Sport is an area where, ironically, the playing field is never level. People are born with the bodies and the psyches they are given, and some are far more suitable for competitive sport than others. Some are physically capable but lack the determination and competitive spirit necessary to succeed, and others may be extremely driven but have short limbs, lungs that don't function very well, flat feet or whatever. It is because of this that some rise to the top and others don't.
For people with similar body shapes and capabilities, it comes down to relentless training schedules and sacrifices of personal time, relationships and so on. Given the sacrifices involved, and because of the fame and fortune associated with success, to make it fairer, as with school sports, people are measured against others with similar physiques. As Molly says, boxers fight people of the same size and weight, jockeys are weighed to ensure fairness, athletes and sportspeople compete in sex groups, infants and juniors have separate races, and in many schools there are girls' and boys' races after puberty, too.
Disrupting that is not 'equality'. It is blatant rigging, and anyone who cared about women would want it to stop.