Bend over backwards

Posted by Lotg on March 14, 2004

If you bend over backwards for someone, you're going out of your way to do make an extra effort to do something for someone.

Clearly bending over backwards is doing something extraordinary (hell knows it's a huge physical effort to me - I can't bend over backwards very far) - but it's also a very strange thing to say or do. Does anyone know when and why anyone would dream up such a contortion to describe an extraordinary deed?