These and other physical limitations have been cause for deferment from the military for a long time. I think a person who has flat feet (fallen arches) is not capable of marching hundreds of miles while carrying a heavy load. Pretty much the same reasons for spinal defects. There are actually different requirements for different branches of the Military I think. My brother had flat feet and could not serve in any service but the Air Force. I am not sure if he tried the Navy. The Marine Corps did not want me because I wore glasses, but mostly because I had the tip of my right index finger amputated as a child. These did not bother the army, but would have kept me out of elite service in almost every branch. Rangers, Recons, Seals (UDT), etc. Incidentally, some women now qualify in these where most men wash out. Pilot standards are high too. And we have more female pilots every year.
And being a conciencious objector, or not physically fit does not prevent a person from serving. Logistical support is every bit as important as combatants.
