V., have you kept up with the correlation between the FirstBeat algorithm vs actual lab measurements? Some people in the Garmin 620 forum are talking about that, since it's Garmin's first watch to incorporate that technology. I'm assuming that FirstBeat has refined their algorithm quite a bit since you had yours done. The few people in the Garmin forum who've had theirs lab tested report a result *fairly* close to what the watch came up with. I've never had a lab test, but my watch is telling me my VO2 Max is 47, which seems insanely high to me.
Speed comes from what you put behind you. - Judi Ketteler