Assuming this is a PL meet? Here's a bit taken from a Berardi article I read several year back:
NUTRITION LEADING UP TO COMPETITION: TAKE HOME MESSAGES
1) Assuming you're following the Precision Nutrition recommendations, there is usually no need to alter your typical food selections leading up to a competition. Although your food volume may vary, you should simply continue to eat the same way you do at home (or as close to it as possible).
2) If your energy levels are waning during a competitive period and you're competing in shorter distance events, simply increase your total calorie intake. Eat more of each of the macronutrients with each meal leading up to an event rather than more carbohydrates alone.
3) Only when competing in longer duration events should carbohydrate loading be considered. In order to effectively carbohydrate load, simply eat your typical menu (as above), but supplement these meals with additional starchy carbohydrates. Choose nutrient dense, fiber rich selections such as whole grain breads and cereals.
4) Regardless of your event, stay away from single, heaping carbohydrate dinners or heaping carbohydrate pre-race meals. This is not to say avoid carbs. However, 3 huge plates of pasta for dinner or pre-race are not necessary. For sprinters, if you're steadily eating more leading up to your competition (as discussed in #2 above) you'll be fine. For distance competitors, the modest increase in carbohydrate intake during each meal (as discussed in #3 above) will increase muscle glycogen without you having to slam huge carb meals.
5) During the competition day itself, be sure to eat small, frequent, easily digested feedings Ã???Ã??Ã?Â¢?? eating your last meal about 2 hours prior to competing. Be sure to experiment with this as some athletes prefer eating their last meal anywhere from 1-4 hours before competition. In the end, as indicated, the goal of the pre-competition feeding should be to eat a comfortable amount of familiar foods within the few hours prior to competing and stopping the solid food intake far enough in advance of the competition to prevent rebound hypoglycemia and to prevent stomach discomfort.
NUTRITION AND SUPPLEMENTS DURING COMPETITION
Short Duration Competition
Assuming you've followed the ideas above, you should have all the stored muscle energy you'll need leading up to your event. Further, dehydration, electrolyte balance, and blood sugar are not a concern for these events. So you won't need to worry about drinking during your races.
However, to maximize energy system efficiency and CNS performance, here are a few strategies that you might employ to optimize performance.
Be sure you're taking your creatine (3-5g/day) for at least a month before your events. (Although about 50% of the PN athletes take creatine every day). The best kind is called micronized creatine.
At 3-5g/day you're unlikely to carry extra body mass. You will, however, benefit from improved maximal power generation, ATP-PC system power maintenance, a reduction in lactate accumulation at each submaximal workload and a reduction in maximal lactate accumulation at highest workloads.
Caffeine, in doses of 3-6mg/kg (150-300mg for a 50kg individual) taken 30-60 minutes prior to competition, can boost CNS output and fat oxidation, making it a great supplement for both short duration and longer duration competition. These benefits can lead to improved race performance as long as you're not overstimulated.
To this end, it's important to experiment with caffeine during training to figure out your personal response to it. While many individuals have no problems with a few cups of espresso or 1-2 caffeine tablets taken about 30-60 minutes before competition, some individuals become far too nervous, others tend to begin races too fast and burn out early, and others can feel sick to their stomachs with caffeine use. Again, experimenting with dose and time of intake can help eliminate most problems while maximizing benefits.
Tyrosine acts as a precursor to the stimulatory hormones epinephrine and norepinephrine. 3g taken 30-60 minutes before competition (mixed with a carbohydrate/protein sports drink) may boost performance.
Potassium bicarbonate, sodium bicarbonate, sodium citrate and other acid buffers may help boost performance by buffering cellular acidity and prolonging fatigue if taken before competition. This is especially true in events where anaerobic contribution is high and lactic acid concentrations are high.
Be careful with these products though, as they are known to cause gastrointestinal discomfort. Potassium bicarbonate tends to be better in this regard vs. sodium bicarbonate. If you can tolerate these, 15-20g taken 60-90 minutes before competition should be a safe dose. Alternatively, you can take 5g every 30 minutes starting a few hours before the competition. Just be sure to experiment before your major competitions as you want to be sure you can tolerate these buffers.
Recovery Drinks Between Events on the Same Day
Between race heats, sipping a quickly, easily digested protein/carbohydrate drink is recommended. One good strategy is to mix up a big batch of recovery drink and just sip it throughout the day, between heats. If you want to snack on whole food between events, please do. However, large meals slow down digestion and absorption and you want rapid digestion and absorption in order to quickly replenish energy stores; so snack lightly in addition to constantly sipping your recovery drink. You can mix this solution with some ringers lactate solution leading up to your heats (the ringers will help with electrolyte replacement and to potentially buffer more acid).