Apple vs Garmin: How accurate are their VO2Max estimates?
A recent study has shed light on the accuracy of VO2max estimates provided by Apple and Garmin devices. It appears that these estimates may not be as precise as we’d like to believe.
Many smartwatch users track their VO2max as a way to monitor their fitness progress and overall health. The appeal lies in the accessibility of this metric, which traditionally required expensive laboratory equipment and trained professionals to measure accurately. Smartwatches use various algorithms, typically combining data from heart rate sensors, user-provided information, and GPS to estimate VO2max.
Researchers compared VO2max predictions from Apple and Garmin smartwatches to measurements obtained through indirect calorimetry, the gold standard method for assessing VO2max. The study involved 40 healthy participants aged 18-35 who completed a treadmill-based ramp protocol while their oxygen consumption was measured using a metabolic gas analyzer.
The results were published in the International Journal of Exercise Science earlier this year. And they showed a significant discrepancy between the smartwatch estimates and the laboratory measurements:
Device Brand | Average Underestimation (ml·kg−1·min−1) | P-value |
|---|---|---|
All Monitors | 7.2 ± 7.0 | <.001> |
Apple | 8.3 ± 7.6 | <.001> |
Garmin | 5.3 ± 6.8 | .011 |
As can be seen from the table, both Apple and Garmin devices consistently underestimated VO2max values. Apple devices showed a larger discrepancy, while Garmin devices performed slightly better but still significantly underestimated the measured values.
It’s worth noting that the study did not specify which particular models of Apple and Garmin watches were used by the participants. This information would be valuable for a more detailed analysis.
Garmin Forerunner 265: A closer look
Another study in the International Journal of Exercise, published a few weeks ago, focused specifically on the Garmin Forerunner 265. It provides interesting comparative data.
This study involved six subjects with an average age of 28.5 years. Participants wore the Garmin during a 10-minute outdoor run, after which the watch’s VO2max estimate was compared to data from a graded exercise test using a Woodway treadmill and Parvo metabolic cart.
Results showed:
Measurement Source | Average VO2max (ml/kg/min) |
|---|---|
Laboratory | 46.1 ± 7.41 |
Garmin Forerunner 265 | 51.3 ± 3.6 |
As can be seen, the Garmin Forerunner 265 showed a tendency to overestimate VO2max! The average percent change was 13.3 ± 15.5%, with a Mean Absolute Percentage Error (MAPE) of 18.4 ± 8.6%.
Comparing Studies: A mixed picture
Now what are we to make of all of this? The results from the second study paint a somewhat different picture from the initial study. While the broader study found that Garmin devices generally underestimated VO2max by about 5.3 ml/kg/min, this focused study on the Forerunner 265 suggests an overestimation of approximately 5.2 ml/kg/min!
This could be due to several reasons:
- The Forerunner 265 study had a smaller sample size (6 participants) compared to the broader study (40 participants), which could affect the reliability of the results.
- The Forerunner 265 study used a 10-minute outdoor run for the watch estimation, while the broader study relied on a indoor treadmill test.
- As the Forerunner 265 is a newer model, it’s possible that Garmin has changed its VO2max estimation algorithm.
One thing is clear – these contrasting results underscore the need for caution when interpreting VO2max data from smartwatches. While these devices can provide valuable insights for tracking personal fitness trends, users should be aware that estimates may vary significantly from laboratory measurements.
Most of us who keep an eye on our Vo2Max know how unreliable it can be. For example, my default watch is the Garmin Forerunner 955. If I do a short run (3-5K), my Vo2Max significantly increases. Anything above 10K, and it will fall.
It is good to see studies highlighting the ongoing challenges in accurately estimating VO2max outside of a laboratory setting. Sure, keep an eye on your Vo2Max, but use this value as a rough guideline rather than a precise measurement.
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Sources:
Kilby, Evan D.; Gomez, Andrew; and Toth, Lindsay P. (2024) “ACCURACY OF PERSONALLY OWNED WEARABLE ACTIVITY MONITORS FOR ESTIMATING VO2MAX,” International Journal of Exercise Science: Conference Proceedings: Vol. 16: Iss. 3, Article 353.
Available at: https://digitalcommons.wku.edu/ijesab/vol16/iss3/353
Howard, Jonathan; Middleton, Ryan; Provost, Olivia; Turner, Morgan; Thompson, Katie; Whatley, Gabby; Zackery, Israel; Otis, Jeffery; and Doyle, J. Andrew (2024) “ACCURACY OF VO2MAX ESTIMATES FROM THE GARMIN FORERUNNER 265.,” International Journal of Exercise Science: Conference Proceedings: Vol. 16: Iss. 3, Article 94.
Available at: https://digitalcommons.wku.edu/ijesab/vol16/iss3/94
