PHYSIOLOGICAL RESPONSES TO PHYSICAL ACTIVITY

VCE PHYSICAL EDUCATIONUNIT 3.

FOODS, FUELS AND ENERGY SYSTEMS

FOOD FUELSOur food intake consists of three basic nutrients:

CARBOHYDRATESFATPROTEIN

CARBOHYDRATESCARBOHYDRATES ARE THE

BODY’S PREFERRED FUEL SOURCE, ESPECIALLY DURING EXERCISE

SUGARS AND STARCHES SOURCES: FRUIT, CEREAL,

BREAD,PASTA, VEGETABLES.

.

FATACTS 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.

PROTEINPROTEINS MAKE A NEGLIGABLE

CONTRIBUTION TO ENERGY PRODUCTION DURING EXERCISE.

MAINLY USED FOR GROWTH AND REPAIR.

SOURCES: MEAT, FISH, POULTRY, LEGUMES, EGGS, GRAINS

STORAGE OF FOOD FUELFood Fuel Stored as Site(s) Recommended

daily proportions %

Carbohydrates Glycogen Muscles and liver

55-60%

Fat Fatty Acids are stored as triglycerides

Adipose tissueMuscles

25-30%

Protein Protein or enzymes

Muscles 10-15%

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.

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.

ATP ADP + P+P+PI

ADENOSINE P P PI

ADENOSINE P P P

ENERGY FOR MOVEMENT

THREE ENERGY SYSTEMS

ANAEROBIC SYSTEMS-WITHOUT OXYGEN

ATP-PC / ALACTACID SYSTEMLACTIC ACID /ANAEROBIC GLYCOLYSIS

AEROBIC SYSTEM – WITH OXYGEN

AEROBIC SYSTEM / AEROBIC GLYCOLYSIS

FOOD FUELS AT RESTFAT 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.

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.

GLYCEMIC INDEX (GI)

THE GLYCEMIC INDEX IS A WAY OF CLASSIFYINNG

CARBOHYDRATES BY THEIR IMMEDIATE EFFECT ON

BLOOD GLUCOSE LEVELS.

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.

GLYCEMIC RESPONSE

EXAMPLES OF GI VALUESA low GI value is 55 or less (bananas,

grain bread, lentils, apples, porridge, spaghetti)

A medium GI value is 56-69 (white bread, mars bar, rye bread, ice cream)

A high GI value is 70 or more (glucose, mashed potato, white rice, doughnut, cornflakes)

GLYCEMIC INDEX AND EXERCISE

BEFORE EXERCISE – Low GI carbohydrates should be consumed 45-60 minutes before

exercise. These are recommended as they sustain blood glucose levels

minimising any increases in insulin release.