What affects VO2 max by gender?

VO₂ max is influenced by sex, but the transcript gives different reference targets, not a specific explanation of why the sexes differ:

• Men: A minimum reference is about 35 mL/kg/min; Galpin says he would prefer values above 50, and considers above 55 a stronger target.
• Women: A minimum reference is about 30 mL/kg/min; he gives above 50 as a comparable higher target to men’s above 55. 1

VO₂ max is expressed relative to body weight and reflects cardiac output multiplied by the difference between oxygen in arterial and venous blood. The cited discussion does not identify the biological reasons for the sex difference. 2