In the Garmin app under Fitness age it gives my 4w average vigorous minutes as 56.5. This appears to be reading far too low as my actual average (under intensity minutes) is 13 average daily (so 91 a week) over 4 weeks. Why this big discrepancy? As a consequence the fitness age calculator Is telling me I need to increase fitness minutes but I am already doing 91 a week. Is it possible there is a bug in the Fitness age vigorous minutes calculation? Any help to resolve this is appreciated. Thanks a lot.