perhaps i misunderstood, but i thought only using a power meter on the bike and running would change one's VO2max metric on the Garmin watches.
yet today, i spied on Runanalyze that my quick test of my watch in our community pool (teaching my daughter to swim and decided to just a couple hundred meters to test out lap detection) showed a small change in my V02max reported on the FIT file by Garmin. it wasn't a huge adjustment, but i was shocked to see the adjustment, nonetheless.