Why do people faint when they have locked knees?

Question

Like when people stand with locked knees for a long time, why do they faint?

Answer 1

When they lock their knees the constrict the blood vessels and the blood does not flow freely up to the heart and brain.  Its lack of blood that causes them to faint.  As soon as they faint the blood starts rushing up to the heart lung and brain and the person recovers.  We had this happen several times when I was ion the Army and we were standing at attention for some sort of ceremony.  They kept telling us to slightly flex our knees.  You could do this in fatigues and not let it be known.

Answer 2

not sure, who are you referring to...maybe they aren't used to it or their legs aren't strong enough so they just give out. I was in cheerleading for 2 years and helped the cheerleaders last year and there's a lot of stunts, flying, and moves that you have to lock your knees in and I never heard of this...No one's ever fainted but if they weren't strong enough and it was a longer routine their knees would give out.-

Answer 3

Cause it blocks the circulation & for some reason cause u to fall & faint. That's what I know I don't know why u faint but I can see why u fall.