I think there is too much emphasis placed on the distinction between the people in the front and the people in the back.  I happen to feel the sensations are exactly the same for all of us. Kenny Moore, marathoner and writer

The body does not want you to do this.  As you run, it tells you to stop but the mind must be strong.  You always go too far for your body.  You must handle the pain with strategy...It is not age; it is not diet.  It is the will to succeed. Jaqueline Gareau, 1980 Boston Marathon champ