Wrist Conditioning?

In "Building the Gymnastic Body" coach Sommer references an, as of yet, unpublished book, stating that it is necessary to condition the wrists prior to starting along several progressions to avoid injury. I was wondering if I could get some tips or perhaps a small peek on methods for conditioning the wrists. I am a practitioner of Aikido, so my wrists are stronger than average but I rather value my wrists and would like to sure before starting, especially if an experienced person feels the need to warn others about it. Thanks for your time!

If you haven't seen it already, there is a sticky on this in the joint prep forum. Also, this thread: http://gymnasticbodies.com/forum/viewtopic.php?f=17&t=860

Hope this helps