APPLY BASIC EXERCISE
SCIENCE TO EXERCISE
INSTRUCTION
THEORY WORKBOOK
VCE / VET
FITNESS FOCUS – BUNDLE ONE
Competencies addressed in this workbook task
SRFFIT005B:
– Apply Basic Exercise Science to Exercise Instruction
Element Three – Apply a knowledge of the body’s energy
systems to exercise instruction
Element Four – Use a knowledge of the lever systems of
the human body and resistance equipment to set safe and
effective exercise intensities.
Element Three Performance Criteria
- Explain the effect of exercise intensity on the energy substrate to clients during fitness
-
instruction
Apply the limiting factors of the body’s energy systems to the setting of exercise
intensities when instructing fitness activities
Element Four Performance Criteria
- Use the common terms used to qualify the basic principles of biomechanics when
-
instructing fitness activities
Identify and explain the basic lever systems in both anatomical and mechanical lever
systems to clients
Use the lever systems in the human body and their role in movement and stability to
provide safe and effective exercises for clients
Take into account the use of levers and cams in resistance equipment to alter the
force required by muscles and affect joint stability when developing programs and
instructing fitness activities
Take into account the effect of changes in lever length on muscle force output in both
anatomical and mechanical lever when instructing fitness activities
Element Three - Energy Systems
How the body converts food to fuel relies upon several different energy pathways. Having a
basic understanding of these systems can help athletes train and eat efficiently for improved
sports performance.
Sports nutrition is built upon an understanding of how nutrients such as carbohydrate, fat, and
protein contribute to the fuel supply needed by the body to perform exercise. These nutrients
get converted to energy in the form of adenosine triphosphate or ATP. It is from the energy
released by the breakdown of ATP that allows muscle cells to contract. However, each
nutrient has unique properties that determine how it gets converted to ATP.
Carbohydrate is the main nutrient that fuels exercise of a moderate to high intensity, while
fat can fuel low intensity exercise for long periods of time.
Proteins are generally used to maintain and repair body tissues, and are not normally used to
power muscle activity.
Energy Pathways
Because the body can not easily store ATP (and what is stored gets used up within a few
seconds), it is necessary to continually create ATP during exercise. In general, the two major
ways the body converts nutrients to energy are:


Aerobic metabolism (with oxygen)
Anaerobic metabolism (without oxygen)
These two pathways can be further divided. Most often it's a combination of energy systems
that supply the fuel needed for exercise, with the intensity and duration of the exercise
determining which method gets used when.
ATP-CP Anaerobic Energy Pathway
The ATP-CP energy pathway (sometimes called the phosphate system) supplies about 10
seconds worth of energy and is used for short bursts of exercise such as a 100 meter sprint.
This pathway doesn't require any oxygen to create ATP. It first uses up any ATP stored in the
muscle (about 2-3 seconds worth) and then it uses creatine phosphate (CP) to resynthesize
ATP until the CP runs out (another 6-8 seconds). After the ATP and CP are used the body
will move on to either aerobic or anaerobic metabolism (glycolysis) to continue to create
ATP to fuel exercise.
Summary - The Phosphagen System:


Creatine phosphate( phosphate compound stored in muscle)
Utilised during all out bursts of energy lasting 10sec (approx.)
Anaerobic Metabolism - Glycolysis
The anaerobic energy pathway, or glycolysis, creates ATP exclusively from carbohydrates,
with lactic acid being a by-product. Anaerobic glycolysis provides energy by the (partial)
breakdown of glucose without the need for oxygen. Anaerobic metabolism produces energy
for short, high-intensity bursts of activity lasting no more than several minutes before the
lactic acid build-up reaches a threshold known as the lactate threshold and muscle pain,
burning and fatigue make it difficult to maintain such intensity.
Summary - The Lactic Acid System:





Anaerobic glycolysis
Glycogen stored in muscle is metabolised to resynthesize ATP
Fairly short duration activity as metabolic end products induce fatigue - lactic acid
On cessation of activity, the lactic acid is transported in the blood stream to the liver
where some is converted back to glycogen and the bulk combines with oxygen to
form co2 and h2o
Muscle glycogen is a readily available source of energy as is glycogen stored in the
liver
Aerobic Metabolism
Aerobic metabolism fuels most of the energy needed for long duration activity. It uses
oxygen to convert nutrients (carbohydrates, fats, and protein) to ATP. This system is a bit
slower than the anaerobic systems because it relies on the circulatory system to transport
oxygen to the working muscles before it creates ATP. Aerobic metabolism is used primarily
during endurance exercise, which is generally less intense and can continue for long periods
of time.
During exercise an athlete will move through these metabolic pathways. As exercise begins,
ATP is produced via anaerobic metabolism. With an increase in breathing and heart rate,
there is more oxygen available and aerobic metabolism begins and continues until the lactate
threshold is reached. If this level is surpassed, the body can not deliver oxygen quickly
enough to generate ATP and anaerobic metabolism kicks in again. Since this system is shortlived and lactic acid levels rise, the intensity can not be sustained and the athlete will need to
decrease intensity to remove lactic acid build-up.
Summary - The Aerobic System:




Aerobic metabolism - energy derived from glycogen or fats to release more ATP
Oxygen transported in the blood stream is utilised in this process
Energy not provided as quickly as anaerobic sources but contributlon is steadier and
longer lasting
Aerobic system more efficient than anaerobic
Fueling the Energy Systems
Nutrients get converted to ATP based upon the intensity and duration of activity, with
carbohydrate as the main nutrient fueling exercise of a moderate to high intensity, and fat
providing energy during exercise that occurs at a lower intensity. Fat is a great fuel for
endurance events, but it is simply not adequate for high intensity exercise such as sprints or
intervals. If exercising at a low intensity (or below 50 percent of max heart rate), you have
enough stored fat to fuel activity for hours or even days as long as there is sufficient oxygen
to allow fat metabolism to occur.
As exercise intensity increases, carbohydrate metabolism takes over. It is more efficient than
fat metabolism, but has limited energy stores. This stored carbohydrate (glycogen) can fuel
about 2 hours of moderate to high level exercise. After that, glycogen depletion occurs
(stored carbohydrates are used up) and if that fuel isn't replaced athletes may hit the wall. An
athlete can continue moderate to high intensity exercise for longer simply replenishing
carbohydrate stores during exercise. This is why it is critical to eat easily digestible
carbohydrates during moderate exercise that lasts more than a few hours. If you don't take in
enough carbohydrates, you will be forced to reduce your intensity and tap back into fat
metabolism to fuel activity.
As exercise intensity increases, carbohydrate metabolism efficiency drops off dramatically
and anaerobic metabolism takes over. This is because your body can not take in and distribute
oxygen quickly enough to use either fat or carbohydrate metabolism easily. In fact,
carbohydrates can produce nearly 20 times more energy (in the form of ATP) per gram when
metabolized in the presence of adequate oxygen than when generated in the oxygen-starved,
anaerobic environment that occurs during intense efforts (sprinting).
With appropriate training, these energy systems adapt and become more efficient and allow
greater exercise duration at higher intensity.
The systems used to resynthesis of ATP depend on a number of factors including;
•
Duration
•
Intensity
•
If oxygen is present
•
Urgency of energy required
•
Athletes level of training
The Three Energy Systems
Figu re 1. Three energy systems and their percentage contribution (Y-axis) to
total energy output during all-out exerc ise of different durations (X-axis).
Question 1
(5 marks)
Considering the above table, explain why a client can only maintain very intense and intense
exercise for up to 30 seconds. What are the limiting factors?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 2
(5 marks)
What explanation would you give to a client to explain the ‘dead legs’ feeling after 2 minutes
of heavy intensity exercise?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 3
(1 mark)
What is the primary food source used by the body at rest?
Question 4
(3 marks)
List the nutrients used by the body to create ATP
___________________________________________________________________________
Question 5
(2 marks)
Why would a high protein diet not aid an athlete in increasing their energy?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 6
(5 marks)
List the predominant energy system used in the following activities
100m sprint
_______________________
1500m run
_______________________
Discus throw
_______________________
Marathon run
_______________________
Reading a book
_______________________
Interplay Between Energy Systems
All activities use some energy from all three systems.
The energy systems overlap – they never work independently.
It it’s the relative contribution of each system that varies.
Element Four - Biomechanics
Biomechanics is the science concerned with the internal and external forces acting on the
human body and the effects produced by these forces. At the highest levels of sports in which
techniques play a major role, improvement comes so often from careful attention to detail
that no coach can afford to leave these details to chance or guesswork. For such coaches
knowledge of biomechanics might be regarded as essential.
BALANCE
Centre of Mass
(Figure 1).
The centre of mass, or centre of gravity, of
an athlete or object is that single point
which we can use to represent the overall
movement of the body. We may refer to
the centre of mass of a tennis racquet, a
person’s forearm, or their entire body. If
we were to balance a racquet on a knife
edge, the centre of mass would lie above it
The location of the centre of mass changes when
we move our body. When we stand upright, facing
forwards with our arms by our sides, our centre of
mass is located slightly above and between the hip
joints (Figure 2). If you raise both arms forwards
and upwards, your centre of mass will also move
forwards and upward (Figure 3). At the peak of
the pole vault when the athlete is piked over the
bar, the vaulter’s centre of mass would lie outside
of their body, further up the trunk and in front of
the body (Figure 4).
Maintaining balance is part of controlling the
body in sport. Being balanced is really
maintaining a position of equilibrium, where
the forces acting on you are not going to
change your body position. There are three
categories of equilibrium:
1. stable equilibrium – where a push will
move you, but you will return to your
previous stable position, e.g. hanging from
the rings in gymnastics (Figure 5),
2. neutral equilibrium – where a push will
move you to a new position which is still in
neutral equilibrium, e.g. a round ball lying on
the floor, (Figure 6), and
3. unstable equilibrium – where a push will
make you start to fall, e.g. standing upright
and someone pushes you from behind,
causing you to take a step (Figure 7).
We balance in positions of unstable equilibrium.
In general, the more unstable you are, the harder it is
to balance. Your stability depends partly on your
base of support. See Figure 8a, b, c for examples of
this. Your base of support may be small, e.g. for
someone doing a one-handed handstand (Figure 8a),
or larger, e.g. in normal standing (Figure 8b), or
quite large, e.g. for a sprinter in their start position
(Figure 8c). However, it’s not the size of your base
of support which is important, but the distance
between a vertical line through your centre of mass
(your gravity line) and the edge of your base of
support.
Stability is directional. For
example, sprint starters will be
relatively unstable in a forward
direction (their gravity line is
close to their fingertips), while
being very stable in a backwards
direction (Figure 9). When we
want to start moving in a
particular direction quickly, we
prepare by making ourselves
move unstable in that direction.
Other factors that affect your stability are your mass (more mass equals more stability), and
the height of your centre of mass above the surface (more height equals less stability).
When you are moving, one more factor which affects your stability, or balance, is your
straight line speed. The faster you are moving, the more stable you are, and the less effect a
push will have in deflecting you.
Question 7
(3 marks)
Which would be more stable, a 2m tall basketball player or a 1.6m tall rugby player? Why?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 8
(3 marks)
If another player was running towards the 2m tall basketball player, how could this player
improve their stability to avoid being knocked over?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 9
(2 marks)
What happens when you take your centre of gravity outside of your base of support?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 10 (2 marks)
Explain how a high jumper can take their centre of gravity outside of their body
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
MOTION
We frequently describe three components of motion. These are position, speed (or velocity),
and acceleration. These terms apply to both linear and angular motion. We use these terms to
describe characteristics of skilled movement.
Position refers to an object’s person’s location
at some time.
Speed is how quickly your position changes
over a period of time, while acceleration is the
rate of change of your speed over time. In other
words, acceleration is how fast your speed is
increasing or decreasing. In sprinting, both your
top speed and your acceleration to top speed are
important in winning a race. Evading a tackle in
rugby may depend on your ability to increase
your speed quickly, i.e. your acceleration.
Linear or straight line motion is when all parts
of a body move the same distance, in the same
direction, at the same time, i.e. same distance,
direction, time. Examples of this are a dart
player’s hand while throwing a dart, or a roller
blade skater gliding along a flat surface (Figures
10, 11).
Angular or rotational motion is when all parts of a body move through the same angle, in the
same direction, in the same time, i.e. same angle, direction, time. Examples of this are the
bowling arm of a cricketer, or a gymnast doing a giant swing on the high bar (Figures 12, 13).
A special case of linear motion is called curvilinear motion. This occurs when all parts of the
athlete’s body still exhibit linear motion, i.e. same distance, direction, time, even though they
might be moving along a curved path. An example would be a skier gliding over the top of a
small hill (Figure 14). Most motion is a combination of the above, and we describe it as
complex or general motion. Examples of complex motion would be a runner, where angular
motion of the foot, leg and thigh produces linear motion of the trunk, or the entire arm of the
darts’ player, where angular motion of the upper arm and forearm produces linear hand
movement (Figure 15a,b).
The movement of objects in the air is another special motion case. These objects, or
projectiles, have a constant horizontal speed, except when air resistance is significant, but
their vertical speed is altered by the effect of gravity from the moment of take-off, or release,
until they contact the ground again. During the time a projectile is in the air, its upward speed
is decreasing by-10m/s every second. A ‘projectile’ can be a shot put in flight, a basketball
player performing a jump shot, a gymnast doing a back somersault, or a badminton player
leaping to play a smash (Figure 16a, c, d). All projectiles, unless affected by air resistance,
follow a trajectory known as a parabola (Figure 17).
Forces
Forces cause or tend to cause a change in an object’s or person’s motion. The change in
movement is in the same direction as the force exerted.
Weight is the gravitational force exerted by the earth on all objects. It equals mass times the
acceleration of gravity, and has units of Newtons. We frequently refer to our body weight as,
for example, 70kilograms. Technically this is incorrect: our mass is 70 kg and our weight is
70kg x 10m/s/s = 700 Newtons (Figure 18). What happens when more than one force acts on
a body? If we see movement, it is due to the sum of the forces acting. Consider a shot put
lying on the ground. Until you exert a force larger than its weight it won’t move (see Figure
19a, b). Once you produce a larger force, the portion causing movement is the difference
between the shot put’s weight and your force (Figure 20).
If the forces on a body act at some angle to each other, their effect is combined. When you
have two forces acting on a body, their joint effect can be estimated by visualising a
parallelogram with the combined, or resultant force joining the start and finish of the box
(Figure 21).
Newton's Laws of Motion

First Law: Every body continues in its state of rest or
motion in a straight line unless compelled to change
that state by external forces exerted upon it.

Second Law: The rate of change of momentum of a
body is proportional to the force causing it and the
change takes place in the direction in which the force
acts

Third Law: To every action there is an equal and
opposite reaction OR for every force that is exerted
by one body on another there is an equal and opposite
force exerted by the second body on the first
Bernoulli Effect
Lift forces interact with objects in flight and are caused by the aerodynamic shape of the
object. If an object has a curved top and flat bottom (wing of an aircraft), the air will have
further to travel over the top than the bottom. For the two airflows to reach the back of the
object at the same time the air flowing over the top of the object will have to flow faster. This
means that there will be less pressure above the object (air is thinner) than below it and the
object will lift. This is often referred to as the Bernoulli effect.
Levers
For your arm, leg or any body part to move the appropriate muscles and bones must work
together as a series of levers. A lever comprises of three components 


Fulcrum or pivot - the point about which the lever rotates
Load - the force applied by the lever system
Effort - the force applied by the user of the lever system
The way in which a lever will operate is dependent on the type of lever.
Classification of Levers



Class 1 - The fulcrum lies between the effort and the load
Class 2 - The fulcrum is at one end, the effort at the other end and the load lies between the
effort and the fulcrum
Class 3 - The fulcrum is at one end, the load at the other end and the effort lies between the
load and the fulcrum
Class 1 Lever
Class 2 Lever
Class 3 Lever
Class 3 is the most common class of lever to be found in the human body.
Examples in strength training



Class 1 - Seated dumbbell triceps extension
Class 2 - Standing heel lift**
Class 3 - Seated biceps curl
Class 1 Lever in the Body
Class 2 Lever in the Body**
Class 3 Lever in the Body
There are advantages and disadvantages to having mostly third class levers. The main
advantage is it allows us to produce very high speeds at the end of the levers, our hands and
feet. The disadvantages are that this lever system requires the muscles to exert much larger
forces than the weight of the object they are moving, and this has implications for injury.
“WE’RE MADE FOR SPEED, NOT FORCE”
Summation of Forces
Many movements in sport are the result of the combination of a number of forces which are
performed in a sequence, e.g. weight lifting, rowing, and projectile sports such as throwing
events in athletics, softball, tennis, and rugby.
For athletes to produce maximum velocity of a projectile or implement, each segment of
the movement should be moved at the instant the previous segment begins to slow down.
The speed of the last part of the body at the moment of contact or release will determine the
velocity attained by the projectile (ball, javelin, discus, etc.) or the implement (racquet, stick,
bat, etc.). This is particularly important if maximum force is desired, as in weightlifting, shot
put, and bowling in cricket, for example, when as many body parts as possible should be
used. In other words, optimal performance requires the body movements to be performed in
the correct sequence, with the correct timing. For example, in a well-timed kick in soccer or
rugby, the leg begins to extend at the knee joint as the thigh reaches maximum velocity. The
final velocity will be less than maximal if this leg action begins either earlier or later than this
point. See Figure 26. In practise, the strongest and slowest body parts begin to move first (i.e.
the thighs and trunk), followed by the weaker and faster extremities (i.e. lower leg, feet, arms,
and hands). In some sports, several actions occur simultaneously, and to achieve maximum
force, the body parts are required to produce force explosively at the same time, e.g.
gymnastics vault, judo kick, netball chest pass, and breaststroke leg kick.
Forces that Oppose Motion
There are forces that act to slow us down in most situations. These are forces such as fluid
(air or water) resistance, or frictional forces. When you push off from the edge of a pool and
try to glide as far as possible, you eventually stop because of the resistance from the water. A
skydiver has a maximum (‘terminal’) speed for any particular body position. This point is
reached when the forces due to air resistance equal their weight, and you have a situation
where there are no resultant forces acting on the skydiver (Figure 27).
Another factor affects our ability to increase or decrease our speed. This factor is called
inertia and is the tendency of the body to resist change in motion. Both Newton’s First and
Second Laws are important here. The inertia of a person or object is related to their mass: the
greater the mass, the greater their inertia. A rugby player with a mass of 100kg running at
5m/s is harder to stop than a 50kg player moving at the same speed. Remember that inertia
means it is just as hard to speed something up as it is to slow it down.
Momentum
Momentum is the ‘quantity’ of motion possessed by a body, and is measured by multiplying
the body’s mass by its speed. Momentum is important in collisions, such as a tackle in rugby,
deflecting a pass in netball, or striking a ball with a bat. The greater an object’s momentum,
the less it will be affected by some other force. When we
apply this concept to athletes, we find in many cases, it is the athlete’s momentum which is
important. Since the athlete’s mass is constant, the important factor is their speed. A greater
speed will make them harder to stop or deflect. In contact sports, Some players ‘bulk up’ to
increase their quantity of motion.
The forearm is a classic example of nature's way of maximising motion rather than force.
The biceps is a muscle that flexes the arm. Tendons attach this muscle close to the elbow.
Question 11 (1 mark)
Identify the type of lever in the image below _________________________
Question 12 (5 marks)
Summation of forces is an exceptionally important principle in teaching, coaching and
training. Explain how someone can appear ‘uncoordinated’ in performing an activity.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 13 (5 marks)
How does Newton’s Third Law of Motion relate to a runner who is over-striding in their
running action?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 14 (2 marks)
What is the main advantage to the human body in having mainly third class levers?
___________________________________________________________________________
___________________________________________________________________________
Question 15 (5 marks)
Several principles refer for the need for speed in sport. Explain why speed is important for a
rugby player.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 16 (5 marks)
If a client is having difficulty lifting a 20kg weight on a bar with straight arms, how can they
modify their position to enable them to lift? Explain this change in terms of lever length and
class.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Question 17 (5 marks)
A client is standing in a position with one foot forward, one back, shoulder width apart, to
perform a bicep curl with a bar and 30kg of weights. Explain this position in terms of
stability.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________