This document defines key terms related to physical activity, health, and exercise physiology. It discusses the differences between health and physical fitness, and describes the three main energy systems (ATP-PC, lactic acid, and aerobic) that the body uses to produce energy during exercise. The duration and intensity of exercise determines which energy system is primarily used to resynthesize ATP and fuel muscular activity.

1. Health, EnergyHealth, Energy
Systems, Training andSystems, Training and
ImprovingImproving
PerformancePerformance
Semester 2Semester 2
Term 4Term 4

2. Physical ActivityPhysical Activity
Defined as participation in some sortDefined as participation in some sort
of bodily exercise, either on aof bodily exercise, either on a
recreational or occupational basis.recreational or occupational basis.
PlayPlay
““An enjoyable experience derivedAn enjoyable experience derived
from behaviour which is self-from behaviour which is self-
initiated, tolerant of abilities, andinitiated, tolerant of abilities, and
develops rules spontaneously. Itdevelops rules spontaneously. It
does not have a predetermineddoes not have a predetermined
ending with a victor or reward.”ending with a victor or reward.”
(Singer, 1975)(Singer, 1975)

3. Sport is a human activity that involvesSport is a human activity that involves
“specific organisational and historical“specific organisational and historical
background of rules which define thebackground of rules which define the
object and limit the pattern of humanobject and limit the pattern of human
behaviour; it involves competition orbehaviour; it involves competition or
challenge and a definite outcomechallenge and a definite outcome
primarily determined by physicalprimarily determined by physical
skill.”skill.”
(Singer, 1975)(Singer, 1975)
HealthHealth vs.vs. Physical FitnessPhysical Fitness
Health is a state of complete physical,Health is a state of complete physical,
mental, social and emotionalmental, social and emotional
wellbeing.wellbeing.
Health can be defined asHealth can be defined as TOTALTOTAL
FITNESSFITNESS..

4. Health
Social
Wellbeing
Emotional
Wellbeing
Mental
Wellbeing
Physical
Wellbeing

5. A strong relationship and interactionA strong relationship and interaction
exists between the 4 aspects.exists between the 4 aspects.
Examples.Examples.
Self esteem (Emotional) & BodySelf esteem (Emotional) & Body
image (Physical)image (Physical)
Academic performance (Mental) &Academic performance (Mental) &
Activity levels (Physical)Activity levels (Physical)
Depression (Mental) & ExerciseDepression (Mental) & Exercise
(Physical)(Physical)

6. Physical Fitness can be describedPhysical Fitness can be described
as the ability of the body toas the ability of the body to
function efficiently andfunction efficiently and
effectively allowing an individualeffectively allowing an individual
to perform daily tasks with ease,to perform daily tasks with ease,
leaving enough energy forleaving enough energy for
unexpected emergencies andunexpected emergencies and
active leisure time.active leisure time.
World Health OrganisationWorld Health Organisation
HEALTH relates to the totalHEALTH relates to the total
person,person,
while FITNESS relates to thewhile FITNESS relates to the
physical attributes of a person.physical attributes of a person.

7. INTRODUCTIONINTRODUCTION
Exercise Physiology is the descriptionExercise Physiology is the description
and explanation of functionaland explanation of functional
changes brought about by singlechanges brought about by single
(acute) or repeated exercise(acute) or repeated exercise
sessions (chronic exercise orsessions (chronic exercise or
training), often the object oftraining), often the object of
improving the exercise response.improving the exercise response.
In this definition the description ofIn this definition the description of
functional changes refers to whatfunctional changes refers to what
happens to the body and thehappens to the body and the
explanation refers to understandingexplanation refers to understanding
how the changes occur.how the changes occur.

8. For example,For example, we know that repeated lifting ofwe know that repeated lifting of
heavy weights usually results in greaterheavy weights usually results in greater
ability to lift even heavier weights.ability to lift even heavier weights.
This functional change brought about byThis functional change brought about by
repeated bouts of exercise can berepeated bouts of exercise can be
explained partly by an increased growth ofexplained partly by an increased growth of
muscle tissue and partly by an improvedmuscle tissue and partly by an improved
ability of the nervous system to causeability of the nervous system to cause
greater number of muscle fibres to contractgreater number of muscle fibres to contract
simultaneously for the greatest possiblesimultaneously for the greatest possible
force of contraction of the entire muscle.force of contraction of the entire muscle.
This understanding of how weight lifting abilityThis understanding of how weight lifting ability
develops has led to better trainingdevelops has led to better training
programs to improve the liftingprograms to improve the lifting
performance.performance.

9. ENERGYENERGY
Energy is the capacity to generate activity, to produceEnergy is the capacity to generate activity, to produce
or do work.or do work.
The Human body produces and uses energy in orderThe Human body produces and uses energy in order
to perform a variety of tasks including:to perform a variety of tasks including:
 The maintenance of vital autonomous functionsThe maintenance of vital autonomous functions
such as electrical brain activity, breathing andsuch as electrical brain activity, breathing and
circulation, body temperature regulation andcirculation, body temperature regulation and
hormonal activity.hormonal activity.
 The digestive process.The digestive process.
 Physical activity.Physical activity.
Energy comes originally from the food we eat.Energy comes originally from the food we eat.
Through digestion, food is broken down and stored inThrough digestion, food is broken down and stored in
our cells in the form of chemical energy reservesour cells in the form of chemical energy reserves
waiting to be used.waiting to be used.
Energy is measured in units, that is, kilojoules orEnergy is measured in units, that is, kilojoules or
calories.calories.

10. FUEL FOR EXCERCISEFUEL FOR EXCERCISE
Our body’s energy needs come fromOur body’s energy needs come from
the breakdown of the nutrientsthe breakdown of the nutrients
carbohydrates, fats and proteins, incarbohydrates, fats and proteins, in
the food we eat.the food we eat.
 CarbohydratesCarbohydrates – preferred source– preferred source
of fuelof fuel
 ProteinProtein – normally not used as fuel– normally not used as fuel
but for growth and repairbut for growth and repair
 FatsFats - acts as a concentrated fuel- acts as a concentrated fuel
source in muscles. It is the body’ssource in muscles. It is the body’s
main source of fuel at rest andmain source of fuel at rest and
during prolonged sub maximalduring prolonged sub maximal
exercise.exercise.
 Water, minerals and vitaminsWater, minerals and vitamins
(although not used directly for fuel)(although not used directly for fuel)

11. However, the energy released duringHowever, the energy released during
the breakdown of carbohydrates, fatsthe breakdown of carbohydrates, fats
and proteins is not immediatelyand proteins is not immediately
used. Instead an important energyused. Instead an important energy
rich chemical compound known asrich chemical compound known as
ATP (adenosine triphosphate) isATP (adenosine triphosphate) is
formed.formed.
Energy is released when ATP isEnergy is released when ATP is
broken down. The ATP stored in thebroken down. The ATP stored in the
muscles is used up within seconds,muscles is used up within seconds,
so it is vital to keep making ATP soso it is vital to keep making ATP so
the muscles can keep contracting.the muscles can keep contracting.

12. Energy for muscular activity comesEnergy for muscular activity comes
from the chemical compoundfrom the chemical compound
ADENOSINE TRIPHOSPATE (ATP).ADENOSINE TRIPHOSPATE (ATP).
This compound contains anThis compound contains an
adenosine molecule with three (tri)adenosine molecule with three (tri)
phosphate groups attached.phosphate groups attached.
ATP stored in the muscles is very smallATP stored in the muscles is very small
and lasts only 1 – 2 seconds. Theand lasts only 1 – 2 seconds. The
body is able to replenish as quick asbody is able to replenish as quick as
it is broken down. This is achievedit is broken down. This is achieved
by resynthesising (rebuilding) ATPby resynthesising (rebuilding) ATP
through the break down of reservethrough the break down of reserve
fuels.fuels.

13. ATP DEPLETIONATP DEPLETION
As the duration of exercise increasesAs the duration of exercise increases
and as the reserves of ATP stored inand as the reserves of ATP stored in
the muscles runs out, our bodythe muscles runs out, our body
needs to find new ways ofneeds to find new ways of
resynthesising ATP, otherwise weresynthesising ATP, otherwise we
would collapse from exhaustion.would collapse from exhaustion.
The body solves this problem by goingThe body solves this problem by going
back to the stored nutrients toback to the stored nutrients to
resynthesise more ATP.resynthesise more ATP.
These stored nutrients are used in aThese stored nutrients are used in a
particular order as illustrated below:particular order as illustrated below:

15. THREE ENERGY SYSTEMSTHREE ENERGY SYSTEMS
1.1. The ATP-PC System also called the alactacidThe ATP-PC System also called the alactacid
systemsystem
2.2. The Lactic Acid System also call anaerobicThe Lactic Acid System also call anaerobic
glycolysisglycolysis
3.3. The Aerobic System also called the oxygen systemThe Aerobic System also called the oxygen system
Which Energy System is Used and When?Which Energy System is Used and When?
There are many factors which determine which energyThere are many factors which determine which energy
system is used and when, depending on:system is used and when, depending on:
 Whether the individual is resting or exercising (orWhether the individual is resting or exercising (or
both)both)
 The duration of the exerciseThe duration of the exercise
 The intensity of the exerciseThe intensity of the exercise
 The athlete’s level of fitness at the timeThe athlete’s level of fitness at the time
The body needs a combination of the three energyThe body needs a combination of the three energy
systems to supply energy for most activitiessystems to supply energy for most activities
particularly team games.particularly team games.