Learning to control your pre-race concentration is absolutely KEY to your swimming loose and fast under pressure! The heart of staying calm and composed pre-event comes from learning to use a set pre-race ritual in order to distract yourself from all of the distractions that could potentially get you too nervous to swim your best.
Here's how it works:
If you notice you're starting to get too anxious when you get behind the blocks, first take a mental note about how nervous you are on a scale of zero to ten. (Zero being that you're totally chill and 10 being that you're freaking out). Shift your concentration to making a fist with either hand. Bring the tension in that hand and up and down your arm to about 90% of your strength and be sure that you place all your attention on the feeling of tension up and down your arm. Hold the tension for about 5 seconds and then deliberately and slowly allow that tension to diminish as you loosen your hand and arm. As you do this, be sure you keep your focus entirely on the feelings of your wrist and arm loosening up. Focus on this loosening up for about 5 seconds.
Next, repeat this same process, tightening your wrist and arm for 5 seconds, and then loosening for that same amount of time, focusing closely on the FEEL of first the tension and then the looseness in your hand and arm. Then check in with yourself to see if your nervousness “score,” (0 – 10) has changed in any way. Whether it's come down a bit or stayed the same, if you have time, repeat this same process for one or two more cycles of tightening and loosening, being sure that all of your concentration is on the feel of what you're doing and NOT on any thoughts that may be-bopping around between your ears.
Don't worry if you notice these kinds of thoughts. They're perfectly normal. Just be sure that when they do pop up and try to get your attention, you immediately direct all your focus back to the feel of what you're doing.
By deliberately tightening and loosening your fist whenever you're anxious pre-race, you'll find that with enough practice, you'll get quite skilled at calming your nervous system down right before you get up on the blocks! However, keep in mind that to enable this technique to really work for you, you must practice it regularly on your own, long before you get to that meet. Sufficient practice will enable this skill to get into your “muscle memory” and thus be much more effective when it's race time and you're feeling nervous!
Credit to Dr. Alan Goldberg (usaswimming.org)