"I am racing tomorrow, what should I eat today for optimal performance?". It amazes me as sports nutritionist how many times I get asked this question. It may seem like there is a simple answer, however, race day nutrition does not start and end on race day. Athletes could get close to metabolizing 500 calories per hour during an intense race, yet the physical capacity for quick absorption to fuel this amount is limited, particularly when the body has not been trained to do so. Furthermore, the practicality of providing this amount "on the go" poses a challenge. In addition to a well balanced diet leading up to race day, some scientifically formulated recommendations and logical solutions to practicality offered here, could enable optimal performance. Race day nutrition can be mastered, just like the body can be trained to endure.

CARBOHYDRATES-- the preferred source of fuel

The human body oxidizes carbohydrates at a rate of 0.5g -- 1.0g per minute. Thus at an average intensity, a maximum of 60g of carbs per hour is recommended. Many athletes are able to train their bodies for more and can get 100g carbs / hour. Although it may not be necessary to absorb this extreme amount, for many Ironman athletes, it may offer a peace of mind that "bonking" or "hitting the wall" is possible to prevent. My recommendation is to strive for moderation, taking into consideration, the distance and perceived intensity of your race. If 45 -- 75g carbohydrates per hour, broken down into 2 or 3 doses at 15 -- 30 min intervals is consistently tolerated during training days, progressive increments are certainly possible towards race day. A general rule for individualizing carbohydrate intake is 1g per kg body weight per hour (70 kg athlete needs 70 g of carbohydrates per hour).

Although this may be a simple calculation, to strive towards, it is necessary however, to practice during training sessions and progress appropriately. The exponential advancement in sports nutrition products, provides a plethora of texture, flavour, and formulas to choose from. Solids, gels, and liquids are all effective, but individual tolerance of certain foods as well as quantity may vary per session. Furthermore, most sports products often require water to aid with digestion. For every 15g of carbs, 8 oz of water is recommended. It may be difficult to digest nutrients at an increased intensity, therefore as a safety net, eat at least 0.5 g of carbs per kilogram of body weight within two hours before the race.

FATS -- reserve tank of fuel

Although fats are vital for physical activity, most individuals, including athletes, have enough body fat stored for energy during prolonged workouts. An increase in fat consumption may result in less consumption of carbohydrates which would impede glycogen stores (glycogen being the immediate source of fuel for physical activity). Furthermore, fats does tend to slow down metabolism. Consider fats as the reserve tank of fuel, and keep them to a minimum during training and racing.

PROTEIN -- muscle repairing supply

Protein, in itself does not provide energy unless glycogen and fat are depleted. Protein, like fat, also slows metabolism, however, minimal protein on race day is appropriate, to reduce muscle damage. If you eat appropriate calories with a variety of high quality proteins (such as whey, egg, whites, milk, soy) as part of your daily intake, you will typically get enough protein for race day.

HYDRATION AND ELECTROLYTES -- water balance supply

Maintaining proper fluid balance is vital for optimal performance. 2 hours before: 8-16oz. of fluid
15 min 0 ½ hour before: 4 -- 8 oz
During: 4 -- 8 oz every 15 -- 20 minutes
Post event: at least 16 oz / 16 -- 24 oz per lb sweat lost*

Drink to replace sweat. Do not over drink. *Sweat lost is the difference in weight before and after the event (weigh with no clothes).

Sodium and potassium are electrolytes which help maintain proper water balance in the body and thus play a major role in effective hydration. These electrolytes are lost in sweat and do need to be replaced. For a general rule, heavy sweaters should consume 500 -- 700 mg sodium and 100 -- 400 mg of potassium per hour. Sports drinks are scientifically formulated for electrolyte replacement and simultaneously provide hydration options. For a variety of texture and taste salty foods, salt tablets, extra sodium gels, Gatorade EnduranceT, bananas and pretzels are easy and convenient "on the run".

FIBER To prevent gastrointestinal distress, keep fiber to a minimum. Fiber is difficult to digest, especially during high intensity.

BEST CHOICE OF FOODS Thus, to bring all the recommendations together, best choice of race day nutrition would incorporate foods that are ultra low in fat, low in protein, low in fiber, and high in carbs? • Powerbar : 41g carbs, 2.4g fat, 9g protein
• Banana : 36g carbs, lower in fiber than other fruit, high in electrolytes, 0 g fat (perfect)
• White bread/bagel -- high glycemic index -- great for glycogen-sparing, 12 g carb per slice, minimal protein and fiber.
• Specially formulated bars (eg. marathon bar): some bars are higher in fat, but great tasting treats help maintain motivation.

Utilize your long training runs to put your race day plan into practice. Do in practice exactly what you hope to do on race day. Monitor each stage of a long training run, log how your energy feels, any gastrointestinal distress, thirst, hunger, etc. Fine-tune your approach by making adjustments one step at a time and then test any necessary tweaks during training. Just like physical training, your metabolism too, needs adequate time formulate a regimen that works for you.

OPTIMAL RECOVERY Recovery nutrition is possibly one of the most important factors for mastering race day performance. After each training session, start with carbs plus some protein as soon as possible after exercise ( a good rule of thumb is 3 or 4 carbs to 1 protein ratio). This will provide the nutrients for replenishing muscle glycogen and for muscle tissue repair to be ready for the next intense session. Within the first hour, and every hour after that (up to 4-- 6 hours), eat 0.75 grams of carbs for every kilogram of body weight. Remember, race day will be one of the "next" intense sessions.

Ilana Katz MS, RD,LD is a sports nutritionist specializing in working with endurance athletes. To learn more about her services, click on the link below.

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