Download physiological responses to physical activity

PHYSIOLOGICAL
RESPONSES TO PHYSICAL
ACTIVITY
VCE PHYSICAL EDUCATION
UNIT
3.
FOODS, FUELS AND
ENERGY SYSTEMS
FOOD FUELS
Our food intake consists of three basic nutrients:
CARBOHYDRATES
FAT
PROTEIN
CARBOHYDRATES
CARBOHYDRATES
ARE THE
BODY’S PREFERRED FUEL
SOURCE, ESPECIALLY DURING
EXERCISE
SUGARS AND STARCHES
SOURCES: FRUIT, CEREAL,
BREAD,PASTA, VEGETABLES.
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.
PROTEIN
PROTEINS
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 FUEL
Food Fuel
Stored as
Carbohydrates Glycogen
Fat
Protein
Site(s)
Recommended
daily proportions
%
Muscles and 55-60%
liver
Fatty Acids are Adipose tissue 25-30%
stored as
Muscles
triglycerides
Protein or
Muscles
10-15%
enzymes
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
 ADENOSINE
ADENOSINE
ADP + P+P+PI
P
P
P
P
P
PI
ENERGY FOR
MOVEMENT
THREE ENERGY SYSTEMS
 ANAEROBIC
SYSTEMS-WITHOUT OXYGEN
ATP-PC / ALACTACID SYSTEM
LACTIC ACID /ANAEROBIC GLYCOLYSIS
 AEROBIC
SYSTEM – WITH OXYGEN
AEROBIC SYSTEM / AEROBIC GLYCOLYSIS
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.
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 VALUES
A
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.