Presentation on theme: "Epidemiology of Physical Activity: 101 July 17, 2007 Steven H. Kelder, PhD, MPH Professor, Division of Epidemiology Co-Director, Michael & Susan Dell Center."— Presentation transcript:
Epidemiology of Physical Activity: 101 July 17, 2007 Steven H. Kelder, PhD, MPH Professor, Division of Epidemiology Co-Director, Michael & Susan Dell Center for Advancement of Healthy Living
The Dilemma l Most Americans are not physically active enough to achieve substantial health benefit l Related disease outcomes are very costly l With adults, traditional PA promotion efforts have had limited effect l Sustaining higher activity levels will require a comprehensive approach
The World According to Steve l Start young – school based programs work. Children can be found at school. Young parents, preschool. l Physical activity quickly declines as students enter middle school and high school (especially girls). l Promote calcium consumption and weight bearing physical activities to women and girls. l Reinforce school lessons at home and in the community. l Promote use of community parks and recreation. l Create social events; eating and PA are social behaviors. l Where: worksites, point of purchase, church, school l Stay in it for the long haul.
What Do We Mean by Food and Physical Activity Environments? (from macro to micro) l Physical and economic environments: food product (including packaging, portion size), price, promotion, placement – access, availability, affordability, convenience, parks and recreation l Information environments: media, marketing, public education (including point of purchase information, food labels) l Social environments: social and cultural norms/practices, role models; health provider and other social support for health behavior change, worksites l Behavioral settings: schools, homes, neighborhoods, communities, youth-serving organizations, child care centers, grocery and convenience stores, restaurants/fast food outlets, vending machines, worksites
l Mass media saturated with unhealthy messages and advertising l Proliferation of easily available low nutrient, calorie dense foods l Increasing frequency of restaurant eating and larger portion sizes (Super Size Me!) The (possible) causes
l Increasing amount of time spent indoors with mass media and games l Increased car travel and less person-powered transport l Increased concerns over child safety - stranger danger and traffic l Fewer walkable destinations - shops, grocery, post office The (possible) causes
More families with two working parents Go inside and lock the door until we get home Parents working longer hours - too tired and too busy to play Personal injury litigation and reduced opportunities for physical activity Poor fundamental movement skills - as children participate less, they fail to develop these fundamental skills so want to participate less The (possible) causes
l Schools increasingly reluctant to devote time to health education Poor fundamental movement skills - as children participate less, they fail to develop these fundamental skills so want to participate less The (possible) causes
Increased Life Expectancy Source:Centers for Disease Control and Prevention (CDC). Increased years due to medical care advances: 5 Increased years due to public health measures: 25
Causes of Death in United States – 2002 Actual Causes of Death 2 Tobacco Poor diet/ lack of exercise 3 Alcohol Infectious agents Pollutants/toxins Firearms Sexual behavior Motor vehicles Illicit drug use Leading Causes of Death 1 Percentage (of all deaths) Heart Disease Cancer Chronic lower respiratory disease Unintentional Injuries Pneumonia/influenza Diabetes Alzheimers disease Kidney Disease Stroke Percentage (of all deaths) Sources: 1 National Vital Statistics Reports, Vol. 53, No. 15, February 28, Adapted from McGinnis Foege, updated by Mokdad et. al., JAMA, April 20, 2005Vol 293, No. 15, pg 1861.
Physical Activity and Fitness Benefits l Builds and maintains healthy bones and muscles, controls weight, builds lean muscle, reduces fat, reduces blood pressure, and improves blood glucose control l Decreases the risk of obesity and chronic diseases (CHD, high blood pressure, diabetes, colon cancer, and osteoporosis) l Reduces feelings of depression and anxiety and promotes psychological well-being l Related to functional independence of older adults and quality of life of people of all ages
Physical Activity Improves Lives A physically active Texas population would expect to see: l 30 % fewer cases of heart disease, stroke, colon cancer, and osteoporosis l 18 % fewer cases of type 2 diabetes and hypertension l 16 % fewer injuries from falls in the elderly l 12 % fewer cases of depression and anxiety l 5 % fewer cases of breast cancer l PA helps the elderly maintain their independence longer. l PA results in more productive employees by decreasing illness and absenteeism.
Sedentary Behavior is a Natural Response to our Environment l Our culture increasingly values cars, television, computers, and convenience, making physical activity less a natural part of our lives. l Newer communities are often designed without sidewalks or streetlights, decreasing walkability. l Communities are designed with housing far from schools, shopping, or other activities, making walking or biking for transportation infeasible. l Increasing traffic congestion and aggressive driving hampers the walkability of neighborhoods. l More and more employees have sedentary jobs decreasing the amount of activity incurred during daily routines. l Children are taking fewer physical education classes in school.
Activity can be Easy l Achieving the recommended amount of physical activity is as simple as taking three ten-minute walks per day. l Health benefits occur even with very modest increases in activity, even if the recommendation is not met. l The largest benefits occur to those who were previously completely sedentary. l Any incremental physical activity is beneficial to health. l Vigorous exercise is very beneficial to health, but a brisk walk is beneficial as well. l Little changes, such as parking farther away from the store or opting for the stairs instead of the elevator, go a long way toward promoting health and preventing disease.
Dietary Guidelines for Americans Aim for Fitness Aim for a healthy weight Be physically active each day Build a Healthy Base Let the Pyramid guide your food choices Choose a variety of grains daily, especially whole grains Choose a variety of fruits and vegetables daily Keep food safe to eat
Dietary Guidelines for Americans Choose Sensibly Choose a diet that is low in saturated fat and cholesterol and moderate in total fat Choose beverages and foods to moderate your intake of sugars Choose and prepare foods with less salt If you drink alcoholic beverages, do so in moderation
Vegetables and Fruits l 5 or more servings of vegetables and fruits each day l Research suggests this one dietary change could prevent as many as 20% of all cancers l Vegetables and fruits provide vitamins, minerals, and phytochemicals l Variety is important to get the widest array – dark green, deep orange, citrus
Other Plant-based Foods l 7 or more servings of other plant-based foods such as whole grains and legumes l Whole grains are higher in fiber, vitamins, minerals, and phytochemicals than refined grains
The New American Plate l 2/3 or more of the plate should be covered by plant-based foods – vegetables, fruits, whole grains, and beans – 1 or more vegetables or fruits and not just grain products l 1/3 or less of the plate should be covered by meat, fish, poultry, or low-fat dairy
Physical Activity l Engage in regular physical activity and reduce sedentary activities to promote health, psychological well-being, and a healthy body weight. l Achieve physical fitness by including cardiovascular conditioning, stretching, and resistance exercises. l Children and adolescents – At least 60 minutes on most, preferably all, days of the week.
New for 2005 l Specificity of recommendations –At least 30 minutes to reduce risk of chronic disease –Up to 60 minutes of moderate to vigorous physical activity may be needed to prevent gradual weight gain that occurs over time –60 to 90 minutes of moderate-intensity physical activity to sustain weight loss l Recommendations for specific populations –Those who need to lose weight, overweight children, pregnant women, breastfeeding women, overweight adults and overweight children with chronic diseases and/or on medication
Change May Occur Slowly
U.S. Obesity and Diabetes Trends in Source: Mokdad AH, Serdula MK, Dietz WH, et al. JAMA, October 27, 1999; 282(16): Source: Mokdad AH, Serdula MK, Dietz WH, et al. JAMA, October 27, 1999; 282(16): The data shown in these maps were collected through CDCs Behavioral Risk Factor Surveillance System (BRFSS).
Obesity Trends* Among U.S. Adults BRFSS, 1985 No Data <10% 10%–14% (*BMI 30, or ~ 30 lbs overweight for 5 4 person)
Obesity Trends* Among U.S. Adults BRFSS, 1990 No Data <10% 10%–14% (*BMI 30, or ~ 30 lbs overweight for 5 4 person)
Obesity Trends* Among U.S. Adults BRFSS, 1995 No Data <10% 10%–14% 15%–19% (*BMI 30, or ~ 30 lbs overweight for 5 4 person)
Obesity Trends* Among U.S. Adults BRFSS, 2000 No Data <10% 10%–14% 15%–19% 20 (*BMI 30, or ~ 30 lbs overweight for 5 4 person)
Obesity Trends* Among U.S. Adults BRFSS, 2004 No Data <10% 10%–14% 15%–19% 20%–24% 25% (*BMI 30, or ~ 30 lbs overweight for 5 4 person)
Source: Mokdad et al., Diabetes Care 2000;23: Diabetes Trends* Among Adults in the U.S., (Includes Gestational Diabetes) BRFSS 1990 No Data <10% 10%–14% 15%–19% 20%–24% 25%
Diabetes Trends* Among Adults in the U.S., (Includes Gestational Diabetes) BRFSS 1995 Source: Mokdad et al., Diabetes Care 2000;23: No Data <10% 10%–14% 15%–19% 20%–24% 25%
Diabetes Trends* Among Adults in the U.S., (Includes Gestational Diabetes) BRFSS 2000 Source: Mokdad et al., J Am Med Assoc 2001;286:10. No Data <10% 10%–14% 15%–19% 20%–24% 25%
Diabetes Trends* Among Adults in the U.S., (Includes Gestational Diabetes) BRFSS 2001 Source: Mokdad et al., J Am Med Assoc 2001;286:10. No Data <10% 10%–14% 15%–19% 20%–24% 25%
Prevalence of Obesity* in Adults by Gender and Race NHANES Source: Ogden et al., JAMA, 2006 *BMI > 30
Most Recent NHANES Results l 66.3% of American adults are overweight (BMI 25) l 4.8% of American adults are extremely obese (BMI 40) –10.5% of Non-Hispanic Black JAMA, 2006:295:
Costs of Obesity $75 billion: Annual U.S. medical expenditures attributed to obesity in 2003 Amount obese people spent on health care costs compared to normal weight people: 37% more For Youth (6-17 years) between 1979 and 1999: Hospital discharges for diabetes were nearly 2x Sleep apnea increased 5x Obesity-associated costs were $35 million during and increased to $127 million during l Annual costs associated with overweight and obesity in Texas in 2001: $10.5 billion dollars l Projected costs for 2040 in Texas: $39 billion in Texas Sources: Surgeon Generals Report on Obesity, 2001; Finkelstein et al., 2004; Thorpe et al., 2004; Wang & Dietz,
W = White, H = Hispanic, A = African American Figure 1. Prevalence of BMI > 30 within BMI category; 11th grade Female Male
2001 Grade 5 SAT 9 and Physical Fitness CA Dept. of Education, 2002
2001 Grade 7 SAT 9 and Physical Fitness CA Dept. of Education, 2002
2001 Grade 9 SAT 9 and Physical Fitness CA Dept. of Education, 2002
Defining Physical Activity Physical Activity = any bodily movement produced by skeletal muscles that results in an energy expenditure. It can be categorized in various ways, including type, intensity, and purpose. In terms of disease prevention, the activity usually considered is aerobic in nature, with large muscle groups contracting in a continuous manner
Defining Physical IN-Activity Physical IN-Activity = a level of activity less than that needed to maintain good health. –Inactive as per CDC: less than 10 minutes per week of moderate or vigorous physical activity –Sallis and Owen, 1999: People are considered sedentary when they report no physical New Description! = Screen Time
Defining Physical Fitness Physical Fitness = The ability to carry our daily tasks with vigor and alertness, without undue fatigue, and with ample energy to enjoy leisure-time pursuits and to meet unforeseen emergencies. A measure of a persons ability to perform physical activities that require endurance, strength, flexibility
Defining Exercise Exercise = physical activity that is planned or structured Repetitive movement to improve/ maintain: –Aerobic capacity –Muscular strength –Muscular endurance –Flexibility –Body composition
Quantifying PA measures l Need PA intensity measure l Need frequency l Need duration l Body weight may be needed
Outcome Measures l 5 Health Related Components of PA l Caloric Expenditure (CE) l Activity Intensity (AI) l Weight Bearing (WB) l Flexibility (FL) l Musculoskeletal (MS)
l Physical activity intensity is frequently quantified in terms of metabolic equivalents, or METS l 1 MET is rest (as in, 1 times your resting metabolic rate) l 1 MET = 1 kcal/kg/hr l All activities are some multiple of this resting MET level
Defining Recommended Activity Recommended Activity = minimum amount of physical activity required for health benefits Either regular moderate or vigorous activities equivalent to burn 150 calories/day (1,000 calories/wk)
Physical Activity Types/Examples Vigorous Activities l Brisk walking or climbing uphill l High Impact Aerobics l Step aerobics l Swim laps l Bicycling (hills) l Jogging Moderate Activities l Walking mph (level surface) l Low Impact Aerobics l Swimming l Bicycling (level ground) l Mowing grass Note: Intensity of activity is often determined in metabolic equivalents (METS). METS estimate the metabolic cost of activity;1 MET=resting metabolic rate.
Measurement l Survey: diary, recall, quantitative history, global self-report. l Direct observation, job classification l Heart rate monitor, motion sensors, pedometer, gait assessment, accelerometers. l Direct calorimetry (heat), indirect calorimetry (oxygen), cycle, treadmill, doubly labeled water (H and O).
Doubly Labeled Water l Drink water with 2 H and 18 O isotopes (natural isotopes) l Urine or saliva samples collected pre- drink, and every few days up to ~14 days l Assumption: 2 H disappears in H 2 O and 18 O disappears in H 2 O and CO 2 removal l Differential loss is equivalent to EE
Doubly Labeled Water 3 l Disadvantages –Isotope is very expensive (~$500 per subject) –Expensive equipment needed for analysis –Assumes that CO 2 ~ O 2 –Only Total EE is measured –Components of PA?
Activity Monitors Assessing PA l What are accelerometers? l They measure accelerations of the human body l They record activity patterns over a period of time l Benefits: small, non-invasive, large storage capacity, used widely in field settings l Different types: –Actigraph (or CSA) - most widely used –Caltrac - estimates energy expenditure –Tritrac - measures PA in 3 directions (Welk, 2002)
The Actigraph l Records levels of PA l Worn on waist, wrist or ankle l Records frequency, time and intensity of PA l Can detail percentage time spent at different activity levels l Monitors continuously
Paediatric monitoring l Used in the Liverpool Sporting Playgrounds Project l Quantified intensity, duration and frequency of activity in playtime (10 year-old girl's data shown) Moderate PA: 46% (6½ mins) High PA: 11% (1¾ mins) Very high PA: 5.6% (1 min)
Heart Rate Monitors l HRM measure cardiorespiratory response to physical activity l Transmitter and belt worn around the upper body l Data commonly displayed on a wrist receiver l Downloaded via interface for analysis
Heart Rate Monitors Advantages l Relationship with energy expenditure l Valid & reliable in lab & field l Describes tempo l Easy & quick for data collection & analyses Limitations l Cost (large samples) l Data attrition l Discomfort over long periods l Age, sex, training status affect HR l No information on physical activity context
Direct observation instruments l Measure behavioural aspects of physical activity l Provides information on specific activities occurring in a variety of settings over time l Quantitative & qualitative information l Useful with younger children l Trained observers l Pen and paper instruments
Direct observation instruments Advantages l Detailed quantitative & qualitative data l Describes tempo l Low financial cost l Computer software allows real time recording & analysis of data Limitations l Time-intensive training l Time & labour intensive data collection l Limited sample sizes l Observer presence (reactivity) l Limited validation against physiological criteria
System for Observing Children's Activity during Playtime (SOCAP) Recording Form Time Area Activity Activities Behaviour Other Level B St T A T to LA 4G W W & T Linked arms B V Tick 2B W-V Chasing PF Benefits: combines PA with behaviours and identifies contextual influences on PA Limitations: new measure which is currently undergoing reliability & validity studies
Physical Activity Questionnaires International Physical Activity Questionnaire (IPAQ) Physical Activity Questionnaire for Adolescents (PAQ-A) Leisure Time Exercise Questionnaire (LTEQ) Advantages Inexpensive, allows large sample size. Can be administered quickly and easily. Limitations Reliability and validity problems associated with recall of activity, especially in children. Lack objectivity. Measures = Frequency, Intensity, Time (and Energy Expenditure).
Pedometers l Ped- Walk l Meters-measure l Fixed to waistband l Small-light-unobtrusive l Display:- Steps Distance Kcals Target:- Adult:- 10,000 steps/day Children:- 127 steps per minute. 60 mins=8000 steps/day
Expediency vs Accuracy l Heart rate monitoring l Accelerometry l Actiheart l GPS systems l Direct Observation l Doubley labelled water l Questionnaires Long Short l Pedometers Cost
Physical Activity Surveillance Routine surveillance Youth Risk Behavior Survey Behavior Risk Factor Surveillance System National Health and Nutrition Examination Survey National Health Interview Survey National Personal Transportation Survey Pediatric Nutrition Surveillance System Cross-sectional or population studies
Guide to Community Preventive Services (www.thecommunityguide.org/pa) l Community-wide campaigns. Large-scale, highly visible, multicomponent campaigns with messages promoted to large audiences through diverse media, including television, radio, newspapers, movie theaters, billboards, and mailings. l Individually targeted programs. Programs tailored to a persons readiness for change or specific interests; these programs help people incorporate physical activity into their daily routines by teaching them behavioral skills such as setting goals, building social support, rewarding themselves for small achievements, solving problems, and avoiding relapse. l School-based physical education (PE). School curricula and policies that require students to engage in sufficient moderate to vigorous activity while in school PE class. Schools can accomplish this by increasing the amount of time students spend in PE class or by increasing their activity level during PE class.
Guide to Community Preventive Services (www.thecommunityguide.org/pa) l Interventions that provide social support for physical activity in community settings. Interventions designed to promote physical activity by helping people create, strengthen, and maintain social networks that support their efforts to exercise more; examples include exercise buddy programs and the establishment of exercise contracts or walking groups. l Interventions to provide people greater access to places for physical activity. Examples include building walking or biking trails and making exercise facilities available in community centers or workplaces.
U.S. and Texas adults who meet physical activity guidelines Source: CDC BRFSS
Physical activity among U.S. adults by gender Source: CDC BRFSS
Physical activity among U.S. adults by race/ethnicity Source: CDC BRFSS
Physical activity among U.S. adults by age Source: CDC BRFSS
Percentage of U.S. adults who meet physical activity recommendations by education level: 2003 Source: CDC BRFSS
Physical activity among U.S. adults by poverty level Source: NHIS
No leisure-time physical activity among U.S. adults by poverty level Source: NHIS
Physical Activity & U.S. Adults Prevalence l More than 50% of adult Americans do not get enough PA to provide health benefits l 26% are not active at all in their leisure time (BRFSS, 2003;)/ 38.6% according to National Health Interview Survey Gender l Men (64.2%) more likely than women (59%) to engage in some leisure- time physical activity; l Men more likely than women to engage in light moderate and/or vigorous physical activity than women five times per week. (NHIS, CDC 2004). Ethnicity l White adults (63.5%) and Asian adults (61.9%) were more likely than African American adults to engage in some leisure-time physical activity (NHIS, CDC 2004). l White adults (49%) more likely to meet moderate PA guidelines compared to African American (36%) and Hispanics (37%). (BRFSS, 2003) l Whites (12%) reported lower inactivity compared to African Americans (24%) and Hispanics (26%) (BRFSS, 2003) Source: CDC
Physical Activity & U.S. Adults Age l Engagement in physical activity declines steadily with age. Education l Physical activity increases with educational level. l Adults with a graduate degree (81%) were about twice as likely as adults with less than a high school diploma (41%) to engage in at least some leisure-time physical activity (NHIS, 2004). l Adults with highest educational attainment were almost twice as likely as adults with the least education to engage in light-moderate or vigorous activities five or more times per week (NHIS, 2004). l Women with a bachelors degree & graduate-level degree were four times as likely as women with less than a high school diploma to engage in strengthening exercise. (NHIS, 2004) Poverty l Adults with incomes four times the poverty level or more (29.1%) were more likely than adults with incomes below the poverty level (20.5%) to engage in light-moderate physical activity at least five times per week and more than two times as likely to engage in vigorous physical activity (17.9% and 7.0%, respectively). Source: CDC
Physical Activity & U.S. Adults Geographic Region l Adults living in the West were more likely to engage in any regular physical activity (35%) and adults living in the south (28.4%) were least likely to engage in any regular physical activity. l Adults living in a Metropolitan Statistical Area were more likely than adults living outside an MSA and adults living in the central city of an MSA to engage in at least some leisure-time physical activity (64%, 59%, and 59%, respectively). Marital Status l Married women (61.0%) were more likely than women in any other marital status group to engage in at least some leisure-time physical activity. (NHIS- CDC, 2004) l Widowed adults (23.6%) were less likely than never married (33.0%), married (31.1%) and divorced or separated adults (29.1%) to engage in regular physical activity. l Adults who had never been married (27.5%) were more likely than adults in any other marital status group to engage in strengthening activities. (NHIS – CDC-NCHS, 2004) Trends l Leisure-time physical activity appears to have increased slightly from 1991 (71.3%) to 2003 (75.6%) Source: CDC-NCHS: National Health Interview Survey,
U.S. Youth Participation in Sufficient Vigorous (V) and Moderate (M) Physical Activity Levels by Gender (Grades 9-12) Source: CDC YRBS 2003
U.S. Youth Participation in Sufficient Vigorous and Moderate Physical Activity Levels by Ethnicity (Grades 9-12): 2003 Source: CDC YRBS 2003
U.S. Youth Participation in Sufficient Vigorous (V) Physical Activity Levels by Grade and Sex Source: CDC YRBS 2003
U.S. Youth Physical Activity Levels by Age and Sex: Vigorous (V) and Moderate (M) Source: CDC YRBS
Trends in Prevalence of Physical Activity among U.S. Youth: Source: CDC YRBS * * *Significant changes over time
Reported Physical Activities from Mid to Late Adolescence - Boys Physical Activity % Participants % Participants Basketball6659 Football6642 Bicycling583 Baseball5529 Street hockey4230 Weight lifting3140 Aaron et al., 2002, Arch Pediatr Adolesc Med
Reported Physical Activities from Mid to Late Adolescence - Girls Physical Activity % Participants % Participants Bicycling522 Softball3622 Basketball3418 Running2928 Aerobics2023 Bowling1910 Aaron et al., 2002, Arch Pediatr Adolesc Med
Prevalence of Obesity by Daily Hours of TV Watching U.S. children aged 8 – 16, Crespo et al., Arch Ped Adol Med. 2001;155:
Physical Activity & Youth Prevalence of Physical Activity & Inactivity l More than a third of young people in grades 9-12 do not engage in sufficient vigorous physical activity. l About 14% of young people report no recent physical activity. l Only 19 percent of high school students are physically active for 20 minutes or more, five days a week, during physical education classes. l 38% of youth watch 3 hours of TV on a school day Gender l Physical activity is higher among male adolescents, and inactivity is more common among females than males (14% vs. 7%). Ethnicity l Physical activity levels differ by race/ethnicity, with white adolescents appearing to engage in more physical activity than African American and Hispanic adolescents Source: CDC
Physical Activity & Youth Age l Participation in all types of physical activity declines strikingly as grade in school and age increases. Trends: l Slight drop in vigorous physical activity, with around a third who do not get enough vigorous activity (66% in 91 to 63% in 2003). l Slight increase in participation in strengthening exercises that was statistically significant, from 48% in 1991 to 52% in l Daily participation in high school physical education classes dropped from 42% in 1991 to around 28% in Source: CDC