Rename multiple MySQL tables by inserting an underscore

Rename multiple MySQL tables by inserting an underscore

How to rename a set of MySQL tables by inserting an underscore after a
keyword. The following example shows what I mean:
current names:
keywordcache
keywordfield
keywordmenu
etc.
expected names:
keyword_cache
keyword_field
keyword_menu
etc.
I use phpMyAdmin to access the data base. Renaming many tables one by one
is too time-consuming so I'm looking for some automatic method.