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FISIOLOGI OLAH RAGA
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Function of Cardiorespiratory System
Transportation of O2and CO2
Transportation of nutrients/waste products
Distribution of hormones
Thermoregulation
Maintenance of blood pressure
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Role of the Heart
Moving O2from lungs to working muscle
Carry metabolism waste from tissue toexcretion organ
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Cardiac output
Cardiac output (Q) = Stroke volume (SV) Heart rate (HR) examples
rest: SV = 75 ml; HR = 60 bpm; Q = 4.5 L/min
exercise: SV = 130 ml; HR = 180 bpm; Q = 23.4L/min
Increased Cardiac Output Increase in HR & SV Enhances oxygen and fuel delivery to active
skeletal muscle and heart and speeds delivery ofcarbon dioxide
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Reflex control of cardiac output
Primary regulators
cardiovascular control center (medulla)
w/ activation of motor cortex, parallelactivation of sympathetic/parasympatheticnerves
parasympathetic inhibition predominatesat HR ~100 bpm
skeletal muscle afferents
sense mechanical and metabolicenvironment
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Reflex control of cardiac output
Secondary regulator
arterial baroreceptors
located in carotid bodies and aortic arch
respond to arterial pressure
Reset during exercise
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Cardiac Regulation
Intrinsic control
Frank-Starling Principle Ca2+influx w/ myocardial stretch
Extrinsic control
autonomic nervous system sympathetic NS (1control at HR >100 bpm)
parasympathetic NS (1control at HR
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Humoral Chemoreceptors
Pao2
Not normally involved in control
Paco2
Central PaCO2 chemoreceptors are 1stcontrol factorat rest
H+
Peripheral H
+
chemoreceptors are important factorduring high-intensity exercise
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Cardiac output affected by:
Preload end diastolic pressure (amount ofmyocardial stretch)
Afterload resistance blood encounters as itleaves ventricles
Contractility strength of cardiac contraction
Heart rate
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Factors Involved in Regulation of Cardiac Output
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Blood redistribution during exercise
Blood distribution muscles to 88% of all blood
other tissues (except brain)
Redistribution of blood to the working musclesby reducing blood flow to the kidneys,stomach, liver and intestines.
Redistribution of blood to the skin in order tomaintain body temperature.
Increased metabolic rate of working muscles
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Effect of blood redistribution
Increases skin blood flow
Helps remove heat
Decreased blood flow to kidneys
Diminished urinary output and maintenance of bloodvolume
Decreased visceral blood flow
Reduced activity in gastrointestinal tract
Vasoconstriction in the spleen
Increases blood volume
Maintenance or slight increase in brain blood flow
Increased blood flow to coronary arteries
Increased muscle blood flow
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Cardiovascular Responses to Exercise
Blood Flow to Muscles
Major portion of exercise cardiac output aredelivered to the working muscles
Rest: 4-7 ml of blood are delivered eachminute to every 100g of muscle increasessteadily until maximal
average 50-75 per 100g
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Figure 25-7: Distribution of cardiac output at rest and during exercise
Cardiovascular Response to Exercise
Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Di t ib ti f di t t t t d d i
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Distribution of cardiac output at rest and duringexercise
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Effect of exercise on blood distribution
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Cardiovascular Response to Exercise
Increased stroke volume only up to 40%-60%of maximal capacity & then caused byreduced filling time at higher heart rate
increased volume of venous blood return increased muscle pumping of venousblood
increased breathing (thoracic pressure)
supine positions
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Cardiovascular Response to Exercise
Increased ventrical enlargement capacity
Frank-starling law: when the ventriclestretches more, it will contract with more
force. Increased ventrical contractility
Aortic or pulmonary artery pressure
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Cardiovascular Response to Exercise
Increased heart rate / cardiac outputAnticipatory response(increased heart ratebefore exercise)
Caused by the release of epinephrine Steady state heart rate: during steady exercise
Maximum heart rate= 220 - age
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Cardiovascular Response to Exercise
Systolic B.P. increases with intensity
valsalva during resistance exercise
increased use of upper body musculature Diastolic B. P. does not change
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Cardiovascular Response to Exercise
Autoregulationis triggered by low musclePO2
Cardiovascular drift: increased H.R.compensates for a decreased S.V. from a
decreased total blood volume to maintain Q.
redistribution
decreased blood plasma
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Cardiovascular drift (CVD, CVdrift)
Phenomenon where some cardiovascularresponses begin a time dependent change, or"drift" after around 10 minutes of exercise in a
warm or neutral environment.
It is characterised:decreases in MAP and SV and aparallel increase in HR.
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Cardiovascular drift (CVD, CVdrift)
It is influenced by: ambient temperature,hydration and the amount of muscle tissueactivated during exercise.
To promote coolingblood flow to the skin isincreased, resulting in a shift in fluids from bloodplasma to the skin tissuedecrease in pulmonaryarterial pressure and reduced stroke volume inthe heart.
To maintain cardiac output at reducedpressurethe heart rate must be increased.
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Cardiovascular Responses to Exercise
Increased A-V O2 difference: representing theamount of O2 extracted from the blood to beused by the muscles.
Decreased plasma volume =decreasedperformance increased blood pressure forces
water from the vascular system to theinterstitial spaces.
increased intramuscular osmotic pressureattracts fluid to the muscles.
sweating
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Cardiovascular Responses to Exercise
Increased blood viscosity
decreasing O2 transport
Decreased blood pH level
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Cardiovascular Endurance
Definition: The ability of the heart, lungs, and blood vessels to
deliver adequate amounts of oxygen to the cells to meet thedemands of prolonged physical activity.
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Oxygen Consumption VO
2
Resting 3.5 ml (one metabolic
equivalent MET) of oxygen perkilogram of body weight perminute
ml/kgBW/min
Maximal oxygen normal 25-80ml*kg-1*min-1or 7.1 to 22.9METs
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Components of Oxygen Uptake
Heart Rate
Number of times the heart beats per minute.
(220-age = MHR)
* Maximal HR drops about one b/yr starting at 12 yr
* Normal Heart rate can range from 40-200
Stroke Volume
Arterial-Venous
Oxygen Difference
Amount of blood pumped by the heart in one beat.
* 50 ml per beat (untrained) to 200ml (trained)
Amount of oxygen removed from the blood in a given tim
period. (a-vO2 difference)
VO2(l/min) = heart rate x stroke volume x a-vO2 diff
CardiacOutput
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Cardiovascular Responses to Exercise
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Cardiovascular Responses to Exercise
Increased Cardiac Output
SV*HR
May increase 4X
5L/min to 20-22L/min
Stroke Volume begins toplateau at about 50-60%VO2max
Average college men:100-115 ml/beat
Average collegewomen: 25% less
Cardiovascular Drift
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Cardiovascular Responses to Exercise
Cardiac Output at Rest
Average HR 70bpm
Stroke Volume 71 ml/beat
Trained HR 50bpm
Stroke Volume 100ml/beat
Cardiac Output during Exercise
Average=5 to 20-22 L/min
Trained=5 to 35-40 L/min Equation: Trained vs. Untrained
195bpm x 113ml= 22,000ml/min
195bpm x 179ml= 35,000ml/min
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Cardiovascular Responses to Exercise
Conclusions about Cardiac Output:
Max SV is considerably larger duringrest and exercise in trained
Heart volume increase
Increased filling (preload)
Increase in venous return
Contractility increases
Frank-Starling Mechanism Can increase Cardiac Output 15-
20%
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Cardiovascular Responses to Exercise
Cardiac Output increases the greatestduring transition from rest to exercise
in trained Heart Rate increases linearly with
intensity
Untrained individuals have very littleincrease in SV from rest to exercise,
main increase in Cardiac Output is HR
Cardiovascular Responses to Exercise
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Cardiovascular Responses to Exercise
Heart Rate during exercise
HR and VO2 are linear Trained will experience a
higher level of exercise andoxygen uptake before reaching
a HR compared to untrained Oxygen uptake during
moderate exercise, HR of anathlete averages 70 bpm lower
than sedentary Maximal HR drops about one b/yr
starting at 12 yr
Normal Heart rate can range from
40-200
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Cardiovascular Responses to Exercise
A-vO2 Difference
The difference in the oxygen contentbetween arterial and venous blood
Untrained at Rest Only 5 ml of oxygen is used from the 20
ml of oxygen in each 100 ml of arterialblood that passes through capillaries
75% of bloods original oxygen load stillremains bound to hemoglobin
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Cardiovascular Responses to Exercise
Trained
Trained athletes have an increased a-vO2difference
Increase in capillaries
Increase in blood volume Shunting blood to working muscles
Increase in mitochondria density
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Cardiovascular Responses to Exercise
Opens dormant capillaries At rest, only 1 of every 30-40 capillaries is active
Opening provides the following:
Provides for a significant increase in muscleblood flow
This increase can be delivered with only aminimal increase in velocity of flow
Enhanced capillaries increases the effectivesurface for exchange between the blood andmuscle cells
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Cardiovascular Responses to Exercise
Blood Flow to Muscles Cont.
Capillaries Capillary to Fiber ratio (average 2.0 capillaries per
fibers)
Increase has been shown with training (5-20%)
Increases diffusion distance for oxygen andmetabolic substrates
Increases transit time, which prolongs thepassive exchange of gases that is essential forprolonged performance
Blood slowly travels through the capillary,gasses and metabolites diffuse from the bloodinto the muscle cell
Homeostatic Balancing of Exercise:
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Homeostatic Balancing of Exercise:Controlled Disruption
Feed forward reflexes
Anticipate demand
Heart & lungs
Protective reflexes
Stretch damage Temperature
sweating
peripheralblood flow
redistribution
Blood pressure constant
Homeostatic Balancing of Exercise:
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Homeostatic Balancing of Exercise:Controlled Disruption
Figure 25-8: Peripheral resistance and arterial blood pressure during exercise
Health Advantages of Regular Exercise:
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Health Advantages of Regular Exercise:Quality of Life
Cardiovascular disease risks: heart attack,
stroke, high BP blood pressure
LDL & triglycerides
HDL risks for diabetes
[blood [glucose]
obesity
stress association
immune function
(to a point)
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