Four Critical Periods for Training for an Endurance Event

By Barbara Day, M.S., R.D., C.N.


There are four critical periods when you are training for an endurance event like a half marathon, marathon, or an ultramarathon.

These include:

1. Your daily training diet.

2. What you eat and drink before daily exercise and before the event.

3. What you eat and drink during long training bouts and the event.

4. What you eat and drink after your daily training and after the endurance event.

Your Daily Training Diet

  1. Calories

Knowing how many calories you need each day will help keep you energized while you are training for your event and doing all the things you need to do each day: work, manage a family, take care our your home.  There are some FREE apps that you can use to help to determine how many calories you need each day. If you eat too few calories and continue to up your miles, you may find you are losing weight which might be your goal but you may also battle with fatigue and then ultimately an injury or an immune related illness.

The Lose It! FREE App for I-Phone or Droid or,  or My Fitness Pal app will help you to determine how many calories you need each day.  In addition, these apps can help you determine how many calories you are burning during the time you are being very active as well.

An Alternative Method of Determining How Many Calories You Burn During Activity

The other method of determining your activity is just to look at a particular definition and pick what activity category that you think you belong in and multiply your resting metabolic rate.  Some people tend to over estimate or under estimate their activity.  See the categories below.

Activity Category

Very Light which consists of: seated and standing activities, painting trades, driving, laboratory work, typing, sewing, ironing, cooking, playing cards, playing a musical instrument, and no regular exercise.

Light which includes walking on a level surface at 2.5 to 3 mph, garage work, electrical trades, carpentry, restaurant trades, house-cleaning, child care, golf, sailing, table tennis and some regular exercise.

Moderate which includes walking/running 3.5 to 4 mph, weeding and hoeing, carrying a load, cycling, skiing, tennis, dancing and regular exercise 3 to 4 times per week — 30 to 40 minutes in duration.

Heavy which includes walking with a load uphill, tree  felling, heavy manual digging, basketball, climbing, football, soccer, wrestling and  regular exercise 4 times per week 40 minutes or more in duration.

Very heavy activity includes training for athletic competition, distance running or regular exercise 5 times per week for at least I hour in duration.

Then, multiply your ACTIVITY CATEGORY times your RMR to get your daily energy needs.

Women                            Men

Very Light Activity =      1.3 X RMR             1.3 X RMR

Light Activity       =        1.5 X RMR             1.6 X RMR

Moderate Activity   =      1.6 X RMR             1.7 X RMR

Heavy Activity      =        1.9 X RMR             2.1 X RMR

Very Heavy Activity =     2.2 X RMR             2.4 X RMR

RMR X ACTIVITY CATEGORY = caloric expenditure per day                                


EXAMPLE:   1300 X 1.6 (moderate activity)  = 2080  calories per day for the a women who weighs 130 pounds. The women works out at least 4 days a week for at least 105 minutes running, weight training and doing yoga.  As you can see there’s a  difference in the caloric expenditures if you use an app based on the exact exercise rather than using the formula mentioned above.  ( 1978 calories vs. 2080 calories with a difference of  102 calories).

 Once you determine how many calories you need each day, the timing of  your food intake is also important. Eating  5 – 6 times per day will help give you bullets of energy but keeping the calories in line with your overall calorie needs is required. Never skip breakfast. Eat or drink something  before early morning workouts to get the most effective workout.

  1. How Much Fluid do you Need to Consume Daily?

Once you determine how many calories you need each day, you can determine how much fluid you need each day.

Fluid Needs = Total calories/30 = how many approximate ounces you need per day.  Example of your goal: 2000 calories/30 = 66.6 ounces of fluid each day.

But you should drink until your urine is pale to clear, if not drink more fluids. You first void of the morning will be yellow but as the day goes your urine should be pale to clear. When exercising in the heat, weight yourself before you workout, then weigh yourself after and drink 16 to 24 ounces of fluid for every pound you have lost.

  1. 3.  Carbohydrates: the Athletes Nutrient

Carbohydrate (CHO) has three main functions in the body.  It provides fuel for the body, dietary fiber, plus a source vitamins and minerals.  CHO is the body’s preferred source of energy and is used to replenish muscle glycogen.  The CHO you eat has two fates:  it will be either burned for energy or it will be stored for future use in the form of muscle glycogen or liver glycogen. CHOs contain only 4 calories per gram.  CHOs are not fattening unless eaten in excessive amounts but can be filling (particularly the complex CHOs that contain a lot of dietary fiber). Recommended CHOs are whole grains like oatmeal, brown rice, quinoa, fruits, vegetables, etc. Read the food label to determine how many grams of carbohydrate is included in each food.

How much and where Dietary CHO is stored

During exercise, [blood] glucose and [muscle and liver] glycogen supply energy to the working muscles. A diet rich in complex carbohydrates will increase glycogen stores and endurance.  Carbohydrates get stored in your blood, muscles and liver in varying amounts.

One of the limiting factors in your performance will be the amount of muscle energy available.  The best way to load up your muscles with energy is by what you put in your mouth!  A proper performance diet can prevent the cumulative effects of muscle glycogen depletion occurs as you increase your mileage. Complex carbohydrates are preferable to simple carbohydrates because they are easily digested, providing a slow, steady supply of glucose to your body.  At the same time, complex carbohydrates contribute other essential nutrients such as vitamins and minerals needed for energy metabolism.

Daily Carbohydrate Recommendations for Athletes

●        2.27 – 3.18 g of CHO/lb/day: athletes engaging in moderate-intensity exercise for 60 to 90 minutes per day.

●        3.18 – 5.45 g of CHO/lb/day: athletes engaging in moderate-to-high intensity endurance for one to three hours.

●        4.55 – 5.45 g of CHO/lb/day: athletes participating in extreme endurance exercise for four to six hours per day (e.g. Tour de France, IronMan)


  1. 4.  Protein:  Builds and Repairs Muscles for Tip Top Performance


Protein is important for growth and development, required for healing injuries, and necessary for the maintenance of body tissues. As our body grows, it uses protein to manufacture cells.  For example, the protein, collagen, serves as both building and mending material in tissues such as ligaments and tendons.  Enzymes, hormones, and antibodies are synthesized from protein.   Proteins within each cell are also constantly turning over – being made and being broken down. Protein is composed of individual amino acids strung together in chains. The constant synthesis and breaking down of protein is known as protein turnover. When protein breaks down, they free amino acids to join the general circulation.  Some are recycled into other proteins; others may be stripped of their nitrogen and used for energy.  Protein provides 4 calories per gram. Although protein is not a major source of energy, an active person needs for protein may be slightly higher than the needs of a sedentary person.


So how much protein do you need each day? 


You do need to consume an adequate amount of protein for good health. Use Table 1 to determine your daily protein needs. Unlike fat and carbohydrate, protein contains nitrogen.  The body strives for a perfect nitrogen balance and when too much nitrogen is available in the body, it needs to be excreted. When you eat too much protein, your kidneys need more water to eliminate the extra nitrogen from the excess protein consumed in order to maintain nitrogen balance. Therefore, weight loss from a high protein diet tends to be due to a water loss rather than a decrease in body fat.

Table 1. Determining Your Protein Needs


Grams of Protein per pound of body weight


Sedentary Adult                                                 0.4

Recreational exerciser, adult                               0.5 – 0.7

Endurance adult                                                  0.6 – 0.7

Growing Athlete, teen age – 24 years                    0.7 – 0.9

Adult Building Muscle Mass                                  0.7 – 0.8

(weight/strength training)

Adult restricting calories                                                0.8 – 0.9

Estimated upper requirement for adults                0.9

SOURCE: Combination from American College of Sports Medicine, American Dietetic Association, Dietitians of Canada Joint Position Paper Statement Nutrition and Athletic Performance, Medicine and Sciences in Sports & Exercise 32 (12): 2130 – 2145, 2000.  R. Maughan & L. Burke, editors.  Sports Nutrition (part of the Handbook of Sports Medicine & Science series, an IOC Medical Commission Publication).  Malden, MA: Blackwell Publishing, 2002; Institute of Medicine.  Dietary Reference for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids.  Food and Nutrition Board, Washington, DC: National Academy Press, 2002.


Example 1:         * 120 pound athletic woman who is an “active adult”

120 lb X 0.6 g/lb = 72 grams of protein needed/day


Example 2:         * 170-pound sedentary adult

170 lb X 0.4 g/lb = 68 grams of protein needed/day

The best way to find out how many grams of protein a food contains is to read the NUTRITION FACTS on the food label. Remember to look at the serving size on the label and compare it to the amount in your actual serving.

  • A small 3-ounce piece of meat  about the size of a deck of cards after cooking has about 21 grams of protein. A typical 8-ounce piece of meat could have over 50 grams of protein.
  • One 8-ounce container of yogurt has about 11 grams of protein.
  • One cup of milk has 8 grams of protein.
  • One cup of dry beans has about 16 grams of protein.

3 Days Before Endurance Event – ½ Marathon

CHO         3.86 grams per pound per day

Fluids       at least 3 grams of water/gram of CHO to ensure adequate hydration during loading phase.  You will gain weight but it is a transient weight gain. Poor hydration may increase muscle damage.

              Example, 3.86 X 150# = 579 grams of CHO.  579 X 3 = 1737/30 = 57.9 oz.   at least 57.9 ounces per day but drink until urine is clear.


Calories     200 – 600 calories depending on how long you eat before event.

CHO         .5 – 1.8 grams per pound 1 to 4 hours before event.  CHO amount depends on when you eat your pre-event meal.

Timing              1 to 4 hours before event.

Fluids       2 – 3 cups (16 – 24 oz) 2 – 3 hours before exercise, then another 8 – 10 oz 30 minutes before exercise, make sure to reserve time before the event for a bathroom stop.

During Events lasting longer than 60 minutes

CHO         30 – 60 grams of CHO per hour; sports drinks, gels, sport jelly beans, bananas, etc. (.45 – .68 grams of CHO/pound)

Fluids       8 – 10 oz every 15 – 30 minutes . One gulp is about 1 oz. Use planned water stops or use a fanny pack that carries a water bottle. A 20-oz water bottle if filled with a sports drink can supply 35 – 50 grams of CHO and 140 – 200 calories. 6 – 8% CHO optimal sports drink; 14 – 19 g CHO/8 oz.

              Examples – Gatorade, Powerade. Accelerade, Endura, etc.


CHO         .5 to .75 grams per pound within 15 to 30 minutes post exercise

Protein      For every 4 grams of CHO eat 1 gram of protein. (chocolate milk)

              (3:1 ratio CHO to PRO = replenishment of glycogen & rebuild muscles)

Timing       Eat and drink 15 minutes to 30 minutes post exercise.

Fluids       Drink at least 20 – 24 oz for every pound of weight loss to rehydrate.  Weigh before and after exercise to estimate water loss.  Drink until urine is clear.


  • Energy bars, gels and drinks can boost calorie intake.
  • Find an energy gel, beans or bloks that you like to eat, and try it during training before the competition. Never try anything new during a competition.
  • If you use gels, beans or bloks, remember they are concentrated CHOs and should be washed down with at least 8 oz of water (DO NOT sports drink – sport drinks immediately following a gel may cause nausea).
  • For running events like a ½ marathon or longer, take alternate water and sports drink at beverage stations to prevent hyponatremia (low blood sodium).


Nancy’s Clark’s Food Guide for New Runners.  Nancy Clark, M.S., R.D. $16.95.  ISBN 978-1-84126-262-8. 2009.


Fueling Your Early Morning Workouts

Training for early morning workouts on an empty stomach does not improve performance and the quality of your training may actually suffer. You wouldn’t consider driving your car from Louisville to Jasper on empty, so why train on empty? It can cause you to run out of gas. After an 8-to-10-hour overnight fast, about 80% of your liver glycogen (not muscle glycogen) is depleted, so you would start exercising with depleted carbohydrate stores. In these conditions, your body converts protein to carbohydrate in order to maintain adequate blood sugar levels.

Your early-morning meal should be primarily carbohydrate, with a touch of protein to help you feel a little more full and satisfied. Keep the meal around 300 calories or less.  Use the food label as a guide. Some people might be able to eat more or need to eat less – it’s very individualized. But be wise and eat or drink something.  You body will thank you by helping you to get the most out of your workout.

The meals recommended below will also work to get you through most morning workouts that last for less than 90 minutes, especially if you take some carbohydrate to eat during the training session. If your morning workout is going to be over two hours, wake up early enough to eat a more substantial breakfast between 90 and 120 minutes before training. (I drink carnation instant breakfast with skim milk & run in an hour).

Pre-run Meals 30 – 60 minutes before your morning run; 300 or less calories

* Carnation Instant Breakfast mixed with skim milk

* Low-Fat Yogurt plus 8 oz of water, sport drink or diluted juice.

* Breakfast Bar or Energy Bar that contains 3 to 4 times as many carbs as protein plus 8 oz water.

* 1 slice of Toast with 1 tbsp jam, jelly or honey (skip the butter) plus 8 oz water or sport drink.

* Multi grain bagel with 1 tbsp peanut butter or other nut butter plus 8 oz water or sports drink.

* 1 large banana plus 8 ounces of sport drink or diluted juice.


Recovery Foods & Meals

* Chocolate milk plus a container of yogurt.

* 1 Can of Carnation Instant Breakfast, Boost, or Ensure.

* Cereal with milk.

* Turkey on a baguette.

* Chicken dinner with brown rice and vegetables.

* Spaghetti with meat sauce.

* Pasta with vegetables.

Sunshine Smoothie

8 oz plain or vanilla yogurt, ½ cup skim milk, ½ cup orange juice 8 ice cubes plus 1 tbsp of honey, sugar, or sweetener. Blend until smooth and frothy.

Banana Smoothie

8 oz plain or vanilla yogurt, ½ cup skim milk, 1 banana 8 ice cubes plus 1 tbsp of honey, sugar, or sweetener. (you can also add blueberries, etc for extra fruit) Blend until smooth and frothy. Frozen berries work well. Use less ice cubes if using frozen fruit.

Crunchy Yogurt

1 contain of yogurt with ¼ cup Kashi Mountain Medley Granola (cranberries, raisins, almonds, pecans, and sunflower seeds). Drink 8 oz water or sports drink.

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Barbara Day, M.S., R.D., C.N., is a registered dietitian with a Master’s Degree in clinical nutrition.  The former publisher of Kentuckiana HealthFitness Magazine, Kentuckiana Healthy Woman magazine and radio show host of Health News You Can Use, Barbara has over 30 years of experience in promoting healthy lifestyles to consumers.  Barbara worked as Nutrition Consultant to the Navy SEALs (8 years) and the University of Louisville Athletic Department (10 years). Barbara has private practice, DayByDay Nutrition,, where she counsels clients on weight loss, cholesterol management, performance nutrition and an array of other medical issues.  Visit Barbara’s new website which is an on-line health & wellness magazine, Barbara writes nutrition and health columns for as well as a weekly nutrition column for the Southeast Outlook. She also designs and presents employee wellness programs to small and large businesses. Barbara is a runner, cyclist, hiker and a mother and grandmother to 12 grandchildren.    

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