aerobic exercise (vo2max)

8/11/2019 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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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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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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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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Testing

1. Safer

2. Controlled pace (motivation not a

factor) 3. Not population specific (no pacing

advantage)

4. Quick assessment 5. Cost effective



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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

aerobic exercise (vo2max)

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