Willipedia - Atrophy

A word to the wise.  If you have a 7 year old that really, really, really likes reading Calvin and Hobbes, be prepared to have discussions about things like atrophy.  Because, you see, a 7 year old just might think that his legs are going to become atrophied and worry about that.  Even if it is just .05%.  Then, you may find yourself explaining that since he uses his legs so much to bike and walk to school and climb the stairs and get into his bunk bed every night, he is in no danger of having his legs atrophy.  Even .05% worth.

And also?  His brain won't atrophy either.