It is false that females are unable to maintain a high level of
cardiorespiratory fitness. There aren't many differences between male
and female bodies and internal organs, so there is no reason why females
couldn't do this if males can. If they exercise enough, they will be
able to do this, if they don't exercise, they won't - this is a rule for
both men and women, it has nothing to do with sex.
The body of a man can have higher cardiorespiratory fitness levels than the body of a female but, females can have a high cardiorespiratory fitness level as well as a male if the female maintains it by exercising and having a healthy diet.
