What sort of symptoms are you thinking of?
As autism causes alot of anxiety and stress I think anything that helps with that is useful. But the child has got to be interested in doing something. Alot of children with ASDs like martial arts because of the measured repetitive movements and the fact that they can copy the others around them. My son likes to copy exercises he sees on TV etc. Some children with ASDs like to learn to play an instrument. My son plays drums, but his teacher is not running the classes as she would for a 'normal' child. It is more about one to one social interaction using drums. But I think anything that encourages an ASD child to also tune into another human being is helpful, but you have to work through their interests and obsessions. Children with ASDs have got huge amounts of attention and focus for their areas of special interest. They are unable to give any attention/focus to something they are not interested in. So you will find out very quickly what are his likes/dislikes.
Trampolining is very good for the body and brain development. Most children with ASD love trampolining because it also helps with their vestibular and proprioceptive senses. Some children with ASD are very good at performance arts, especially if they like to copy and mimick.
Anything involving team games usually doesn't work because they have no concept of 'the team' or their role within the team. There are also usually problems with having to get physical with another person eg. a tackle in football etc. Alot of these children are also touch sensitive and fear unpredictable touch or sound.
I would say anything that gets him interacting with another person is going to be good. The other person may have to change what they usually do eg. even at trampoline class my son is not aiming for getting his awards. I am happy that he is turn taking, listening to instructions, trying to follow them out and his vestibular/proprioceptive senses are receiving input.
There are exercises you can do called 'brain gym' there are books you can find about it. Alot of special schools use these exercises because they help with brain development. Other activities such as crawling are also very good. Alot of children with ASDs don't crawl that so their brain doesn't get this vital element that helps brain formation. So you can practice pretending to be an animal on all fours, or pretend to be a soldier crawling on your tummy etc.
Out of all the professionals probably an Occupational Therapist is the one who gets more physically involved with a child with ASDs.
Hope some of that is helpful.
i don't know a lot about autism, but as you described your situation, i think yoga and ayurveda (i think) can be useful for your son. i know you are only allowed to do pranayama after you are 12 years old, but he can do asanas. Also, there is something like, i don't know what it is called, but warm oil with special herbs is dripped on the forehead of a person to reduce stress and alleviate other psycological problems, maybe it is helpful in autism.
just a thought here
Supposedly yoga helps reduce stress with most people. It may help with those dxed with autism as well.
I don't think it will alleviate any "autistic" behaviors, but if it helps may calm down. I wish I knew whether you're refering to your child, someone you know, a child you work with, adult you work with, or yourself.
It'd be nice to know where you're coming from. Personally I don't do yoga, but if I find any task that effectivly calms me down helps prevent me from darting around and grunting or screaming at any exhasperating thing. I don't really associate it with being an "autistic" behavior even if other people may think so. It's just an expression of frustration abeit one that can be a bit loud...at least I find it more suitable than shouting certain key words that some people may use if they are in a stressful situation....