Exercise and Nutrition

Copyright 2010. PEER.tamu.edu

Benefits of Exercise• How do you think exercise

helps your body?• Exercise:

– Helps prevent obesity– Strengthens muscle, bones,

and joints– Reduces mental stress– Makes you feel better, have

more energy– Helps you sleep better at

night

Why Does Exercise Help Prevent People From Getting Overweight?

Exercise makes muscles contract

Energy comes frombreakdown of food

Unused energy is stored as fat

Muscle contractionrequires energy

Muscle Contraction• Muscles have many fibers• Fibers contain protein filaments (thick and thin) that slide past each other.• The sliding is caused by ratchet-like movements of parts of the proteins• The ratchet-like movements consume energy

Do you know what a ratchet-like movement is? Have you ever seen a ratchet wrench? Such wrenches can be set to turn in only one direction because it has a gear-like toothed wheel that grabs only one way when the handle is cranked.

This is what it looks like:

See slide notes on how joints work

Two Kinds of Muscle ActionBoth shorten the fibers, consume energy, and exert force,

but only one shortens the actual muscle

• Isotonic: muscle shortens (as in flexing the biceps)

• Isometric: muscle does not shorten (as in carrying a suitcase)

Review Time

• How does exercise help prevent people from being overweight?

• How do muscles contract?

• What are the two types of muscle action?

Food As The Energy Source• Body uses glucose as its energy source• Food breaks down to glucose, a simple sugar

– table sugar (sucrose) is a compound that has two simple sugars, glucose and fructose

– In plants, glucose is produced by photosynthesis and builds up into proteins and carbohydrates in the plants Oxygen

Hydrogen Carbon

A Molecule of Glucose

Can you tell what the chemical formula for

glucose is from looking at this

diagram?

Producing the Energy From Glucose• Process is called “glycolysis”

(glyco = glucose, lysis = break down)

• Energy is released by enzymes in a chain of reactions that break bonds between atoms in glucose. Bond energy is what is released.

• Energy release occurs in small steps, to reduce loss as heat

Aerobic Metabolism

• Complete breakdown of glucose requires oxygen.

• Vigorous exercise requires lots of energy and lots of oxygen.

• Therefore, vigorous exercise (aerobic exercise) breaks down a lot of glucose that otherwise would be used to build fat.

Calories• Calories are a unit of measurement of

food energy. They measure the amount of potential heat energy contained in the chemical bonds of a food.

• People need a certain amount of calories per day.

• For the average teenage girl, the recommended daily allowance is 2200 calories. The average teenage boy needs 2500-3000 calories.

• See slide note for an activity on measuring calories in foods.

Calories in Foods

• Protein and Carbohydrates contain 4 calories per gram.

• Fat contains 9 calories per gram!

• That's why one food with the same serving size as another may have far more calories.

• A high-fat food has many more calories than a food that's low in fat.

½ cup of ice cream contains 178 calories 2 grams of protein 12 grams of fat and 15.5 grams of carbohydrate

½ cup of carrots contain 36 calories1 gram of protein 0 grams of fat and 8 grams of carbohydrate

Managing EnergyIntake

To maintain weight:•Energy consumed must be EQUAL to energy USED by the body.•Food intake and exercise are in balance.•Make sure food choices are healthy and contain the essential nutrients

Calorie In = Calories Out

To lose weight:•Energy consumed must be LESS than energy USED by the body.•Eat LESS, Exercise MORE•Make sure food choices are low in calories but still contain essential nutrients

Calorie In < Calories Out

Stop and Remember:• What is the energy source for

exercise?• How is this energy source broken

down in the body?• What are calories?• Why do calories in foods differ for

the same portion size?• How should you manage your

energy if you want to lose weight?

Exercise Burns Calories!What Kind of Exercise Would You Choose?

Learn about over 30 kinds of activities, from Ballet to Yoga

Stretch Before and After: Here Are Some Yoga Stretches

Famous Body Builders• Do you know about Charles

Atlas?– He was a weakling who

became a famous body builder by using isometrics

• How about Arnold Schwarzenegger?– A world champion body

builder that became an actor and governor of California.

– He used weight lifting to build his muscles.

http://www.charlesatlas.com/

http://healthruns.com

Aerobic ExerciseModerately intense exercise that improves the

heart and lungs • Can you run four laps around the

track (~ 1 mile)?• Common adult standard of

fitness: run 1.5 miles in 12 minutes.

• Running long distances several times every week is probably a bad idea (too hard on growing joints).– Use low-impact equivalents:

cycling, swimming, stair climbing, cross-country skiing, ice skating.

A Balanced Exercise Program

• Running, cycling, or swimming: both sprints and long distance

• Body building: weight lifting and isometrics

• Intersperse with rest–Example: cycle every

other day, do body-building exercises on the other days.

Ruth Fremson/The New York Times

To Keep You on TrackKeep Track of Your Food and Exercise

• Make a plan (decide the kinds of exercise)• Set goals (such as certain number of

minutes/day)• Mix two or more kinds of exercise during each

week• Keep track. Use this on-line exercise calendar.

Keep a Food Journal• It can be very helpful to keep a written record of the food

you eat each day.• There are many resources to help you keep track of your

daily food choices.Examples:

•http://www.livestrong.com/myplate/

•http://www.my-calorie-counter.com/

•http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/diary.htm

•http://www.personal-nutrition-guide.com/food-diary-template.html

Conclude:• Name 5 different types of

exercise.• What are the two types of

exercises that should be included in a balanced exercise program?

• What is a food journal?• What is one thing from this

lesson that is important to you?