Chinese medicine makes a bunch of statements such as that chi flows through meridians. If one is actually intersted in scientific criticism it's useful to directly address an individual practice like Reiki and not meddle it up with other practices that contain a bunch of different assumptions.
Very interesting decision from the one of the leading scientific publications to publish an article about Reiki therapy.
http://www.nature.com/news/consider-all-the-evidence-on-alternative-therapies-1.18547
[Edit: should be Nature publishes an article about alternative therapy]