Assessing Cardiorespiratory
Endurance
A Fitness Indicator
Determination of Fitness Level
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Everyone possesses some degree of
cardiorespiratory endurance (CRE)
CRE=a health associated component
that relates to the ability of circulatory
and respiratory systems to supply fuel
during sustained physical activity and to
eliminate fatigue products after
supplying fuel.
VO2 max
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VO2 max is the most commonly used
index to assess CRE
Definition - The largest amount of
oxygen that an individual can utilize
during strenuous exercise to complete
exhaustion
Has become the accepted measure of
CRE
VO2 max
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Units
– liters/minute or ml/minute (absolute)
– ml/kg/min (relative to body weight)
– ml/kg of FFM/min (relative to FFM)
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Range 15 (sedentary with disease) to
75 (young endurance runner) ml/kg/min
Women about 10-20% lower than men
Methods of Determining VO2
max
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Submaximally
Maximally
GXT
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Graded Exercise Testing - GXT
(incremental increases in workload)
General Guidelines
– measure the subject’s 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
GXT
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General Guidelines
– All testing begins with a 2-3 min warm-up
– Cool- down at a low intensity for at least 4
minutes - continue measuring HR, BP and
RPE
– increase intensity in .5-2 MET increments
– closely observe subject for
contraindications
Submaximal Protocols
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Oxygen consumption for any given WL
does not vary between subjects
The slope of the line is about the same
for any two given subjects
The rate of increase in O2 consumption
with increasing WL does not vary
between subjects
Bruce Treadmill Protocol
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5. Stage 1
– Increase grade to 10%
– 3 minutes long
– Measure HR at end of each minute and BP
at end of each stage
Bruce Treadmill Protocol
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6. The objective is to reach a steady
state HR between 115 and 155 bpm
(usually occurs during the first 6
minutes of exercise or by the end of the
2nd stage) – Page 98 guidelines
7. Once subject reaches proper HR
terminate the test at the end of that
stage
Bruce Treadmill Protocol
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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
Treadmill Protocol
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10. Calculate VO2 from the gender specific
equations
Males
– VO2=SMVO2 [(HRmax-61)/(HRSM-61)]
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Females
– VO2=SMVO2[(HRmax-72)/(HRSM-72)]
– SMVO2 = submaximal VO2 from table or ACSM
equations
– HRSM = submax HR from test
Modified Bruce Protocol
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Start at 1.7 mph, 0% grade or at 1.7
mph and 5% grade (used on diseased
and elderly populations)
Treadmill Protocol
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Protocols should be individualized
Test time should ideally be 8-12min
Increments of 10-15 W/min or 1-3%/min
grade can be used for the elderly
Maximal Protocols
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Field Tests
4. 12 minute run
5. 1.5 mile run
6. Rockport Walking Test
Normal Responses to GXT
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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
Abnormal responses to GXT
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1. ST segment depression
2. Increased R-wave amplitude
3. V-tach
4. Multiform PVC’s
5. Failure of HR to rise with WL
6. Failure of systolic to rise
7. Systolic and diastolic greater than 250 or
120
Test Termination
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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)
Absolute
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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 PVC’s
10. ST segment depression
Absolute
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11. Excessive rise in BP (systolic >250;
diastolic >120)
12. Failure of HR to increase
Relative
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1.
2.
3.
4.
5.
6.
7.
ECG changes from baseline
Chest pain that is increasing
Wheezing
Leg cramps
High Systolic/Diastolic
Less serious arrhythmias
Less severe shortness of breath
Advantages of Submaximal
Testing
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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
Testing
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6. Don’t need highly trained personnel
7. Can do mass testing
8. No physician supervision required (if
symptom and disease free)
Disadvantages of Submaximal
Testing
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1. VO2 max is not directly measured
(error rate of 10-20%)
2. Don’t get a measure of true maximal
HR
– estimates of max HR using 220-age can
vary by +15 bpm for individuals of the
same age
Advantages and Disadvantages of
a Maximal Test
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Advantages
1. More accurate
Disadvantages
1. Motivation is a factor
2. More risk involved
3. Time
4. Cost of equipment (if using metabolic
cart)