“ T H E O F F IC E O F T H E S C H O L A R I S TO … G U ID E M E N B Y S H O W IN G T H E M FA C T S
A M I D S T A P P E A R A N C E S …H E P L I E S T H E S L O W, U N H O N O R E D , A N D U N PA ID TA S K O F
O B S E RVAT I O N … H E I S T H E W O R L D ’S E Y E . ”
R A L P H WA L D O E M E R S O N , 1 8 3 7

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Behavioral epidemiology is the observation and study of behaviors, including physical inactivity, which leads to disease or early death and of the distribution of these behaviors.
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This contains 2 main features: (1) the study of relationships of behavior and disease (2) the study of the behavior, its distribution in a population and its determinants.
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In modern behavioral epidemiology, the focus shifts to understanding behaviors that increase or decrease the risk of people developing the disease (hand washing, sharing needles).
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Important for understanding and preventing chronic diseases that develop over a period of years because of people’s habits.
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Pandemic : an epidemic that spreads widely across a region or the world.
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About half the mortality from the top 10 leading causes of death in the U.S.A. can be traced directly or indirectly to behavior.
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Behavioral epidemiology is especially important for understanding and preventing chronic diseases that develop over periods of years largely as a result of people’s habits—this includes physical inactivity or sedentariness.

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Until the mid-20 th century, the major threat from disease was infectious contagion.
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Flu epidemic of 1918 killed 40,000,000 people worldwide, including 675,000 Americans in just 11 months. (Look at Ebola today).
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Infectious diseases remain a serious threat to public health, ranking as the 3 rd leading cause of death worldwide—failure to maintain public sanitation and vaccination can lead to an exponential growth of death from infectious disease in a short period of time.
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Most infectious diseases are now controllable.
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Modern-day epidemiologists are equally concerned about chronic diseases—may be partly cause by pathogens but usually require many years to fully develop and their signs and symptoms manifest often in middle age or later.
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Noninfectious diseases are now the top causes of illness, disability and death.
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Pathogen s: e.g., bacteria and viruses causing diseases that can spread to humans.

• It is now known that about half the mortality from the top 10 leading causes of death in the USA can be traced directly or indirectly to behavior.
• Hence, it is understood that certain behaviors, such as insufficient PA can be pathogenic.
• Today, epidemiologists are as concerned with the prevention of behaviors that cause disease as well as containing diseases once they occur.

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What is physical activity? p—39.
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3 parts of energy expenditure: (1) Metabolism (2) Physical activity (3) Thermic effect of food
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Objective vs. Subjective measurements.
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Measures of Physical Activity: Used to be done by occupational classification—ignoring leisure-time physical activity.
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Then both measured by the Tecumseh Community Health Survey—there are about 50 physical activity questionnaires.---No gold standard to compare questionnaire results though.
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Imperfect measures of calorimetry: by using variables influenced by physical activity (BP, fat, blood lipids, aerobic power, muscular strength & endurance).
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Direct (sealed insulated chamber) vs. indirect calorimetry (doubly labeled water, heart rate monitors;
Motion sensors—accelerometers, pedometers, multiplane accelerometers, diaries, self-reports).

• A good measure of PA provides reliable and valid information on specific features of PA, including type, intensity, duration, frequency, and timing.
• HR monitors—page 42.
• Motion sensors—page 43.
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Dose-response—page 43.
• PA Questionnaires—page 46.
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Descriptive epidemiology of PA: the assessment of variation in PA by age, sex, race, ethnicity, health status, and geographic location.

1.
Minnesota Leisure Time Physical Activity Questionnaire (p-45)
2.
Harvard Alumni/Paffenbarger Physical Activity Survey
3.
Stanford Seven-Day Physical Activity Recall Interview
4.
International Physical Activity Questionnaire
5.
Global Physical Activity Questionnaire
6.
3-Day Physical Activity Recall (3-D PAR)
7.
CHAMPS Physical Activity Questionnaire
 Self-Reports of physical activity ( subjective ) are the most feasible method for measuring physical activity in national surveys and surveillance systems.
Objective measures, such as motion sensors, heart rate monitors, and doubly labeled water can estimate different components of physical activity and are commonly used to validate self-report measures.

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Physical fitness is both genetic and influenced by what you do.
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Health-Related Physical Fitness Components: (Table 3.2, page 49).
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Performance-Related Fitness.
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Morphological: Fatness—BMI, overweight, overfat, % body fat, distribution of fat; Bone Mass;
Flexibility.
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Cardiorespiratory—max and submax aerobic capacity, cardiac function—HR, ejection fraction, stroke volume, Q; Blood Pressure.
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Metabolic Component: aids in preventing diabetes and atherosclerosis; Glucose Tolerance; Blood
Lipid & Cholesterol Profiles; Lipid Oxidation.
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Muscular Component--Muscular—strength, endurance, power.
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Motor: Psychomotor—childhood skills, etc.

 F I T T.
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ACSM guidelines: (p-53).
 Frequency: cardio—3 to 5 days per week.
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Intensity—(p-53 & 54).
 Time or Duration: cardio—20 to 60 minutes (ACSM). J-Curve & Dose-Response..
 Type or Mode: (p-54).
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Dose-Response : Establishing dose-response is one of Mill’s canons for determining the causality of a health risk factor, but it is also important for public health policy recommendations about the types and amounts of physical activity that are healthful.

 P-55
 National Runner’s Health Study: Cross-Sectional study about a linear dose-response relationship between activity and health outcomes.
 Current Scientific Consensus: An inverse, and generally linear, relationship exists between physical activity and rates of all-cause mortality, CVD mortality, and the incidence of type 2 diabetes.
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Consensus was not reached bout dose-response for other health outcomes evaluated…
 P-58, Table 3.5
 Surveys and Surveillance of Physical Activity, p-57 through 62.

 Physical activity in the U.S.A., p—60.
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Geographic variation.[West is most active, South the least].
 Population subgroups. [PA lower among women, older people, minorities, less educated].
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Secular changes in culture can strongly influence the prevalence of physical activity. Examples are increased TV viewing and computer use among youths and a decrease in daily physical education during the past decade.
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Physical activity, fitness and aging. P—68.
 Objectively measured PA rates are strikingly lower than those estimated from people’s self-ratings
( subjective ) of their PA. Americans spend nearly half their waking hours in sedentary behavior.