PHYS-10 · Principle
Why is my friend faster with a lower VO2max?
VO2max is only the ceiling. Speed also depends on how much of it you can hold for the race, how much speed each litre of oxygen buys, and how well those hold late in a long effort.
How the body works, agreed across the reviews below; a study entry shows what one experiment measured.
Practical Application
Why is my friend faster with a lower VO2max? VO2max is only the ceiling. Speed also depends on how much of it you can hold for the race, how much speed each litre of oxygen buys, and how well those hold late in a long effort.
What it means for training: a block may move any of the factors, though evidence that training moves fractional utilisation in trained athletes is limited (REF-986); the base picks the lever by what the athlete has been missing, not by a profile (SYNTH-42), and treats fresh test numbers as hour one, not hour four (SYNTH-32).
What it does not mean: that a profile names the limiter or predicts which factor will respond: what separates athletes need not be what changes within one (SYNTH-42).
Mechanism
VO2max and the lactate threshold fix the oxygen uptake that can be sustained, the "performance VO2", and efficiency, the least understood factor, turns it into speed or power (REF-092). Speed at the lactate threshold, which integrates all three, best predicted distance-running performance (REF-462).
Common misreading
"VO2max decides the race"; "a lab profile tells me what to train".