Martial arts is a good sport and can build the body and mind and if a kid wants to do it find ,better then being a couch rat.
I am not talking about a 12 and older child by that time they are getting some size and muscle to be able to do something. But smaller children just do not have the size or power to make it work. Learning to throw a good kick and punch well help them later when they get big enough to have some power behind it.
Fighting back is a good idea screaming biting, kicking ect anything to make someone else take notice that the child isn't going along freely. But to think a child is going to out fight some one that is 2,3,4 times their size who is determined to do them harm, it just isn't going to work.
Pinching works well, too. Ever have your toddler run up to you and grab your leg. Those grabs on the inside of my thigh ALWAYS put me through the ceiling.
"Fighting back is a good idea screaming biting, kicking ect anything to make someone else take notice that the child isn't going along freely."
Valid point. In addition, there are sometimes odd psychological factors. We had a recent incident here in Western PA where a man abducted a 12 year old girl into his car and drove away. She never stopped fighting him, insulting him, calling him wierd, etc. After a short while, the guy just stopped the car and let her out. She is now safe and he is in custody. (Not saying this is remotely guaranteed to work.)