It's not surprising to learn office workers and those who spend the majority of their day seated suffer more lower-back pain than those with physical jobs. Sitting around all day causes a whole multitude of health issues for the human body - weak core muscles being one of the more obvious effects of a sedentary career choice. Working in gyms gives you more than enough opportunities to see how strength has decreased massively over the decades... unfortunately, this downward spiral is a continuing trend
p.s Not suggesting you sat around all day long, that's certainly not how warfare was done... perhaps a little more nowadays with drones and stuff though.