... I doubt they would let a 5'4" 145 pound man fight on the frint lines...
I don't know what today's standards are (if, indeed, there are any), but I can tell you that back in World War II, my father - who was 5'2", and not exactly an outstanding physical specimen - was sent to the front. Everyone but him was killed, and then (with his emotional state hanging by a thread), they sent him back again almost immediately. Almost the identical thing happened, and he had a total breakdown. He never wanted to discuss his wartime experiences; I found all this out from my aunt (his sister) after his death.
I also knew a co-worker years ago who served in the Korean War (in the Navy) as part of a destroyer escort. He was even shorter than my father, but he was one tough SOB.
So, as far as physical requirements for combat? For men, I kinda doubt there are any. But, I could be wrong.
Sorry for the thread drift.
Signor V.