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FOR IMMEDIATE RELEASE
January 16, 2007

STUDY LINKS SOCIAL CLASS AND PHYSICAL INACTIVITY
Education, income predict inactivity better than race, ethnicity

Indianapolis – Education, family income, employment status, and other factors related to social class tend to moderate the effect of race/ethnicity on physical inactivity, according to new research published in this month's issue of Medicine & Science in Sports & Exercise®, the official journal of the American College of Sports Medicine (ACSM).  While research is just beginning to look at how social class affects leisure-time rates of physical activity in various ethnic and racial groups, previous studies have shown cultural trends such as blacks and Hispanics being more inactive during their leisure time than whites. 

The study also indicates education level—particularly for women—is related to physical inactivity.  And, physical demands of one's occupation play a lesser role than previously thought in leisure-time inactivity levels, after adjusting for age and social status.

"This is the first study to look at the effect of race and social class on the prevalence of inactivity while controlling for occupational activity levels," said lead researcher Simon J. Marshall, Ph.D.  "Focusing solely on differences in health behaviors between racial and ethnic groups downplays the importance of socioeconomic factors which exert a powerful influence on lifestyle. It is surprising that socioeconomics have largely been ignored in physical activity research.  Physical activity has a protective effect on your health; it doesn't matter where it comes from."

Physical activity was measured across multiple domains such as home, leisure, and transportation—providing a more complete picture of the subjects' overall activity levels.  Marshall led a team of researchers in analyzing data collected by the National Physical Activity and Weight Loss Survey (NPAWLS). The study was a cooperative agreement funded by the CDC's Division of Nutrition and Physical Activity to Barbara E. Ainsworth, Ph.D., FACSM, at Arizona State University with the purpose of understanding more about physical activity, nutrition, and weight loss behaviors in U.S. adults.

Previous research most often uses a single factor—such as educational attainment or family income—as a measure of social status.  According to Marshall, "Using a single measure of social class or socioeconomic status is limited because of the independent and interactive effects that different social class markers have on health."  Compared to previous studies, Marshall and colleagues found a somewhat lower prevalence of inactivity overall, probably because multiple domains of activity were assessed, not just recreational exercise.

Among the findings:

• Hispanic women who did not complete high school are at the greatest risk of inactivity (32.3 percent).

• Black men with a college education had the lowest prevalence of inactivity (4 percent).

• Hispanics and non-Hispanic blacks had similar levels of inactivity, but both groups were more inactive than their white counterparts.

• Women tended to report being more physically inactive than men.  Across all racial/ethnic groups, the age-adjusted prevalence of leisure-time physical inactivity was 12.4 percent for men and 15.1 percent for women.

• Marital status, traditionally included along with income, education, and occupation as a measure of social class, seemed to have little effect on inactivity levels.

While earlier studies have showed that being inactive was linked to race/ethnicity, Marshall et al. found lower income and lower education attainment were likely to explain these differences.  "Comparing the prevalence of inactivity across racial/ethnic groups but within the same social class strata yielded interesting results," said Marshall. "Differences between whites, African Americans, and Hispanics largely disappeared.  Also, occupational levels of physical activity proved to have little influence on leisure-time activity levels after adjusting for age, sex, and social class factors."

Also worthy of closer examination, said Marshall, are the reasons activity levels vary among people of different social classes.  "People in poverty are more likely to live in neighborhoods where public recreation is unavailable or dangerous.  We also know that wholesome food is likely to be less available or more expensive in low-income neighborhoods, which makes it even harder for the poor and uneducated to make healthy choices.  Although social class factors are important, this does not mean that culture does not play a role. For example, African-American women tend to be heavier than Caucasian women but more satisfied with their bodies.  For some, body dissatisfaction may be an important determinant of physical activity."

Further Research Needed

According to the author, these findings point to the need for further research into how social class factors explain varying rates of physical activity among racial and ethnic minorities.  The study design precludes making causal inferences about social class and inactivity and the sample sizes of some subgroups of NPAWLS data were smaller than 100, limiting their applicability to the general population.

Study Methodology

NPAWLS polled 9,806 adults in telephone interviews between September and December 2002.  Respondents were asked whether, "in a usual week," they engaged in moderate intensity activities (those that cause small increases in breathing or heart rate) or vigorous intensity activities (causing larger increases) for at least 10 minutes at a time.  Activities included those done at home, for recreation, or for transportation. Participants who answered "no" to both questions were classified as physically inactive. Similar questions were asked about physical activity at work.

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NOTE: Medicine & Science in Sports & Exercise® is the official journal of the American College of Sports Medicine, and is available from Lippincott Williams & Wilkins at 1-800-638-6423. For a complete copy of the research paper (Vol. 39, No. 1, pages 44-51) or to speak with a leading sports medicine expert on the topic, contact the Department of Communications and Public Information at 317-637-9200 ext. 127.  Visit ACSM online at www.acsm.org.  The conclusions outlined in this news release are those of the researchers only, and should not be construed as an official statement of the American College of Sports Medicine.
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