I haven't had the privilege to work with kids with Autism, but because of its meditative and calming aspects, I've long suspected that they would connect with hooping. This article on hooping.org speaks about the "Power of a Hula Hoop." One of the comments also made a lot of sense to me:
"I think the repetitive sound is soothing for them and it provides sensory input without anyone being in their “bubble” as well."
Hooping most definitely puts you in a "bubble." This is why I, someone who is not keen on drawing attention to myself, am able to hoop in public...I am so focused on my hooping on that I lose most of my awareness of the external world.