How nutrition can optimize your performance

By Dave Scott

This report filed December 4, 2002

Diet is often one of the most overlooked ingredients in the formula for optimal performance. Finding the right mix of food and fluid in your training will alleviate much nutritional guesswork on race day. The daunting selection of fluid replacement drinks (FRD), bars, gels and self-proclaimed super foods is overwhelming. Nonetheless, one simple fact has not changed over the past 20 years - food by itself does not make you go faster. It simply allows your body to perform at its peak level for the longest period of time. By selecting optimal foods you will train more consistently and race more effectively.

Fuels for training
As we begin to exercise, the body uses carbohydrate to fuel the muscles. The carbohydrates are broken down into a sugar - primarily glucose, which is the substance used by the muscles, liver and other organs. Your fitness level, the length of your exercise session, intensity of your workout and the environmental conditions collectively determine how much and what type of fuel will be utilized. Additionally, what you eat prior to and during exercise will affect your access to, and the availability and efficiency of, energy metabolism. The following chart will help define the available calories that are potentially utilized during exercise.

A 160-pound person has the following calories available to burn; however, availability depends on fitness level, exercise duration and intensity and feedings before and during exercise.

Blood sugar (glucose) 300-600 calories
Muscle glycogen 1600-2000 calories
Liver glycogen 300-600 calories
Free fatty acids 50,000 calories
Protein 300-800 calories

Your body is always burning blood sugar and, during a workout, initially taps into the muscles' glycogen then, as the session lengthens, liver glycogen. Additionally, the release of free fatty acids (FFA) can provide a nearly unlimited bank of fuel; however, accessing FFA is a more complex physiological process. Amino acids from the breakdown of protein are also an energy substrate during intense and longer sessions. So the ultimate question is: "What, when and how do you eat to maintain the fastest sustained speed for the longest period of time?"

You are what you eat
Rule 1: Eat a higher carbohydrate (CHO) diet (6-7 grams per kilogram of body weight).

For example: 154 pounds/2.2=70kg; 70kg X 6gm = 420 grams of CHO. Additionally, there are approximately 4 calories per each gram of CHO. Thus, 4 cal x 420gm CHO = 1680 cal of CHO per day.

Rule 2: Endurance athletes need more protein (PRO) than a sedentary person. Consume 1.5-2.2 grams of PRO per kg of body weight.

For example: 2gm x 70kg = 140 grams. Protein calories = 4 x 140 = 560 calories.

Rule 3: Eat light to moderate fat calories each day (primarily mono and polyunsaturated fats). Consume .5-.8 grams per kg of body weight per day.

For example: 0.5gm x 70kg = 35 grams. Fat calories = 9 calories per gram x 35 = 315 calories.

The total calories for this individual at 154 pounds or 70 kg = 1680 CHO calories, 560 PRO calories, 315 fat calories or 2555 calories per day. Approximately 60 to 65 percent of calories should be CHO, 15 to 25 percent of calories should be PRO and 15 to 20 of calories should be fat. Intense exercise requires an additional 400 to 800 calories per hour of exercise. Divide your daily calories and allocate 20 to 25 percent for each meal with two or three snacks of 10 to 15 each.

Pre-exercise top-up tips
In the morning, your blood sugar and liver glycogen stores are low. The liver glycogen is primarily "eaten up" by your brain during sleep. Eating a morning meal will not only elevate blood sugar and top off liver glycogen but also will provide nutrients for the remainder of the day. If your workouts are less than an hour, the intensity is light and the outside temperature and humidity comfortable, food is not necessarily required for this session. However, fluids in the form of a sports drink or, at a minimum, water, are necessary.

If the intensity and duration of a workout will be elevated, pre-exercise food and fluids are vital.

Rule 1: Eat between 200-800 calories (an additional 200-700 more if the workout will exceed three hours).

Rule 2: Hydrate upon awakening with 8-16 ounces of water.

Rule 3: If you plan to drink a FRD, it will work well to elevate blood sugar. Ingesting a FRD will stimulate the secretion of the hormone insulin, which facilitates the transport of energy into the muscles. Most FRD are 100 percent CHO. However, consuming protein with the CHO at approximately a 4:1 ratio will synergistically enhance this insulin response. Consume carbohydrate, protein and light to moderate fat for your first meal.

Rule 4: If your training session is late in the day, consume a PRO/CHO snack 30 minutes to two hours before your workout and 8-16 ounces of FRD or water.

Following are some breakfast suggestions to kick-start your training.
1. Bagel, 1 teaspoon peanut butter, 6 oz. skim milk

2. Two waffles, light syrup or jam, banana, whole grain toast, 1 teaspoon margarine

3. Four pancakes, 20 raisins, light syrup, 1 teaspoon margarine, 6 oz. skim milk

4. Soy drink, whole grain toast, banana

5. Cereal, one percent or skim milk, whole grain toast with 1 teaspoon margarine

Here's mine: Ironman Smoothie (850 calories) plus two slices whole grain toast
1 soy drink
1-2 bananas (or substitute 1 cup blueberries)
1 teaspoon peanut butter
1 carrot
2 scoops whey protein isolate
5 ice cubes

Sustaining the burn
The most recent studies indicate that a 4:1 ratio of CHO to PRO is optimal during exercise longer than 60 minutes.

Rule 1: Drink at 10-15 minute intervals. Consume 4 to 8 ounces of 4:1 CHO/PRO mix.

Rule 2: The total calories ingested should be 200 to 500 per hour of exercise. Race day will be slightly higher.

Rule 3: A guideline for consumption during training is 50-60 percent FRD and 40-50 percent solid/semi-solid. Race day is 10-15 percent higher in FRD with a corresponding 10-15 percent decrease in solid/semi-solid. These percentages will vary according to your stomach tolerance.

Rule 4: Do not eat or drink right before your workout. Allow your body to warm up, heart rate to elevate, then begin taking in calories. During a triathlon, wait for a few minutes after exiting the swim before taking in any fluids.

Rule 5: Do not dilute or mix FRD with other fluids or powders. Fruit juices, high protein (+25 percent) or fat-laden snacks will only impair performance.

Rule 6: To access FFA, your body must train for 8-12 weeks with fewer calories and longer sessions. There is a fine line between maintaining your level of exertion and limiting calories. Race day is not the day to experiment by withholding calories.

Fluid loss
Looking at your training partners (assuming they are of comparable weight and fitness) and noting your sweat rates (shirt saturation) during and after exercise will provide a practical means of evaluation. However a more scientific approach is to weigh yourself (naked) before you exercise. Note the fluids/calories you consume during a training session and immediately weigh yourself upon completion. Anything greater than a two-percent loss in body weight can affect your plasma volume. Excessive loss of fluids will elevate your core temperature and increase the muscle glycogen demands.

To fully rehydrate after exercise, the fluid volume lost via sweat, evaporation, heat dissipation and respiration must be replaced at 125 to 150 percent. For every pound of fluid lost, you should drink 20 to 24 ounces of water.

Furthermore, the quantity, quality and total caloric density required by your body will be affected by several additional factors when you train and race. These are:

1. Training background and preparation Building your mileage slowly over the year and incrementally adding intensity will enhance your understanding of your physiology.

2. Weather Hot, humid weather increases calorie and fluid needs. Cold weather will increase urine production.

3. Session intensity Hills, high intensity and long duration all elevate caloric demands. Also, wind on the bike can dramatically increase evaporative losses. Plan accordingly.

4. Clothing Choose wicking, breathable fabrics.

On the rebound: Tips for a speedy recovery
1. There is a 10- to 60-minute post-exercise window at which time you must re-stock. If your exercise session is 60 minutes or longer, this window is critical.

2. Protein and carbohydrates (ideally 4:1 ratio) stimulates insulin response, which raises glycogen storage and enhances muscle repair. Depending upon intensity, fitness level, duration of exercise, previous exercise sessions and food/fluids before and during exercise, you will need between 100 grams of CHO/25 grams of PRO and 200 grams of CHO/50 grams of PRO in this window.

3. A buildup of free radicals will increase muscle soreness and damage. This occurs not only from exercise but additional environmental pollutants and even sunlight exposure. Therefore, antioxidants (Vitamins E, C, Beta Carotene and Selenium) should be included post-exercise. Additionally, with protein catabolism, there is an extra demand on the B Vitamins.

4. As muscle protein is broken down, amino acids and glutamine can expedite and reduce muscle stress. They also work synergistically to enhance the immune system.

5. Continue feedings over the next two hours at approximately 25-50 percent of the volume within the window.

To optimize recovery, select foods that are nutrient dense. Endurance athletes during stressful training sessions will need additional vitamins and minerals along with their food selection. Upper limits in vitamins and minerals have been established to supplement an athlete's diet. Following are my suggestions for vitamin supplementation.

Vitamin E 400 to 1000 IU (If you take anticoagulants, check with your doctor)
Vitamin C 500 to 1500mg split this dosage to 2 x 250mg to 750mg per day
Mixed carotenoids 5000 to 2500 IU
Selenium 200 to 400 Mcg
Alpha-Lipoic Acid 25 to 30 mg (Caution diabetics - may lower blood sugar)
Coenzyme Q10 20 to 30 mg (Avoid if on blood thinners i.e. Coumadin)
N-Acetylcysteine 200 to 500 mg

1. Iron and iron stores should be checked before taking additional iron. Iron should be consumed with B12 and Vitamin C and not within an hour of any calcium food sources.

2. B vitamins, specifically Folic Acid (500 mcg per day), B6 (50 mg per day), B12 (200 mcg per day) should be added to the diet as protein is catabolized in high-intensity or long sessions. Also, vegetarians, anemic athletes or athletes over 50 will need to boost the B12 to 500 mcg per day.

3. If you are a vegetarian, consider taking a zinc supplement - 50 mg every other day.
Planning your meals will give you an edge on your competition. Yes, it's still okay to indulge - have a cup of coffee, drink a few beers or wine - but holding off that late-night pepperoni pizza is advisable. Start now and revamp your diet for the upcoming season.