Acute exercise and the body’s
response
Unit 2: physiology of fitness
Kevin Browne
Learning Aims
• In relation to the assignment
P1
P2
M1
Describe the musculoskeletal
and energy systems response
to acute exercise
Describe the cardiovascular and
respiratory systems response to
acute exercise
Explain the response of the
musculoskeletal, cardiovascular
and respiratory systems to acute
exercise
Learning aims
• So what do you think that you should be able
to do by the end of the lesson?
• What is meant by the term “acute”
• Acute means quick onset, something that
happens suddenly
• Chronic?
• Chronic is something that happens over time
or is persistent
• Exercise places different demand on the body
when compared to rest
• The changes are dependent on a number of
things such as intensity, duration, the muscles
being used, external and internal
environment/situation
• Using the points above use an example to
explain the acute changes
• Acute responses will affect all 4 major systems
which are:
• Musculoskeletal system
• Energy system
• Cardiovascular
• Respiratory
Task
• You will be split into 4 groups of 2
• In 2s you will research the acute response of
exercise to your allocated system
• You will record key information (what sort of
things do you think you will need to record) both
pairs
• Then the pairs will split and join with 3 other
researchers forming a group of 4. you will then
teach the others about your system until all 4
systems have been covered.
• Group discussion.
Hover over a hexagon for more
information
Muscle
fibre
micro
tears
Blood supply
Effects
Range of
movement
Muscle
pliability
Musculoskeletal responses to acute
exercise
Blood supply
Muscle
fibre
micro
tears
Blood supply
The temperature and metabolic
activity in the muscles increases as
you exercise. To meet the increased
demand of oxygen by the muscles,
blood supply increases through
capillary dilation.
Effects
Range of
movement
Muscle
pliability
Musculoskeletal responses to acute
exercise
Muscle pliability
As the muscles get warmer they
become more pliable. This reduces
the risk of injury.
Muscle
fibre
micro
tears
Blood supply
Effects
Range of
movement
Muscle
pliability
Musculoskeletal responses to acute
exercise
Range of movement
Exercise stimulates the production
of synovial fluid into the joint. The
fluid also becomes less viscous and
the range of movement at the joint
increases.
Muscle
fibre
micro
tears
Blood supply
Effects
Range of
movement
Muscle
pliability
Musculoskeletal responses to acute
exercise
Muscle fibre micro tears
Muscle
fibre
micro
tears
Blood supply
Effects
Range of
movement
The stress of exercise causes tiny
micro tears in the muscle fibres.
These cause swelling in the muscle
tissue and muscle soreness. The
soreness felt a few hours after
exercise or the next day is often
referred to as DOMS (delayed onset
muscle soreness).
Muscle
pliability
Musculoskeletal responses to acute
exercise
Energy systems
• This should only be a recap
• When you begin to exercise your body must
immediately adjust to the change in activity
level. Energy production must increase to
meet demand with changes to the
predominant energy system and fuel source
occuring throughout the exercise in order to
maintain the required level of performance.
Response to anaerobic exercise
• In order to immediately meet the sudden higher energy demand,
stored ATP is the first energy source. This lasts for approximately 2
seconds.
• When stored ATP is broken down into ADP + P, the rising ADP level
stimulates Creatine Kinase to begin the breakdown of
Phosphocreatine.
• As discussed on the energy systems page the ATP-PC system can only
last 8-10 seconds before PC stores are depleted.
• The lactic acid system (Anaerobic glycolysis) must then take over as the
predominant source of energy production. High intensity (but submaximal) exercise can last for between 3 and 5 minutes using this
system
• If the exercise continues at a high intensity, and so Oxygen is not
available at a fast enough rate to allow aerobic metabolism to take
over, the production of lactic acid will reach the point where it
interferes with muscular function. This is called the Lactate threshold.
• Muscles begin to fatigue when ATP resynthesis can no longer match
Responses to aerobic Exercise
• Due to the necessity of Oxygen being present for aerobic
metabolism, the first few minutes of low to moderate intensity
exercise are powered by anaerobic metabolism.
• Continued low to moderate intensity exercise is then fuelled by
carbohydrate and fat stores using aerobic metabolism.
• The intensity and duration of exercise determines which fuel
source is used. Fat metabolism is a slow process and so can only
be used as fuel for exercise at less than 60% VO2 max.
• Carbohydrate is a much faster fuel source and so can be used for
exercise up to 80% (in trained individuals).
• Carbohydrate stores within the muscle and liver can fuel exercise
for up to 80 minutes. As carbohydrate stores get lower, the body
has to rely more and more on fat stores.
• The intensity of exercise which can be maintained drops as fat
cannot supply the required amount of energy.
• www.teachpe.com
Prior to the start of exercise the
heart rate usually increases. This is
caused by the release of
neurotransmitters in the blood
known as adrenaline and
noradrenalin. This rise in heart rate
is known as the anticipatory heartrate response.
Blood pressure is the pressure
of the blood against the artery
walls. During exercise the
systolic blood pressure rises
progressively while the
diastolic stays the same or
decreases slightly.
CV
response
Prior to and at the start of exercise
the nerve centres in the brain can
detect cardiovascular activity and
adjust the frequency and strength of
the hearts contractions. At the same
time blood flow is altered in
proportion to the intensity of the
activity. This is known as the activity
response.
Blood flow to tissues that are not
needed during exercise can also be shut
down to temporarily lessen their supply.
This is achieved through the
constriction of the blood vessels and is
known as vasoconstriction.
Blood flow will increase (to
meet the increased oxygen
demand). This is achieved
through the dilation of the
blood vessels and known as
vasodilatation.
Respiratory system
• During exercise there is an increased
production of carbon dioxide. The respiratory
system is very sensitive to this, yet insensitive
to the falling levels of oxygen. To combat the
increase in carbon dioxide levels our breathing
rate increases in an effort to expel this.
As we breathe faster and deeper we
take in more air per breath. The
amount of air we breathe in and out in
one breath is known as tidal volume.
Tidal volume increases during exercise
to allow more air to pass through the
lungs.
During exercise the capillary
network surrounding the
alveoli expands, increasing
blood flow to the lungs and a
greater pulmonary diffusion.
During exercise your muscles demand
more oxygen and produce more carbon
dioxide. This stimulates an increase in
breathing rate, and breathing becomes
faster and deeper.
Breathing is controlled by neural and
chemical factors. Increases in the rate and
depth of breathing are detected by stretch
receptors in the lungs, which signal the
respiratory centres of the brain to send
nerve impulses to the respiratory muscles to
control the breathing rate and tidal volume
Respiratory
response
Question Time
• In 2s write 3 questions that cover any of the 4
systems that we have covered in lesson.
• Join up with another pair and pick 4 questions
out of the combined 6
• 4 vs 4
• Losers will have a forfeit
• Have you met your learning aim?