I have a new mystery...I noticed getting to  the 20 mile and beyond that there are new factors to consider.  One is the hip soreness.  But the thing is that I have had problems with chaffing now, which is a new thing to me.  I guess the mileage and sweat combination are taking its toll.  Thighs, toes, nips and my arm where I hold the ipod strap on my arm.
I think I need a visit to the running store for some lube.  
I went shirtless a few days ago for a 10k and believe it or not, when I got back, my nipples were feeling sore n chaffed!  What?  A strange mystery, since there was nothing but wind touching!  Theories?