The Garmin Fenix series watches make a calculated estimate of VO2 max based on recorded physiological data over time. People tell me it’s pretty accurate. I remain skeptical, but only because it thinks I’m better than I think I am. Still, a VO2max of 48, or even anywhere in the 40s for that matter is as about as good as a non-competitive woman in her 40’s can get. I’m going to bask in the feeling of achievement this analysis that Garmin gave me.