show #1202

David trains for an Arctic expedition with explorer Will Steger. Segment length: 26:40

Contents

Insights & Connections


Vocabulary


Resources


Main activity


Try this

INSIGHTS & CONNECTIONS

Day in, day out, Arctic explorers and their sled dogs perform fantastic feats of endurance and strength. They maneuver sleds that can weigh more than 500 kilograms (1,100 pounds) each across harsh, unforgiving terrain. On the move almost constantly--as much as 12 hours a day--the human explorers can burn up as much energy every day as someone running a marathon.

Will Steger and members of his team will each burn 4,000 to 6,000 calories daily--the amount found in 70 slices of bread! To maintain their energy they must eat more than two pounds of food a day. However, what these explorers eat is as important as how much they eat. Their ability to perform and think clearly depends on proper diet. If nutrition and energy needs are not met, an explorer can suffer fatigue syndrome, a condition that causes dizziness and violent mood swings. Expedition members plan carefully to make sure they have enough of the right food to last the entire trip--for both people and dogs.

Explorers also need water for drinking and food preparation. Dehydration is a danger during their long hours of physical exertion. Although snow is the most abundant source of water, it must be melted--a process that takes time and burns valuable fuel.

An endurance diet can provide the energy and nutrients necessary for peak performance in the Arctic. In the past, such diets contained 35% of calories from fat. That's because fat is a concentrated energy source that supplies nine calories per gram. Carbohydrates and protein, on the other hand, provide four calories per gram each.

But consuming fat does not allow the body quick access to calories. Current thinking favors a diet low in fat and high in carbohydrates. Carbohydrates supply large amounts of the sugar glucose. They can be stored in muscles and in the liver as a compound called glycogen, which quickly converts to sugar when needed, providing ready energy for exerting muscles. The Steger team will consume a diet in which 61% of calories come from carbohydrates and 26% from fat. They'll eat rice, pasta, and many grains and supplement those foods with products specifically designed for muscle recovery after strenuous exercise. On days of rest, the explorers will stock up on carbohydrates to replenish their muscle reserves of glycogen.

A carbohydrate-rich diet does have drawbacks. Because it takes about twice the amount of carbohydrates to provide the same number of calories found in fat, the sleds must carry heavier loads. The explorers also must prepare more food and eat more often to refuel their bodies, requiring additional time and cooking fuel.

VOCABULARY

calorie a unit of heat that is also used as a measurement of energy in food

carbohydrates three classes of components that include sugars, starches, and cellulose found in such foods as fruit, vegetables, milk, and grains

endurance diet a diet with concentrated amounts of nutrients and calories that fuel an athlete's muscles and brain during rigorous exercise

fat a more concentrated source of energy than carbohydrates. The body can store unlimited amounts of fat, but it takes more time to turn it into energy than to access energy in glycogen stored in muscles.

fatigue syndrome a condition in which the body can't meet the energy needs of its muscles and brain

glycogen a carbohydrate stored in muscles and liver which converts to the sugar glucose as muscles work, providing quick energy

protein a class of components found in foods and made of amino acids. Protein helps muscles grow and repair and it provides energy and heat.

RESOURCES

Additional sources of information

Arctic Institute of North America
The University of Calgary
2500 University Drive NW
Calgary, AB  Canada T2N 1N4
(403) 220-7515

International Federation of Sled Dog Sports
Glenda Walling, President
7118 N. Beehive Road
Pocatello, ID  83201
(208) 232-5130

Community resources

Nutritionist or dietitian

Specialist at a sports medicine clinic

Marathon runner

MAIN ACTIVITY

Maybe you've heard the saying "You are what you eat." Each food you eat provides its own set of nutrients and calories. Every day you need to restock certain nutrients that your body uses as it moves, digests, thinks, grows, and repairs itself. By reading nutrition labels on food packages, you can learn more about what you're eating and what you need to help your body do its work.

Materials

  1. For one week, collect nutrition labels from different foods you eat. (Look on packages of cereal, yogurt, snacks, and frozen vegetables, for example.) Cut out the labels and bring them to school to share with others.
  2. Read and discuss the labels. Include in the discussion what the foods contribute in calories and nutrients. How much does the food weigh in the amount you normally eat at one meal? What foods provide a wide combination of nutrients?
  3. Figure out how much of the different foods would be required to make up the 4,000 to 6,000 calories an explorer needs each day. Compare the percentages of a person's daily nutrients that are supplied by each food.
  4. New requirements for food label information went into effect in May 1994, adding details in terms of "percent daily values" (%DV). Calculations are based on a 2,000-calorie diet, determining what percentage of your body's daily needs are provided by the food. Some labels also provide additional information on these values. Discuss how you can use this information to improve your food choices.
  5. Make a list of foods an explorer could take along for a seven-day trip. Consider the practicality of taking each food on a skiing or camping trip.

Questions

  1. Explorers need up to 6,000 calories a day, or 42,000 calories a week. How much would 42,000 calories worth of food weigh?
  2. How would you handle foods that need refrigeration on a camping trip? What kinds of food would simply be too heavy to take?

TRY THIS!

Discuss what happens when someone experiences fatigue syndrome and what can cause it. Identify ways to prevent fatigue syndrome.

TRY THIS!

Track your activities for three days and record how long you did each activity. Estimate the amount of energy you used each day. Figure your base caloric needs first and then add the calories needed for each activity to calculate the total calories expended. Compare this number with your caloric intake.

TRY THIS!

Discuss the route food, calories, and nutrients take through the digestive tract. Where does food go after you swallow it and it enters your stomach? Discuss what contributes to a meal's digestion, such as enzymes in saliva and the stomach's actions, called peristalsis. Analyze a meal to learn what nutrients the foods supply.

TRY THIS!

Will Steger and his team will fill out food records during their Arctic trek. For three days, make a list of everything you eat. Review the list with your classmates. Did you get enough calories and nutrition? Which did you eat most--fat, protein, or carbohydrates?
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