Amazing achievements by martial-artists

In “Discovery Chanel” I have seen some martial artists making things really
amazing:
Put the tip of a spear in his neck, press it and get no hurts, being hit
with wood stuffs in the back and no broken ribs, insert thick needles in his
skin, hang recipients with water and his skin doesn’t
tear down neither blood appears. If I remember correctly one of this people
is called
Lee Chan Ming, a Shaolin monk. They say all of this is get by mental energy.
How can our mind get all this? and if someone suddenly try to hurt this
people, can they avoid injures at the very moment, or does they need time
to get concentrated , so they are
vulnerable to a sudden attack.

First of all, many of these"incredible feats" are usually either plain old trickery or simple understanding of the physics involved.

So it ranges depending on the “trick” involved. Sticks used to hit the “martial artist” might be cut, or made in such a way as to serve a specific purpose. You may have other instances where the amount of force used is misleading, or where knowing where and how to hit something will do somehting seemingly magical.

You’d need to provide some specific tricks for us to help explain how it is done.

And as to wether or not any of these tricks are helpful in an actual fight, usually no, not at all.