VO2max

VO2max is the maximum rate at which your body can take in and use oxygen during exhaustive exercise, measured in millilitres of oxygen per kilogram of body mass per minute (ml/kg/min). It is the ceiling on aerobic power production and one of the strongest predictors of endurance performance.

For trained amateur cyclists, VO2max typically ranges from 55 to 70 ml/kg/min; elite road pros are often 75–85+. Genetics set a plausible range; training determines where within that range you operate.

VO2max is trainable primarily with short, hard intervals near maximum sustainable aerobic output — 3–8 minute efforts at 105–120% of FTP are the classical prescription. 30/30s and 40/20s (short bursts with incomplete recovery) work a related but partially different mechanism.