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Chapter 11Physical Activity Epidemiology

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What is Epidemiology? The study of health events in a population Seeks to address three applications:

Describe the distribution of a disease/ condition/health event. The who, what, where, and when

Analyze descriptive information by identifying potential risk factors

Use this information for the prevention of a health-related occurrence by developing and implementing strategies

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Physical Activity Epidemiology Concerned with the systematic examination

of factors related to participation in the health behavior of physical activity.

How does this behavior relate to the likelihood of improved health or function and/or disease occurrence.

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Health Goals for the Nation “Objectives for the Nation”

Published each decade since 1980 by the Dept. of Health and Human Services Healthy People 2010

Surveillance systems are necessary to monitor progress Behavioral Risk Factor Surveillance System (BRFSS) National Health Interview Surveys (NHIS) National Health and Nutrition Examination Surveys

(NHANES I, II, III, IV)

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Epidemiologic Methods Web of causation

A complex interaction of causes rather than the result of a single cause

Causal factors Agent--genetic, physical, nutritive, exogenous

chemical Host--personal attributes including age, sex, immune

status, behavioral attributes, race/ ethnicity Environment--climate altitude, urban, rural

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Epidemiologic Methods Measures used to quantify disease/ injury/

event occurrence in the population Incidence/ Incidence rate Cumulative incidence Prevalence

If the incidence or prevalence of a condition is known, incidence and prevalence rates can be calculated

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Epidemiologic Methods Rate

The frequency or number of events that occur over some defined time period divided by the average size of the population risk

Rate= Numerator X Constant Denominator

Proportion

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Epidemiologic Methods Prevalence rates

Useful for planning purposes Not useful when trying to determine which factors

may be related to an increased probability of disease

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Measurement of Physical Activity and Fitness Physical Activity is measured using three

approaches Questionnaires Activity diaries Direct measurement

Observation Movement technology

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Measurement of Physical Activity and Fitness Direct Measurement

Observation Watching and recording playground/ park/ facility use

during a specified time Movement technology

Pedometers, motion detectors, heart rate monitors

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Study Designs in Epidemiology Cross-sectional/ Observational Case-control Prospective Cohort Randomized Clinical Trial

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Study Designs in Epidemiology Cross sectional/Observational study

Physical Activity or fitness is measured simultaneously with a measure of the frequency of disease, injury or death

Least convincing design Proper temporal sequence is not provided Iowa Farmers Study

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Study Designs in Epidemiology Case-Control Study

There are no clear suspected causes of a disease. Attempt to piece together the causes after the fact. Retrospective case-control study

Likened to a flashback in cinematography Seattle Heart Watch Study

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Study Designs in Epidemiology Prospective Cohort Study

Permits observation of the characteristics and behaviors of a group or cohort of people across time

Longitudinal Aerobics Center Longitudinal Study (ACLS)

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Study Designs in Epidemiology The Randomized Clinical Trial

Determines whether associations uncovered in epidemiologic observations represent cause and effect relations

Random assignment of subjects to treatment or control groups

National Exercise and Heart Disease Project

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Assessment of Causality Strength of Association Consistency of association Specificity of association Temporality Biologic gradient Plausibility Coherence

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Assessment of Causality Experimental Evidence Analogy

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Key Journals Medicine and Science in Sports & Exercise Journal of Physical Activity and Health

(JPAH) Preventing Chronic Disease (PCD) The American Journal of Preventive Medicine British Journal of Sports Medicine

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Educational Requirements Undergraduate degree

Exercise science, kinesiology, social sciences, life sciences

Master’s degree Master of Public Health (MPH) in epidemiology,

biostatistics, or health promotion Good quantitative skills/ inquisitive mind

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Job Opportunities Federal, state, and local public health

agencies Universities and colleges Non-governmental health agencies Private and community foundations National, regional, and local park and

recreation organizations