I'm using Vivosmart 4 for quite some time, and due to gym closure, I started to use for outdoor running using the phone GPS.
Only now I realized how inaccurate is this device.
1. The pace calculation is sometimes just not calculated for the first few minutes in the beginning of the run (see 0:00 - 3:57).
2. This one is really ridiculous - the average pace appears as faster than best pace.
3. Incorrect distance offset - I used Google Fit and "Nike Run Club" applications - both of them are quite accurate with a known distance I measured, but Vivosmart, that use the phone GPS, is measuring ~10% lower distance.
4. Vo2Max calculation is way off - I used to run 4km in 6 min/km pace (average HR ~170), now I run 5km in 5 min/km pace (~160 average HR) and my Vo2Max has lowered from 48 to 45.
5. Sleep is measured while I'm awake - Sometimes, just watching TV is considered as sleep time.
6. Climbed floors - same number of floors is sometimes counted as 9 and sometimes as 6. I had cases when just moving between my office to another office is counted a floor climbed.
All in all, the watch is inaccurate and can't be trusted.
I had Vivosmart 3 before (I replaced it as its strip was ruined and there's no option to replace) and Vivosmart 4 is my last Garmin watch ever.