Karate, body conditioning and the Makiwara

A recent debate on the website bullshido.com piqued my interest in a traditional Okinawan practice. Karate practitioners in very hard styles of karate will pound their fists into boards, condition their shins and arms with wood or other surfaces, in an attempt to harden the bones. This supposedly makes the karate practitioner more effective in combat.

The subject is a matter of controversy and there isn't really a lot of scientific evidence