Relationship of physical fitness to prevalence and incidence of overweight among schoolchildren.
OBJECTIVE
We examined the relationship between comprehensive fitness tests and overweight using a school surveillance system in a racially diverse city in the United States.


METHODS
Trained physical education teachers measured weight, height, and fitness annually from 2001 to 2003. We compiled data for a cross-sectional analysis (11,845 measurements on 6297 students, 5 to 14 years of age) and a 1-year prospective analysis (4215 measurements on 2927 students not overweight at baseline, 5 to 13 years of age). Overweight was defined as a BMI > or =95th percentile (Centers for Disease Control and Prevention 2000 growth charts), and underfit was defined as failing at least one of five fitness tests: endurance run, abdominal strength, flexibility, upper body strength, and agility (Amateur Athletic Union and Fitnessgram). Associations between fitness and overweight were examined using multivariate logistic regression models, adjusting for sociodemographic status and repeated measurements over time.


RESULTS
The mean number of fitness tests passed was lower among students with a BMI above the 80th percentile. Overweight incidence over 1 year was 7% and 2% for underfit and fit girls, respectively (odds ratio, 3.3; 95% confidence interval, 2.0 to 5.6). Not passing either the endurance run or upper body strength test was associated with overweight incidence in both boys and girls. After adjusting for baseline BMI, the endurance run remained a significant predictor of incident overweight among girls (odds ratio, 2.0; 95% confidence interval, 1.1 to 3.5).


CONCLUSIONS
Findings support a cross-sectional inverse relationship between physical fitness and overweight among school-aged children. The direction of causation between fitness and overweight is not clearly established and merits further study.
Kim
Juhee
J
677 Huntington Avenue, III-616, Harvard School of Public Health, Boston, MA 02115, USA. juheekim@hsph.harvard.edu
Must
Aviva
A
Fitzmaurice
Garrett M
GM
Gillman
Matthew W
MW
Chomitz
Virginia
V
Kramer
Ellen
E
McGowan
Robert
R
Peterson
Karen E
KE
D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D015331:Cohort Studies; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology*; D016017:Odds Ratio; D010809:Physical Fitness / Q000502:physiology*; D015995:Prevalence; D011446:Prospective Studies