When you've synced your activity details to your TomTom Sports account you can see your VO2max rate on your TomTom Sports website page. Select the Progress tab, then select Body from the drop-down menu. Select VO2max below the graph to show your VO2max trend. You can filter the trend for week, month, year, and all.
For more information about VO2max, see More about Fitness Age.