Anxiety disorders can vary both in type and magnitude. They can also be phobic in nature or generalized. The panic attack which includes the rapid heart beat, sweating, and shortness of breath may or may not be triggered by a specific incident.
What the orginal poster seemed to be refering to is different its performance diminishing anxiety. Anxiety and racing are inextricably woven. In few other sports is your performance so visible, public and clearly measurable. Your not as much individually on the spot in most team sports.
Unfortunately many misjudge the sport to be an assessment of character rather than of training, speed and endurance. "The winner showed more character, wanted it more, more guts, etc., etc. This is nonsense. Also our own self perceptions of being the determined, fast athlete may be also threatened by the race.
Anxiety is exacerbated when one not only stresses about the race but stresses about the anxiety. The first signs of being anxious can start a behavior chaining of increased anxiety and negativity.
Its important to break the change and to be OK with the poor night's sleep or the increase in heart rate or the hand tremble. Keep the thoughts positive !