Re: Back injury and starting aikido?
Ditto with what was said above. If he is given an okay by his Dr. to train, then the next step is to find a dojo/instructor that you like that is willing to accomodate and take injuries into consideration. It seems that most aikido dojo's are willing to work with those who have injuries. Some people find their injuries slowly get better with aikido practice (though I wouldn't reccomend aikido as a treatment!) Best of luck!