Pediatric Weight Management

Pediatrics and Physical Activity


Dowda, M., Ainsworth, B.E., Addy, C.L., Saunders, R. Riner, W. Environmental influences, physical activity, and weight status in 8 to 16 year-olds. Archives of Pediatric and Adolescent Medicine 2001; 155:711-717.

PubMed ID: 11386963
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

Purpose was to determine what associations exist between overweight in youth and vigorous physical activity, participation in sports and time spent in a sedentary activity

Inclusion Criteria:

Participants were from a subset of the sample that had BMI data on both parents.

Exclusion Criteria:
  • Participants who did not complete the PA questions were deleted.
  • Other deletions included youth categorized as “other” for race, those with a limiting physical condition, missing data on poverty index or BMI of parents.
Description of Study Protocol:
  • Data from NHANES III were used in the analyses.
  • Data were collected during a visit to a mobile data collection center.
Data Collection Summary:

Body mass index was primary outcome. Value was dichotomized into overweight and non overweight groups using age and sex specific 85th percentile of BMI from the CDC.

Physical activity assessed with a self-report question:

How many times per week the subjects played or exercised enough to make them sweat and breathe hard.

  • < 3 = low active group
  • >= 3 = active group


Sport participation was asked with a question about number of sport teams involved with over past year

  • 0 = low active group
  • 1 + = high active group


Television was assessed with a question about number of hours of television watched on the day prior to the survey

  • < 4 = low TV
  • >= 4 = high TV

Statistical Analyses:

  • Chi square analyses were used to determine differences by sex in activity, TV and percentage overweight.
  • Crude odds ratios were used to examine associations between weight status of youth and variables of interest.
  • Multiple logistic regression models were calculated to examine the relationship of the independent variables with weight status
Description of Actual Data Sample:
Sample included 2791 children 8-16 years of age with complete data.
Summary of Results:
  • 81% of youth reported vigorous activity three or more times per week.
  • 65% reported participating in one or more sport teams or in 1 or more exercise programs.
  • 24% reported watching 4 or more hours of television per day.
  • Percentage of overweight children were 7%, 39% and 54% with 0,1, or 2 overweight parents.
  • Participants in sports or exercise programs were less likely to be overweight [Males: OR = .59 (.38-.92) / Females: OR = .67 (.47-.97)]
  • Participation in more than three bouts of activity a week was not associated with risk of overweight [Males: OR = 1.21 (.59-2.47) / Females: OR = .99 (.64-1.53)]
  • Odds of being overweight if watching more than 4 hours of TV were 1.29 for males and 2.13 for females but only the result for females was significant.
Author Conclusion:
  • Participation in vigorous physical activity was not related to being overweight.
  • Being on a sports team or in an exercise program was associated with not being overweight among all males and 14-16 year old females.
  • Females who watched 4 or more hours of television per day preceding the survey were more likely to be overweight.


Overall conclusion:


Overweight youth were less likely to have participated in sports teams and were more likely to have overweight parents.
Funding Source:
University/Hospital: University of South Carolina
Reviewer Comments:
  • The frequency of participation in activity was high (> 80%) so there may not have been sufficient variability in the data. A different cutpoint may have yielded different results.
  • Use of only 2 categories for PA and TV limits ability to look at dose response characteristics.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? N/A
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? N/A
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A