SAC ATTACK PACK
Increased Ventilation
Increased blood flow to skin
Untrained vs trained
Increased Heart Rate
Unit 3 AOS 2
Physiological Responses to Physical Activity
Acute Responses to Exercise
List the acute responses for each of the body systems below:
The Respiratory System
The Cardiovascular System
The Muscular System
Acute Responses
When we start to exercise, the body must change to meet the demands we are placing on it. The
changes that occur will vary according to the duration and intensity of the task.
Why do changes occur in the body?
Changes occur to meet the needs of the task. Three major body systems make immediate changes to
cope with the demands. It is important you are aware of the role each of these play in assisting the
body during exercise and recovery.
System
Respiratory System
Cardiovascular
System
Muscular System
Role within the body
Acute responses
Heart Rate
Ventilation
Blood flow
Motor Unit recruitment
Lactate levels
Stroke Volume
Cardiac Output
Temperature
Diffusion
Blood Pressure
Substrate levels
A-VO2 diff
The Respiratory System
Ventilation:
When we start exercising, the amount
of air we breathe in per minute
increases. You will breathe more often
(respiration rate) and more deeply
(tidal volume)
Ventilation = TV x RR
Diffusion:
During exercise, gases move from a
region of high concentration to a
region of low concentration, down
a concentration gradient. Carbon
dioxide moves from the blood into
the lungs in deoxygenated blood
and oxygen moves into the blood
to reoxygenate the blood so
oxygen can be carried to working
muscles.
Gas exchange increases during
exercise due to the increased
surface area of the lungs.
What happens at the muscle site?
Ventilation (litres per minute) = TV (L) x RR (breaths per minutes)
The Cardiovascular System
The cardiovascular system undergoes many changes in order to deliver oxygen to and remove carbon
dioxide from the muscles.
The primary task of the system is to get more oxygen to working muscles. In order to increase cardiac
output (the amount of blood pumped per minute in L/min), the stroke volume (amount of blood
pumped per beat) and the heart rate (number of times the heart beats per minute) increases. Sound
familiar?
Q (cardiac output) = HR (strokes per minute) x SV (mL per beat)
Similarly to the respiratory system, SV peaks sub maximally, which means HR takes care of the extra
delivery of oxygen during maximal intensity exercise.
Submaximal exercise: Cardiac output will have a rapid increase early on in the session but will reach
a plateau when oxygen demand matches oxygen supply. This is known as steady state.
Maximal exercise: HR will increase until demands can no longer be met and exercise will conclude.
Describe the relationships you see in the graphs below:
Describe the other cardiovascular responses during exercise:
Blood pressure:
Venous return:
Blood volume:
Redistribution of blood flow:
Organ
Liver
Skin
Brain
Muscles
Heart
Kidneys
Increase/decrease/ same
A-VO2 difference:
The difference in oxygen concentration between the arterioles and the venules is known as the a-VO2
difference. As soon as we start exercise, the muscles extrapolate more oxygen from the blood. This
means there will be a greater difference in concentration between the arterioles and the venules and
thus a-VO2 difference increases. As an individual increases their fitness level their a-VO2 difference
also increases.
When we are looking at an individual’s VO2, we are looking at the amount of oxygen they use in a
minute. We find the VO2 by multiplying cardiac output with a-VO2 difference.
V02 = CO x A-VO2
Muscular
Responses
For each of the responses
below, circle the correct
response (decrease or
increase) and explain your
selection
↑
↓
Motor Unit recruitment
Why?
↑
↓
Blood flow
Why?
↑
↓
Energy substrate
Why?
↑
↓
Lactate
Why?
↑
↓
Body temperature
Why?
↑
↓
A-VO2 Difference
Why?
Cardiovascular Response
Respiratory Response
Muscular Response
Muscle
temperature
Heart Rate
Blood flow to the GI tract
H+ ions
Tidal Volume
Gas
diffusion
PC
stores
Acute
Responses to
exercise
Muscle glycogen
Blood flow to
kidneys
Muscle fibre recruitment
Blood flow to
muscles
Respiration
Rate
Stroke Volume
Enzyme activity in
the muscle
Task:
1. For each of the responses above, identify whether they increase, decrease or remain the same at the onset on exercise.
2. Using three highlighters, categorize each as either a cardiovascular, respiratory or muscular response i.e. all muscular responses are highlighted in the
same colour.
Key Terminology
Key terms will always have ‘key words’ which will help you form meaningful links as well as aid in the complexity of your answers. Look at the key words
below and begin to make your own list, using the glossary of terms as well as your text book and alternative resources.
Key Term
Associated Key Word
Associated Key Word
Associated Key Word
Gas Exchange
Alveoli
CO2/O2
Capillary
Ventilation
Respiratory Rate
Tidal Volume
L/min
Cardiac Output
Cardiovascular System
Stroke Volume
Heart Rate
Muscle Pump
Recovery
Venous Return
Active
Vasodilation
Muscles
Skin
Redistribution
Substrate
Fuel
Muscular
Decrease
Motor Unit
Recruitment
Force
Muscle Fibres
Haemoglobin
Blood
Red Blood Cells
Oxygen
A-VO2 Difference
Muscular
Concentration
Increased
Glossary of Terms
Term
Cardiac Output
Ventilation
Tidal Volume
Respiratory Rate
Gas Exchange
Stroke Volume
Heart Rate
Haemoglobin
A-VO2 Difference
Diaphragm
Venous Return
Vasoconstriction
Vasodilation
Muscle Pump
Systolic Blood Pressure
Diastolic Blood Pressure
Respiratory Pump
Definition
Multiple Choice Questions*
1. When considering gas exchange between the alveoli and the capillaries:
a) Gases move from a region of low pressure to a region of high pressure
b) The diaphragm is responsible for the gas exchange process
c) The veins, filled with oxygenated blood, will carry the blood back to the heart
d) The air inhaled and exhaled each breath is called vital capacity
2. Which of the following statements is correct?
a) CO2 is a metabolic by product which is transported in the blood via myoglobin
b) Most trained athletes will have a lower stroke volume at rest
c) Pre-training, an individual will have a minute ventilation of about 200 L/min
d) An untrained athlete will generally have a lower stroke volume
3. An increase in Cardiac Output during submaximal exercise is:
a) An acute response via the muscular system
b) Driven by the body’s need for increased lactate removal
c) Determined by an increase in both SV and HR
d) Determined by an increase in HR only
4. If the respiratory system is responsible for intake of oxygen, the cardiovascular system is
responsible for…
a) The utilisation of oxygen
b) The transport of oxygen
c) The uptake of oxygen
d) All of the above
5. When considering the recruitment of Motor Units
a) All Motor Units are recruited during exercise
b) The cardiovascular system is responsible for the recruitment
c) Motor Units are recruited based on force required
d) One Motor Unit will contract the entire muscle
6. An increase in muscle temperature is primarily due to:
a) Heat production via the blood
b) Heat production via the anaerobic systems
c) Heat production via the aerobic system
d) Sweating
7. The mechanisms responsible for increased venous return include:
a) Vasodilation of the vessels
b) A passive recovery
c) Putting your legs up, to ‘drain’ the blood back to the heart
d) The muscle pump