ByBy

Riham Hazem RaafatRiham Hazem RaafatLecturer of Chest DiseasesLecturer of Chest Diseases

Ainshams UniversityAinshams University

Physiology of ExercisePhysiology of Exercise

Adapted from J. Dempsey

Takes place by means of diffusion of Takes place by means of diffusion of substances.substances.

External respiration: External respiration: (within the lungs)(within the lungs)Respiratory exchange ratio (R) is the ratio of Respiratory exchange ratio (R) is the ratio of

this exchange within the lungs between this exchange within the lungs between oxygen and carbon dioxideoxygen and carbon dioxide..

R= 200/250=0.8R= 200/250=0.8Internal respiration: Internal respiration: (within the muscles)(within the muscles)Gas exchange and nutrients.Gas exchange and nutrients.

Oxygen is consumed in the production of Oxygen is consumed in the production of

ATP and that co2 is produced as waste ATP and that co2 is produced as waste

product.product.

Respiratory quotient (RQ) Respiratory quotient (RQ) this ratio of o2 this ratio of o2

consumption to co2 production.consumption to co2 production.

It equals 0.8 It equals 0.8

1- The fuel needed for ATP production must 1- The fuel needed for ATP production must be supplied.be supplied.

2- Waste products that result from ATP 2- Waste products that result from ATP production must be removed.production must be removed.

- Metabolic parameters: Metabolic parameters: VO2, VCO2, VO2 max, AT, VO2, VCO2, VO2 max, AT, RER (RQ), PHRER (RQ), PH

- Pulmonary parameters:Pulmonary parameters: Ventilatory: Ventilatory: VE’ (RR x Vt), BR (VE max/MVV), PAO2-VE’ (RR x Vt), BR (VE max/MVV), PAO2-

PaO2PaO2 Gas Exchange (respiratory): Gas Exchange (respiratory): So2, Vd/Vt (for V/Q So2, Vd/Vt (for V/Q

mismatch), VE’/VO2, VE’/VCO2mismatch), VE’/VO2, VE’/VCO2

- Circulatory parameters: Circulatory parameters: HR, HRR, O2 Pulse (for SV HR, HRR, O2 Pulse (for SV COP), ABG, ECG COP), ABG, ECG

- Metabolic parameters:- Metabolic parameters: 1- Oxygen consumption:1- Oxygen consumption:

-Normally at rest average 250 ml/min (3.5-4 -Normally at rest average 250 ml/min (3.5-4 ml/min/kg), with exercise it will increase directly ml/min/kg), with exercise it will increase directly with the level of muscular work, VO2 increase with the level of muscular work, VO2 increase until exhaustion occurs and maximum level of until exhaustion occurs and maximum level of O2consumption(VO2max) is reached.O2consumption(VO2max) is reached.-- VO2 max is a reproducible , well defined VO2 max is a reproducible , well defined physiologic end point so it is used as a definitive physiologic end point so it is used as a definitive indicator of an individual s muscular work indicator of an individual s muscular work capacity. Normally range from 1700-5800 ml/ capacity. Normally range from 1700-5800 ml/ min min

2- CO2 production:2- CO2 production:

Normally 200ml/min (2.8 ml/min/kg)Normally 200ml/min (2.8 ml/min/kg)

During the initial phase of exercise it During the initial phase of exercise it

increase at a rate similar to VO2, once the increase at a rate similar to VO2, once the

anaerobic threshold has been reached , anaerobic threshold has been reached ,

VCO2 increases at a faster rate than VO2. VCO2 increases at a faster rate than VO2.

the faster rate is the result of additional CO2 the faster rate is the result of additional CO2

production from HCO3/CO2 buffering production from HCO3/CO2 buffering

mechanism.mechanism. PET CO2PET CO2 (end tidal pressure of CO2): is an index (end tidal pressure of CO2): is an index

of pulmonary blood flowof pulmonary blood flow

3- Anaerobic threshold:3- Anaerobic threshold: In normal individuals occurs at approximately In normal individuals occurs at approximately

60% ± 20% of the persons VO2 max.60% ± 20% of the persons VO2 max. At the onset of the AT , there is marked At the onset of the AT , there is marked

increase in CO2 production because of lactic increase in CO2 production because of lactic acid buffering and a compensatory increase acid buffering and a compensatory increase in ventilation.in ventilation.

After the onset of the AT, a breathlessness After the onset of the AT, a breathlessness develops and a burning sensations begins in develops and a burning sensations begins in working muscles.working muscles.

4- Respiratory Quotient:4- Respiratory Quotient: CO2 production ↑ during exercise esp. after the AT CO2 production ↑ during exercise esp. after the AT

has been achieved →↑RQ from resting levels of 0.8 has been achieved →↑RQ from resting levels of 0.8 to beyond 1.0to beyond 1.0

The subject will be able to continue exercise for a The subject will be able to continue exercise for a short period of time as much as 1.5short period of time as much as 1.5

5- Blood PH:5- Blood PH: Remains relatively unchanged till the onset of AT → Remains relatively unchanged till the onset of AT →

the blood gradually becomes more acidotic as the the blood gradually becomes more acidotic as the body is less able to buffer the excessive acid (H) body is less able to buffer the excessive acid (H) produced by anaerobic metabolism .. It’s a direct produced by anaerobic metabolism .. It’s a direct way to measure AT with Lactate Level.way to measure AT with Lactate Level.

- Pulmonary Parameters:- Pulmonary Parameters:1-Minute Ventilation (VE’):1-Minute Ventilation (VE’): Normally = 5-6 l/min,100 l/min in maximal exercise.Normally = 5-6 l/min,100 l/min in maximal exercise. At the very start of an exercise → vent. ↑(d.t. resp. At the very start of an exercise → vent. ↑(d.t. resp.

centers stimulation by the brain motor cortex and centers stimulation by the brain motor cortex and joint proprioceptors)joint proprioceptors)

Humeral factors (chemoreceptors) do the fine tuning Humeral factors (chemoreceptors) do the fine tuning of vent.of vent.

The level of vent. continue increasing The level of vent. continue increasing correspondingly with the increase of the workload till correspondingly with the increase of the workload till AT reached → vent. ↑ in a rate greater than the rate AT reached → vent. ↑ in a rate greater than the rate of workload ↑to compensate for the additional C02 of workload ↑to compensate for the additional C02 produced during anaerobic metabolism.produced during anaerobic metabolism.

2- Tidal Volume: 2- Tidal Volume: Normally = 500 ml, 2.3-3 L during exercise Normally = 500 ml, 2.3-3 L during exercise Increase early in exercise and are initially Increase early in exercise and are initially

responsible for the increase in ventilationresponsible for the increase in ventilation

3- Respiratory Rate:3- Respiratory Rate: Normally = 12-16 bpm, up to 40-50 bpmNormally = 12-16 bpm, up to 40-50 bpm Responsible for the increase in minute ventilation Responsible for the increase in minute ventilation

that occur late in maximal exercise, esp. after AT that occur late in maximal exercise, esp. after AT reached reached

4- Dead space/ Tidal volume Ratio:4- Dead space/ Tidal volume Ratio:

Normally = 0.20-0.40, ↓ during exercise Normally = 0.20-0.40, ↓ during exercise

0.04-0.280.04-0.28

↓ ↓ significantly during exercise d.t ↑ in tidal significantly during exercise d.t ↑ in tidal

volume with constant dead spacevolume with constant dead space

5- Pulmonary capillary blood transit time:5- Pulmonary capillary blood transit time:

Normally= 0.75 second, ↓ 0.38 second d.t Normally= 0.75 second, ↓ 0.38 second d.t

↑ C.O.↑ C.O.

6- Alveolar-Arterial Oxygen Difference:6- Alveolar-Arterial Oxygen Difference:

Normally= 10 mmHg changes little until a Normally= 10 mmHg changes little until a heavy workload is achieved . However, it heavy workload is achieved . However, it can increase to 20-30 mmHg.can increase to 20-30 mmHg.

PAO2 = (FiO2- PaCO2) = (150- PaCO2)PAO2 = (FiO2- PaCO2) = (150- PaCO2)

PAO2-PaO2 = {150- (PaCO2 ÷ 0.8)}- PaO2 PAO2-PaO2 = {150- (PaCO2 ÷ 0.8)}- PaO2 (alveolar air equation)(alveolar air equation)

7- Oxygen Transport:7- Oxygen Transport:

Local conditions of increased temp., Local conditions of increased temp.,

PCO2 and a relative acidosis in the PCO2 and a relative acidosis in the

muscle tissues → greater release of muscle tissues → greater release of

oxygen by the blood for use by the tissues oxygen by the blood for use by the tissues

for metabolism. for metabolism.

8- Maximum Voluntary Ventilation:8- Maximum Voluntary Ventilation: Calculated at rest either directly or by the Calculated at rest either directly or by the

equation: FEV1 x 35 or 40equation: FEV1 x 35 or 40

9- Breathing Reserve:9- Breathing Reserve:

MVV – VE max = 11 l/min or equals 10-MVV – VE max = 11 l/min or equals 10-40% of MVV40% of MVV

It lowers in primary lung diseases It lowers in primary lung diseases (smallest in Obstructive Lung Diseases)(smallest in Obstructive Lung Diseases)

- Cardiovascular Parameters:- Cardiovascular Parameters:

1- Cardiac Output:1- Cardiac Output:

Normally = 4-6 L/min up to 20 L/minNormally = 4-6 L/min up to 20 L/min

Increase linearly with increases in the Increase linearly with increases in the

workload during exercise till the point of workload during exercise till the point of

exhaustion.exhaustion.

At work levels of up 50% of an individuals At work levels of up 50% of an individuals

exercise capacity, the ↑ in COP is d.t ↑ in exercise capacity, the ↑ in COP is d.t ↑ in

heart rate and stroke volume together. heart rate and stroke volume together.

After this point, it’ll be d.t. ↑ in heart rate.After this point, it’ll be d.t. ↑ in heart rate.

2- Stroke Volume:2- Stroke Volume:

Normally = 50-80 ml can double during Normally = 50-80 ml can double during exercise.exercise.

Increase linearly with increase in workload Increase linearly with increase in workload until a maximum value is achieved, ≈ 50% until a maximum value is achieved, ≈ 50% of an individuals capacity for exercise.of an individuals capacity for exercise.

After a HR of about 120 bpm , there is little After a HR of about 120 bpm , there is little additional increase in SV → COP additional increase in SV → COP increase based in HR.increase based in HR.

3- Heart Rate:3- Heart Rate:

Can increase as much as 2.5-4 times the Can increase as much as 2.5-4 times the

resting HR.resting HR.

HR max is achieved just prior of total HR max is achieved just prior of total

exhaustion, considered as physiologic end exhaustion, considered as physiologic end

point for each individual.point for each individual.

HR max (±10bpm)= 210-(0.65 X age)HR max (±10bpm)= 210-(0.65 X age)

HR max (±10bpm)=220- ageHR max (±10bpm)=220- age

4- Oxygen Pulse:4- Oxygen Pulse:

In order to meet the demands of In order to meet the demands of

increasing muscle work during exercise, increasing muscle work during exercise,

each heart contraction must deliver a each heart contraction must deliver a

greater quantity of oxygen out to the body.greater quantity of oxygen out to the body.

O2 pulse= VO2/HRO2 pulse= VO2/HR

Normally = 2.5-4 ml O2/ heart beat up to Normally = 2.5-4 ml O2/ heart beat up to

10-15 ml in exercise.10-15 ml in exercise.

Gives an idea about SV Gives an idea about SV COP COP

5- Blood Pressure:5- Blood Pressure: During exercise During exercise →↑systolic blood pressure (up to →↑systolic blood pressure (up to

200mmHg) while diastolic blood pressure remains 200mmHg) while diastolic blood pressure remains relatively stable( may ↑up to 90mmHg)relatively stable( may ↑up to 90mmHg)

Pulse pressure (difference between systolic and diastolic Pulse pressure (difference between systolic and diastolic pressure) ↑ during exercise.pressure) ↑ during exercise.

6- Arterial- Venous O2 Content Difference:6- Arterial- Venous O2 Content Difference: During maximal exercise the difference ↑ 2.5-3 times During maximal exercise the difference ↑ 2.5-3 times

the resting value. (N: 5 vol %)the resting value. (N: 5 vol %) The ↑ is due to the greater amounts of O2 that are The ↑ is due to the greater amounts of O2 that are

extracted by the working muscle tissue during exercise.extracted by the working muscle tissue during exercise.

7- Distribution of Circulation:7- Distribution of Circulation:

Circulation to the skeletal muscles Circulation to the skeletal muscles

increases which in turn increase the increases which in turn increase the

cardiac output.cardiac output.

Circulation to the heart ↑.Circulation to the heart ↑.

Skin perfusion ↑ as cooling mechanism for Skin perfusion ↑ as cooling mechanism for

the body but can ↓ at extreme exercise levels the body but can ↓ at extreme exercise levels

(as the muscles demand ↑)(as the muscles demand ↑)

Variables Normal Values in Exerc.

VO2max or VO2peak < 84% predicted

Anaerobic threshold 40–80% of VO2 max

Heart rate (HR( HR max 90% age predicted

Heart rate reserve (HRR( HRR <15 beats/min

O2 pulse (VO2/HR( < 80% )> 10-15 ml(

Breathing reserve (BR(MVV –VE max =11 l/min

)10-40% of MVV(

Respiratory frequency (f( > 60 breaths/min

VE/VCO2 (at AT( <34

VD/VT > 0.28; > 0.30 for age > 40 y

P(A–a)O2 > 35 mm Hg

Nine Panel PlotNine Panel Plot

Tests For Cardio-Pulmonary Tests For Cardio-Pulmonary InteractionsInteractions

Reflects gas exchange, ventilation, tissue O2, CO2.Reflects gas exchange, ventilation, tissue O2, CO2.

QUALITATIVE- QUALITATIVE-

History, examination, ABG, Stair climbing testHistory, examination, ABG, Stair climbing test

QUANTITATIVE-QUANTITATIVE- 6 minute walk test, CPET6 minute walk test, CPET

1) Stair Climbing Test1) Stair Climbing Test If able to climb 3 flights of stairs without stopping/dyspnea - If able to climb 3 flights of stairs without stopping/dyspnea -

↓ed morbidity & mortality↓ed morbidity & mortality If not able to climb 2 flights – high riskIf not able to climb 2 flights – high risk

2) 6MWT or CPET:2) 6MWT or CPET:- Gold standardGold standard- C.P. reserve is measured by estimating max. O2 uptake C.P. reserve is measured by estimating max. O2 uptake

during exerciseduring exercise- Modified if pt. can’t walk – bicycle/ arm exercisesModified if pt. can’t walk – bicycle/ arm exercises- If pt. is able to walk for >2000 feet during 6 minIf pt. is able to walk for >2000 feet during 6 min- VO2 max > 15 ml/kg/minVO2 max > 15 ml/kg/min- If 1080 feet in 6 mins : VO2 of 12 ml/kg/minIf 1080 feet in 6 mins : VO2 of 12 ml/kg/min- Simultaneously oximetry is done & if Spo2 falls >4%- high Simultaneously oximetry is done & if Spo2 falls >4%- high

riskrisk

Indications of Exercise TestingIndications of Exercise TestingA) Evaluate exercise intolerance or level of fitnessA) Evaluate exercise intolerance or level of fitnessB) Document or diagnose exercise limitation as a result of fatigue, B) Document or diagnose exercise limitation as a result of fatigue,

dyspnea, or paindyspnea, or pain1. 1. Cardiovascular diseasesCardiovascular diseases a. Myocardial ischemia or dyskinesiaa. Myocardial ischemia or dyskinesia b. Cardiomyopathyb. Cardiomyopathy c. Congestive heart failurec. Congestive heart failure d. Peripheral vascular diseased. Peripheral vascular disease e. Selection for heart transplantatione. Selection for heart transplantation2. 2. Pulmonary diseasesPulmonary diseases a. Airway obstruction (including cystic fibrosis) or hyperreactivitya. Airway obstruction (including cystic fibrosis) or hyperreactivity b. Interstitial lung diseaseb. Interstitial lung disease c. Pulmonary vascular diseasec. Pulmonary vascular disease3. 3. Mixed cardiovascular and pulmonary etiologiesMixed cardiovascular and pulmonary etiologies4. 4. Unexplained dyspneaUnexplained dyspneaC) Exercise evaluation for cardiac or pulmonary rehabilitationC) Exercise evaluation for cardiac or pulmonary rehabilitation1. Exercise desaturation/hypoxemia1. Exercise desaturation/hypoxemia2. Oxygen prescription2. Oxygen prescriptionD) Assess preoperative risk, particularly lung resection or reductionD) Assess preoperative risk, particularly lung resection or reductionE) Assess disability, particularly related to occupational lung diseaseE) Assess disability, particularly related to occupational lung diseaseF) Evaluate therapeutic interventions G) Pulmonary RehabilitationF) Evaluate therapeutic interventions G) Pulmonary Rehabilitation

Contraindications to Exercise TestingContraindications to Exercise TestingAbsoluteAbsolute A recent significant change in the resting ECG suggesting significant ischemia, recent A recent significant change in the resting ECG suggesting significant ischemia, recent

myocardial infarction (within 2 days), or other acute cardiac eventmyocardial infarction (within 2 days), or other acute cardiac event Unstable anginaUnstable angina Uncontrolled cardiac dysrhythmias causing symptoms or hemodynamic compromiseUncontrolled cardiac dysrhythmias causing symptoms or hemodynamic compromise Symptomatic severe aortic stenosisSymptomatic severe aortic stenosis Uncontrolled symptomatic heart failureUncontrolled symptomatic heart failure Acute pulmonary embolus or pulmonary infarctionAcute pulmonary embolus or pulmonary infarction Acute myocarditis or pericarditisAcute myocarditis or pericarditis Suspected or known dissecting aneurysmSuspected or known dissecting aneurysm Acute systemic infection, accompanied by fever, body aches, or swollen lymph glandsAcute systemic infection, accompanied by fever, body aches, or swollen lymph glandsRelativeRelative Left main coronary stenosisLeft main coronary stenosis Moderate stenotic valvular heart diseaseModerate stenotic valvular heart disease Electrolyte abnormalities (e.g., hypokalemia, hypomagnesemia)Electrolyte abnormalities (e.g., hypokalemia, hypomagnesemia) Severe arterial hypertension (>200 mm Hg / >110 mm Hg) at restSevere arterial hypertension (>200 mm Hg / >110 mm Hg) at rest Tachydysrhythmia or bradydysrhythmiaTachydysrhythmia or bradydysrhythmia Hypertrophic cardiomyopathy and other forms of outflow tract obstructionHypertrophic cardiomyopathy and other forms of outflow tract obstruction Neuromuscular, musculoskeletal, or rheumatoid disorders that are exacerbated by exerciseNeuromuscular, musculoskeletal, or rheumatoid disorders that are exacerbated by exercise High-degree atrioventricular blockHigh-degree atrioventricular block Ventricular aneurysmVentricular aneurysm Uncontrolled metabolic disease (e.g. diabetes, thyrotoxicosis, or myxedema)Uncontrolled metabolic disease (e.g. diabetes, thyrotoxicosis, or myxedema) Chronic infectious disease (e.g. mononucleosis, hepatitis, AIDS)Chronic infectious disease (e.g. mononucleosis, hepatitis, AIDS) Mental or physical impairment leading to inability to exercise adequatelyMental or physical impairment leading to inability to exercise adequately

Indications for stopping exerciseIndications for stopping exerciseAbsolute indications:Absolute indications: Drop in systolic blood pressure (persistently below baseline) despite an Drop in systolic blood pressure (persistently below baseline) despite an

increase in workloadincrease in workload Increasing anginal painIncreasing anginal pain Central nervous system symptoms (ataxia, dizziness, or near syncope)Central nervous system symptoms (ataxia, dizziness, or near syncope) Signs of poor perfusion (cyanosis or pallor)Signs of poor perfusion (cyanosis or pallor) Serious arrhythmias (high-grade ventricular arrhythmias such as Serious arrhythmias (high-grade ventricular arrhythmias such as

multiform complexes, triplets, and runs)multiform complexes, triplets, and runs) Technical difficulties monitoring the ECG or systolic blood pressureTechnical difficulties monitoring the ECG or systolic blood pressure Subject's request to stopSubject's request to stopRelative indications:Relative indications: ST or QRS changes such as excessive ST displacement, extreme ST or QRS changes such as excessive ST displacement, extreme

junctional depression, or marked axis shiftjunctional depression, or marked axis shift Fatigue, shortness of breath, wheezing, leg cramps, or claudicationFatigue, shortness of breath, wheezing, leg cramps, or claudication General appearance.General appearance. Less serious arrhythmias, including supraventricular tachycardiasLess serious arrhythmias, including supraventricular tachycardias Development of bundle branch block that cannot be distinguished from Development of bundle branch block that cannot be distinguished from

ventricular tachycardia.ventricular tachycardia.

Patterns of abnormal response to Patterns of abnormal response to exercise in different diseasesexercise in different diseases

 COPD ILD PVD Obesity Deconditio

ningHeart

failure

V’O2,peak Reduced Reduced ReducedReducedor Normal Reduced Reduced

ATNormal or Low

Normal or Low

Low Normal Normal Low

BR Vd / Vt

ReducedIncreased

ReducedIncreased

Normal Normal Normal Normal

HRRNormal or Increased

Normal or Increased

Normal Normal Normal Reduced

O2 pulse Normal Normal Reduced Normal Normal Reduced

Fall in SaO2

Present Present Present Absent Absent Absent