VO2 max is one of the most important metrics for any endurance athlete. Smartwatch manufacturers have realized this and started including VO2 max measurements on their smartwatches. But the big question is whether you can trust the number shown on the watch.
The VO2 max value on a smartwatch is its estimate. It’s impossible to measure VO2 max without actually measuring oxygen intake, which can only be done in a lab. Smartwatches calculate VO2 max based on your pace and heart rate, which can only give you an estimate but not an actual value.
The VO2 max value given by your watch should not be taken as sacred. But it's a good idea to check it regularly and monitor your progress, even if the estimates are usually not that accurate.
Is the VO2 max value on my smartwatch reliable?
It’s nice to see a high VO2 max value on your smartwatch, but don’t get too excited if you do. The VO2 max is only an estimate, so chances are the value is not 100% accurate.
Unfortunately, VO2 max cannot be measured accurately without the face mask that measures the level of oxygen you intake. The smartwatch’s only information is your heart rate and your pace. The level of oxygen intake is a mystery to it.
Smartwatch manufacturers, therefore, take the info they can get and try to develop a formula that best estimates VO2 max. But if you don’t have the main information (oxygen intake), you can only come up with good or better estimates, which will never be 100% accurate.
VO2 max on smartwatches is only an estimate.
But don’t get discouraged. While the VO2 max estimate is not entirely accurate, it still provides you with a ballpark value, which gives you an idea of where you are ranking.
The estimate is also quite accurate on some devices, while other more or less just guess your VO2 max and can’t really be trusted.
Which smartwatch gives the most reliable VO2 max estimate?
No matter which smartwatch you use, Garmin, Suunto, Apple Watch, or any other brand, they all rely on two values to estimate your VO2 max — heart rate and pace.
What’s different among brands is the algorithm they use. Some absolutely nailed it, while others still wonder how to calculate your VO2 max accurately.
If you want the most accurate VO2 max estimate, then definitely choose the Garmin smartwatch. They come up with the best algorithm, which estimates your VO2 max quite well. Again, it’s not 100% accurate, but it’s close.
Studies showed that Garmin smartwatches estimate VO2 max with an average margin of error of 5%. It usually overestimates it, especially with men.
While 5% might sound like a lot, it actually isn’t. If you have a VO2 max of 50 ml/kg/min, the error is 2.5 ml/kg/min. This kind of discrepancy may be significant for professional athletes, but for recreational athletes, the error does not do much harm.
Suunto used the same algorithm as Garmin until Garmin patented it. They were forced to change the algorithm, which reduced the accuracy of the VO2 max estimate.
The main problem with Suunto smartwatches is that the VO2 max is quite fluid. It will change a lot based on your workouts, so don’t be surprised if it drops 10 or more points after an easier workout. It will eventually come back up.
If you're an athlete who wants to know every metric of your workout, then Apple Watch isn't for you, especially if you're interested in VO2 max.
Based on our experiences, Apple’s VO2 max is nowhere near accurate. It underestimates the value by a lot, and it often reduces the number the more you train. You would think that with training, the number would have gone up, right? Not if you asked Apple.
How can I improve VO2 max estimate accuracy?
All smartwatches determine VO2 max based on the same data. You need to enter your resting heart rate and maximum heart rate and then do the actual workout.
The workout must be done outside, so the watch has a GPS connection. This is the only way it can determine your pace. It must last at least 10 minutes, with the heart rate not dropping below 70% of the maximum heart rate.
This is the basic requirement to actually get the VO2 max estimate. But then there are a few tricks on how you can improve its accuracy.
For more accurate VO2 max estimate use chest strap heart rate monitor.
If you want a more accurate estimate, use a chest strap heart rate monitor during exercise. This is because it measures heart rate with up to 2% accuracy, while the accuracy of measuring heart rate at the wrist is between 1 and 13%. The better the heart rate accuracy, the better the VO2 max estimate accuracy.
The accuracy of the VO2 max estimate also improves with more workouts. The more data the smartwatch has, the easier it will be to give an accurate estimate.
How can I improve my VO2 max?
If you regularly track your VO2 max, you probably want to improve it. We have a few advice on how to do that.
Unfortunately, there are no shortcuts to higher VO2 max. You need to train hard if you want to see the results.
However, just training without a goal will not be enough. VO2 max can be improved only with specific training, which is based on high-intensity intervals. We advise you to follow a VO2 max-specific training plan, as this is the only way to ensure positive results.
Once you're training properly, there are a few supplements that can help you go beyond your natural limitations and boost your VO2 max even further.
The best one is certainly Absolute. The natural VO2 max booster contains a blend of adaptogens such as cordyceps, ashwagandha, and rhodiola, with added beta-alanine.
Absolute helps you improve oxygen flow, giving you the feeling of breathing easier at a high intensity. It also increases ATP energy efficiency and helps reduce stress and muscle acidity. All this will lead to better training and improved VO2 max.
In a study we conducted, Absolute was shown to help athletes increase VO2 max by as much as 6%.
Monitoring VO2 max is surely interesting, but when it is tracked via a smartwatch, care must be taken when interpreting the results. Your Garmin or Apple watch can only give you the estimates, not the actual VO2 max values.
Even if the values on the smartwatch are not the most accurate, they can still give you a good estimate of how well-trained you are. In this respect, Garmin watches are the best, giving the best estimate, while the Apple Watch's estimate is unreliable and useless for a serious athlete.
You can improve estimate accuracy, but it will never be 100% accurate. If you want to know your real VO2 max value, you need to do a lab test. However, if you do more workouts and enter the correct values for resting heart rate and maximum heart rate, your VO2 max estimate will be closer to the real value.
Training is the basis for improving VO2 max. If you want a higher VO2 max, you need to train. There’s no way around it. But once you reach a certain level, however, supplements like Absolute can help you increase your VO2 max above the level where you would normally hit a plateau.