The Fitbit Versa 4's heart rate monitoring during intense exercises has been reported to have significant accuracy issues. Users and reviewers have noted that the device tends to lag behind in detecting rapid heart rate changes, often underestimating peak heart rates. For example, during high-intensity workouts like interval training or cycling, the Versa 4 may struggle to accurately track heart rate, sometimes showing readings that are too low compared to other devices like chest straps or other smartwatches[1][2][4].
In specific scenarios, such as indoor cycling or spinning sessions, the Versa 4 has been observed to frequently lose heart rate tracking or report much lower heart rates than actual, even when the user is at peak effort[7]. For instance, one user reported that during a spinning session, the Versa 4 barely broke 120 bpm, while a spin bike measured a heart rate of 177 bpm[7]. This discrepancy highlights the device's difficulty in accurately capturing heart rate during intense exercise.
The issue seems to be more pronounced when heart rates exceed 100 bpm, with some users noting that readings can be 20-30 bpm too low[3]. This problem is not unique to the Versa 4, as similar issues have been reported with other Fitbit models like the Versa 3[3].
Overall, while the Versa 4 performs reasonably well at rest or during low-intensity activities, its heart rate monitoring during intense exercises is less reliable compared to other devices on the market[2][4].
Citations:[1] https://www.youtube.com/watch?v=HQ4wGFMb0Aw
[2] https://www.pcmag.com/reviews/fitbit-versa-4
[3] https://www.reddit.com/r/fitbit/comments/1373nhe/versa_4_heart_rate_accuracy_is_terrible/
[4] https://connectthewatts.com/2022/10/03/fitbit-versa-4-review/
[5] https://www.heartratemonitorsusa.com/products/fitbit-versa-4-smartwatch
[6] https://pmc.ncbi.nlm.nih.gov/articles/PMC6107736/
[7] https://www.reddit.com/r/fitbit/comments/10r0prh/versa_4_inaccurate_heart_rate_during_exercise/
[8] https://community.fitbit.com/t5/Versa-4/Versa-4-is-not-tracking-my-heart-rate-or-any-health-metrics-data/td-p/5522282
[9] https://pmc.ncbi.nlm.nih.gov/articles/PMC11109865/