Few single metrics track with all-cause mortality as strongly as cardiorespiratory fitness. The number you'll see in the scientific literature is VO2 max.
What VO2 max measures
VO2 max is the maximum volume of oxygen your body can use per kilogram of body weight per minute during intense exercise. It reflects the combined capacity of your lungs, heart, blood, and muscles to move and use oxygen.
What the numbers mean
VO2 max is reported in mL/kg/min and compared against age- and sex-adjusted reference tables (Cooper Institute data is commonly cited). Moving up a fitness category — say, from "below average" to "above average" — is associated with meaningful reductions in mortality risk across large observational studies.
Why trend matters more than any single reading
VO2 max declines naturally with age. What you want to see is your trajectory against that curve. Holding or improving your VO2 max over a decade is a different signal than declining faster than age-adjusted norms.
What can move it
The most consistent driver is structured cardiovascular training — particularly the combination of long, easy volume and shorter, high-intensity intervals. Body composition, altitude, anemia, and overtraining all influence the number. Genetic ceiling varies person to person, but trainability is real at essentially every fitness level.
How VisitRecall tracks it
Log VO2 max readings from lab tests, submax estimates, or wearables on the same timeline as your labs and visits. See lab tracking and the longevity hub.
FAQ
Are wearable VO2 max estimates accurate?
They're estimates — useful for trend, less reliable as absolute numbers. For an accurate baseline, a lab test with a mask is the standard.
How often should I test?
A structured retest every 6–12 months is plenty to see real change from training.
Is there a "minimum effective dose" of training?
Meaningful VO2 max gains generally require sustained aerobic training multiple times a week. Your clinician or coach can help calibrate intensity.
