I bought a Forerunner 55 back in October, and while it's a great watch, the VO2 max metric is stuck at 44. It's only ever been two values: 45.0 when I first put it on, and 44.0 ever since. I run 5-10 km, 2-3 times a week, and have improved my time quite a bit in the months I've had the watch, from 5:24/km in October, to 4:54/km in February.
I know a lot of people will say VO2 max is an unreliable metric. Regardless, I would at least expect the functionality to work as documented. My race predictor is often slower than my average runs for the same distance.
