This document discusses various methods for measuring physical activity, including questionnaires, diaries, direct observation, accelerometers, pedometers, heart rate monitoring, indirect calorimetry, and room calorimetry. It provides details on the principles, strengths, limitations, and validity of each method. The optimal choice of method involves balancing the research question, available resources, and feasibility of the study. Objective methods like accelerometers are now suitable for large epidemiological studies, while more precise tools are needed to quantify relationships between physical activity and health outcomes.

1. METHODS TO MEASURE PHYSICAL
ACTIVITY
XNN001 Population nutrition and physical
activity assessment

2. Definitions of physical activity
 Physical Activity is ”any bodily movement produced by
skeletal muscles that results in energy expenditure”
 The energy cost of physical activity may not
necessarily be equivalent to body movement
 Exercise is ”a specific type of PA that is planned,
structured and repetitive done to improve or maintain
physical fitness”
 Physical fitness is ”a set of attributes either health- or
performance related” and is not synonymous with
physical activity

3. Why bother to measure physical
activity ?
 To specify which dimension of physical
activity is of most importance for a particular
health outcome
 To make cross-cultural comparisons
 To monitor temporal trends within populations
 To measure the effect of interventions

4. Four parameters to describe PA
 Type
 The main physiological systems that are activated
during the activity
 Frequency
 The number of times a person engages in an activity
over a pre-determined period of time
 Duration
The temporal length of the activity
 Intensity
 The degree of overload an activity imposes on
physiological systems in comparison to resting states

8. Validity terminology 1
Criterion validity:
A questionnaire is validated against an objective
method.
The relationship is frequently reported as a
correlation coefficient (Pearson,Spearman)

9. Validity terminology II
Absolute validity:
The absolute outcome (i.e. EE or time spent in
activity) is compared to data from an objective
instrument which provides the same outcome
measure.
The association is usually reported as the
degree of agreement (Bland and Altman
method).

10. Validity terminology III
Concurrent validity:
A questionnaire is compared to another self-
report instrument (i.e. diary or another
questionnaire).
Although a high correlation between two
subjective instruments suggest validity, the
instruments are not of a different type and may
be subject to correlated error.

11. Self-Report Methods
 Questionnaires
 Activity Diaries
 Recall interviews

12. Questions to be asked of any
questionnaire
 What type of PA is it trying to assess ?
 What is the frame of reference of the
questionnaire ?
 Is the validation sample representative of the
study population?
 Has the questionnaire been validated against an
appropriate comparison method ?
 Is the instrument reliable?

13. PAQs used in the general
population
 Aerobic Center Longitudinal Study PAQ
 Baecke PAQ
 Bouchard 3-day physical activity record
 CARDIA physical activity history
 Framingham Physical activity index
 Godin Leisure-time exercise questionnaire
 HIP activity questionnaire
 Historical leisure activity questionnaire
 Kuopio Ischemic Heart Disease Study Q’s
 Lipid research clinics questionnaire
 Minnesota Leisure-time PA
 Modifiable Activity Questionnaire
 Paffenbarger Physical Activity Questionnaire
 Seven-Day Physical Activity Recall
 Stanford Usual Activity Questionnaire
 Tecumseh Occupational PAQ

17. Reliability and Validity of the
International Physical Activity
Questionnaire (IPAQ)
 8 forms
 14 centres in 12 countries
 Test-retest reliability (n=2632)
 Criterion validity (n=1854)
 Accelerometry as comparison instrument
https://sites.google.com/site/theipaq/questionnaires

19. Summary; Questionnaires
 Reliability; usually good to excellent
 Criterion validity; poor to moderate (although
significant)
 Absolute validity; questionable
 Questionnaires provide prevalence estimates of
physical activity
 Questionnaires provide the possibility to categorise
respondents into activity categories
 Questionnaires provide a poor measure of the
absolute time spent at different intensity levels and the
associated energy expenditure
 Questionnaires should be used with caution in
children

20. Looking for validation studies?
http://appliedresearch.cancer.gov/tools/paq/validation.ht
ml

21. 7-day physical activity diary
 Self completion diary
 High validity
 Reliability unknown

22. Stanford 7-day recall
 Interviewer administered questionnaire
 ~15 minutes to complete
 Acceptable validity and reliability
 High concurrent validity (r = 0.82 – 0.83)
 High test-retest reliability (r = .31, p = .021), and
very hard activities (r = .61, p = .0001)
 Acceptable validity
http://sallis.ucsd.edu/measures.html

23. Summary of subjective measures
of PA
 Many questionnaires available
 No gold standard measure
 All self-report measures associated with error
 Effective indicators of which people/ sub-
groups are more/ less active

24. Direct observation
 Used widely among children
 Children observed using specific observational system. Rating of
PAL into computer/ coding form.
 Number of available sustems (many validated against
accelerometry, heart rate monitoring, or energy expenditure
assessed by indirect calorimetry)
 Fargo Activity Timesampling Survey (FATS)
 Activity Patterns and Energy Expenditure (APEE)
 Behaviours of eating and physical activity for children’s health evaluation system
(BEACHES)
 Childrens activity rating scale (CARS)
 Studies of children’s activity and nutrition: Children’s activity Timesampling survey
(SCAN CATS)
 Level and Tempo of children’s activity LETO
 System for observing play and leisure activity in youth (SOPLAY)
 System for observing play and recreation in communities (SOPARC)
 Observational system for recording physical activity in children – preschool version
(OXRAC-P)

26. Assessment of body movement
based
on accelerometry
Principle:
Direct measure of body movement (acceleration).
When a person moves, the body is accelerated in
relation to the muscular forces responsible for the
acceleration of the body, and in theory to EE.
The acceleration can be measured in one
(vertical), two (vertical + medio-lateral) or three
(vertical + medio-lateral+anterior-posterior)
directions.

27. Physical activity assessment by the
MTI
Actigraph accelerometer
• Provide a detailed description of activity
patterns
•Excellent data storage capacity
• Extensively validated
• EE from complex movements are not reflected
by acceleration of the body (i.e. bicycling,
upper body work, walking up/down, carrying
goods etc.)
• Accelerometer data needs careful
interpretation

28. Summary of laboratory based
validation studies
 Strong association (r > 0.75) between EE and
activity counts in controlled settings
 EE prediction equations and thus, cut-off
points for different intensity levels, differ
depending on the calibration activities
performed and the setting of these activities
 Published cut-off points are highly variable

29. Summary; Accelerometers
 Extensively validated
 Applicable to children and adults
 Provide data on patterns of physical activity
 Valid for assessing the total amount of PA
 Cut-off points are arbitrary
 Laboratory based EE prediction equations are
not valid for free-living
 Applicable in relatively large studies (n=4000)

30. Pedometers
 Provide information about number of steps
 Should not be used to estimate energy
expenditure/ distance
 Cheap, readily available
 Unable to assess intensity of activity/ activities
other than walking
 Valid compared to accelerometers (r=0.86)
 Ideally worn over 7 days but 3 sufficient

32. Heart Rate Monitoring
Principle:
Linear relationship between heart rate and
energy expenditure during steady state work
loads with large muscle groups

34. Summary; Heart Rate
monitoring
 Extensively validated in adults, children
athletes, and obese
 Applicable in relatively large studies (n = 1000)
 Provide data on EE and pattern of PA
 Require individual calibration
 HR is affected by other factors than PA

36. The next generation of free-living
physical activity assessment
 Actiheart is a combined HR and movement
sensor (8g, waterproof) currently being
validated
 It will combine the advantages of body
movement and HR for prediction of PAEE
during free-living conditions

37. Indirect calorimetry
Measurement of the amount of heat produced
by a subject by determination of the amount
of oxygen consumed and the amount of
carbon dioxide eliminated.

38. Doubly labeled water
 Hydrogen & oxygen in water partially or completely replaced
with atypical isotopes deuterium & 18O
 Ingested by subject – elimination rate of deuterium isotope
assessed by measuring concentration in body water over
time
 CO2 production measured during the interval between first
and last body water samples
 O2 in body water equilibrates with the body's bicarbonate and
dissolved carbon dioxide pool, lost from body in CO2
 Additionally lost through body water loss
 Deuterium is lost only in water  deuterium change in body
water over time can be used to mathematically compensate for
the loss of tracer 18O to provide estimate for total carbon dioxide
production
 Can be used to calculate BMR

39. Room calorimetry
 Energy expenditure to be calculated
based on measurements of air
samples
 Study subject remains in closed
room
 Constant and measured supply of
fresh air
 Gas analysers attached to the unit
measure oxygen consumed and
carbon dioxide produced
 Balance of oxygen consumed and
carbon dioxide produced varies
according to activity and the
utilisation of different fuels by the
body (carbohydrate, protein and fat).

40. Other ways to measure PA at the
community/ population level
Environmental
 Miles of trails per capita
 # of PA facilities per capita in schools
 Availability of facilities to the public
 # of programs for PA in community
 # of agencies that sponsor PA events
 Zoning regulations
Behavioral Outcome Measures
 Observation of usage
 Membership in PA organizations (YMCA, Health clubs)
 Sales of selected PA equipment, videos, etc.

41. Other ways to measure PA at the
community/ population level
Policy & Regulations
 PE in school curriculum
 Amount/% of local budget per capita devoted to
physical activity/recreation
 Density of recreation facilities & new construction
Information
 % of health-care providers that engage the public to
exercise more
 # of worksite materials linked to PA
 % of schools offering curricula in grades k-12
 # of medical reports dealing with PA
 “Point of purchase” education materials on PA

42. SUMMARY
 The choice of a method is a trade off between
the research question, the available resources
and feasibility
 Valid objective methods are now available
which can be used in relatively large scale
epidemiological studies (n~5000)
 Precise methods are needed in order to
quantify dose-response relationships, gene-
environment interactions, and longitudinal
changes in activity patterns