I've recently been reading "The science of yoga" by WIlliam Broad. I'd really recommend it if you want to know more about the science behind yoga. It demolishes a few myths and talks about the risks of yoga as well as the benefits. A really balanced book written by a yoga practitioner. It's well written too, I'm already on my second read as it's full of little gems that I can use in my teaching and my practice. Also on my recommended reading list is "The wisdom of yoga" b