Maximal Oxygen Uptake.
VO2 max is the maximum volume of oxygen the body can use per minute, normalized to body mass. It represents the ceiling of cardiorespiratory capacity.
Why it matters
The single best predictor of all-cause mortality past age 50. Higher VO2 max is associated with reduced risk across cardiovascular disease, certain cancers, and all-cause death. Trainable at any age, and gains accumulate measurably with consistent work.
How it is built
Z2 base training builds the cardiovascular floor. Z5 intervals (1 to 4 minutes at 90 to 100 percent max heart rate) raise the ceiling. Polarized training (80 percent Z2, 20 percent Z5) is the most evidence-supported distribution.
Measurement
Direct testing in a sports science lab using a metabolic cart. Wearable estimates are improving but should be calibrated against a real test annually.