommend:
- Get an official test in the exercise mode you prefer the most, i.e. Bike, Run or Walk. Aim for 1-2 tests per year.
- Over-ride your VO2 watch score after getting an official test. This should be in the watch settings or associated desktop software. From here, you now have a proper set point.
- As noted above, your score will go up and down depending on your training status. That's OK! You cannot hold a peak score 12 months a year.
VO2 and Longevity
Overall, VO2 is a strong metric in your watch to follow once it is calibrated. VO2max is associated as the most important score associated with your longevity and healthspan. This is BIG news! So, keep VO2 in the back on your mind as number that you want to monitor for healthy living for decades to come.
