Pre-race jitters are a very common, expected aspect of competition which all athletes experience in varying degrees. The sympathetic nervous system, the part of the body responsible for the symptoms an athlete experiences pre-race, produces adrenalin as one of several hormones released into the bloodstream. The goal of this nervous system activation is to help the body achieve peak performance-it's actually a survival mechanism. Jitters, therefore, are a manifestation of processes occurring in the body that help prepare it for action -- the "fight or flight" response
Some of the specifics of this type of nervous response include improved reflexes, enhanced memory, regulation of blood flow, and a switch to a catabolic state. The latter causes fat stores and liver glycogen to be broken down. This insures a steady stream of fuel -- fatty acids and glucose, respectively -- for the heart, muscles, and vital organs.
The downside of too much activation of your nerves is that it causes a series of annoying symptoms. Diarrhea, intestinal cramping, shakes, sweating, palpitations, nervousness and irritability are some of the distractions that an athlete may face. Sometimes these symptoms become so great that they go beyond the nuisance stage and performance suffers.
Thus, since some degree of nervous activation is important to race well but too much causes a decrease in performance, the goal is to reach a middle ground. A middle ground will maximize performance yet keep the adverse symptoms to a minimum. How do you find that sweet spot? There are mechanisms athletes can use to regulate the degree of nervousness - and there are some things to avoid as well -- and these are vital to achieving consistent, high performance.
Establish a routine. The race day routine starts when you wake up, ending when the gun goes off. You should determine how many hours before the race you need to get up to accomplish all of the steps in your routine. A few of the components in the routine are calorie intake, fluids, travel time to race location, warm-up, stretching, equipment check, mental exercises, etc.... Some components will vary depending upon the type and length of the race, but the basic framework remains constant. Every race is different, but developing a consistent routine provides a familiar base from which to launch your race. It also gives you confidence that you are ready to race. Don't be convinced by family members or other runners to change your routine once you've established it.
Mental exercises. You will often see top athletes close their eyes and engage in seemingly strange behavior, appearing either catatonic or moving to some unseen rhythm. The latter is especially evident in downhill skiers, who sway and gyrate. They are rehearsing all the elements required in the race. This mental imagery helps you focus and plan each stage of your race. This takes the over-energized concept of "GO FAST, WIN", and changes it into a series of calmly planned and executed steps. Sometimes music is useful but it must not be distracting nor result in the wrong mood.
Breathing exercises and progressive muscular relaxation are other techniques that can alter your level of nervousness and reduce unwanted muscular tension.
Body monitoring. Look for, and pay attention to, the signals your body provides. This will give you feedback as to the state of your nerves. Pulse rate, respiration rate, sweat rate, tremor and other clues give you a way to see where you are, and how effective your modulating techniques are.
Diet and Drugs.
Avoid fiber rich foods in the two days leading up to a race. The extra ‘bulk' in the intestines means cramping and diarrhea will be worse.
Avoid anti-inflammatory medications (e.g., ibuprofen) since these can result in intestinal cramps and diarrhea.
Avoid protein/ fat rich foods for breakfast on race day.
Avoid excess alcohol consumption. One 12 oz. beer before bed is unlikely to hurt you, but six will definitely make your guts and brain very unhappy on race day.
Be careful of caffeine. Some athletes use caffeine as a performance aid, but too much can definitely cause intestinal cramping and diarrhea, and contribute to nervousness and rapid pulse.
Stay away from stimulants. Not only are decongestants banned, but they may have considerable neurological (e.g., anxiety) and cardiovascular (e.g., rapid pulse) side effects.
Avoid over-the-counter antihistamines for 24 hours before the race since their sedating effects may carry over. Also some people get a paradoxical reaction and get too hyped up.