Steven N. Blair Director of Research—Cooper Institute Visiting Professor and

The Public Health Importance of Physical Inactivity

National Physical Activity Task Force

EdinburghJune 13, 2001Steven N. Blair

Director of Research—Cooper InstituteVisiting Professor and

Benjamin Meaker FellowUniversity of Bristol

A Brief Historical Note• Systematic research on the relation of

sedentary habits to coronary heart disease began in the 1950s with the pioneering work of Professor Jeremy Morris of London

• Dozens of studies now present a compelling body of evidence supporting regular physical activity as a good health habit

• Today I will attempt to persuade you that inactivity is one of the most important public health issues, and that governments must act to deal with this threat to health. Further, I predict that this will become widely recognized

Outline of Lecture• Strength of inactivity/low fitness as

predictors of mortality• Prevalence of inactivity• Population attributable risk• Hostile environment• Lifestyle physical activity interventions• Summary and conclusion

Death Rates and RR for Selected Mortality Predictors, Men, ACLS

All-Cause Mortality Mortality Predictors

Deaths/10,000 MY

Relative Risk

Low Fit 45.5 2.03 Smoking 42.7 1.89 SBP>140 43.6 1.67 Chol>240 37.0 1.46 BMI>27 34.3 1.33

Death rates and relative risks are adjusted for age and examination yearRelative risks are for risk categories shown here compared with those notat risk on that predictorBlair SN et al. JAMA 1996; 276:205-10

Death Rates and RR for Selected Mortality Predictors, Women, ACLS All-Cause Mortality Mortality Predictors

Deaths/10,000 WY

Relative Risk

Low Fit 28.8 2.23 Smoking 29.0 2.12 SBP>140 15.1 0.89 Chol>240 18.9 1.16 BMI>27 19.5 1.18

Death rates and relative risks are adjusted for age and examination yearRelative risks are for risk categories shown here compared with those notat risk on that predictorBlair SN et al. JAMA 1996; 276:205-10

Cardiorespiratory Fitness, Risk Factors and All-Cause Mortality, Men, ACLS

0102030405060

Deat

hs/1

0,00

0 M

Y*

Low Mod High

01

2 or 3# of risk factors

Risk Factorscurrent smokingSBP >140 mmHgChol >240 mg/dl

Cardiorespiratory Fitness Groups*Adjusted for age, exam year, and other risk factors

Blair SN et al. JAMA 1996; 276:205-10

Cardiorespiratory Fitness, Risk Factors, and All-Cause Mortality, Women, ACLS

0

10

20

30

40

50

Deat

hs/1

0,00

0 W

Y*

Low Mod-High

0

1

2 or 3

# of risk factors

Risk factorscurrent smokingSBP >140 mmHgChol >240 mg/dlCardiorespiratory Fitness Groups

*Adjusted for age, exam year, and other risk factorsBlair SN et al. JAMA 1996; 276:205-10

Functional Health Status

Fitness and Functional Limitations

• Prospective study of 1,175 women and 3,495 men age 40 years and older

• Medical exam during 1980-88• Average follow-up of 5.5 years• Self-report of functional limitations in 1990 by

mail-back survey– Are you physically able to do?

• personal care activities• household activities• recreational activities

Huang et al. MSSE 1998, 30:1430-5

Prevalence of Self-reported Functional Limitations by Fitness and Age Groups

Age Groups (years)Fitness Group 40-49 50-59 60+WomenLow 18* 23 46Moderate 8 13 26High 7 3 18MenLow 7 14 24Moderate 3 5 9High 3 1 7*Prevalence (%) Huang et al. MSSE 1998, 30:1430-5

Fitness and Functional Limitations, Women and Men, ACLS

• OR for self-reported functional limitation adjusted for age, follow-up, BMI, smoking, alcohol intake, baseline disease, & disease at follow-up 0

0.10.20.30.40.50.60.70.80.9

1

Women Men

LowModerateHigh

Huang et al. MSSE 1998, 30:1430-5

Cardiorespiratory Fitness and Longevity

Population Attributable Riskof Low CRF

and Economic Issues

Physical Activity Levels for U.S. Adults

25%25%

38%38% 22%22%15%15%

Sedentary and Irregularly Activity Regularly Active, Low to Moderate Intensity

Regular Vigorous Activity (3 days, 20 minutes)Surgeon General’s Report, 1996

Population Attributable Risk (PAR) for All-Cause Mortality in 10,623

Normal Weight Men, ACLSCo-morbidity # at

riskRR ofdeath

PAR %death

Baseline CVD 845 2.3 19Diabetes 322 1.3 2High Chol 1621 1.0 0Hypertension 1823 1.5 12Smoking 1681 1.4 7Low fit 987 1.6 10

RR adjusted for age, examination year, parental CVD, and all other items in the tableWei et al. JAMA 1999; 282:1547

Population Attributable Risk (PAR) for All-Cause Mortality in 11,798

Overweight Men, ACLSCo-morbidity # at

riskRR ofdeath

PAR %death



Population Attributable Risk (PAR) for All-Cause Mortality in 3293 Obese

Men, ACLSCo-morbidity # at

riskRR ofdeath

PAR %death



Physical Inactivity and Direct Medical Costs

• Cross-sectional stratified analysis of 1987 National Medical Expenditures Survey

• Non-institutionalized women and men 15 years and older

• 35,000 persons in 14,000 households• Detailed information on health care costs were

collected and confirmed by an additional survey of medical providers

• 20,041 non-pregnant participants included in the analyses

Pratt M et al. Physician & Sportsmedicine 2000


• Physical activity categories– Physically active=30 minutes of moderate or

strenuous activity 3 or more days/week– Physically inactive=all others

• Medical care costs included– Hospital admissions– Physician visits– Medication use



• Total medical care costs – All respondents=$1,690

• Physically active=$1,242• Physically inactive=$2,277

• Differences in costs between active and inactive individuals were present by categories of smoking habit, gender, and age groups

• Total cost of inactivity for medical care for the U.S. in 2000 is estimated at $76.6 billion


Summary: Physical Inactivity and Health

• A sedentary and unfit way of life is harmful to health and function

• A high proportion of adults in most countries are sedentary

• Population attributable risks and health care costs of physical inactivity are substantial

• There is a crucial need to develop policies to address this major public health problem

Decline in Energy Expenditure in the United Kingdom, 1970-1995

• Estimate of energy intake from surveys of household food intakes and making assumptions about food and drink outside the home– Decline of 750 kcal per day

• Average weight gain of 2.5 kg in the population over the same period– Accounts for an additional 50 kcal per day

• Therefore, the average decline in the UK is about 800 kcal per day in the past 25 years

James PT. Int J Obes 1995

Lifestyle and Energy ExpenditureSedentary Way

kcalActive Way

kcal

Using remote tochange channel

<1 Getting up andchanging channel

3

30 min of phonecalls--reclining

4 Standing for 3 X 10minute calls

20

Using garage dooropener

<1 Opening garagedoor twice/day

2-3

Hiring maid toclean and iron

0 30 min of ironing30 min vacuuming

152

Kcal estimates for 150-160 pound personTaken from article by L. Beil, Dallas Morning News, 1999


kcalActive Way

kcal

30 min waiting forpizza delivery

15 30 min of cooking 25

Buying pre-slicedvegetables

0 15 min washing,slicing & chopping

10-13

Using a leafblower for 30 min

100 30 min of rakingleaves

150

Using a lawnservice

0 30 min/week eachgardening, mowing

360



kcalActive Way

Kcal

Using car washonce/month

18 Washing & waxingcar, 1 hr/month

300

Letting dog out theback door

2 Waling dog for 30min

125

Drive 40 min, 5min walk (parking)

22 15 min walk to busstop, 2 X day

60

Emailing colleague,4 min

2-3 Walk 1 min, talk 3min (standing)

6



kcalActive Way

kcal

Taking elevatorup 3 flights

0.3 Walking up 3flights of stairs

15

Park close as poss,10 sec walk

0.3 Park 1st spot, 2 minwalk, 5 X week

8

Cashier unloadsshopping cart

2 Unload fullshopping cart

6

Ride escalator 3times

2 1 flight of stairs, 3X week in mall

15



kcalActive Way

kcal

1 hour internetshopping

30 Shopping mall,walking 1 hour

145-240

Sitting in car atdrive-in window,30 min

15 Parking & walkinginside, 3 X week,total of 30 min

70

Paying at thepump

0.6 Walking in to pay,1 X week

5

Sitting & listeningto lecture, 60 min

30 Giving lecture 70


Lifestyle and Energy Expenditure• Assume a person’s caloric intake remains the

same• Completing all of the tasks reviewed daily or as

listed– Active way=10,500 kcal/month– Sedentary way=1,700 kcal/month

• Difference of 8,800 kcal/month is energy equivalent of 2.5 pounds/month or 30 pounds/year


Lifestyle Physical Activity Interventions

Experimental Design Two year, parallel randomized design

Two treatment groups:LifestyleStructured

Six months of active intervention;18 months of follow-up intervention

Three successive recruitment cohortsProject Project ActiveActiveDunn A et al. JAMA 1999

Structured Intervention: Project Active

Exercise prescription model, e.g., 50-85% of maximal aerobic power for 20-60 minutes per session, at least 3 and preferably 5 days per week

State-of-the-art fitness center for first 6 months

Follow-up includes quarterly newsletter and group activities, e.g., fun runs Project Project ActiveActive

Dunn A et al. JAMA 1999

Lifestyle Intervention: Project Active Goal is to increase energy expenditure

using behavioral interventions and processes matched to stage of motivational readiness

Small group meetings once per week for four months, then every two weeks for two months

Follow-up includes monthly meetings through the end of year 1 then graduated down through year 2

Project Project ActiveActiveDunn A et al. JAMA 1999

Behavioral Approaches to Physical Activity Interventions

• Theoretical foundations– Social Learning Theory– Stages of Change Model– Environmental/Ecological Model

• Methods– Problem solving– Self-monitoring– Goal setting– Social support– Cognitive restructuring– Incremental changes– Manipulating the environment


Curriculum OverviewWeek Session Title Discussion Topic Beh./Cog. Processes

1 Getting to KnowYou

Personal TimeStudy

Brainstormingabout inactivity

Increasing knowledge

2 Coming Up witha Plan

2-minute walk Finding

opportunities

Increasing knowledge Committing yourself

3 UncoveringBarriers andBenefits

Brainstormbarriers andbenefits tobecomingphysically active

Comprehendingbenefits

Increasing healthyopportunities

Decisional balanceDunn A et al. JAMA 1999

How Do People Change? Cognitive Strategies

Increasing Knowledge Encourage person to read and think about physical activity

Warning of Risks Provide person with message that being inactive is very unhealthy

Caring about Consequences Encourage person to recognize to Others how his/her inactivity affects

his/her family and friends

Comprehending Benefits Help person to think about the personal benefits of being active

Increasing Healthy Help person to become aware of Opportunities societal changes in regard to

physical activity


How Do People Change? Behavioral Strategies

Substituting Alternatives Encourage person to engage in physical activity when it might be most beneficial, yet is rarely done

Enlisting Social Support Encourage person to find a friend or family member who will provide support for being active

Rewarding Yourself Encourage person to reward and praise self for being active

Committing Yourself Encourage person to make commitment to be active

Reminding Yourself Help person to set up reminders to be active


2526272829303132

0 6 12 18 24

Lifestyle Structured

Mean Peak Oxygen Consumptionm

l. kg-1

. min

-1

time in months


24-Month Change in Weight and Percent Body Fat

Weight Percent Body Fat

* p < 0.001 within group*

*

kilo

gram

s

Project Project ActiveActive- 3

-1.5

0

1.5

LifestyleStructured

1.5

perc

ent

0

-1.5

- 3


24-Month Reduction in Blood Pressure

-7

-6

-5

-4

-3

-2

-1

0

LifestyleStructured

mm

Hg

Systolic Diastolic

* p < 0.01 within group

* *

* *

Project Project ActiveActive


Enlisting social support

• Seeking out others to provide support for and encourage participation in physical activity

I have a healthy friend that encourages me to be physically active when I don’t feel up to it

I have someone on whom I can depend when I am having problems with being physically active

Rewarding yourself

• Using rewards to encourage or maintain physical activity behavior

I reward myself when I am physically active

I do something nice for myself for making efforts to be more physically active

Reminding yourself

• Positive reminders to engage in physical activity

I put things around my home to remind me of exercising

I keep things around my place of work that remind me to be physically active

Substituting alternatives

• Replacing sedentary pursuits with more active behaviors

Instead of remaining inactive, I engage in some physical activity

When I’m feeling tense, I find that being physically active helps relieve my worries

Committing yourself

• Making commitments toward being more physically active

I make commitments to be physically active

I am the only one responsible for my health, and only I can decide whether or not I will be physically active

Measures• Independent Measures

– Processes of Change - 40-item questionnaire• Marcus, Rossi, Selby, Niaura, & Abrams,

1992

• 5 Cognitive Processes

• 5 Behavioral Processes

Implications• Effective measurement of these key mediating

constructs exist • Interventions have been shown to be effective in

modifying these variables• Change in the mediating variables is associated with

changes in behavior • Researchers and practitioners should address

behavioral and cognitive strategies in the promotion of short- and long-term physical activity

Public Health Recommendations for Physical

Activity

Public Health Recommendation for Physical Activity

• Recent statements from the American College of Sports Medicine/Centers for Disease Control and Prevention, American Heart Association, NIH, and the office of the US Surgeon General conclude:– All adults should accumulate at least 30 minutes

of at least moderate intensity physical activity each day

– This is equivalent to walking about 2 miles at a pace of 3 to 4 mph

Summary

• Physical inactivity and low levels of cardiorespiratory fitness are strong predictors of mortality and other health problems

• There is a high prevalence of sedentary habits—40-50 million adults in the U.S.

• Population attributable risks and economic costs of inactivity are high

Best Exercise Advice to Give to the Public?

• Traditional, structured program--3-5 times/week, 20-60 minutes/session, relatively vigorous

• Consensus recommendation--accumulate at least 30 minutes of moderate intensity exercise each day

• The important question is not whether one approach is better than the other, but do both approaches work?

What Is the Best Exercise?

• The one you will do regularly• No matter how excellent the

exercise is or how effective the program might be, it will not produce any benefits for you if you do not do it

Conclusion• Physical inactivity is one of the most

important public health problems and it is important to develop an action plan to address this issue– Policy makers– Public health professionals– Health service providers– Educators– Grassroots activists

Steven N. Blair Director of Research—Cooper Institute Visiting Professor and

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