|Nutrition Evidence Library|
Fulton, Jante E. et al Physical Activity, Energy Intake, Sedentary Behavior, and Adiposity in Youth Am J Prev Med 2009;37(1S): S40-S49
B - Click here for explanation of classification scheme.
Research Design and Implementation Rating:
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Primary objective was to describe the relationship of physical activity, energy intake, and sedentary behavior with BMI, Fat Free Mass Index (FFMI) and Fat Mass Index (FMI). The hypothesis was that greater energy intake and time spent in sedentary behavior is directly associated with higher BMI and FMI, and more time spent in moderate to vigorous activity was inversely associated with BMI and FMI.
Participants in Project Heartbeat age 10-14 years of age.
Not stated in this article
Description of Study Protocol:
Recruitment : Participants in Project Heartbeat, a longitudinal study designed to evaluate cardiovascular disease risk factors and behavioral determinants in children and adolescents.
Design : Longitudinal study of three age cohorts. Repeated annual measurements were assessed.
Blinding used (if applicable): No
Intervention (if applicable): None
Statistical Analysis: Bivariate correlations. Multi-level modeling of BMI, fat free mass index (FFMI), and fat mass index (FMI). Alpha set at 0.05.
Data Collection Summary:
Timing of Measurements: Although repeat measures were taken throughout 4 years of participation, analysis was done yearly measurements taken at time of annual diet and physical activity assessment.
NOTE: Body Fat, FFMI, and FMI were calculated from above measurements using cross validated formulas
Description of Actual Data Sample:
Data sets were divided in groups: Cohort 1: aged 8 at entry and attained 10 years by followup assessment. Cohort 2: entered at 11 years, and Cohort 3 entered at 14 years.
Initial N: 678
Attrition (final N):472 (227 male, 245 female)
Age:Cohort 1 mean age 10.4 years, Cohort 2 mean age 11.5 years and Cohort 3 14.4 years.
Ethnicity: % non black were reported across cohort and gender. Range was 74.6-92.7. There was no information presented regarding similarity among groups.
Other relevant demographics: Sexual maturation stages were reported across groups. As expected due to age differences, groups differed in distribution of sexual maturation stages.
Anthropometrics (e.g., were groups same or different on important measures):
Location: Conroe, TX, USA
Summary of Results:
The following factors were statistically significantly associated with the outcome variables In the final multivariate models after controlling for sexual maturation and gender:
Fat Free Mass Index:
Fat Mass Index:
Energy intake and sedentary behavior were not associated with any of the outcomes in the final models.
Table: Correlation coefficients, adjusted for age between BMI and it's components. (FFM: fat free mass index, FMI: fat mass index, MVPA: moderate to vigorous physical activity, energy intake, and sedentary behavior)
* significance at p<0.05
In children aged 10-18 years, MVPA was inversely associated with fat mass and with BMI. Investigations in youth of dietary intake and physical activity, including interventions to prevent or reverse overweight as represented by BMI should address its fat and lean components and not BMI alone.
The article did not describe the methods of group assignment well, but rather referred to other articles from the same study (not analyzed here). So, it was impossible to fully assess the methodological quality of this study on its own merits.
This article demonstrated a number of important concepts related to body composition, changes with age and sexual maturation, and behavioral factors. The authors point out the limitations of BMI alone as an indicator of obesity. The article supports the impact of activity alone on body composition, irrespective of energy intake and sedentary behavior. Although this article received a neutral rating, (based on the checklist questions and study design), I belive it contributes useful information to the body of evidence related to adiposity assessment and influential behaviors in children and adolescents.
Copyright American Dietetic Association (ADA).