Why locking your knees could cause you to faint.
In: Biology
I have vasovagal syncope, or as my daughter says, “you get passy outy a lot!”
I have discovered there are a lot of reasons why people pass out: altitude, overexertion, dehydration, pressure changes in the abdomen, alcohol intake and the knee locking thing.
The knee locking thing has to do with the gates in your leg veins: when you contract leg muscles the valves in the veins open to allow blood to flow back towards the heart. As I understand it, each valve has two opposing flaps that act like gates opening one way. That stops blood from moving back down.
When you lock your knees, the muscles sometimes relax and the gates can open, effectively dumping blood into your legs. Down you go!
Conversational aside to guys: peeing standing up at night can have the same effect for some. It’s called micturation syncope. The pressure change causes a misfire of the vagus nerve and those same gates open. A bunch of dudes die every year from falls when this occurs because there are so many hard surfaces in the bathroom.
Latest Answers