I think martials art for kids should be more about self esteem and self confidence, and less about self defence.

"If you have to fight, you are doing it wrong." (I said that while teaching wing tsun, a few years back.)

I've been training in martial arts my whole life (four or five different ones, at various times, starting when I was 10, I'm 41 now) and have many many years experience teaching martial arts to children and adults.

Here's my opinion: four is WAY too young. They just don't have the physical coordination or the mental focus (or judgment). They are certainly not learning "self defense" of any value, though it's possible that they may pick up other helpful values and skills (but no different than any other structured physical activity). Anybody teaching 4-year-olds is basically babysitting, "playing" martial arts at best, having your kids do dangerous things at worst.

There's no particular harm in this kind of play (though I think it's a waste of money, since they won't retain anything useful), but I do have a rather serious thought: martial arts can be a wonderful, life-long pursuit with many benefits, not the least of which are being great form of exercise to keep fit and possibly saving your life someday in a self-defense situation. But IMHO as an instructor with 30 years experience (on and off), the chances of a kid under 10 getting any real training or developing a lifelong interest is very very small. Chances are much higher for tweens and teens.

So in short, if you want babysitting now that happens to include kicking and punching, by all means go for it. If you want a lifelong gift, wait 10 years for martial arts, and in the mean time try some yoga or other physical activity. (Tai Chi, as one other poster suggested, is also fine, but having tried it, I would be shocked if it weren't too slow to keep a 4-year-old interested.)

When I took karate (in jr high) all school age students were required to turn in their report cards when they tested for specific belt levels. Because karate teaches discipline, we were expected to apply that discipline in all areas of our life and raise our grades. If your grade average was too low, you had to wait until your next report card came out to test for your belt.

My spouse used to teach traditional karate at a wonderful school. They taught kids starting at around 6 or 7. There was no sparring in the kids' class and they were emphatically taught to handle conflicts by: "apologize, walk away, run away." Kids caught fighting in school were disciplined with in ways like being made to mop and clean after class or even not being allowed to attend class for a while. It taught wonderful discipline and a great feeling of empowerment. The best part: to a person, the parents were thrilled about the classes, the teachers, and the positive changes they saw in their children.

On the other hand, I attended a school where children were taught that their martial arts training would enable them to defend themselves against adults which is mindblowingly inaccurate and dangerous. I would never let my child go to a place like that.

My point is, even with "hard" martial arts, there are good and bad schools for children of all ages.

A very close friend of mine teaches Yoga to 4 and 5 year olds at the local Montessori school. When done right, it can teach concentration, imagination, flexibility and strength. Because many of the American names for the poses are nature or animal based, It is really easy for the kids to get creative and Play act as dogs, lions etc. It is amazing the attention they devote to it when introduced this way.

Also, because Yoga can be enjoyed at any fitness level, and there is little compound learning involved, it is OK to teach it in a free form manner, and missing classes is not such an issue, while still teaching control and concentration.

It is also worth noting that Yoga teaches peacefulness, concentration and discipline without the implication of violence.

I always wanted to introduce my son to martial arts, I think it would give him security, focus, and discipline (I did martial arts when I was younger, and found it very beneficial at the time and now)

I have to wait until he's a little older though

I would think kids would get bored with yoga. Martial arts seems fun and exciting!

Good question!