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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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Fig. 1. The movement continuum, illustrating the different focus of sedentary physiology and exercise physiology. METs, metabolic equivalent tasks.

Prolonged uninterrupted sitting, independent of physicalactivity may be a risk factor for chronic disease.

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Fig. 3. Illustration of accelerometer data portraying an active couchpotato (moderate to vigorous intensity physical activity meetingguidelines considered ‘‘physically active’’ but also a high level ofsedentary behaviour) versus an active non-couch potato (similar levelof moderate to vigorous intensity physical activity but low levelof sedentary behaviour). (From Dunstan et al. 2010a, reproducedwith 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 sedentarytime, 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– 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 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 (ml/kg/min)

Athlete 16-20+ 56-70+

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 <3 <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

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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 productSBP = systolic blood pressure

HR = heart rate

expect RPP to rise to > 25,000 (minimum adequate)

- age, clinical status, and medications( blockers) can influence results

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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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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 Fig’s 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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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

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