Are schools responsible for ethnic disparities in adolescent exercise patterns?

A study of 17,000 adolescents in the United States found that African-American and Hispanic girls are less physically active than white, non-Hispanic girls—but that those differences are attributable to the schools they attend, not to their ethnic or racial background: African-American, white, and Hispanic girls attending the same school exhibit no difference in physical activity. The findings of the study, led by Tracy Richmond, MD, of the division of adolescent medicine at Children's Hospital Boston, can be found in the June 2006 issue of Pediatrics.

Among boys, the study's findings stand in contrast to what was observed in girls: African-Americans and Hispanics were more physically active than whites attending the same schools.

Dr. Richmond and her colleagues, who analyzed data from the National Longitudinal Study of Adolescent Health, a school-based study of 7th-to-12th graders, also found that:

• on average, African-American and Hispanic adolescents had a higher body mass index (BMI) than did white adolescents

• overall, adolescent girls were less physically active than boys, reporting fewer physical activities a week

• overall, African-American and Hispanic girls reported less activity than white girls—on average, 5.4, 5.2, and 6.0 activities a week, respectively

• among boys, in contrast, the number of activities a week was similar for African-Americans (7.6), Hispanics (7.5), and whites (7.6).

Most adolescents included in the study attended schools that were racially segregated: Nearly 40% of whites attended schools in which the student body was more than 94% white, whereas approximately 80% of African-Americans and Hispanics attended schools in which the population was less than 66% white. African-American and Hispanic adolescents attended schools in which the median family income was lower (African-Americans, $30,000; Hispanics, $32,500; whites, $45,000). In general, African-American and Hispanic girls attended poorer schools, in which all girls, in general, had a lower physical activity level.

But when school factors were accounted for, there was no longer a racial or ethnic difference in physical activity among girls; among boys, there were only minimal racial or ethnic differences in physical activity level overall. But within the same schools, both African-American and Hispanic boys had a higher rate of physical activity than did white boys. Students with a lower household income reported less physical activity. After taking into account the average household income of the schools' student body, however, individual household income was no longer significantly associated with physical activity in either males or females.

"This suggests that poorer and richer students attending the same school have similar levels of physical activity," Dr. Richmond says.

In the case of boys, the finding that African-Americans and Hispanics are more physically active than whites at the same school could be seen as positive and health-promoting, the authors write—or it could reflect the fact that minority males are being differentially channeled into sports, rather than toward academics.

The researchers note that they were not able to assess whether their findings reflect differences in the schools themselves-such as inequalities in gym facilities and programs—or whether the school differences reflected social or cultural factors in the surrounding neighborhood or community that might influence teens' physical activity patterns.