1B exercise capacity

Question 1

Define exercise

Answer 1

Purposeful, structured activity that involves gross muscular activity to improve physical condition (e.g. jogging, stretching)

Question 2

Define physical activity

Answer 2

A holistic term that includes all (purposeful and incidental) muscular activity of all intensities (e.g. walking, stairs)

Question 3

Define activities of daily living

Answer 3

Basic independent self-care tasks done on a daily basis that require coordination, strength and range of motion

Question 4

What (in the lungs) is needed for efficient gas exchange?

Answer 4

• Maximum coupling between ventilation and perfusion
• Inadequacy of either V or Q will have significant impact on removal of CO2 and blood oxygenation

Question 5

How does the capillaries react to non-ventilated alveoli due to pathology?

Answer 5

• Pulmonary circulation has specialised cells to detect local O2 conc
• If there’s an ischaemic environment with low O2, the capillaries will vasoconstrict
• This increases resistance and decreases blood flow so blood preferentially goes to other more ventilated areas in lungs

Question 6

What does the cardiopulmonary exercise test involve?

Answer 6

• Uses a cycle ergometer or treadmill
• Intensity is incremental
• Undertaken under close clinical supervision in a controlled environment
• ECG, ventilation, O2 and CO2 routinely measured

Question 7

What are the outputs of cardiopulmonary exercise test?

Answer 7

• Lots of data
• Peak VO2 usually the primary outcome (volume of oxygen consumed)
• ECG changes monitored throughout

Question 8

What are the advantages to a cardiopulmonary exercise test?

Answer 8

• Quantifies performance in relation to metabolism
• Precise and reproducible
• Continuous monitoring for safety

Question 9

What are the disadvantages of a cardiopulmonary exercise test?

Answer 9

• Requires skilled technical support (calibration)
• Very expensive (initial and ongoing costs)
• Needs dedicated space

Question 10

What is the six minute walk test?

Answer 10

• Uses a 20-30m flat course (e.g. corridor)
• Objective is to cover greatest distance as possible in 6 minutes
• Externally timed by assessor
• Sub-maximal test

Question 11

What are the outputs of a six-minute walk test?

Answer 11

• Primary outcome is total distance walked in 6 mins
• Secondary variables may be ‘perceived exertion’ scales, heart rate and pulse oximetry

Question 12

What are the advantages of the six minute walk test?

Answer 12

• Patient-driven pace- speeding up, slowing down and rest OK
• Cheap to deploy
• Validated in many clinical populations

Question 13

What are the disadvantages of the six minute walk?

Answer 13

• Requires a significant unobstructed course, it often undertaken in a public hospital corridor
• The pace is not reregulated

Question 14

What does the incremental shuttle walk test involve?

Answer 14

• Uses a 10m circuit
• Externally paced by an audio recording (like a bleep test)
• Each minute has one extra length than the previous minute e.g. minute 1 = 3 lengths of 20s, minute 2 = 4 lengths of 15s)

Question 15

What are the outputs of the incremental shuttle walk test?

Answer 15

• Primary outcome is total distance walked before volitional end
• Secondary variables may be ‘perceived exertion’ scales, heart rate and pulse oximetry

Question 16

What are the advantages of the incremental shuttle walk test?

Answer 16

• Cheap to deploy
• Validated in many clinical populations
• The external pacing helps some to achieve maximum levels

Question 17

What are the disadvantages of the incremental shuttle walk test?

Answer 17

• Requires an unobstructed course, it’s often undertaken in a public hospital corridor
• For some the incremental nature is difficult (min. speed 1.8km/hour)
• Ceiling effect of 1020m
• Patient can be penalised for poor pace management

Question 18

What disease most commonly limits exercise?

Answer 18

COPD- key symptom of it is breathlessness, especially during activities of daily living

Question 19

Describe this chart

Answer 19

• Pink lines indicate the ventilatory (anaerobic) threshold
• Top right chart- there is a gradient change at the anaerobic threshold where volume of CO2 produced is at a much higher rate than O2 being consumed
• Middle chart- shows VE (ventilation- amount of gas moving in and out of lungs). Starts to increase a lot at anaerobic threshold because of higher rate of VCO2 from then so ventilation needs to be higher to maintain acid-base homeostasis
• Top left chart- red line is VO2 which shows it plateaus- this means we have recorded max VO2- tricky to reach with older patients since they might not be able to ride the bike well in the cardiopulmonary test due to weak legs/uncomfortableness in sitting on saddle
• Bottom middle chart- RER is respiratory exchange ratio- VCO2 divided by VO2- this increases exponentially showing unsustainable rates of exercise as VCO2 increases a lot due to reliance on anaerobic energy production