Yes, I competed and finished a ten mile race. I really enjoyed it and until shortly after I finished, knew I wanted to do it again next year. The whole race was gorgeous rolling hills, farmland, forests: very inspiring scenery. It was well organized and very clearly marked. Individuals called out our times at each mile mark and they were so encouraging, too. I ran a modest (slightly less than) ten minute/per mile pace. But, it was the first time I've ever ran more than 7-8 miles!
Unfortunately shortly after my run was completed cramping set in. Now, I'll spare you the many details, but the cramping intensified until I was literally in tears and doubled over in pain. This went on for about 6 hours until I finally asked B to call our doctor. He advised us to go into the ER and after some awesome friends stepped in to make that possible (by watching C, E, and P) I was taken in to the hospital. I was given some drugs for the cramping, the nausea, the pain, after urine and blood samples were taken. I was given two bags of fluids overall and left the hospital in still a fair amount of pain. i.e. I almost puked in the car on the ride home.
Now, I know you think I was dehydrated, but that wasn't the case. My sodium levels were low, but I wasn't severely depleted of fluids. I've done some reading and I know that some other long distance runners experience this problem, but is looks like I might have to see a specialist to really find out more on how to prevent it in my specific case. Right now I have no desire to run ever again - the pain is still so fresh in my mind. And, it was a little scary that it wouldn't go away.