Measurement of Cardiorespiratory Fitness

Question 1

Why do we test cardiorespiratory fitness (CRF)?

Answer 1

• To provide baseline data that can be used to develop an exercise programme
• To provide an objective measure of fitness
• To provide follow up data which can be used to evaluate an exercise programme
• To provide motivation for participants
• To educate participants concerning their fitness status

Question 2

How do we minimise risk in CRF testing?

Answer 2

1. Screening (medical contraindications to exercise)
2. Informed consent prior to exercise (signed consent)
3. Ensuring a safe environment
4. Monitoring patient throughout test

Question 3

List the precautions/contraindications for CRF testing

Answer 3

• Myocardial infarction (<1month)
• Unstable angina
• Uncontrolled cardiac arrhythmias
• Resting HR >120bpm after 10mins rest
• Resting SpO2 <85% on room air (RA)
• Acute non-cardiac disorder
• Physical disability affecting performance or safety
• Inability to obtain consent

Question 4

What are the pros and cons of maximal VO2max tests?

Answer 4

PROS: measure VO2max exactly, gold standard measure of fitness (used in research or elite sport)
CONS: require high level of motivation from pt, requires specialised equipment, labour intensive

Question 5

What are the pros and cons of submaximal VO2max tests?

Answer 5

PROS: more relevant to clinical/general population, less equipment required, safer & easier to perform
CONS: not as precise (VO2max found through extrapolation), motivation still required, staff need to be trained

Question 6

What are submaximal predictive and performance tests?

Answer 6

Predictive tests estimate VO2max by extrapolation. The test is terminated when the subject reaches 85% of predicted HRmax (220 – age = HRmax). This is due to the linear relationship btw HR and VO2. This is better suited to clinical areas.
Performance tests involve measuring responses to everyday (often functional) activities. This is more applicable to a clinical population

Question 7

Describe the 6-minute walk test (6MWT)

Answer 7

The pt walks a 25m track as fast as they can, as many times as they can in 6mins. Instrumentation is used for measuring HR, BP, SpO2, and dyspnoea (Borg scale). The instructions and encouragement is standardised, and the participant must walk only, not run

Question 8

What are the predictive equations for 6MWT?

Answer 8

For males: 6MWD(m) = 867 – (5.71xage in years) + (1.03xheight in cm)
For females: 6MWD(m) = 525 – (2.86xage in years) + (2.71xheight in cm) – (6.22xBMI)

Question 9

Describe the incremental shuttle walk test (ISWT)

Answer 9

The pt walks a 10m track and must cross the opposite line to complete that shuttle before beep goes. Instrumentation is used for measuring HR, BP, SpO2 and dyspnoea (Borg scale). The instructions are standardised, and it is important that the participant walks, not runs

Question 10

What is the predictive equation for ISWT?

Answer 10

VO2peak (ml/kg/min) = 4.19 + 0.025 x distance (m)