A GOOD martial arts teacher should emphasise the need for personal control and not attacking other people. So in that regard it could be a good idea.
However, do check it out carefully. Also make sure you are allowed to be present observing, should you choose to. Because we put difficult child 1 in a martial arts class (karate) when he was about 8 years old. It was a mixed class - ranging from difficult child 1's age up to adult. The teacher was young, we explained to him what we needed for difficult child 1 because of his being a bit unco as well as having a lot of energy to burn, to deal with the fidgets. I really thought the teacher understood.
The teacher explained that karate was a self-discipline and tat difficult child 1 would have to take personal responsibility for his own actions; he needed to learn to rely on himself and to learn his own capabilities. That sounded OK to me. But the teacher also said, "If you're there hovering, he won't learn any of this because he always looks to you to help him through it. He has to know it's up to him."
OK, fair enough. I was a bit reluctant, but it WAS in a group and it was only a few minutes from home.
So karate classes began. difficult child 1 would come home a bit subdued, the teacher would say nothing about the class other than, "He's been worked fairly hard, he could be tired."
We asked difficult child 1 about class and what was happening in class, he replied, "Karate is a discipline, we're not supposed to talk about what goes on because you're an outsider and we're not supposed to divulge to outsiders." or some such rubbish. I tried talking to the teacher about it who nodded and smiled. "Good," he said. "This is part of the beginning of self-discipline and learning self-reliance. Don't worry, he's doing well. I'll soon have this hyperactivity knocked out of him."
That last had us worried, but difficult child 1 didn't want to quit the class. He said he wasn't a quitter. So reluctantly, we backed off but watched as best as we could. Mostly we just watched difficult child 1's reactions.
Over the weeks difficult child 1 became more withdrawn and more irritable. We became more concerned.
Finally a (adult male) friend of ours came to us. This guy is fairly senior in the Australian Defence Forces (equivalent to a US Marine Top Sergeant). "I'm also a student in this guy's karate classes, and I'm telling you that I think you should pull difficult child 1 out of the class. He's not learning anything; this guy is tough on difficult child 1, stupidly tough. He's constantly disciplining him, telling him he has to be disciplined so he can learn self-control but we all know, I now understand better than I ever did, but difficult child 1 simply can't control his fidgetiness and this guy has basically ended up punishing him for simply being difficult child 1."
difficult child 1 still didn't want to quit; turned out the karate teacher told him that if he quit the classes then he was setting the pattern for the rest of his life and he would therefore always be a quitter in life and therefore a failure. We were starting to believe increasingly that this karate teacher was a nut-job, a real head-case, when we got a note - karate classes were cancelled until further notice. The guy had a breakdown, apparently.
Our adult male friend kept us posted on things - he wanted to complete the course, plus he'd paid up for more sessions than we had for difficult child 1. The karate teacher did make a half-hearted attempt to get classes going again (he didn't contact us to get difficult child 1 back on board - so HE quit on difficult child 1! A point we made clear to difficult child 1 at the time, although by then he had stopped caring, he didn't want to know the guy).
I believe for a while some other bloke ran karate classes for a few weeks, and our friend said there was none of the "secret society" BS, but it still fizzled out.
So go in carefully. Some of these martial arts things do have this "we are a secret society" attitude, or "we are superior to the rest of the world" attitude. It took a few years but difficult child 1 finally told us that the karate teacher had really reinforced the secrecy thing, plus the fact that just about every lesson was a waste for difficult child 1 because if he couldn't keep up (and he was the youngest by far, in a class which included adults who mostly had prior experience) or he was fidgetty (which was worse when he was anxious, and this class had his anxiety ramped up to panic level) then he had to be 'punished" by having to do roll-outs, over and over, for the entire duration of the class. And he was expressly forbidden from telling us about it.
It was about this time we had a talk to difficult child 1 (yet again) about good secrets and bad secrets. Although there was nothing sexually deviant about this teacher's behaviour, the result was the same - he used control and secrecy to abuse our child emotionally and physically.
difficult child 1 now (as an adult) has begun to hook up with the Society for Creative Anachronisms. It's a sort of medieval martial arts. None of the secret society crud, none of the BS he got caught up in. HE is in control and can walk away if he chooses and now sees that walking away when it gets unpleasant is the responsible, mature thing to do and is NOT the hallmark of a quitter or a failure.
So go carefully. Vet it well. Martial arts for a hyperactive kid can be a godsend, or a disaster. You need to be kept informed and monitor it.
One point I leave with you about how easy it is to get hooked in to the BS - that adult male friend of ours who told us about what was happening - the ENTIRE TERM had gone passed, there had been a break due to the early stages of the teacher's breakdown, before our friend told us that the teacher had been abusing our son. The secrecy injunction was so strict, that even an adult male who had enough of a relationship to our son to be a protector, had failed to protect him and failed to tell us sooner.
Even strong adults can also be rapidly brainwashed.
Go carefully.
Marg