Exercise Physiology MAP = CO x TPR Cardiac output Structure of the heart Cardiac cycle Control of heart rate Control of stroke volume Total peripheral

Exercise PhysiologyExercise Physiology

MAP = CO x TPRMAP = CO x TPRCardiac outputCardiac output

Structure of the heartStructure of the heart

Cardiac cycleCardiac cycle

Control of heart rateControl of heart rate

Control of stroke volumeControl of stroke volume

Total peripheral resistanceTotal peripheral resistanceFunctions of vesselsFunctions of vessels

Local control of resistanceLocal control of resistance

Central control of resistanceCentral control of resistance

Regulation of CO and TPRRegulation of CO and TPR

Cardiovascular changes during exerciseCardiovascular changes during exercise

The Cardiac CycleThe Cardiac Cycle

SystoleSystole___________ phase___________ phase

DiastoleDiastole_________ phase_________ phase

Fig 9.5

• Systolic Blood Pressure (SBP) pressure measured in brachial artery during systole (ventricular emptying and ventricular contraction period)

• Diastolic Blood Pressure (DBP) pressure measured in brachial artery during diastole (ventricular filling and ventricular

relaxation)

• Mean Arterial Pressure (MAP) "average" pressure throughout the cardiac cycle against the walls of the proximal systemic

arteries (aorta)• estimated as: MAP = DBP + 1/3(SBP – DBP)

• Total Peripheral Resistance (TPR) - the sum of all forces that oppose blood flow

• Length of vasculature

• Blood viscosity

• Vessel radius

Definitions

TPR = ( MAP - MVP)

CO

Factors That Influence Arterial Factors That Influence Arterial Blood PressureBlood Pressure

Fig 9.8

LATE DIASTOLE

ATRIALSYSTOLE

ISOMETRIC VENTRICULARCONTRACTION

VENTRICULAR EJECTION

ISOMETRICVENTRICULARRELAXATION

THE CARDIAC CYCLE

DIASTOLE

PRELOAD AND AFTERLOAD IN THE PRELOAD AND AFTERLOAD IN THE HEARTHEART

INCREASE IN FILLING INCREASE IN FILLING PRESSURE=INCREASED PRELOADPRESSURE=INCREASED PRELOAD

PRELOAD REFERS TO END PRELOAD REFERS TO END DIASTOLIC VOLUME.DIASTOLIC VOLUME.

AFTERLOAD IS THE AORTIC AFTERLOAD IS THE AORTIC PRESSURE DURING THE EJECTION PRESSURE DURING THE EJECTION PERIOD/AORTIC VALVE OPENINGPERIOD/AORTIC VALVE OPENING..

LAPLACES’S LAW & WALL STRESS, LAPLACES’S LAW & WALL STRESS, WS = P X R / 2(wall thickness)WS = P X R / 2(wall thickness)

THE HEART AS A PUMPTHE HEART AS A PUMP

REGULATION OF CARDIAC OUTPUTREGULATION OF CARDIAC OUTPUT Heart Rate via sympathetic & parasympathetic nervesHeart Rate via sympathetic & parasympathetic nerves Stroke VolumeStroke Volume

Frank-Starling “Law of the Heart”Frank-Starling “Law of the Heart” Changes in ContractilityChanges in Contractility

MYOCARDIAL CELLS (FIBERS)MYOCARDIAL CELLS (FIBERS) Regulation of ContractilityRegulation of Contractility Length-Tension and Volume-Pressure CurvesLength-Tension and Volume-Pressure Curves The Cardiac Function CurveThe Cardiac Function Curve

CARDIAC OUTPUT = STROKE VOLUME x HEART RATE

Autoregulation (Frank-Starling “Law of the Heart”)

Contractility

SympatheticNervous System

ParasympatheticNervous System

ExerciseExercise

Cardiorespiratory System At Rest and With Cardiorespiratory System At Rest and With ExerciseExercise

Heart RateHeart RateRest Rest 50-90 bpm50-90 bpmExerciseExercise Up to 170-210 bpmUp to 170-210 bpm

RespirationsRespirationsRestRest 12-20 breathes per minute12-20 breathes per minuteExerciseExercise 40-60 breathes per minute40-60 breathes per minute

Blood Pressure (Systole=Contraction Diastole=Relaxation)Blood Pressure (Systole=Contraction Diastole=Relaxation)RestRest 110/70110/70ExerciseExercise 175/65175/65

Cardiac Output (SV x HR)Cardiac Output (SV x HR)RestRest 5 quarts/min. 5 quarts/min.ExerciseExercise 20 or more quarts/min.20 or more quarts/min.

CO is redirected due to:

local metabolic autoregulation in working muscle causing arteriolar dilation

offset by centrally mediated generalised sympathetic arteriolar constriction

circulating epinephrine causes- arteriolar constriction in most tissues

(ie those expressing receps)

Blood flow during exercise

Redistribution of Blood Flow Redistribution of Blood Flow During ExerciseDuring Exercise

Fig 9.24

The Effects of ExerciseThe Effects of Exercise

Immediate Effects:Immediate Effects:

*Increase in HR, since higher demand for oxygen.*Increase in HR, since higher demand for oxygen.

*Increase in BP, as a result of ↑ blood flow.*Increase in BP, as a result of ↑ blood flow.

*Increase in supply, delivery, and use of oxygen by *Increase in supply, delivery, and use of oxygen by muscle.muscle.

*Increase in body temperature.*Increase in body temperature.

*Increase in certain hormones/ neurotransmitters , *Increase in certain hormones/ neurotransmitters , especially epinephrine which stimulates a rise in especially epinephrine which stimulates a rise in all body functions.all body functions.

*Increase in metabolism.*Increase in metabolism.

Effects of Aerobic Training on Effects of Aerobic Training on Cardiovascular FunctionCardiovascular Function

Heart rateHeart rateStroke volumeStroke volumea-v O2 differencea-v O2 differenceCardiac outputCardiac outputVO2VO2Systolic blood Systolic blood pressurepressureDiastolic blood Diastolic blood pressurepressure

Coronary blood flow Brain blood flow Blood volume Plasma volume Red blood cell mass Heart volume

Myocardial HypertrophyMyocardial Hypertrophy

Aerobic training. Thicker walls Aerobic training. Thicker walls and greater volumeand greater volumeStrength training. Thicker walls Strength training. Thicker walls onlyonlyPathological. Thicker but weaker Pathological. Thicker but weaker wallswalls

CV Function and Endurance TrainingCV Function and Endurance Training

Increase in EDV (increase chamber size)Increase in EDV (increase chamber size)Endurance trainingEndurance training

Increase myocardial mass (increase force Increase myocardial mass (increase force of contraction)of contraction)

Strength trainingStrength training

CV Function and Endurance TrainingCV Function and Endurance Training

Increase in parasympathetic inhibition of Increase in parasympathetic inhibition of the SA node (mostly at rest)the SA node (mostly at rest)

Decrease in sympathetic stimulation Decrease in sympathetic stimulation (mostly during exercise)(mostly during exercise)

BLOOD PRESSUREBLOOD PRESSURE

Greatest effect on high blood pressureGreatest effect on high blood pressure

Systolic: lower resting and submaxSystolic: lower resting and submax10 mm Hg decrease10 mm Hg decrease

Diastolic lower maximumDiastolic lower maximum

Why?Why?Weight lossWeight loss

Reduce sympathetic stimulationReduce sympathetic stimulation

OtherOther

BLOOD FLOWBLOOD FLOW

Blood flowBlood flow

Coronary: higher at rest, submax, and Coronary: higher at rest, submax, and max.max.

Greater SV and lower HR cause a Greater SV and lower HR cause a reduction in mVO2.reduction in mVO2.

Greater vascularity only in diseased Greater vascularity only in diseased heartshearts

Redistribution of Blood Flow Redistribution of Blood Flow During ExerciseDuring Exercise

Fig 9.24

BLOOD FLOWBLOOD FLOW

Skeletal blood flowSkeletal blood flow

Increase vasularity (capillaries)Increase vasularity (capillaries)Increased O2 and fuel deliveryIncreased O2 and fuel delivery

Decrease resistance Decrease resistance →→ decrease afterload decrease afterload →→ increase Qincrease Q

Decrease flow at submax exerciseDecrease flow at submax exerciseCompenstated by an increase O2 extractionCompenstated by an increase O2 extraction

Greater blood flow to skinGreater blood flow to skin

Increase flow at maximal exercise (10%)Increase flow at maximal exercise (10%)Due to greater Q and vasularityDue to greater Q and vasularity

20mmHg 20mmHg0mmHg

20mmHg

0mmHg

20mmHg

+80mmHg

-40mmHg

-20mmHg

100mmHg

Causes venous distension in legsCauses venous distension in legs VR, VR, EDV, EDV, preload, preload, SV, SV, CO, CO, MAP MAP causes orthostatic (postural) hypotensioncauses orthostatic (postural) hypotension

Chronic adaptations to Aerobic trainingChronic adaptations to Aerobic training

WITHIN THE MUSCLE TISSUEWITHIN THE MUSCLE TISSUE The following tissue changes occur:The following tissue changes occur: Increased O2 utilisationIncreased O2 utilisation

increased size and number of mitochondriaincreased size and number of mitochondria Increased myoglobin storesIncreased myoglobin stores

Increased muscular fuel storesIncreased muscular fuel stores Increased oxidation of glucose and fatsIncreased oxidation of glucose and fats Decreased utilisation of the anaerobic glycolysis Decreased utilisation of the anaerobic glycolysis

(LA) system(LA) system Muscle fibre type adaptations Muscle fibre type adaptations

Chronic adaptations to Aerobic Chronic adaptations to Aerobic trainingtraining

Cardiac hypertrophy (increased Cardiac hypertrophy (increased ventricular volume)ventricular volume)

Increased capillarisation of the heart Increased capillarisation of the heart musclemuscle

Increased stroke volume Increased stroke volume Lower resting heart rateLower resting heart rateLower heart rate during sub max Lower heart rate during sub max

workloadsworkloads Improved heart rate recovery ratesImproved heart rate recovery rates


Increased cardiac output at max. Increased cardiac output at max. workloadsworkloads

Lower blood pressureLower blood pressure Increased arterio-venous oxygen Increased arterio-venous oxygen

difference (a-VO2 diff)difference (a-VO2 diff) Increased blood volume and Increased blood volume and

haemoglobin levelshaemoglobin levels Increased capillarisation of skeletal Increased capillarisation of skeletal

musclemuscle


Changes to blood cholesterol, Changes to blood cholesterol, triglycerides, lipoprotein levels triglycerides, lipoprotein levels (L.D.L’s and H.D.L’s)(L.D.L’s and H.D.L’s)

Increased lung ventilationIncreased lung ventilation Increased max. oxygen uptake (VO2 Increased max. oxygen uptake (VO2

max)max) Increased anaerobic thresholdIncreased anaerobic threshold

Cardiovascular Adjustments Cardiovascular Adjustments to Exerciseto Exercise

Fig 9.23

LACATE LEVELSLACATE LEVELS

Lactic acid comes to blood from muscles, in which Lactic acid comes to blood from muscles, in which aerobic resynthesis of energy stores cannot keep aerobic resynthesis of energy stores cannot keep pace with their utilization and a oxygen debt is pace with their utilization and a oxygen debt is being incurred. being incurred.

With increased production of Lactic acid, the With increased production of Lactic acid, the increase in ventilation and production of carbon-increase in ventilation and production of carbon-dioxide remains proportionate, to an extent.dioxide remains proportionate, to an extent.

If lactic acid accumulates further , it causes If lactic acid accumulates further , it causes metabolic acidosismetabolic acidosis

Accumulation in skeletal muscles causes pain.Accumulation in skeletal muscles causes pain.

The respiratory rate after exercise does not The respiratory rate after exercise does not reach basal levels until the oxygen debt is reach basal levels until the oxygen debt is paid.paid.

This may take as long as 90 minutes. This may take as long as 90 minutes.

Stimulus: elevated lactic acid in blood Stimulus: elevated lactic acid in blood

When the oxygen debt is paid,When the oxygen debt is paid,

-ATP & phosphorylcreatine resynthesized-ATP & phosphorylcreatine resynthesized

-lactic acid is removed – 80% converted to -lactic acid is removed – 80% converted to glycogen, 20% metabolised in to CO2 & glycogen, 20% metabolised in to CO2 & H2OH2O

INCREASED ANAEROBIC OR LACTATE INCREASED ANAEROBIC OR LACTATE THRESHOLDTHRESHOLD

As a result of improved O2 delivery & As a result of improved O2 delivery & utilisation a higher lactate threshold (the utilisation a higher lactate threshold (the point where O2 supply cannot keep up with point where O2 supply cannot keep up with O2 demand) is developed.O2 demand) is developed.

Much higher exercise intensities can therefore Much higher exercise intensities can therefore be reached and LA and H+ ion accumulation be reached and LA and H+ ion accumulation is delayed.is delayed.

The athlete can work harder for longerThe athlete can work harder for longer

Blood Lactate LevelsBlood Lactate Levels

Effects of Exercise on Effects of Exercise on RespirationRespiration

When talking about When talking about the respiratory the respiratory system we are system we are talking about the talking about the lungs, air passages lungs, air passages and our breathing and our breathing (ventilation).(ventilation).

Respiratory CapacitiesRespiratory Capacities

Figure 13.9

Lung capacitiesLung capacitiesTotal lung capacity: The volume lation in the lungs at maximal in Total lung capacity: The volume lation in the lungs at maximal in

Tidal volume: The amount of air inhaled in or exhaled out of the lungs Tidal volume: The amount of air inhaled in or exhaled out of the lungs during quiet breathingduring quiet breathing

Inspiratory reserve volume: The maximal volume that can be inhaled Inspiratory reserve volume: The maximal volume that can be inhaled from the end inspiratory levelfrom the end inspiratory level

Expiratory reserve volume: The maximal volume of air that can be Expiratory reserve volume: The maximal volume of air that can be exhaled from end expiratory positionexhaled from end expiratory position

Residual volume: The volume of air that remains in the lung after a Residual volume: The volume of air that remains in the lung after a maximal expirationmaximal expiration

Vital capacity: the volume of air exhaled out after the deepest Vital capacity: the volume of air exhaled out after the deepest breathingbreathing


RESPIRATORY ADAPTATIONSRESPIRATORY ADAPTATIONS Just as there are cardiovascular Just as there are cardiovascular

adaptations to AEROBIC training adaptations to AEROBIC training there are also respiratory there are also respiratory adaptations. These include:adaptations. These include:

Increased lung ventilationIncreased lung ventilation Increased oxygen uptakeIncreased oxygen uptake Increased anaerobic or lactate Increased anaerobic or lactate

thresholdthreshold


RESPIRATORY ADAPTATIONSRESPIRATORY ADAPTATIONS INCREASED LUNG VENTILATIONINCREASED LUNG VENTILATION Aerobic training results in a more efficient Aerobic training results in a more efficient

and improved lung ventilation.and improved lung ventilation. At REST and during SUB MAX. work At REST and during SUB MAX. work

ventilation may be decreased due to ventilation may be decreased due to improved oxygen extraction (pulmonary improved oxygen extraction (pulmonary diffusion), however during MAX. work diffusion), however during MAX. work ventilation is increased because of ventilation is increased because of increased tidal volume and respiratory increased tidal volume and respiratory frequency.frequency.

Respiratory Adaptations Respiratory Adaptations From Aerobic TrainingFrom Aerobic Training

Respiratory system functioning usually does not limit Respiratory system functioning usually does not limit performance because ventilation can be increased to performance because ventilation can be increased to a greater extent than cardiovascular function.a greater extent than cardiovascular function.

Slight increase in Total lung CapacitySlight increase in Total lung Capacity Slight decrease in Residual Lung VolumeSlight decrease in Residual Lung Volume Increased Increased TTidal idal VVolume at maximal exercise levelsolume at maximal exercise levels Decreased respiratory rate and pulmonary ventilation Decreased respiratory rate and pulmonary ventilation

at rest and at submaximal exerciseat rest and at submaximal exercise (RR) decreases because of greater pulmonary efficiency(RR) decreases because of greater pulmonary efficiency

Increased respiratory rate and pulmonary ventilation Increased respiratory rate and pulmonary ventilation at maximal exercise levelsat maximal exercise levels from increased tidal volumefrom increased tidal volume

Cardiorespiratory EnduranceCardiorespiratory Endurance

VOVO2MAX2MAX is the best indicator of is the best indicator of

cardiorespiratory endurance.cardiorespiratory endurance.

VOVO2MAX2MAX

Maximal O2 consumption by tissues Maximal O2 consumption by tissues VO2VO2max = max = COCOmax * max * maximum O2 extraction maximum O2 extraction

by the tissue by the tissue

Absolute and relative measures.Absolute and relative measures.absoluteabsolute = = l l . . minmin-1-1

relativerelative = = ml ml .. kg kg-1 . -1 . minmin-1-1

VOVO22 = SV x HR x a-vO = SV x HR x a-vO2diff2diff

Effects on Oxygen Uptake or Effects on Oxygen Uptake or Volume of Oxygen Consumed Volume of Oxygen Consumed

(VO2)(VO2)Oxygen uptake (VO2) is the amount of Oxygen uptake (VO2) is the amount of

oxygen taken up and used by the body. It oxygen taken up and used by the body. It reflects the total amount of work being reflects the total amount of work being done by the body.done by the body.

During strenuous exercise there can be a During strenuous exercise there can be a twenty-fold increase in VO2 which twenty-fold increase in VO2 which increases linearly with increases in the increases linearly with increases in the intensity of the exercise.intensity of the exercise.

VO2VO2

Training has little effect on resting VO2Training has little effect on resting VO2Training has little effect on submaximal Training has little effect on submaximal VO2 VO2

Example, running at 8 mph at a 0% grade Example, running at 8 mph at a 0% grade is always at VO2 of ~24.9 ml/kg/minis always at VO2 of ~24.9 ml/kg/min

Training increases maximal VO2 Training increases maximal VO2 (VO2max) (VO2max)

15-2015-20% (but as high as 50%) increase.% (but as high as 50%) increase.

Effects on Oxygen Uptake or Effects on Oxygen Uptake or Volume of Oxygen Consumed Volume of Oxygen Consumed

(VO2)(VO2)As a person approaches exhaustion, his or As a person approaches exhaustion, his or

her VO2 will reach a maximum above her VO2 will reach a maximum above which it will not increase further.which it will not increase further.

This figure is his or her This figure is his or her VO2 Maximum; VO2 Maximum; that is, the largest amount of oxygen that a that is, the largest amount of oxygen that a person can utilize within a given time (for person can utilize within a given time (for example, 50 litres per minute). example, 50 litres per minute).

VO2maxVO2max

Training to increase VOTraining to increase VO2max2max

Large muscle groups, dynamic activityLarge muscle groups, dynamic activity

20-60 min, 3-5 times/week, 50-85% VO20-60 min, 3-5 times/week, 50-85% VO2max2max

Expected increases in VOExpected increases in VO2max2max

15% (average) - 40% (strenuous or 15% (average) - 40% (strenuous or prolonged training)prolonged training)

Greater increase in highly deconditioned or Greater increase in highly deconditioned or diseased subjectsdiseased subjects

Genetic predisposition Genetic predisposition Accounts for 40%-66% VOAccounts for 40%-66% VO2max2max

VO2maxVO2max

Higher Q at maxHigher Q at maxHigh a-v 02 High a-v 02 differencedifference


RESPIRATORY ADAPTATIONSRESPIRATORY ADAPTATIONS INCREASED MAXIMUM OXYGEN INCREASED MAXIMUM OXYGEN

UPTAKE (VO2 MAX)UPTAKE (VO2 MAX) VO2 max is improved as a result of aerobic VO2 max is improved as a result of aerobic

training – it can be improved between 5 to training – it can be improved between 5 to 30 %. (LIU page 255)30 %. (LIU page 255)

Improvements are a result of:Improvements are a result of:-Increases in cardiac output-Increases in cardiac output-red blood cell numbers-red blood cell numbers-a-VO2 diff -a-VO2 diff - muscle capillarisation- muscle capillarisation- greater oxygen extraction by muscles- greater oxygen extraction by muscles


RESPIRATORY ADAPTATIONSRESPIRATORY ADAPTATIONSVO2 MAX VO2 MAX

Respiratory Adaptations From Respiratory Adaptations From Aerobic TrainingAerobic Training

Unchanged pulmonary diffusion Unchanged pulmonary diffusion at rest and submaximal exercise.at rest and submaximal exercise.

Increased pulmonary diffusion Increased pulmonary diffusion during maximal exercise.during maximal exercise. from increased circulation and from increased circulation and

increased ventilationincreased ventilation from more alveoli involved during from more alveoli involved during

maximal exercisemaximal exercise

Increased A-VO2 difference Increased A-VO2 difference especially at maximal exercise.especially at maximal exercise.


RESPIRATORY ADAPTATIONSRESPIRATORY ADAPTATIONS WORDS to KNOWWORDS to KNOW Arterio-venous oxygen Arterio-venous oxygen

differencedifference Pulmonary diffusionPulmonary diffusion Lung ventilationLung ventilation Tidal volumeTidal volume Respiratory frequencyRespiratory frequency VO2 maxVO2 max Lactate thresholdLactate threshold

Pulmonary Adaptations:Pulmonary Adaptations:

Most static lung volumes remain Most static lung volumes remain essentially unchanged after training.essentially unchanged after training.


Tidal volume, though unchanged at rest Tidal volume, though unchanged at rest and during submaximal exercise, and during submaximal exercise, increases with maximal exertion.increases with maximal exertion.


Respiratory rate remains steady at rest, Respiratory rate remains steady at rest, can decrease slightly with submaximal can decrease slightly with submaximal exercise, but increases considerably with exercise, but increases considerably with maximal exercise after training.maximal exercise after training.


The combined effect of increased tidal The combined effect of increased tidal volume and respiration rate is an increase volume and respiration rate is an increase in pulmonary ventilation at maximal effort in pulmonary ventilation at maximal effort following training.following training.


Pulmonary diffusion at maximal work rates Pulmonary diffusion at maximal work rates increases, probably because of increased increases, probably because of increased ventilation and increased lung perfusion.ventilation and increased lung perfusion.


a-vOa-vO2diff2diff increases with training, reflecting increases with training, reflecting an increased oxygen extraction by the an increased oxygen extraction by the tissues and more effective blood tissues and more effective blood distribution.distribution.

Cardiorespiratory Adaptations Cardiorespiratory Adaptations From Anaerobic TrainingFrom Anaerobic Training

Small increase in cardiorespiratory enduranceSmall increase in cardiorespiratory endurance Small increase in VO2 MaxSmall increase in VO2 Max Small increases in Stroke VolumeSmall increases in Stroke Volume

Cardiorespiratory Adaptations Cardiorespiratory Adaptations From Resistance TrainingFrom Resistance Training

Small increase in left ventricle sizeSmall increase in left ventricle size Decreased resting heart rateDecreased resting heart rate Decreased submaximal heart rateDecreased submaximal heart rate Decreased resting blood pressure is greater than from Decreased resting blood pressure is greater than from

endurance trainingendurance training Resistance training has a positive effect on aerobic Resistance training has a positive effect on aerobic

endurance but aerobic endurance has a negative effect on endurance but aerobic endurance has a negative effect on strength, speed and power.strength, speed and power. muscular strength is decreasedmuscular strength is decreased reaction and movement times are decreasedreaction and movement times are decreased agility and neuromuscular coordination are decreasedagility and neuromuscular coordination are decreased concentration and alterness are decreasedconcentration and alterness are decreased

Aerobic TrainingAerobic Training

The minimum The minimum period for chronic period for chronic adaptations to adaptations to occur is 6 weeks.occur is 6 weeks.

Adaptations from Adaptations from aerobic training can aerobic training can occur at the muscle occur at the muscle site and in the site and in the cardio-respiratory cardio-respiratory systems.systems.

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Exercise Physiology MAP = CO x TPR Cardiac output Structure of the heart Cardiac cycle Control of heart rate Control of stroke volume Total peripheral