5: CRF

Question 1

Cardiorespiratory Fitness

Answer 1

– Maximal aerobic capacity
– Functional capacity/Physical work capacity
– Cardiovascular endurance, fitness or capacity
– Cardiorespiratory endurance, fitness or capacity

Question 2

Cardiorespiratory Fitness

Answer 2

• One’s ability to aerobically perform dynamic exercise utilising large
  muscle groups (maximal ability = max aerobic/CR capacity)
• Ability to perform dynamic, moderate to high intensity exercise
  involving large-muscle groups for prolonged periods (CR endurance).
• Reflects the functional capabilities of the heart, blood vessels, lungs
  and skeletal muscles to perform work.
• One of the best indicators of the health and function of the body

Question 3

Reasons for assessing
Cardiorespiratory Fitness

Answer 3

• Inform people about their current CRF status relative to
  standards and age & sex matched norms
• Tailor goals/training programme to current CRF levels -
  motivational
• Periodically assessing CRF allows progress to be tracked
  – motivational
• Determine risk of developing cardiovascular disease
  (client education & developing appropriate exercise
  prescriptions to reduce their CVD risk)

Question 4

Why is CRF important for health?

Answer 4

1) Relates to functional status/capacity (ability
to perform common everyday activities)
2) Low CRF is an independent risk factor for
all-cause and cardiovascular (CV) mortality.

Question 5

Risk Factors for CVD

Answer 5

• Positive risk factors:
  – Age
  – Family history
  – Cigarette smoking
  – Sedentary lifestyle
  – Obesity
  – Hypertension
  – Dyslipidemia
  – Prediabetes
  – Low CRF
• Negative risk factor:
  – High serum HDL
  cholesterol

Question 6

• Low CR fitness increases the risk of:

Answer 6

– premature death from all causes (regardless of weight status)
– Premature death from CVD (regardless of weight status)
– developing CVD, Type 2 diabetes, some cancers

Question 7

Improving CRF (regardless of weight status) can reduce the risk of

Answer 7

all-cause and CVD death

Question 8

• High CR fitness is related to:

Answer 8

– higher levels of habitual PA
– higher PA levels are associated with many health benefits
– Higher functional status (ability to perform common
everyday activities without tiring)

Question 9

Pretest Standardizations for CRF
Assessments,
* Participants should be instructed to:

Answer 9

– Wear appropriate clothing
– Avoid tobacco & caffeine 3 hours prior to test
– Avoid alcohol 12 hours prior to test
– Obtain adequate sleep night before test
– Keep hydrated
– Avoid strenuous exercise for 24 hours before the test

Question 10

Gold standard measure of CRF

Answer 10

• Maximal exercise test with collection of
  expired gases to determine VO2max
• Performed in the Lab setting
• Primary outcome is directly measured
  VO2max
• Participant cycles or runs until complete
  exhaustion

Question 11

Selecting the Mode for Max Testing:
Common modes

Answer 11

• Treadmill—the default mode for most facilities due to its
  similarity to daily activities and typically the highest VO2max
• Cycle ergometer—non weight bearing exercise, good for obese or
  disabled individuals, trained cyclists, lower values for VO2max why?
• Test stopped at maximal capacity (indicators?) or if subject
  experiences any absolute or relative indications (see box 8.1. of
  ACSM textbook)
• Need to use a standard protocol for treadmill or cycle ergometer
  – Accurate and reliable measure of CRF
  – Interpret CRF results by comparing to normative data

Question 12

Measured and Estimated VO2max

Answer 12

• Gold standard tests will directly measure VO2max with a
  metabolic measurement system
• If metabolic system not available
  – VO2max can be estimated (based on exercise test time or workload achieved) using equations
  and/or
  normative data (as long as a standard protocol has been used)

Question 13

If maximal exercise testing with collection of expired gases is the gold standard:
Why can we not always perform this test?

Answer 13

• Lack of…
  – Facilities
  – Equipment
  – Personnel
  – Time
• Risk associated maximal exercise testing

Question 14

• Alternatives to estimate CRF are:

Answer 14

– Field tests
- Takes place in a variety of non laboratory settings, typically by a group people, max/near max tests and submax tests (level of effort limited to submaximal exertion)

Question 15

Field tests of CRF

Answer 15

– 1-mile walk test
– 1.5-mile run test
– 12 minute run test
– 3 minute step test
– 20 metre shuttle run test/bleep test

Question 16

Step Tests

Answer 16

• Fixed amount of work in a set amount of time (submax test)
• Subjects step up and down on a step height (16.25in) for 3
  minutes at a set rate (different step rates for men & women)
• Immediately after completion, heart rate (HR) is measured
  and used to estimate VO2max

Question 17

1 Mile walk test

Answer 17

• Subject asked to walk 1 mile around a measured course
  as quickly as possible
  – 1 foot in contact with ground at all times

Question 18

1.5 Mile run test

Answer 18

• Subject asked to run 1.5 miles around a measured course as
  quickly as possible
• VO2max(ml.kg.min-1) = 3.5 + 483/1.5 mile time (mins)

Question 19

• 12 minute walk/run test

Answer 19

• Subject covers maximum distance (expressed in meters)
  in 12 minutes
• VO2max(ml.kg.min-1) = (distance in meters – 504.9)/44.73

Question 20

Multistage Fitness Test (Bleep Test)

Answer 20

• Maximal exercise test
• Use the level and shuttle achieved to estimate VO2max using published equations or tables
  – e.g. see the bleep test score calculator on Topend Sports
• Use the level and shuttle achieved and compare it to normative data (age and sex) to categorise fitness level

Question 21

weakness of field tests to measure CRF

Answer 21

• Majority of field tests have been developed for use with younger, low risk individuals
• Many of these tests would not be suitable for individuals with moderate or high risk of CVD
• Estimating VO2max using prediction equations, measurement error

Question 22

Strengths of field tests to measure CRF

Answer 22

• Minimal equipment
• Low cost
• Personnel
• Time efficient
• Generally safe (for young, low risk groups)

Question 23

Factors influencing the accuracy &
reliability (consistency) of the measurement of CRF from field tests

Answer 23

• Subject not following pre-test instructions
• Tester not following standardised procedures
• Learning effect, not practising the test
  – 1.5 mile run test & 12 min walk/run test
• Subject motivation
  – bleep test, 1.5 mile run test & 12 min walk/run test
• Estimating VO2max using prediction equations introduces measurement error
• If the characteristics of the subject do not match the characteristic of the population used to develop the equation or the norms table then VO2max might be overestimated/underestimated