Measuring Physical Activity: Tools and Indicators Bill Kohl University of Texas Health Science Center – Houston School of Public Health University of Texas at Austin Department of Kinesiology and Health Education 19 th International Physical Activity and Public Health Training Course
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Measuring Physical Activity: Tools and Indicators Bill Kohl University of Texas Health Science Center – Houston School of Public Health University of Texas.
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Measuring Physical Activity:Tools and Indicators
Bill Kohl
University of Texas Health Science Center – HoustonSchool of Public Health
University of Texas at AustinDepartment of Kinesiology and Health Education
19th International Physical Activity and Public Health Training Course
Palm Beach Aruba, June 2012
Objectives
• Conceptual framework
• Key issues in physical activity assessment
• Overview of physical activity surveillance
Behavior
Sleep
NonDiscretionary
Sedentary
Discretionary
Human Movement
Characteristic Outcome
Activity-Related Energy Expenditure
Energy Expenditure
Balance Body Composition
Muscular Fitness Flexibility
Cardiorespiratory
Physical Fitness
Thermogenesis
Basal (or Resting) Metabolic Rate
Health Enhancing
Health Compromising
Variable Association with Health Outcomes
Gabriel et al 2011
Leisure
TransportHousehold DomesticSelf-Care
Occupation
Physical Activity
ExerciseSpecific Activity Type
e.g., soccer, lifting heavy boxes or children, walking
Intensity Categorye.g., light, moderate, vigorous
Recall Cue
Frequency
Characteristic
Intensity
Duration
Pattern
Gabriel et al 2011
Methodological Concepts
• Validation standard
• A predetermined criterion against which the accuracy of the test instrument is measured. The standard is presumably less variable than the test method.
• Variety of validation standards in physical activity
Methodological Concepts
• Validation standards in physical activity assessment
• Energy expenditure• Physical fitness• Physical activity• Body composition
• Assume mathematical relation between measurements and physical activity
• Many can can measure quantity and intensity of physical activity
• Recent advances make devices more practical
Physical Activity Assessment
• Self-report
• Diaries, interviews and self-administered surveys• Varying lengths of recall, all assumed to be
indicators of “usual” physical activity• Varying quality of summary indices• May not be transferrable among populations• Most often used in population-based research• Highly variable and questionnable accuracy
Physical Activity Assessment • Dietary measures
• Caloric value of food consumed used as a measure of corresponding energy utilized
• Assumes energy balance• Body weight is confounding factor• Expensive and difficult to weigh all food
prior to intake for any period of time• Intake in free-living populations is highly
variable• Diet surveys are not practical
Incr
easi
ng p
reci
sion
Decreasing difficulty
Self-Report
Monitoring
Direct Observation
Indirect Calorimetry
Doubly-Labeled Water
Direct Calorimetry
Physical activity assessment cascade
Physical Activity Assessment: Future Directions
• Emphasis must be on measuring more than just total “dose”: understanding intensity, frequency, and patterns is critical
• Methods to assess historical physical activity (recall) are important
• Accelerometers are likely the most productive future trend in physical activity assessment. More work on electronics is needed
Physical Activity Assessment: Future Directions
• Intra-individual variation in physical activity assessment: How many days are enough?
• Methods for assessing non-aerobic activities
• How can existing physical activity assessment instruments be adapted/adopted into different populations and subgroups?
The Uses of Public Health Chronic Disease and Behavioral Surveillance Systems
• Quantify magnitude of health problem• Describe natural history of disease• Detect “outbreaks”• Document Person, Place and Time• Test hypotheses• Evaluate intervention measures
(control/prevention)• Detection of changes in health practices• Policy and planning
Adapted from Thacker, 1994
Steps in Planning a Public Health Surveillance System
• Establish objectives• Develop case definitions• Determine data source(s) and mechanism of
collection• Develop instruments• Field-test methods – refine as necessary• Develop and test analytic approaches• Develop and test dissemination mechanisms• Evaluate analysis and interpretation
Adapted from Teutsch, 1994
Caution!
SurveillanceVersus
Assessment
Public Health Physical Activity Surveillance – The Ideal?
Individuals
Policy
EnvironmentalDeterminants
Non-public health data sources
Public Health Physical Activity Surveillance – Individual-level data
Individuals
• Frequency• Intensity• Duration• Mode• Domains• “Meeting” recommendations• Health Objectives
eg. BRFSS; YRBS; HANES; NHIS; NHTS, etc.
International PA surveillance
International trends in “Regular Physical Activity”: Adults
0
10
20
30
40
50
60
70%
80 82 84 86 88 90 92 94 96 98
18+, 3+ kkd
18+, 1625+ kwk
18+, vigorous
15+, 2+/wk
18+, 3/wk
Finland
Canada
Scotland
Australia
USA
Australia18+, 150m/wk, 5 sessions
With thanks to Cora Craig, CFLRI, Ottawa
IPAQINTERNATIONAL PHYSICAL ACTIVITY
QUESTIONNAIRE
first steps towards global measurement of physical activity
IPAQ group : measurement and development tasks 1997-2004
Phase I dreaming up a global measure 1997-8
Phase II testing, formative work on questions internationally
Phase III formal reliability and validity testing in 11 countries 2000
Phase IV International prevalence study – testing it in the field 2003-4
IPAQ summary
• Reasonable measurement properties• First internationally comparable studies used
IPAQ – initially in Europe only • Short and long versions• IPS - prevalence differences noted• Differences in sitting time• Methodological issues with international work
• An example of good PAPH collaboration of national physical activity scientists
Proximo?
• IPAQ developed 1998-2000
• IPAQ reliability and validity study
• IPAQ prevalence study
• But IPAQ was not enough …..
Development of GPAQ
• Half way between IPAQ short form and IPAQ long form
• STEPwise approach to NCD risk Factor surveillance
(“STEPS”)
especially for developing countries
GPAQGPAQ Strengths+ domains+ quantifies exposure+ cross cultural application
GPAQ Weaknesses+ new measure+ needs testing
IPAQ LONG IPAQ SHORTJob related = 7; Transport = 6; Home = 6; Recreation = 6; Sitting = 2Total n=27
6 items on PA across the 4Domains; sitting = 1Total n=7
Developments
• Portugal meeting 2005 and Rome meeting 2007: consensus re findings of GPAQ- discussion of GPAQ in the field
• Feedback from STEPS countries; Suggestions for change
• Remaining issues– How well GPAQ or IPAQ reflects PA patterns in sub
populations in developing countries– Recall of time and understanding of 10 minute minimum– More research warranted in developing countries /
continue to build capacity
Current Global PA surveillance
• WHO has canvassed across countries (May 2005) and made slight changes to GPAQ - new version is called GPAQ2
• So global surveillance has 2 currently used PA instruments
• “IPAQ” adapted countries will use IPAQ, and “GPAQ experienced” countries continue to use GPAQ / GPAQ2
• Other countries with existing PA surveillance will likely rely on existing systems
Public Health Physical Activity Surveillance – Environmental Data
EnvironmentalDeterminants
Urban designDensityAccess to destinationsConnectivityAesthetics
Land useGreen space
TransportationInfrastructure, Public transit
SafetyPerceptions
Prevalence environmental determinants and supports for physical activity, US 1990-1998
Public Health Physical Activity Surveillance – Policy-level Data
Policy
Physical Activity Policy Research Framework
Outcomes of Policy
Develop and Implement Policy
Determinants of Policy
Identify Policies
LocalRegional
StateNational
Research Type
Sector
TransportationParks/Public Spaces
WorksiteSchool Level
Prevalence of policy supports for physical activity, US 1990-1998
Year
Pe
rce
nt
Initial legislative topic areas
• Urban design• Land use• Transportation• Community physical activity
promotion• Physical education
Upcoming Challenges
• Emerging research• Level? Local versus state (and linkages)• Indices and weighting• Appropriations• Measuring change• Legislative policies, regulations, organizational
policies, social norms?• Appropriate outcome data• How will data be most useful (and to whom)?
Public Health Physical Activity Surveillance – The Ideal?
Media attention“Critical mass”Industry and marketing data
individual and aggregateTrade associationsOthers?
Non-public health data sources
Public Health Physical Activity Surveillance – The Ideal?
Other Issues:Definitions, definitions, definitionsDataLevel of monitoring?Type of system?How will data be used?PeriodicityAggregation to conduct analyses with other types of surveillance dataLocal, State and Regional needs
Public Health Physical Activity Surveillance – The Ideal?
Surveillance systems must:
• Address a measurable construct.• Be able to quantify changes as they occur.• Apply to the majority of the population of
interest.• Must address public health issues that are
changeable.• Be responsive to new data and methodolgic
advances.
Public Health Physical Activity Surveillance – The Ideal?
Individuals
Policy
EnvironmentalDeterminants
Non-public health data sources
National Household Transportation Survey (NHTS)• Conducted by U.S. D.O.T.• Household survey using telephone interviews and
a 24-hour travel diary (N=69,817 households)• Travel patterns for work, school, and other daily travel were assessed
• How did the child get to (or from) school? • How far is it from home to child’s school (or from child’s school to home)?
Absolute changes between 1969 and 2001 for School Transport – United States