Cardiorespiratory Fitness (Assessment)

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Cardiorespiratory Fitness (Assessment)
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Purpose of Evaluation

• to assess current fitness levels relative to age
  and sex
• aid in development of an exercise program
• identify areas of health/injury risk and possible
  referral to the appropriate health professional
• to establish goals and provide motivation
• to evaluate progress

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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

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Cardiovascular responses to Acute exercise

• Cardiac output - rises with work rate
• Rest 5 L/min Max 20 L/min
• Heart rate increases linearly with work rate and
  O2 consumption (fig 4.10 - Neiman)
• Max HR 220 - Age (one standard deviation is /-
  12bpm)
• Stroke volume rises with exercise to maximum at
  50 of aerobic capacity
• Rest 60-100ml exercise 100-120 ml
• Blood Pressure - Systolic increases linearly with
  intensity (max 190 - 220 mmHg) - Diastolic may
  increase slightly ( 10 mmHg) or not change
• A-VO2 difference - Rest 5 ml/dl Max 15 ml/dl
• Blood flow to working muscle increases with
  exercise

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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
• VO2 HR X SV (A-V O2)
• Table 15.2 ACSM
• 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 three assumptions
• Linear relationship between HR, 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 10-15
  error in estimating VO2 max
• Tend to overestimate in highly trained,
  underestimate in untrained

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Sub-maximal Tests

• We have done (or will do) the following sub-max
  tests
• YMCA sub-maximal bicycle test
• Sub-maximal step test (mCAFT)
• Rockport Fitness Walking 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 VO2max
• Athlete 16-20 56-70
• Physically Active 10-15 35-53
• Sedentary 8-10 28-35
• Cardiac Patient
• - Class II 5-7 18-25
• - Class III 3-5 11-18
• - Class IV lt3 lt11

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Stress Tests

• Bruce protocol is a maximal stress test
• 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
• ECG (electrocardiograph) is used as 30 with
  confirmed CAD have normal resting ECG
• but 80 of these abnormalities will show during
  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 gt20 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

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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 gt 25,000
• - age, clinical status, and medications(b
  blockers) can influence results

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Guidelines for Stopping a Stress Test

• Repeated presence of premature ventricular
  contractions (PCVs).
• 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.
• Subject requests to stop

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Guidelines for Stopping a Stress Test

• Electrocardiographic changes that include the
  presence of
• S-T segment depression of 2 mm or more,
• AV block -
• 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 gt 260 mmHg
• Headache, blurred vision, pale, clammy skin, or
  extreme fatigue.
• 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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CPAFLA - 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

• Ensure Par-Q and consent completed
• Determine starting stage Figs 7-8,9
• have clients practice (p. 7-26)
• note ceiling HR for that client (fig 7-10)
• Upon completion client walks around for 2 minutes
• Sit down and get recovery BP and HR (set times
  listed in CPAFLA)

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Modified CAFT (mCAFT)
to be continued?
The CAFT was too sub-max for many people.
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mCAFT

• Aerobic Fitness Score 10 X 17.2 ( 1.29 X O2
  cost) - (0.09 X wt (kg)) - (0.18 X age (yrs))
• O2 cost is determined using Fig 7-11
• 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 zone using fig 7-12