A new study has taken a close look at how well a popular Garmin smartwatch performs when measuring key fitness metrics, and the results are a mix of good news and a clear warning for anyone relying on advanced recovery data.
Smartwatches today pack a growing list of health sensors. Heart rate tracking via optical sensors is now standard across most models, and many devices also offer heart rate variability (HRV) tracking. While heart rate is straightforward to capture, HRV is much harder to measure accurately because it depends on tiny changes in the time intervals between beats. It’s the kind of metric you can’t realistically verify with a simple DIY check the way you can with basic pulse counting.
In the study, researchers evaluated the Garmin Forerunner 265 and compared its readings to a single-lead ECG, a more clinically grounded reference. The participant group was relatively small, with 30 adults taking part. That matters because it limits how confidently the findings can be applied to broader populations, and it also makes it difficult to judge how factors such as skin type might affect measurement quality. Another limitation is that the research was produced as an academic thesis, meaning it likely had academic supervision but did not go through the full traditional peer-review process.
Even with those caveats, the findings are still useful for everyday users trying to understand what their watch can and can’t do well.
For resting heart rate, the Forerunner 265 performed strongly. The study reports high precision and accuracy when compared with the ECG baseline. The typical deviation between the two methods was around two beats per minute depending on body position, a difference that’s effectively minor for most real-world fitness and wellness use. If your main goal is dependable resting heart rate tracking for general health monitoring, training awareness, or lifestyle insights, this is encouraging.
HRV is where the watch struggled. According to the study’s conclusions, HRV measurements from the Forerunner 265 were not reliable enough for research contexts and may also fall short of what serious athletes expect. That’s important because HRV is commonly used as a recovery and readiness signal, helping athletes judge whether they’re adapting well to training, managing stress, or drifting toward fatigue and potential overtraining. If the HRV data isn’t consistent, it can lead to misleading conclusions—either pushing someone to train hard when they should back off, or causing unnecessary rest when they’re actually fine.
What this means for Garmin Forerunner 265 owners and shoppers is fairly straightforward: the watch appears to be a strong option for accurate resting heart rate tracking, but HRV should be treated with caution—especially if you’re using it to make training decisions. For many users, HRV can still be interesting as a general trend or an extra data point, but it may not be dependable enough to act as a primary signal for performance planning or recovery management.
As always with wearable health metrics, the safest approach is to treat smartwatch HRV as supportive information rather than a definitive measurement—particularly if your training, health, or performance goals depend on accuracy.
