"Extreme Hikers"

Not sure exactly what this means . . . I'm just reporting it: 
 
In an article called "Catfish And Dog Days Of Summer" by Nicky Reynolds posted July 19, 2004 at "The Chatanoogan.com; Chatanooga's Source for Breaking Local News" she (or is it "he"?) lists a lot of outdoor type activities and recreation locations in Tennessee.  Then Reynolds writes, "For extreme hikers, just over 156 miles of the Appalachian Trail run through the heart of Northeast Tennessee."

So, is the Tennessee portion of the AT only accessible to "extreme hikers"?  What is an extreme hiker anyway?  One who hikes to extremes?  Is it a play on words, punning off of "ex-stream hiker" (which would be someone who used to hike in streams (as in running bodies of water) ... or possible someone who used to hike not in fits and starts, but in long bursts [streams])??
 
What would an extreme hiker look like?  What would a non-extreme hiker (a "treme hiker"?) look like?
 
Would I want to be one?
 
Am I already one?