Decline in physical activity in black girls and white girls during adolescence

N Engl J Med. 2002 Sep 5;347(10):709-15. doi: 10.1056/NEJMoa003277.


Background: Physical activity declines during adolescence, but the underlying reasons remain unknown.

Methods: We prospectively followed 1213 black girls and 1166 white girls enrolled in the National Heart, Lung, and Blood Institute Growth and Health Study from the ages of 9 or 10 to the ages of 18 or 19 years. We used a validated questionnaire to measure leisure-time physical activity on the basis of metabolic equivalents (MET) for reported activities and their frequency in MET-times per week; a higher score indicated greater activity.

Results: The respective median activity scores for black girls and white girls were 27.3 and 30.8 MET-times per week at base line and declined to 0 and 11.0 by year 10 of the study (a 100 percent decline for black girls and a 64 percent decline for white girls, P<0.001). By the age of 16 or 17 years, 56 percent of the black girls and 31 percent of the white girls reported no habitual leisure-time activity. Lower levels of parental education were associated with greater decline in activity for white girls at both younger ages (P<0.001) and older ages (P=0.005); for black girls, this association was seen only at the older ages (P=0.04). Pregnancy was associated with decline in activity among black girls (P<0.001) but not among white girls, whereas cigarette smoking was associated with decline in activity among white girls (P<0.001). A higher body-mass index was associated with greater decline in activity among girls of both races (P< or =0.05).

Conclusions: Substantial declines in physical activity occur during adolescence in girls and are greater in black girls than in white girls. Some determinants of this decline, such as higher body-mass index, pregnancy, and smoking, may be modifiable.

Publication types

  • Multicenter Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Black People*
  • Body Mass Index
  • Child
  • Educational Status
  • Exercise*
  • Female
  • Humans
  • Income
  • Pregnancy
  • Prospective Studies
  • Smoking / epidemiology
  • Surveys and Questionnaires
  • United States / epidemiology
  • White People*