In this area of study, we are going to :
• Explore the various systems and mechanisms associated with the energy
required for human movement.
• Consider the cardiovascular, respiratory and muscular systems
and the roles of each in supplying oxygen and energy to the working
muscles.
• Examine the way in which energy for activity is produced via the three
energy systems and the associated fuels used
for activities of varying intensity and duration.
• Consider the many contributing factors to fatigue as well as recovery
strategies used to return to pre-exercise conditions.
• Participant in practical activities that explore the relationship between the
energy systems during physical activity.
• Complete One Test (20 marks) and one Laboratory based SAC (40 marks
and 40 marks)
Key Knowledge
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Mechanisms responsible for the acute responses to exercise in the
cardiovascular, respiratory and muscular systems
Characteristics and interplay of the three energy systems (ATP – CP,
anaerobic glycolysis, aerobic system) for physical activity, including rate
of ATP production, the capacity of each energy system and the
contribution of each energy system
Fuels (both chemical and food) required for resynthesis of ATP during
physical activity and the utilisation of food for energy
Relative contribution of the energy systems and fuels used to produce
ATP in relation to the exercise intensity, duration and type
Oxygen uptake at rest, during exercise and recovery, including oxygen
deficit, steady state, and excess post-exercise oxygen consumption
The multi-factorial mechanisms (including fuel depletion, metabolic byproducts and thermoregulation) associated with muscular fatigue as a
result of varied exercise intensities and durations
Passive and active recovery methods to assist in returning the body to
pre-exercise levels.
Key Vocabulary
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Acute
Adenosine Diphosphate (ADD)
Plateau
Aerobic capacity
ATP-CP energy system
Reciprocal inhibition
Aerobic glycolysis
Cardiac Output
Respiratory Rate
Aerobic pathway
Chronic adaptations
Stroke Volume
Anaerobic capacity
Diffusion
Systolic Blood Pressure
Anaerobic glycolysis
Diastolic Blood Pressure
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Tidal Volume
Anaerobic pathway
Heart Rate
Vasoconstriction
Anaerobic power
Lactate Inflection Point
Vasodilation
Arteriovenous Oxygen difference
(a-vO2 diff)
Interplay
Ventilation
Adenosine Triphosphate (ATP)
Motor Unit
Ventilation Threshold
Phosphocreatine (PC)
Acute Responses to Exercise
Immediate physiological responses to
exercise are called ACUTE RESPONSES.
 The body responds to the demands of
exercise by making a number of
physiological short-term changes to the
cardiovascular, respiratory and muscular
system.
 Once exercise is stopped, these three
systems will return to pre-exercise levels.
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THINKING TASK: BRAINSTORM ACUTE RESPONSES TO EACH SYSTEM
Acute Responses to Exercise
Respiratory
Cardiovascular
Muscular
Ventilation
Oxygen
Consumption
Temperature
A-V02 difference
Diffusion
Motor Unit
Recruitment
Cardiac Output
Energy Substrates
Venous Return
Lactate
Blood Pressure
Redistribution of
blood flow
Heart Rate Response to Exercise
Aim: To determine the change in heart rate in response
to submaximal and maximal exercise.
Equipment:
Method: Subjects to sit quietly for 3-5 minutes. Record
heart rate.
Submaximal Group
Maximal Group
Complete 10 minutes of continuous
exercise
Subjects to perform five maximal sprints
(20 metres)
Record subjects heart rate after each
minute of exercise
Record HR at completion of last sprint
Subject to perform active recovery until
heart rate is below 100 bpm.
Record the subjects HR 5 minutes after
exercise.
Record subjects heart rate at 1, 3 and 5
minutes post exercise
RESULTS
 Input data into Excel and graph results
DISCUSSIONG
1.
Graph the heart rate responses for both submaximal and
maximal exercise on the same axis. Describe the shape of
each graph in terms of heart rate changes?
2.
Did heart rate increase more with maximal exercise or
submaximal exercise? Explain your answer with reference to
physiological responses to exercise.
3.
Why does heart rate need to increase with exercise?
4.
Compare your data with that of another person n the class.
Explain any differences that are evident.
5.
Predict (by drawing on the graph) the heart rate response of a
highly trained triathlete to this same activity.
CONCLUSION
Write a conclusion based on your results and the discussion.
Acute Respiratory Responses
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Exercise places increased demands on the
body’s need for oxygen to meet the rising
energy demands of the activity
Ventilation increases prior to the begging of
exercise and continues to rise to meet the
oxygen demands of the exercise
Increases in ventilation are a result of an
increase in tidal volume, respiratory rates or
both
Gas exchange occurs at the alveolar-capillary
interface (in lungs) and at the tissue-capillary
interface (in the muscles) by process of
diffusion
Respiratory Response to Exercise
Ventilation and Diffusion
Read page 99-100
Complete Thinking Things Through (p.101)
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Thursday 22nd March
Thinking Things Through (101)
Respiratory rate and tidal volume.
2 Ventilation increases as the demand for oxygen increases and the need to remove
carbon dioxide. Ventilation is increased through an increase in the respiratory rate (the
number of breaths per minute) and/or the tidal volume (the amount of oxygen breathed in
or out in one breath). Diffusion increases as a result of exercise. The increase in oxygen in
the lungs causes an increase in diffusion of oxygen from the lungs into the blood and at the
muscle, carbon dioxide levels are high so diffusion across the tissue-capillary interface
increases also.
3 At rest the need for oxygen is low, but as exercise begins, the body’s need for oxygen
increases significantly. To meet this need the body responds in a number of ways. The
individual will breathe more often and more deeply (increased respiratory rate and
increased tidal volume). These increases result in the rapid rise in ventilation as V = RR x
TV. The levelling off represents a period of time where the oxygen demand is being met
with supply (steady state) and no further increase in ventilation is required. The recovery
section of the graph represents the gradual return of RR and TV to pre-exercise levels as
the demand for oxygen has now decreased.
4 During submaximal exercise, the respiratory system will increase ventilation by
increasing both TV and RR linearly, with respect to oxygen consumption, until a steady
state is reached. At this point there will be no further increase in ventilation. During maximal
exercise, ventilation will continue to increase until exercise ceases. The increase in
ventilation is a result of increases in RR only. The rate of increase is linear up to the
ventilator threshold, at which point ventilation
1.
Acute Cardiovascular Responses
to Exercise
During exercise, the CV system needs to
deliver greater demands of oxygen and
energy substrates to the working muscles
 The focus is on getting more blood to the
muscles to meet the increased oxygen
demands and to speed up the removal of
carbon dioxide and other waste products.
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TO DO THIS THE CARDIOVASCULAR
SYSTEM UNDERGOES A NUMBER OF
CHANGES
CARDIAC OUTPUT
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Cardiac Output (Q): The amount of blood pumped by
the heart in one minute.
Stoke Volume: is the amount of blood ejected by the
left ventricle per beat.
Heart Rate is the number of times the heat beats in
one minute
Cardiac Output is the product of stroke volume (SV)
and Heart Rate (HR)
Q= HR x SV
Increase in cardiac output increases blood pressure
(BP)
Explanation of
Cardiac Output
Read Table 4.2 and
Figure 4.3 on Page 102
Copy these into your
books
BLOOD PRESSURE
Copy Figure 4.4
(p.104)
Describe what this
graph is displaying
During exercise, the increase in cardiac
output (Q) results in an increased in
blood pressure.
 Using large muscles groups affects
Systolic Blood Pressure more then
diastolic.
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Systolic pressure
Diastolic Pressure
Pressure in the arteries following
the contraction of ventricles as
blood is pumped out of the heart
Pressure in the arteries when the
heart relaxes and ventricles fill the
blood
VENOUS RETURN
As the cardiac output increases, it’s
important that the venous return also
increases.
 The process of assisting venous return is
done by one of 3 mechanisms
1. The muscle pump
2. The respiratory pump
3. Venoconstriction
Copy Figure 4.6 (page 104) into books
Read paragraph on page 105 to summarise
the three mechanisms listed above.
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Venous Return
Describe the three mechanisms that allows
venous return to occur? P. 104
Oxygen Consumption
Oxygen consumption is the volume of
oxygen that can be taken up and used
by the body.
 As intensity of exercise increases, so
does oxygen consumption.
 This is a direct result of:
1. An increase in Cardiac Output (Q)
2. An increase in a-VO2 difference
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Arteriovenous oxygen difference
(a-VO2 Difference)
Difference in oxygen concentration in the arteries
compared to the venuoles.
 At rest, the arterial blood releases as little as 25% of
it oxygen content to the tissue and the remaining 75
% is returned to the heart in the venous blood.
 During exercise, the working muscles extract
greater amounts of oxygen from the blood,
increasing the a-VO2 difference.
 While there is always some oxygen remaining in
the blood returning to the heart, oxygen extraction
can approach 100%.
Copy Figure 4.8 (p.106) into books, with heading and a
brief explanation.
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Redistribution of Blood Flow
During exercise blood flow is redirected away from
the spleen, kidneys, gastrointestinal tract and
inactive muscles to the working muscles.
 This is done so that the working muscles receive the
greatest percentage of the cardiac output.
 Copy Figure 4.7 (p.106) into books, with heading and
a labels.
 This process is assisted by vasoconstriction in the
arterioles supplying the inactive areas of the body
and by vasodilation in the arterioles supplying the
working muscles.
Explain the relationship between body temperature and
redistribution of blood flow in the body as a result of
continuous exercise.
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Relationship between blood flow
and temperature.
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At submaximal exercise intensities blood
flow is directed to the working muscles
and to the skin to aid in temperature
control. At maximal exercise intensities
the increased demand for oxygen
means that more blood is directed to the
muscles and less to the skin (2 per cent)
which means that temperature increases
and the risk of heat related injuries
increases.
Blood Volume
During exercise, blood volume
decreases.
 Plasma can decrease by 10% during
prolonged exercise. Plasma decreases
rapidly in the first 5 minutes of exercise,
but then stablises.
 The size of the decrease depends on
intensity, duration and environmental
factors (temperature, humidity, etc.) and
level of hydration of the individual.
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Acute Muscular Response to
Exercise
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When exercise commences, there is an
increase in the rate of metabolism required to
produce ATP.
This results in heat as chemical energy (fuel)
is converted to mechanical energy
(movement)
This causes the body’s temperature to
increase
The body accommodates for these changes
through increased blood flow, motor unit
recruitment, using different energy substrates
to fuel the body and remove lactate from
working muscles
Motor Unit Recruitment
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The motor unit is
the means by
which the central
nervous system
‘talks’ to the
muscles in order
to control
muscular
contractions.
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1.
2.
During exercise, the
amount of force
developed in the
working muscles
increases. To do this
the brain
Increases the
number of motor
units recruited.
Or increases the
frequency of
If motor units always contact
messages sent to
maximally, explain how the
activate the motor body controls movements
units.
that require more or less
force?
Motor Unit Recruitment and
Movement
Fewer motor units
are recruited for
activities that
require less force;
more motor units
are recruited for
activities that
require more force.
Energy Substrates
When exercise commences Adenosine Triphosphate
(ATP) is the immediate energy source
 However, this ATP is in short supply and when used up
the muscles must rely on other energy substrates to
fuel the body
 Glycogen (stored energy) is used in both anaerobic and
aerobic respiration to produce ATP.
 During exercise phosphcreatine (PC) donates a
phosphate to adenosine diphosphate (ADP) to
resynthesis ATP.
 The net result of exercise is a decrease in all fuel (ATP,
PC, muscle glycogen) levels within the muscle.
Study figure 4.3 )p.108). Copy the two diagrams into book
and discuss. Why does the endurance athlete experience
greater depletion in glycogen content than high-intensity
sprint athletes?
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Energy Substrate levels of a 100
metre sprinter and a marathon at
the end of their event.
marathon
runner:
decreased
glycogen
and
intramusc
ular fat
stores
100-metre sprinter:
decreases ATP and
CP stores
Lactate
As exercise starts large amounts of lactate
are released from the muscles due to
anaerobic production of ATP (without oxygen).
 This means that during submaximal exercise
there is a sharp increase in lactate
 Lactate levels will rise until oxygen
consumption can increase to meet energy
demands of the muscle, and the lactate can be
delivered to sites for removal.
Lactate is present at rest and during submaximal
and maximal exercise. However, it accumulates
only at high exercise intensities. Discuss.
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The Accumulation of Lactate
At rest and during submaximal exercise
intensities, lactate is produced, but
sufficient oxygen is available for it to be
broken down and removed by the body. At
high intensities, lactate is being produced
at higher rates than the body can clear it
so it accumulates.
Acute Muscular Responses to
Exercise
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4.
5.
There are a number of mechanisms responsible for acute
responses in the muscles
Increased blood flow -through redistribution there is more
blood flowing to the muscles, delivery of large volumes of
blood, increase to the surface area to increase diffusion rates
Increase in number of motor units recruited (dependent on the
speed and strength required)
Decrease in Energy Substrates- ATP immediate source of
energy, glycogen, phosphocreatine donation to resynthesis
ADD to form APT.
Release of Lactate due to anaerobic production of ATP
Increase in heat production as a by-product of converting
chemical fuel to movement energy. This increases core body
temperature. The body must then employ methods ad
mechanism to cool the body and restore homeostasis.
Acute Response to Exercise
Laboratory
Read Lab P. 112
 Before class, write aim, equipment,
method and an empty results table
(Respiratory Rate no Tidal Volume
 Agree upon team sport to play (e.g.
soccer, netball, basketball)
 We will discuss the question in the last
15 minutes of class in the fitness centre.
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AMAZING REVISION SITE!
REVISION
 prezi.com/msbfrxwphypl/acuteresponses-to-exercise/
Links
 Aerobic System (Aerobic glycolysis)

Fatigue-Fuel Depletion
Homework
Links
Thinking things through p. 107
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1 Cardiac output (Q) = stroke volume (SV) x heart rate (HR). Any
increase in SV, HR or both will result in an increase in cardiac
output.
2 Resistance exercises cause compression of the blood vessels by
the muscles causing an increase in blood pressure. Blood
pressure can also increase due to the Valsalva response elicited in
heavy resistance training, where air is forcefully expired against a
closed airway.
3 During exercise blood is redirected to the working muscles. This
means more blood is delivered to the muscles and the muscles
can extract greater amounts of oxygen to be used for energy
production, causing an increase in a-vO2 difference.
4 Each of the mechanisms has an impact on the others. Increases
in ventilation and diffusion mean that more oxygen is available in
the blood. Increases in cardiac output mean more blood is pumped
out with each beat and delivered to the working muscles. The
increase in venous return means that more blood is available to be
ejected with each beat. Increases in cardiac output and a-vO2
difference lead to an increase in oxygen