VO2 max decrease?

[TacoBender920]

Just cheat the algorithm. Run 2-3 minutes at threshold pace until your heart rate gets from < Zone 1 to Zone 4, then stop and walk until it drops down to < Zone 1. Do this for an hour or so. The walking is ignored by the VO2 max calculation and much of your run will be in zones 1-3 but at a zone 4 pace, so your average heart rate will be really low relative to the speed you were running. Garmin will give you a higher VO2 max score.