aerobic exercise (vo2max)
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Assessing CardiorespiratoryEndurance
A Fitness Indicator
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Determination of Fitness Level
Everyone possesses some degree of
cardiorespiratory endurance (CRE)
CRE=a health associated componentthat relates to the ability of circulatory
and respiratory systems to supply fuel
during sustained physical activity and toeliminate fatigue products after
supplying fuel.
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VO2max
VO2max is the most commonly used
index to assess CRE
Definition - The largest amount ofoxygen that an individual can utilize
during strenuous exercise to complete
exhaustion Has become the accepted measure of
CRE
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AEROBIC GLYCOLYSIS AND THEELECTRON TRANSPORT CHAIN
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KREBSCYCLE
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METABOLISM OF FAT
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OXIDATIVE PHOSPHORYLATION
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VO2max
Units
liters/minute or ml/minute (absolute)
ml/kg/min (relative to body weight)
ml/kg of FFM/min (relative to FFM)
Range 15 (sedentary with disease) to
75 (young endurance runner) ml/kg/min
Women about 10-20% lower than men
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Methods of Determining VO2
max Submaximally
Maximally
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GXT
Graded Exercise Testing - GXT
(incremental increases in workload)
General Guidelines
measure the subjects HR and BP and
RPE at regular intervals (near the end of
each stage [HR, BP, RPE] or every minute[HR])
if HR does not reach steady state during
the stage extend stage 1 minute
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Submaximal Assumptions
1. A steady-state HR is obtained for
each exercise work rate
2. A maximal HR for a given age isuniform (220-age)
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Assumptions
3. Mechanical efficiency (ie. VO2at a
given work rate) is the same for
everyone. This may not be true and it has been
suggested that submaximal exercise
testing underestimates VO2maxin theuntrained and overestimates in the trained
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Submaximal Assumptions
4. There is a linear relationship
between HR and Workload
5. HR will vary depending on fitnesslevel between subjects at any given
workload
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Age vs. HR
HR vs. Age
90
140
190
240
10 20 30 40 50 60 70 80
Age (years)
HR(beats
/min)
HR - max
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Submaximal Protocols
Oxygen consumption for any given WL
does not vary between subjects
The slope of the line is about the samefor any two given subjects
The rate of increase in O2 consumption
with increasing WL does not varybetween subjects
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EXERCISE INTENSITY AND OXYGENUPTAKE
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Submax Protocols
HR does vary between subjects
rate of increase in HR depends on
fitness level
The more fit you are the lower your HR
at any given WL
An untrained person will reach their HR
max at a lower WL vs. a trained person
of the same age.
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HEART RATE AND INTENSITY
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HEART RATE AND TRAINING
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HR vs. Workload
90
110130
150
170
190
300
600
900
1200
1500
1800
2100
Workload (kgm/min
HR
(bpm)
untrn
trn
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HEART RATE, VO2, AND INCREASINGWORK
.
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HR vs. WL and VO2
0
50
100
150
200
250
150
0.6
600
1.5
1050
2.4
1500
3.5
1950
4.6
VO2(l/min) and Workoad
(kgm/min)
HR
(bpm)
Hr
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Submaximal Protocols
1. YMCA - bike
2. Astrand Rhymingbike
3. ACSM - bike
4. Bruce Protocol - treadmill
5. McCardles Step Test
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YMCA
Multi-stage protocol
3-4 consecutive 3 minute stages
HR between 110-150 bpm (the HR
range at which the relationship between
VO2and WL is most linear)
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YMCA Procedures
1. Adjust seat height (legs nearly
straight when extended - 5 bend)
2. Measure pre-exercise BP and HRwith subject seated on bike
3. Pedal at 50 rpm (if using a
metronome - 100x/minute)
4. Warm-up, zero resistance for 2-3
minute
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YMCA Protocol
5. Stage 1
.5 kp for 3 minutes
at every stage measure BP at 2.0 min(more often if hypertensive)
at every stage measure HR during last half
of minutes 2 and 3 if HR at 2 and 3 minutes differ by more
than 6 bpm extend the stage for 1 min
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YMCA Protocol
6. Stage 2
Workload in this stage and successive
stages depends on HR during stage 1 (p75 guidelines)
7. Continue test until HR recorded at
two successive WL are between 110and 150 bpm (for many this occurs
during 2nd and 3rd WL)
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YMCA Protocol
8. Note that if HR is greater than 110 at
end of 1st stage then only one more
stage is necessary 9. At completion of test reduce
resistance to .5kp and allow subject to
pedal for at least 4 minutes or until HRfalls below 100 bpm and BP stabilizes.
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YMCA Protocol
10. The HR measured during the last
minute of each stage is plotted against
workload. 11. The line generated from the plotted
points is extrapolated to the age-
predicted HR max 12. A perpendicular line is dropped to
the x-axis to estimate the work rate this
person would achieve if taken to max.
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0
50
100
150
200
150
0.6
450
1.2
750
1.8
1050
2.4
1350
3.2
1650
3.8
VO2(l/min) and Workload
(kgm/min)
HR
Hr
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ACSM Bike Test
1. 2-3 minute warm-up
2. Take HR twice during each stage (3
minute stages) and RPE/BP once(similar to YMCA)
3. If HRs are greater than 110, steady
state should be reached (HRs within6bpm) before increasing the workload
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ACSM
Protocol A B C (kgm/min)
Stage 1 150 150 300 Stage 2 300 300 600
Stage 3 450 600 900
Stage 4 600 900 1200
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ACSM
Protocol Selection
BW Very Active
(kg) No Yes 91 B C *very active is defined as aerobic exercise
20 minutes, 3 days/week
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ACSM
5. Terminate test when HR reaches
85% of age-predicted max HR or 70%
of HR reserve 6. Recovery at workload equal to the 1st
stage or less for at least 4 minutes with
HR, BP, and RPE monitored.
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ACSM
Plot HRs from last two stages to
determine VO2max much like YMCA.
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Astrand Rhyming
Single-stage test (VO2 max is
determined using 1 submaximal data
point-HR) Duration of test is 6 minutes
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Astrand Rhyming
1. Adjust seat height (legs nearlystraight when extended - 5 bend)
2. Measure pre-exercise BP and HRwith subject seated on bike
3. Pedal at 50 rpm (if using ametronome - 100x/minute)
4. Warm-up, zero resistance for 2-3minute
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Astrand Rhyming
5. Pedal rate is 50 rpm
6. Determine Workload
unconditioned males - 300 or 600 kgm/min
conditioned males - 600 or 900 kgm/min
unconditioned females - 300-450 kgm/min
conditioned females - 450 or 600 kgm/min
7. 6 minute test
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Astrand Rhyming
8. At end of 2nd minute of pedalingtake HR (BP at 1.25-1.5 min)
want the HR to be between 125-170bpm if less than 125 increase resistance by 1 kp
for men and 1/2 kp for women
if greater than 170 bpm decrease
resistance by 1 kp continue to monitor HR every minute until
HR exceeds 125
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Astrand Rhyming
9. At the end of the 5th and 6th minute
take HR and average the two values
(make sure values are within +6bpm toassure a steady state HR was obtained)
10. BP at 4:30 and 5:30
11. Reduce resistance and cool-downfor 4 minutes.
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Astrand Rhyming
10. Determine VO2from nomogram (p.
73 guidelines, p.69 Heyward)
11. Age-correction factor (p. 74guidelines, p.72 heyward)
12. Convert to relative value
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Treadmill Protocols
Bruce and Ellestad
larger increments
use on younger and/or more physicallyactive
Balke-Ware
smaller increments (1MET/stage or lower) use on older, deconditioned, and/or
diseased subjects
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Treadmill Protocol
Single-stage (using one data point)
even though we may have more than
one stage May need to have a long
accustomization period and explanation
of procedures before beginning
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Bruce Treadmill Protocol
1. Measure resting BP and HR while
standing on the belt of the treadmill
2. Ask subject to straddle the belt whilestarting treadmill at 1.7 mph and 0% grade
3. Ask subject to begin walking and when
comfortable release handrails
4. This is a warm-up and should continue
until subject is comfortable
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Bruce Treadmill Protocol
5. Stage 1
Increase grade to 10%
3 minutes long Measure HR at end of each minute and BP
at end of each stage
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Bruce Treadmill Protocol
6. The objective is to reach a steady
state HR between 115 and 155 bpm
(usually occurs during the first 6minutes of exercise or by the end of the
2nd stage)Page 98 guidelines
7. Once subject reaches proper HRterminate the test at the end of that
stage
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Bruce Treadmill Protocol
8. Reduce treadmill speed to 1.7mph
and 5% grade and cool-down for 4
minutes. 9. VO2 is estimated from the last
minute of a fully completed stage
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Treadmill Protocol
10. Calculate VO2from the gender specific
equations
Males VO2=SMVO2[(HRmax-61)/(HRSM-61)]
Females
VO2=SMVO2[(HRmax-72)/(HRSM-72)]
SMVO2= submaximal VO2from table or ACSM
equations
HRSM= submax HR from test
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Modified Bruce Protocol
Start at 1.7 mph, 0% grade or at 1.7
mph and 5% grade (used on diseased
and elderly populations)
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Treadmill Protocol
Protocols should be individualized
Test time should ideally be 8-12min
Increments of 10-15 W/min or 1-3%/mingrade can be used for the elderly
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McCardles Step Test
Bench ht. = 41.25 cm
Step Rate = 24 step/min (metronome =
96) for men and 22 step/min(metronome=88) for women
3 minutes of stepping
Record HR from the first 15secondsafter the stepping has stopped
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McCardle
Men
VO2= 111.33 - (0.42 x HRrec)
Women VO2= 65.81 - (0.1847 x HRrec)
value is ml/kg/min
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Maximal Testing
Assumption: The subject was highly
motivated and gave a maximal effort.
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Max Testing
Laboratory Tests
1. Open Circuit Indirect Calorimetry
2. Cycle
3. Treadmill (Bruce)
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Maximal Protocols
Field Tests
4. 12 minute run
5. 1.5 mile run
6. Rockport Walking Test
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Measuring Energy Costs of
Exercise
Direct calorimetrymeasures thebody's heat production to calculate
energy expenditure. Indirect calorimetrycalculates
energy expenditure from the respiratoryexchange ratio (RER) of CO2and O2.
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A CALORIMETRIC CHAMBER
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Open Circuit Indirect
Calorimetry (Gas Analysis)% O2in the Air=20.93% VI=Volume of Air
(for simplicity 21%) Inhaled by the subject For example 100L/min
Gas
Analysis
VE-Volume of Air
Expired by Subject
VO2E=Volume of O2expired=16L/min (lets assume for simplicity = VI
=100L/min)
VO2max= 21L/min 16 L/min
= 5L/min
R i t E h R ti
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Respiratory Exchange Ratio
The ratio between CO2released (VCO2)and oxygen consumed (VO2)
RER = VCO2/VO2 The RER value at rest is usually 0.78 to
0.80
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Cycle to Max
15 W/min protocol
VO2males=10.51 (power in W) + 6.35
(BW in kg) - 10.49 (age in y) + 519.3 VO2females=9.39 (power in W) + 7.7 (BW
in kg) - 5.88 (age in y) + 136.7
values are in ml/min - divide by BW inkg
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Treadmill to Max (Bruce)
VO2= 14.8 - 1.379 (time in min) + 0.451
(time2) - 0.012 (time3)
While holding handrail
VO2= 2.282 (time in min) + 8.545
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Population-specific Equations
P. 61 Heyward
Active vs. Sedentary, Gender specific,
Cardiac patients
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12 minute run
VO2
0
20
4060
80
1.1 1.3 1.5 1.7 1.9
Distance
VO2
VO2
12 i
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12 minute run
The further you can run in 12 minutes
the higher your VO2max
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1.5 mile run/Rockport Walking
0
20
40
60
80
6 8 10 12 14 16 18
time
VO2
VO2
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Normal Responses to GXT
1. Systolic BP increases in direct
proportion to increasing WL
2. HR increases linearly with WL 3. Diastolic BP changes very little
4. Shortened QT Interval
5. Reduced R-wave amplitude
6. Positive upslope of ST segment
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Abnormal responses to GXT
1. ST segment depression
2. Increased R-wave amplitude
3. V-tach 4. Multiform PVCs
5. Failure of HR to rise with WL
6. Failure of systolic to rise 7. Systolic and diastolic greater than 250 or
120
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Test Termination
1. Have reached a pre-determined
endpoint
Absolute 1. Suspicion of myocardial infarction
2. Moderate to severe angina
3. Drop in Systolic BP with increasing
Workload (>20)
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Absolute
4. Arrhythmias
5. Pale or cold and clammy skin
6. Severe shortness of breath
7. Dizzy, blurred vision, or confusion
8. Patient requests stop
9. V-tach or multiform PVCs
10. ST segment depression
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Absolute
11. Excessive rise in BP (systolic >250;
diastolic >120) 12. Failure of HR to increase
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Relative
1. ECG changes from baseline
2. Chest pain that is increasing
3. Wheezing
4. Leg cramps
5. High Systolic/Diastolic
6. Less serious arrhythmias
7. Less severe shortness of breath
Advantages of Submaximal
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Advantages of Submaximal
Testing
1. Safer
2. Controlled pace (motivation not a
factor) 3. Not population specific (no pacing
advantage)
4. Quick assessment 5. Cost effective
Advantages of Submaximal
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Advantages of Submaximal
Testing
6. Dont need highly trained personnel
7. Can do mass testing
8. No physician supervision required (ifsymptom and disease free)
Disadvantages of Submaximal
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Disadvantages of Submaximal
Testing
1. VO2max is not directly measured
(error rate of 10-20%)
2. Dont get a measure of true maximalHR
estimates of max HR using 220-age can
vary by +15 bpm for individuals of thesame age
Advantages and Disadvantages of
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Advantages and Disadvantages of
a Maximal Test
Advantages
1. More accurate
Disadvantages
1. Motivation is a factor
2. More risk involved
3. Time
4. Cost of equipment (if using metabolic
cart)
Walking/Running vs
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Walking/Running vs.
Cycling/Stepping
Walking/Running are the most natural
forms of locomotion (most Americans
are unaccustomed to cycling In general, subjects reach higher
VO2max values during treadmill tests
Treadmill are more expensive thancycles
Treadmill is less portable
Walking/Running vs
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Walking/Running vs.
Cycling/Stepping
Body weight has a much smaller effect
on cycle ergometry versus treadmills
Treadmill more dangerous (greater riskof a fall
Measurement of HR is more difficult on
a treadmill and while stepping
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