Facts of Life
Facts of Life:
Issue Briefings for Health Reporters
Vol. 9, No. 3
March 2004
Working Out the Problem of Insufficient Exercise
The Issue
The Facts
More Than Just Burning Calories
Expert Sources
References
The Issue:
Physical activity is
often considered an individual issue. But there’s a larger dimension,
say scientists who are examining exercise in terms of the environment as
well as the body.
Built Communities
“We’ve built communities that make it difficult
to be active,” says James Sallis, Ph.D., of San Diego State University. “We’ve
deleted physical activity from work, entertainment and transportation. The
system is designed for cars, not pedestrians or bicycles.”
Americans say they want walkable neighborhoods and parks with more access
to foot and bike trails. But zoning laws and political pressures direct resources
away from parks and bike paths and toward highway funding, Sallis says. The
consequences? People who live in sprawling suburbs drive everywhere and walk
less, so they weigh more and have higher blood pressure. [14]
Taking Small Steps Forward
Since the simplest,
most accessible form of exercise is walking, Sallis says, even modest changes
in towns and cities can help. Some changes that open up opportunities for walking
include well-maintained sidewalks, safe street crossings, ramps from sidewalks
to street level, connections between suburban cul-de-sacs, trees to provide
shade and new developments with housing, offices and shops.
The Facts:
- Seventy-two percent
of women do not engage in regular leisure-time physical activity, compared
to 64 percent of men. [1]
- Thirty minutes of exercise a day can decrease the risk
of chronic diseases including breast cancer. Coupled with appropriate
dietary restraint, this
level of activity can help overweight women lose weight. [2]
- Strength training, including lifting weights or doing
calisthenics, increases muscular strength, endurance and bone density,
but only 10 percent
to 12 percent of Americans over 65 meet national standards. [3]
- Despite well-known benefits of physical activity
for older adults, about two-thirds are not as active as they should
be. Individually tailored programs
to encourage lifestyle changes in seniors may be effective. [7]
- Exercise training has the potential to prevent
or reverse the bone loss in postmenopausal women by almost 1
percent per year. [13]
- A 20-year study says that increasing exercise
levels may be more of a deterrent against cardiovascular disease
than eating less. [10]
- Increased physical activity for a few hours
a week is associated with reduced risk for breast cancer
in post-menopausal women. More time spent
exercising, even if not strenuously, provides the most benefit.
[11]
- Treadmill fitness tests conducted 15 years
apart found that poor fitness in young people was linked
to twice the risk of diabetes, hypertension
and the metabolic syndrome. [12]
- The American Heart Association, the Centers
for Disease Control and Prevention and the American College
of Sports Medicine all recommend 30
minutes or more of activity such as brisk walking on most
days. [9]
- The U.S. Preventive Services Task Force
agrees that regular physical activity promotes health
and reduces risk of illness, but finds insufficient
evidence to recommend primary care counseling to promote
it. [6]
- Most current zoning practices limit
physically integrated mixed-use designs that provide
destinations that can be conveniently and safely
reached
by walking or bicycling. [8]
- “New Urbanism” city
planning leads to development that combines
first-floor shops with second- and third-floor
apartments or
townhouses.
Such planning encourages walking rather than driving
to shops. [5]
- To encourage
bicycling and public transportation, BikeStation in Palo
Alto, Calif., and other cities offers secure daytime parking
for bikes
while commuters take the train or bus the rest
of the way to their jobs. [4]
More
Than Just Burning Calories
Exercise does more than burn calories.
Physical activity not only lowers body weight, it cuts cardiovascular
risk and blood pressure, improves lipid profiles, has positive effects
on the immune system and can reduce the risk of certain cancers. It
strengthens the heart, helps the lungs function better, enables the
blood to carry more oxygen, makes muscles stronger and improves motion
in the joints.
There is some evidence that exercise can enhance mood and even counter
mild to moderate depression. Active people have a lower risk of stroke.
[15]
Starting an exercise program at any point in life boosts health. Activity
helps older people remain active longer. Walking three to four hours
a week reduces death by any cause by 54 percent even among people who
have diabetes. [16]
All these benefits vanish quickly once people stop exercising.
The Centers for Disease Control and Prevention and the American College
of Sports Medicine set the standard for physical activity in 1995,
recommending at least 30 minutes a day of moderate exercise on most
or all days of the week, in increments as short as 10 minutes. [17]
“
From the 1970s up to the 1990s, ‘exercise’ was geared to
improving fitness and was based on the model of an athletic male college
student,” says Harvard’s I-Min Lee, M.D. “Today,
the new model is health, not athletic training.”
One new study tested various combinations of high and moderate exercise
intensity and duration, combined with a 30 percent reduction in calories
consumed. The level of intensity produced no significant differences
in weight loss. What did make a difference, the researchers say, was
time.
Women who exercised 150 minutes a week lost 4.7 percent of their starting
weight, while those who spent 200 minutes or more exercising lost 13.6
percent. [18]
Cheap,
high-calorie foods and too much time in front of the TV or computer
combine to
fatten America’s children, say many experts.
Nearly half of American youths age 12 to 21 get no regular vigorous
exercise, says a U.S. Surgeon General’s report.[19]
Meanwhile, older people want to exercise to improve their health and
appearance, maintain their independence and remain active with their
families. But they are discouraged by poor health conditions that interfere
with ease of exercise, lack of time and the toll of aging. [20]
Almost
any form of physical activity can improve overall health and the
cardiovascular
system: walking, gardening, pushing a stroller,
swimming laps, jumping rope, riding a bike. A “start low and
go slow” approach is a good way to begin a personal exercise
plan, experts say.
“The point is, at least do something,” Lee says. “Something
is better than
nothing.”
Expert
Sources:
I-Min Lee, Sc.D., M.P.H.
Harvard School of Public Health
Brigham and Women’s Hospital
(617) 278-0817
ilee@rics.bwh.harvard.edu
James Sallis, Ph.D.
San Diego State University
Active Living Research Program
(619) 260-5535
sallis@mail.sdsu.edu
Bess H. Marcus, Ph.D.
Ctr. for Physical Activity Research
The Miriam Hospital and
Brown University Medical School
(401) 793-8003
bmarcus@lifespan.org
References
1. BarnesPM, Schoeborn CA. Physical
Activity Among Adults: United States, 2000:Advance Data From Vital
and Health Statistics. Hyattsville,
Md: National Center for Health Statistics; 2003
2. Lee I-M. Physical
activity in women. JAMA. 2003 Sep 10;290(10):1377-1379
3. Centers for Disease Control and Prevention. Morbidity
and Mortality Weekly Report. 2004 Jan 24;53(2):25-28. or http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5302a1.htm [1/22/2004]
4. www.bikestation.org
5. www.activeliving.org or www.orencostation.com
6. U.S. Preventive Services Task Force. Behavioral counseling in primary
care to promote physical activity: Recommendation and rationale. Annals
of Internal Medicine. 2002 Aug 6;137(3):205-208
7. Stewart AL, Verboncoeur CJ, McLellan BY, Gillis DE, Rush S, Mills
KM, King AC, Ritter P, Brown BW Jr, Bortz WM 2nd. Physical activity
outcomes of CHAMPS II: a physical activity promotion program for older
adults. J Gerontol A Biol Sci Med Sci. 2001 Aug; 56(8): M465-70.
8. Hirschhorn JS. Zoning should promote public health. Am
J Health Promotion. 2004 Jan/Feb;18(3):258-260
9. Thompson PD, Buchner D, Pina IL, Balady GJ, Williams MA, Marcus
BH, Berra K, Blair SN, Costa F, Franklin B, Fletcher GF, Gordon NF,
Pate RR, Rodriguez BL, Yancey AK, Wenger NK. Exercise and physical
activity in the prevention and treatment of atherosclerotic cardiovascular
disease. Circulation. 2003 Jun 24; 107(24): 3109-16.
10. Fang J, Wylie-Rosett J, Cohen HW, Kaplan RC, Alderman MH. Exercise,
body mass index, caloric intake, and cardiovascular mortality. Am
J Prev Med. 2003 Nov; 25(4): 283-9.
11. McTiernan A, Kooperberg C, White E, Wilcox S, Coates R, Adams-Campbell
LL, Woods N, Ockene J; Women's Health Initiative Cohort Study. Recreational
physical activity and the risk of breast cancer in postmenopausal women:
the Women's Health Initiative Cohort Study. JAMA. 2003 Sep 10; 290(10):
1331-1336.
12. Carnethon MR, Gidding SS, Nehgme R, Sidney S, Jacobs DR Jr, Liu
K. Cardiorespiratory fitness in young adulthood and the development
of cardiovascular disease risk factors. JAMA. 2003 Dec 17;290(23):3092-3100
13. Wolff I, Croonenborg JJ van, Kemper HCG, Kostense PJ, Twisk JWR
et al. The effects of exercise training programs on the bone mass;
a meta-analysis of published controlled trials in pre- and post menopausal
women. Osteo Int; 1999
14. Ewing R, Schmid T, Killingsworth R, Zlot A, Raudenbush S. Relationship
between urban sprawl and physical activity, obesity, and morbidity.
Am J Health Promot. 2003 Sep-Oct;18(1):47-57.
15. Lee CD, Folsom AR, Blair SN. Physical activity and stroke risk:
a meta-analysis. Stroke. 2003 Oct;34(10):2475-81.
16. Gregg EW, Gerzoff RB, Caspersen CJ, Williamson DF, Narayan KM.
Relationship of walking to mortality among US adults with diabetes.
Arch Intern Med. 2003 Jun 23;163(12):1440-1447.
17. Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C,
Buchner D, Ettinger W, Heath GW, King AC, et al. Physical activity
and public health. A recommendation from the Centers for Disease Control
and Prevention and the American College of Sports Medicine. JAMA. 1995
Feb 1;273(5):402-407.
18. Jakicic JM, Marcus BH, Gallagher KI, Napolitano M, Lang W. Effect
of exercise duration and intensity on weight loss in overweight, sedentary
women: a randomized trial. JAMA. 2003 Sep 10;290(10):1323-1330.
19. Smith BJ, Merom D, Harris P, Bauman AE. Do primary care interventions
to promote physical activity work? A systematic review of the literature.
Report No. CPAH 03-0002. National Institute of Clinical Studies, Melbourne,
Aus. 2002 Dec
20. U.S. Department of Health and Human Services. Physical
Activity and Health: A Report of the Surgeon General, Atlanta, Ga. U.S. Department
of Health and Human Services, Centers for Disease Control and Prevention,
National Center for Chronic Disease Prevention and Health Promotion.
1996 http://www.cdc.gov/nccdphp/sgr/pdf/sgrfull.pdf
21. Grossman MD, Stewart
AL. "You aren't going to get better
by just sitting around": physical activity perceptions, motivations,
and barriers in adults 75 years of age or older. Am J Geriatr Cardiol.
2003 Jan-Feb;12(1):33-37
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The Center for the Advancement
of Health is an independent nonprofit organization that promotes
greater recognition of how psychological, social, behavioral,
economic and
environmental factors influence health and illness. The Center advocates the highest
quality research and communicates it to the medical community and the public. The
fundamental aim of the Center is to translate into policy and practice the growing body of
evidence that can lead to the improvement and maintenance of the health of individuals and
the public. The Center was founded by the John D. and Catherine T. MacArthur Foundation
and the Nathan Cummings Foundation, which continue to provide core funding. Funding for
this series was provided by the Robert Wood Johnson Foundation.
For Information Contact:
Kristina Campbell
Editor, Health Behavior News Service
Center for the Advancement of Health
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