ACUTE RESPONSES TO EXERCISE KEY KNOWLEDGE The mechanisms responsible for the acute responses to...
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ACUTE RESPONSES TO EXERCISE KEY KNOWLEDGE The mechanisms responsible for the acute responses to exercise in the cardiovascular, respiratory and muscular systems Oxygen uptake at rest, during exercise and during recovery including oxygen deficit, steady state and excess post-exercise oxygen consumption KEY SKILL Participate in physical activities to collect and analyse data relating to the range of acute effects that physical activity has on the cardiovascular, respiratory and muscular systems of the body
ACUTE RESPONSES TO EXERCISE KEY KNOWLEDGE The mechanisms responsible for the acute responses to exercise in the cardiovascular, respiratory and muscular
ACUTE RESPONSES TO EXERCISE KEY KNOWLEDGE The mechanisms
responsible for the acute responses to exercise in the
cardiovascular, respiratory and muscular systems Oxygen uptake at
rest, during exercise and during recovery including oxygen deficit,
steady state and excess post-exercise oxygen consumption KEY SKILL
Participate in physical activities to collect and analyse data
relating to the range of acute effects that physical activity has
on the cardiovascular, respiratory and muscular systems of the
body
Slide 2
FOOD FOR THOUGHT After completing the prac on Acute Responses
to exercise think about why Your heart rate increased? Your
breathing increased? The colour of your face changed? You started
sweating?
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WHAT ARE ACUTE RESPONSES?? Only occur for the duration of
exercise and recovery. Short Term. Are dependent on the intensity,
duration and type of exercise being undertaken Involve the
respiratory, cardiovascular and muscular systems working together
to supply more energy / ATP and oxygen to working muscles and then
again to remove any waste products
Slide 5
ACUTE REPONSES OF THE CARDIOVASCULAR SYSTEM Acute
Cardiovascular responses All of these responses are aimed at
getting more blood, oxygen & fuels to working muscles and speed
up removal of wastes. Stroke Volume (ml of blood pumped out of the
left ventricle per beat) Heart Rate (beats per minute) Cardiac
Output (litres per minute) = SV x HR
Slide 6
INCREASED HEART RATE Why when you start exercising your heart
rate starts pumping? Heart rate is the number of times per minute
your heart contracts. (bpm) Resting heart rate is generally between
60-80 bpm. At the beginning of exercise the heart beats faster to
deliver oxygen to the muscles and help remove waste products. Heart
rate increases in accordance with intensity of exercise
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HEART RATE
Slide 8
ABOUT HEART RATE (HR) Your heart rate has a maximum and this
can be APPROXIMATELY calculated by following equation MAX HR = 220
- age Trained athletes will have a lower resting heart rate Heart
rate increases exein anticipation to exercise Anticipatory
rise
Slide 9
WHAT REGULATES OUR CHANGE IN HR? Our heart rate is controlled
by our nervous system and our endocrine system. To find out more
read pg.92 of textbook
Slide 10
INCREASED STROKE VOLUME (SV) Stroke volume is the amount of
blood ejected from the heart with each contraction. Stroke volume
increases with exercise but only u pto 40-60% of maximum intensity
of exercise. Untrained individual SV @ rest =60-80mL and @ exercise
=80-110mL Trained individual SV @rest = 80-110mL and @ exercise =
160-200mL Question Does this help you understand why a trained
person has a lower resting HR? Males will have generally higher
stroke volumes due to their increased heart size.
Slide 11
INCREASED CARDIAC OUTPUT (Q) Cardiac Output (Q) is the amount
of blood ejected by the heart each minute. It is calculated by
multiplying heart rate and stroke colume Q = HR x SV Increases
during exercise For average adult @ Rest = 4-6 Litres per minute @
Exercise = 20-25L For trained athlete this can get up to 35-40 L
per minute
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YOUR TURN! Jim is 32 years old. He has a resting HR of 72. His
resting stroke volume is 68mL.. Jim goes for a run at about 50% of
maximum and his HR increases to 146 and his stroke volume increases
to 98mL. Calculate his resting Cardiac output Q Calculate his Q at
exercise
Slide 14
YOUR TURN What is meant by the term acute responses to
exercise? Define what is meant by the term heart, stroke volume and
cardiac output. How can I calculate my maximum heart rate? Why do
females have smaller stroke volumes that males? Describe how HR, SV
and Q change with increasing intensity. How do they
interrellate?
Slide 15
MORE ACUTE CARDIOVASCULAR RESPONSES Blood pressure (mainly
systolic) Aterio-Venous Difference (a-VO2 diff) Redistribution of
blood toward working muscles
Slide 16
INCREASED BLOOD PRESSURE Blood pressure is the pressure exerted
by the blood against the walls of the arteries. Systolic blood
pressure is the blood pressure recorded as blood is ejected during
contraction phase of the heart cycle. Will be the higher of the 2
values Diastolic blood pressure is the blood pressure recorded
during the relaxation phase of the heart cycle. Will always have a
lower value. A normal blood pressure is 120 over 80. During dynamic
whole body exercise e.g running cycling blood is pumped more
forcefully and quickly out of the heart, this increases systolic
blood pressure but diastolic blood pressure barely changes. In
resistance type of exercise such as lifting wieghts there is an
increase in both systolic and diastolic blood pressure
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REDISTRIBUTION OF BLOOD FLOW TO WORKING MUSCLES @ Rest 15-20%
of blood flow is directed at the skeletal muscles. The rest goes to
your organs. When exercising 80-90% of blood flow will go to your
muscles. How can this happen? Our blood vessels can expand and
increase their internal diameter to allow more blood to be pumped
through to muscles. This is called VASODILATION Our blood vessels
can constrict to allow less blood through. This is called
VASOCONSTRICTION See figure 3.7 on pg 97 for more info
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INCREASED ARTERIOVENOUS DIFFERENCE (A-VO2 DIFF) a-VO2 diff is a
measure of the difference in the concentration of oxygen in the
arterial blood (arteries and venous blood (veins). @ Rest arteries
usually contain around 20mL of oxygen per 100mL of blood and the
veins contain 15mL of oxygen per 100mL of blood. Therefore the
a-V02 diff is 20-15 = 5mL per 100mL During exercise will the a-VO2
diff increase or decrease. Why?
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YOUR TURN Explain how the different blood pressures are
affected by exercise. Explain vasodilation and vasoconstriction.
How do these help you increase blood flow around the body? Explain
a-VO2 diff. Explain why it increases during exercise
Slide 23
OTHER CARDIOVASCULAR RESPONSES Venous return to heart (assisted
by muscle pump, respiratory pump and venoconstriction still approx
4% but 5 times as much blood compared to rest) Blood volume (plasma
loss)
Slide 24
ACUTE RESPONSES OF THE RESPIRATORY SYSTEM : Increased
respiratory frequency Increased Tidal Volume Increased Ventilation
Diffusion
Slide 25
INCREASED RESPIRATORY FREQUENCY (BREATHING RATE) Respiratory
frequency or breathing rate is the amount of breaths taken per
minute. Usually around 12 breaths per minute. Up to around a
maximum of 35- 50 during exercise. Can you think of an example of
maximal exercise where respiratory frequency might decrease?
Increase in respiratory frequency due to more CO2 in the blood.
Time yourself for one minute and work out your respiratory
frequency
Slide 26
INCREASED TIDAL VOLUME Tidal volume is the depth of your
breathing. Increases from 0.5L per breath at rest to a max of 3-5L
per breath.
Slide 27
INCREASED VENTILATION Ventilation is the amount of air inspired
or expired per minute by the lungs. It is calculated by multiplying
respiratory frequency by tidal volume VENTILATION (V) = RESPIRATORY
FREQUENCY X TIDAL VOLUME @ Rest = 5-6L per minute @ Maximal
Exercise = 130-180L or beyond Greater in males than females due to
lung volume. Your Turn! Calculate the Ventilation of an individual
who has respiratory rate of 15 breaths per minute and a tidal
volume of 0.5L?
Slide 28
INCREASED OXYGEN UPTAKE Oxygen uptake (VO2) is the amount of
oxygen transported to, taken up by and used by the body for energy
production. @ Rest 0.25L per minute When exercise begins oxygen
uptake increases as the working muscles use it made possible by the
responses by the cardiovascular and respiratory systems. It
increases linearly. Reaches a MAXIMUM OXYGEN UPTAKE (VO2 max).
Usually occurs around 2-3.5L. How is oxygen uptake different to
ventilation?
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DIFFUSION Gas exchange occurs at the lungs between the alveoli
and the cappilaries Gas exchange occurs in the muscle between the
muscle tissue and the capillaries. When oxygen or carbon dioxide
concentrations are high they want to move to a area of low
concentration Refer to diagram During exercise diffusion increases
to make more O2 available and to get rid of more CO2.
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YOUR TURN Define the terms respiratory frequency, tidal volume,
ventilation, oxygen uptake and maximum oxygen uptake Explain my
respiratory responses in a 3km run. Extend yourself: Explain the
mechanisms of inspiration, expiration and diffusion. Pages 99-100
in textbook
Slide 32
FACTORS AFFECTING MAXIMUM OXYGEN UPTAKE Body SizeGenderGenetics
Age Training Status
Slide 33
BODY SIZE A larger heavier person requires more oxygen than a
smaller person. Therefore VO2 max is expressed relative to body
size in mL/kg/min so it can be compared.
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GENDER Females tend to have lower oxygen uptake than males of a
similar age and athleticism. For untrained individuals can be as
great as 20-25% less. Why? Females tend to have a higher amount of
body fat and lower muscle mass. Body fat doesnt use oxygen. Females
have lower blood volumes and lower levels of red blood cells and
haemoglobin. Therefore less oxygen carrying capacity Females
typically have smaller lung size and volume.
Slide 35
GENETICS Aerobic capability is largely genetically determined.
Up to 25-50% of variance. Training can still largely improve VO2
max.
Slide 36
AGE Peaks around late adolescence and early adulthood and then
declines after the age of 25. Declines around 10% per decade.
Training and being physically active can reduce the decline.
Slide 37
TRAINING STATUS (AEROBIC OR CARDIOVASCULAR FITNESS LEVEL)
Aerobic training can substantially increase VO2 max. Average VO2
max for untrained adult male 20-29 is 43-52 mL/kg/min. Average VO2
max for untrained adult female 20-29 is 33-42 mL/kg/min. Trained
endurance athlete can be up to 50-75 mL/kg/min. Refer to table 3.1.
Why does a swimmer have a higher VO2 max than a weight lifter of
the same sex and age?
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YOUR TURN Why is VO2 max expressed relative to bodyweight. List
and briefly summarize the factors that can affect VO2 max in a
table Have a look at the table on pages 102-103 and explain why
nordic skiiers have a much higher VO2 max than a weightlifter?
Slide 39
OXYGEN DEFICIT O2 deficit is the state where there is a
shortfall of oxygen consumption and use. This can often occur at
the beginning of exercise. Particularly maximal intensity exercise.
Where the oxygen your body requires isnt being delivered by the
cardiovascular and respiratory systems. In other words it takes
your body a while to adjust. What acute responses cause oxygen
deficit to occur?
Slide 40
STEADY STATE Steady state is the state in which OXYGEN DEMAND =
OXYGEN SUPPLY. Anywhere from a few seconds to a few minutes into
exercise Coincides with a plateau in HR and V.
Slide 41
EPOC Your turn Define EPOC? What did it used to be called? Why
doesnt our breathing and HR return to normal resting levels
straight away after exercise
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YOUR TURN Why does O2 deficit accrue at the start of exercise?
What factors determine the size of the O2 deficit? When is steady
state achieved during exercise? What are the functions of EPOC? How
are O2 deficit and EPOC related?
ACUTE MUSCULAR RESPONSES Increased motor unit and muscle fibre
recruitment needed for muscular contractions to create force
Increased blood flow to muscles to deliver oxygen to working
muscles Increased muscle temperature due to increased blood flow
Increased muscle enzyme activity enzymes are required to break down
the ATP for energy Increased oxygen supply and use muscles extract
and use more cells from the blood Depleted energy substrates
(muscle energy stores depleted ATP, PC, glycogen and triglyceride
stores