Can Physical Activity be Designed Back into American Lives?

Mark Fenton

Pedestrian and Bicycle Information Center

Univ. of North Carolina

Point 1: There’s an epidemic of physical inactivity in America.

Point 2. Just trying to change individual behavior has NOT solved the problem.Point 3. We know how to build more

pedestrian and bike-friendly communities.

Point 4. We must do it all—build active settings, and work to change behavior!

Point 1:It’s not just an obesity

epidemic. It’s an epidemic of physical inactivity.

Surgeon General’s 1996 Activity Recommendation • 30 minutes of

activity.• Most days of the

week.• Can be broken up.• Reduced risk for

CVD, diabetes, osteoporosis, obesity, clinical depression, some forms of cancer.

The Obesity Epidemic in the USFlegal et. al. (JAMA 288, 14; Oct. 2002)

10

15

20

25

30

35

1960 1965 1970 1975 1980 1985 1990 1995 2000

National Health and Nutrition Examination Survey data

% Obese (BMI>30)

Physical Activity in the US (MMWR 50 (09); 166-9; Mar. 9, 2001)

10

20

30

40

50

1990 1992 1994 1996 1998 2000

CDC/BRFSS

% of US Population

Inactive Sufficiently Active

Physical activity recommendation for children: (1994 consensus conf.)

• Physically active everyday as part of

lifestyle (30-60 minutes).

• 20 minutes of vigorous activity, at least 3

days/week.

US Youth Overweight RatesJAMA 288 (14); Oct 9, 2002.

US Youth Physical Activity Rates(CDC: Youth Risk Behavior Survey)

Self-help vs. CommercialWeight Loss Programs

(Heshka et.al., JAMA 289, 14; April 9, 2003)

First Law of Thermodynamics:

EIN – EOUT = ESTORED

Can’t just focus on nutrition (EIN). Have to increase physical activity

(EOUT) to attain a balance!

Point 2. It’s not just about individual behavior change.

Interventions to change behavior last for several

months, then the effects tend to

wear off.

Exercise ParticipationEffect of Short Bouts, Home Treadmills

(Jakicic et.al., JAMA 282, 16)

Individual Behavior Change AidsSee Dunn & Blair, “Active Living Everyday”

• Social support

• Scheduling

• Goals, rewards

• Measurement

• Recording (log)

• Substitution

• Mapping

Energy ExpenditureLifestyle vs. Structured Activity

(Dunn et.al., JAMA 281, 4)

Point 3. The Goal:

Reintegrate physical activity into the lives

of all Americans.

Transportation: We’ll walk and bike, if we have places to do it.

But we still build mostly this:

US Walking Trips 1977-1995National Personal Transportation Survey, USDOT

US Auto Trips 1977-1995National Personal Transportation Survey, USDOT

The ideal “trip” decision hierarchy for a more physically active America*:

Walk

BikeTransit

Drive

*Nearly 25% of trips are less than or equal toone mile.(1995, NPTS)

Do incidental walking trips matter? Imagine:

Eliminate 20 minutes of walking, 5 days a week (2 kcal/min vs. 4 kcal/min).

Net loss of 40 kcal/day.

200 kcal/week = 10,400 kcal/year~ 3 lbs./year (30 lbs./decade!)

Simplified elements of pedestrian and bicycle friendly settings:

Network.

Land use.

Safety.

Site Design.

Commitment.

Walkable, bikable places have:

Continuous networks of footpaths, multi-use trails, and sidewalks.

Walkable, bikable places have:

Compact, dense, and

diverse

development and zoning.

Walkable, bikable places are:

Safe for all cyclists and pedestrians

(not just skilled ones).

Walkable, bikable places are:

Aesthetically pleasing and functional for pedestrians

and bicylists.

Walkable, bikable places have:

A civic commitment to walking

and cycling, from top to

bottom.

Point 4. A better way for public health:

A socio-ecological approach

to increasing physical activity.

Social Ecology ModelDeterminants of behavior change

Sallis, Owen, “Physical Activity and Behavioral Medicine.”

• Individual (readiness, efficacy)

• Interpersonal (family, friends)

• Institutional (school, work, HMO)

• Community (networks, local gov’t)

• Public Policy (transport, land use)

Social EcologyModel of success: tobacco

• Individual – education, medication• Interpersonal – 2nd hand smoke, kids• Institutional – work place bans• Community – smoke free policies• Public Policy – taxes, enforcement,

advertising bans, SG’s warning label.

The Future of Physical Activity in the US? (Nothing more than hopeful conjecture.)

10

20

30

40

50

1990 1995 2000 2005 2010 2015

% of US Population

Inactive Sufficiently Active