PHYS-09 · Principle
How do I raise my VO2max, and what limits it?
Mostly the heart and blood. VO2max is cardiac output times the oxygen the muscles take out, and training raises it chiefly through a bigger stroke volume, more plasma and more haemoglobin.
How the body works, agreed across the reviews below; a study entry shows what one experiment measured.
Practical Application
How do I raise my VO2max, and what limits it? Mostly the heart and blood. VO2max is cardiac output times the oxygen the muscles take out, and training raises it chiefly through a bigger stroke volume, more plasma and more haemoglobin.
Mechanism
Raising or lowering delivery (blood doping, hypoxia, beta-blockade) moves VO2max; training gains come mainly from maximal cardiac output; a small overperfused muscle mass can use far more oxygen than whole-body delivery allows (REF-462).
A gram of haemoglobin mass is worth about 4 mL/min of VO2max; training expands plasma and red cells, hypoxia red cells only (REF-464); more plasma raises filling pressure and stroke volume (Convertino 1991); in 12 trained cyclists heat acclimation expanded plasma 6.5% and raised maximal cardiac output and VO2max in the cool (REF-001, B+).
In pooled individual data maximal cardiac output and two-leg blood flow rose 4.9-6.0 L/min per L/min of VO2max and leg extraction approached 90-95% (Skattebo 2020); multifactorial models still give the cardiovascular side most of the limit in normoxia (Ferretti 2014); in 16 highly trained cyclists maximal power tracked haemoglobin mass (REF-470, B).