How do you experience fatigue in running?
Inspired by Aerochicas thread, when you run what causes you to fail? For me it is 98% of the time a cramp in my right ab in a fairly specific spot. My legs may feel tired and I might be winded but I can push through both of those pains, however the sharp stabbing pain is crippling. I can keep going a bit by pushing in on the spot, but that makes running itself harder and only delays the inevitable.
Note: I am no frequent runner. I go through periods of running regularly for different sports, but outside of that I almost never do it.