It's nice to see that chiropractors in China are just as pseudoscientific as they are in the West. It's the one pseudoscience that most people assume is pretty legitimate, and at the basic level they can be as decent as a physiotherapist or qualified masseuse, but the trouble is mixing all the other things in there that make them far worse, yet you get charged even more.
1. 'adjustments' are at best fairly useless, and at worst highly dangerous. Some basic lower back pain might be helped by physical therapy, but adjustments of the spine through chiropractic have actually killed people.
2. The magnesium probably won't do you much damage, but there isn't a great deal of evidence that it helps muscle cramps, even in very severe cases where extreme cramping is possible (eg long distance cycling).
As I said though, nice to see an area where East and West fail equally.
http://www.skeptic.com/eskeptic/09-10-21/