Honestly women were pretty physically active pre-victorian era (especially those that lived on farms), so doubt even the average man would today would be able to do their job. Automation of basic household tasks has made women soft and negligent.
All the strong men got killed off in the wars and an illusion of stability was provided to make the surviving men soft and complacent. After all, if the "good guys" won, what reason is there to learn how to fight or maintain vigilance?