Cardiorespiratory Fitness
Purpose of Evaluation
• educate client about current fitness levels
relative to age and sex
• Inspire individuals to take action to improve
their health-related physical fitness
• Use data to develop an individualized exercise
program
• identify areas of health/injury risk and possible
referral to the appropriate health professional
• to establish goals and provide motivation
• to evaluate effectiveness of exercise program
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Prolonged uninterrupted sitting, independent of physical
activity may be a risk factor for chronic disease.
Fig. 1. The movement continuum, illustrating the different
focus of sedentary physiology and exercise physiology. METs,
metabolic equivalent tasks.
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Fig. 3. Illustration of accelerometer data portraying an active couch
potato (moderate to vigorous intensity physical activity meeting
guidelines considered ‘‘physically active’’ but also a high level of
sedentary behaviour) versus an active non-couch potato (similar level
of moderate to vigorous intensity physical activity but low level
of sedentary behaviour). (From Dunstan et al. 2010a, reproduced
with permission of Touch Briefings, European Endocrinology,
Vol. 6, p. 21, # 2010.)
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Fig. 4. Portrayal of significantly different patterns of breaks in sedentary
time, based on accelerometer data from 2 different individuals
(a ‘‘prolonger’’ and a ‘‘breaker’’). (From Dunstan et al. 2010a,
reproduced with permission of Touch Briefings, European Endocrinology,
Vol. 6, p. 21, # 2010.)
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Pretest and Safety Procedures
• we have already discussed screening in
this area (HR, BP, observation)
• note the very cautious stance in the USA
(everyone over 45 should have physician
supervised graded exercise test)
• written emergency procedures
• written consent
• Cardiovascular responses to Acute
exercise are described on the
following slides
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•Cardiac output - rises with work rate
–Rest 5 L/min; Max 20 L/min
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•Heart rate increases linearly with work rate and O2 consumption
–Max HR = 220 - Age (one standard deviation is +/- 12bpm)
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•Stroke volume rises with exercise to maximum at ~50%
•Rest 60-100ml; exercise 100-120 ml
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Blood Pressure - Systolic increases linearly with intensity
(max 190 - 220 mmHg)
-Diastolic may increase slightly (+ 10 mmHg) or not change
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(a-v)O2 difference - Rest 5 ml/dl; Max 15 ml/dl
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Blood flow to working muscle increases with exercise
- from 20% to 85% of Q
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Oxygen Consumption
• Maximal oxygen consumption is most widely
recognized measure of cardiopulmonary fitness
• VO2 Max - highest rate of O2 use that can be
achieved at maximal exertion
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–
–
–
Fick Equation - VO2 = HR X SV X (a-v) O2
Table 3.3 ACSM
Absolute VO2- L/min or ml/kg/min (relative to body weight)
Relative VO2- given as % of VO2 max
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Oxygen Consumption
• Direct measurement of maximal oxygen uptake is the
most accurate - Douglas Bag
– Can also be estimated from peak work rate
– Treadmill speed and grade, cycle work rate
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O2 consumption
Sub max estimates
• sub-maximal tests have four assumptions
– Linear relationship between HR and O2 uptake
• Valid between 110 and 150 bpm
– Linear relationship between O2 uptake and
workload
– That the max HR at a given age is uniform
– That the mechanical efficiency (O2 uptake at a
given workload) is the same for everyone
• Not entirely accurate - can result in 1015% error in estimating VO2 max
– Tend to overestimate in highly trained,
underestimate in untrained
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Sub-maximal Tests
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•
•
•
•
We have done (or will do) the following
sub-max tests
YMCA sub-maximal bicycle test
Sub-maximal step test (mCAFT)
Rockport One Mile Walking Test
Treadmill walk test
Cooper test
• 1.5 mile test
Caution client to stop if feeling dizzy,
nauseous, very short of breath…
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Metabolic Equivalent (MET)
• Absolute resting O2 consumption
– 250 ml / min divided by body weight
• An MET is the average amount of oxygen
consumed while at rest. It is used a lot in ACSM
exercise prescription guidelines.
• MET = 3.5 ml / kg min
• Capacity to increase work rate above rest is
indicated by number of METs in max test
– Sedentary can increase to 10, an athlete up to 23 MET
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Cardiorespiratory Capacities
METs*
Athlete
Active
Sedentary
Cardiac Patient
- Class II
- Class III
- Class IV
16-20+
10-15
8-10
5-7
3-5
<3
VO2max
(ml/kg/min)
56-70+
35-53
28-35
18-25
11-18
<11
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Stress Tests
• Bruce protocol is a maximal stress test
– 3 min stages on treadmill
• Increase speed and percent grade (~3.5 MET / stage)
– Used as a diagnostic test for coronary heart
disease and estimating VO2 max
• must be cautious as Coronary Heart
Disease is the #1 killer in Canada
– if client has positive PAR-Q or is over 45 in the
states need physician to be present
• ECG (electrocardiograph) is used during
stress test, as 30% with confirmed CAD
have normal resting ECG
– but 80% of these abnormalities will show during
the stress of exercise
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Why Use Stress Tests?
• To establish, from ECG, a diagnosis of heart
disease and to screen for "silent" coronary
disease in seemingly healthy individuals.
• To reproduce and assess exercise-related
chest symptoms.
• To screen candidates for preventive and
cardiac rehabilitative exercise programs.
• To detect abnormal blood pressure response
• To define functional aerobic capacity and
evaluate its degree of deviation from normal
standards.
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Exercise-Induced Indicators of CHD
• Angina Pectoris present 30% of time.
• Electrocardiographic Disorders
– S-T segment depression
• Cardiac Rhythm Abnormalities
– premature ventricular contractions
– ventricular fibrillation
• Other Indices of CHD
– blood pressure (hypertensive and
hypotensive)
– heart rate (tachycardia or bradycardia)
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Blood Pressure Response
• normal for systolic to rise to 190-220
mmHg
• normal for diastolic to increase by 10
mmHg (can actually drop or stay the same)
• systolic should not exceed 260 mmHg
• diastolic increase >20 mmHg =
hypertensive
• exertional hypotensive response
– failure of Systolic pressure to rise by at least 20-30
mmHg, Or SBP drops (20 mmHg)
– Correlated with myocardial ischemia, left
ventricular dysfunction and risk of cardiac events 25
Heart Rate Response
• average resting HR 60-80 bpm but males
usually 7-8 beats/min lower than females
• tachycardia early in exercise is indicator of
potential problems
• bradycardia during exercise could be sinus
node malfunction or other heart disease
problems - or extreme fitness
• Remember max HR declines with age
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Rate Pressure Product
• Commonly used estimate of myocardial
workload and resulting oxygen
consumption.
RPP = SBP x HR
Where:
RPP = rate pressure product
SBP = systolic blood pressure
HR = heart rate
expect RPP to rise to > 25,000 (minimum adequate)
- age, clinical status, and medications(b blockers)
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can influence results
Guidelines for Stopping a Stress Test
• Repeated presence of premature ventricular
contractions (PVCs).
• Progressive angina pain regardless of the presence
or absence of ECG abnormalities consistent with
angina.
• An extremely rapid increase in heart rate may reflect a
severely compromised cardiovascular response.
• Electrocardiograph changes that include;
– S-T segment depression of 2 mm or more,
– AV block, PVC
• Failure of heart rate or blood pressure to increase
with progressive exercise
– or a progressive drop in systolic blood pressure (20mmHg)
with increasing work load.
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Guidelines for Stopping a Stress Test
• An increase in diastolic pressure of 20 mm Hg or
more, a rise above 115 mm Hg.
• Rise in systolic pressure > 250 mmHg
• Headache, blurred vision, pale, clammy skin, or
extreme fatigue.
• Subject requests to stop
• Marked dyspnea (breathlessness) or cyanosis.
• Dizziness or near fainting, light-headedness or
confusion
• Nausea
• Failure of equipment
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Interpretation of Bruce
• Prediction equations for VO2 max available
based on activity and health status and
gender (see lab book)
• Outcomes
– True positive - correctly predicts problem
– False Negative - results are normal - patient has
disease
– True Negative - results normal - no disease
– False Positive - abnormal test - no disease
• With any positive results secondary tests
are performed to confirm diagnosis
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CSEP-PATH - mCAFT
• mCAFT- modified Canadian Aerobic Fitness
Test
– Ability and efficiency of lungs, heart, bloodstream,
and exercising muscles in getting oxygen to the
muscles and putting it to work.
• Benefits of larger aerobic capacity
– daily activities
– reserve for recreation and emergencies
• decline 10 % per decade after age 20
– regular vigorous activity to deter this decline
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mCAFT Structure
• Step for 3 min intervals
– predetermined height and frequency (work rate)
– Note - final stages use one large step up from
back of steps
• Men stages 7 and 8, women stage 8
• Take HR at end of each stage
– assess if client will continue based on ceiling HR
(fig 7-10)
– utilize heart rate monitor, or radial pulse
• Take BP and HR after recovery
– to determine if client is back to resting levels
before release
– Cuff can be attached before trial, or quickly after
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Before Starting mCAFT
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•
•
•
Ensure Par-Q and consent completed
Determine starting stage p 62 CSEP-PATH
have clients practice
determine ceiling HR for that client
– 85% HR max = 0.85(220-age)
• Supervise client during recovery
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mCAFT
• V02 max= [17.2 +( 1.29 X O2 cost) - (0.09 X wt (kg))
- (0.18 X age (yrs))]
– O2 cost is determined using table on p 63 CSEP-PATH
• The final heart rate is not considered, only the
stage attained in assessing benefit zone
– Heart rate can be used to determine improvement
upon reappraisal if client does not move zones
• Determine health benefit rating p 68
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