Kratochvilova was always a little TOO jacked. You didn't see male runners running that kind of cycle.
Male runners in anything but the 200m down are probably all sitting at very near the physiological range, if not within or lower.
Based Jarmila was an absolute Godzilla of a woman at her peak. I'd guess she was near 160 ripped at 5'7"-5'8", which with a slender frame, is jacked out of her ged damn tree! Absolutely a flippin' truck stick of a human.
When we consider that Jarmila may not have been some absolute one-in-500Bn talent, it's easily conceivable that someone else could better her record, with modern day practices, 1% faster shoes, etc