1. FOODS, FUELS AND ENERGY SYSTEMS
PHYSIOLOGICAL RESPONSES TO PHYSICAL ACTIVITY vce physical education unit 3.
FOODS, FUELS AND ENERGY SYSTEMS

2. CARBOHYDRATES FAT PROTEIN FOOD FUELS
Our food intake consists of three basic nutrients:
CARBOHYDRATES
FAT
PROTEIN

3. CARBOHYDRATES
CARBOHYDRATES ARE THE BODY’S PREFERRED FUEL SOURCE, ESPECIALLY DURING EXERCISE
SUGARS AND STARCHES
SOURCES: FRUIT, CEREAL, BREAD,PASTA, VEGETABLES. .

4. FAT ACTS AS A CONCENTRATED FUEL STORAGE IN MUSCLES.
IT IS THE BODY’S MAIN SOURCE OF FUEL AT REST AND DURING PROLONGED SUBMAXIMAL EXERCISE.
SOURCES: BUTTER, CHEESE, OIL, NUTS, FATTY MEATS.

5. PROTEIN
PROTEINS MAKE A NEGLIGABLE CONTRIBUTION TO ENERGY PRODUCTION DURING EXERCISE.
MAINLY USED FOR GROWTH AND REPAIR.
SOURCES: MEAT, FISH, POULTRY, LEGUMES, EGGS, GRAINS

6. STORAGE OF FOOD FUEL Carbohydrates Glycogen Muscles and liver 55-60%
Stored as
Site(s)
Recommended daily proportions %
Carbohydrates
Glycogen
Muscles and liver
55-60%
Fat
Fatty Acids are stored as triglycerides
Adipose tissue
Muscles
25-30%
Protein
Protein or enzymes
10-15%

7. How does food help us move?
ALL FOODS ARE BROKEN DOWN AND STORED AS CHEMICAL ENERGY.
THIS MUST BE THEN BE CONVERTED TO MECHANICAL ENERGY TO ALLOW MUSCULAR CONTRACTIONS AND MOVEMENT TO OCCUR.

8. ATP – ADENOSINE TRIPHOSPHATE
MOLECULES OF ATP CONSIST OF ATOMS HELD TOGETHER BY BONDS THAT STORE ENERGY.
CHEMICAL ENERGY IS PRODUCED WHEN ATP IS BROKEN DOWN.
ENERGY IS THEN RELEASED TO FUEL ALL PROCESSES WITHIN THE BODY.
ONLY A VERY SMALL AMOUNT OF ATP EXISTS AT THE MUSCLES.

9. ATP ADP + P+P+PI P P P
ADENOSINE
ENERGY FOR MOVEMENT P P PI
ADENOSINE

10. THREE ENERGY SYSTEMS ANAEROBIC SYSTEMS-WITHOUT OXYGEN
ATP-PC / ALACTACID SYSTEM
LACTIC ACID /ANAEROBIC GLYCOLYSIS
AEROBIC SYSTEM – WITH OXYGEN
AEROBIC SYSTEM / AEROBIC GLYCOLYSIS

11. FOOD FUELS AT REST
FAT AND GLYCOGEN ARE THE PREFERRED FUELS UNDER RESTING CONDITIONS.
RESTING CONDITIONS SUPPLY THE HEART, LUNGS AND BLOOD VESSELS WITH SUFFICIENT OXYGEN, AND THEREFORE ATP, TO MEET THE ENERGY REQUIREMENTS.

12. FOOD FUELS DURING EXERCISE
THE INTENSITY AND DURATION OF EXERCISE DETERMINES WHICH ENERGY SYSTEM IS THE MAJOR CONTRIBUTOR GOR ENERGY.
HIGH INTENSITY EXERCISE / ANAEROBIC EXERCISE – FOOD FUEL IS CARBOHYDRATES
LOW INTENSITY EXERCISE / AEROBIC EXERCISE –
CARBOHYDRATES THEN FAT.
PROTEIN AS A FUEL IS ONLY USED IN EXTREME ULTRA LONG DISTANCE EVENTS, SUCH AS MARATHONS/IRONMAN TRIATHLONS.

13. GLYCEMIC INDEX (GI)
THE GLYCEMIC INDEX IS A WAY OF CLASSIFYINNG CARBOHYDRATES BY THEIR IMMEDIATE EFFECT ON BLOOD GLUCOSE LEVELS.

14. GLYCEMIC INDEX
HIGH GLYCEMIC INDEX -
Carbohydrates are rapidly absorbed into the blood stream and have an immediate effect on blood glucose levels.
LOW GLYCEMIC INDEX –
Carbohydrates take a lot longer to break down and be absorbed into the bloodstream, thus having a slower, more sustained effect on blood glucose levels.

15. GLYCEMIC RESPONSE

16. EXAMPLES OF GI VALUES
A low GI value is 55 or less (bananas, grain bread, lentils, apples, porridge, spaghetti)
A medium GI value is (white bread, mars bar, rye bread, ice cream)
A high GI value is 70 or more (glucose, mashed potato, white rice, doughnut, cornflakes)

17. Glycemic index and exercise
BEFORE EXERCISE –
Low GI carbohydrates should be consumed minutes before exercise. These are recommended as they sustain blood glucose levels minimising any increases in insulin release.