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Measuring PA
Subjective and Objective Measures
What to look for when comparing instruments:
- All common dimensions: Frequency, Duration,
Intensity, Type, and Context
- Energy expenditure measure in METS or calories/kilojoules
- Expense; cost in dollars
- Reactivity; level at which the measure biases the behaviour
- The trade off between practicality and accuracy/validity. More practical measures such as subjective measures (e.g. recall) are practical but have a corresponding loss of accuracy.
- Big groups= most practical measure needed, Individuals= most accurate measure
- Participant burden, obtrusive, unobtrusive, non-invasive, small, lightweight etc.
- Is it aerobic or walking only? Will it work for aquatic activities
- Settings; can it be used in a variety of settings? Is it used in the laboratory or field?
SUBJECTIVE MEASURES OF PA
|
Advantages of Recall,
Diaries or Logs: -Can capture both
qualitative and quantitative information -Quick and easy for large
groups -Cost-effective for large
studies -Usually low participant
burden -Can assess physical activity across multiple domains |
Disadvantages of Recall,
Diaries or Logs: -Not suitable for children under 10 or old adults due to cognitive limitations -Reliability and validity
problems; social desirability bias, memory limitations, misinterpretations of
PA dimensions -Interviewer may be needed |
OBJECTIVE MEASURES OF PA
|
Advantages of Direct
Observation: -Excellent qualitative and
quantitative information -Allows for specific PA
behaviours to be observed -Can collect contextual
information -Useful in community and
school -Software; easy data
collection |
Disadvantages of Direct
Observation: -Difficult with large
groups -Obtrusive -Time-intensive and
labour-intensive -May cause reactivity |
|
Advantages of Heart-Rate
Monitors: -Strong association with
energy expenditure -Describes Frequency,
Duration, Intensity -Quick and easy data
collection -Valid in Lab and
field-based settings -Low participant burden
(under 8h) |
Disadvantages of
Heart-Rate Monitors: -Expensive for large
groups -Only useful for aerobic
activities -Influenced by other
factors (e.g. stress) -Changes in HR lag behind
PA and can mask the sporadic nature of kids PA -Some discomfort (extended
periods) |
|
Advantages of Pedometers: -Inexpensive -Small, lightweight,
non-invasive -Easy to administer for
large groups -Objective measure of most
common PA (walking) -Can promote behavioural
change -Can identify changes in
rank-order -Appropriate for all
settings |
Disadvantages of
Pedometers: - Assesses only one PA
(walking, etc.) -Can’t store data or
record in real time -Not appropriate for
children as the pedometer misjudges locomotion. |
|
Advantages of
Accelerometers: -Small, lightweight,
non-invasive -Describes Frequency,
Duration, Intensity -Low burden compared to HR
monitors -Good for children over
self-reports -Can be used in field or
laboratory -Records in real time,
stores data |
Disadvantages of
Accelerometers: -Expensive for large
groups -Cannot be worn during
aquatic-based activities -Can underestimate
movement that is predominantly upper body -Provides no contextual information -Requires someone with knowledge to administer it |
|
Advantages of Doubly
labelled Water: -Unobtrusive,
non-invasive, any age group -Calculates VO2 -Accurately measures
energy expenditure |
Disadvantages of Doubly
labelled Water: -Very expensive -Provides no information
about dimensions -Provides no contextual
information |