Pediatric Weight Management

PWM: Physical Activity and Inactivity of Youth (2006)


DuRant R, Baranowski T, Johnson M, Thompson W. The relationship among television watching, physical activity, and body composition of young children. Pediatrics.  1994;94:449-455.

PubMed ID: 7936851
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To study the relationship among observed time of television watching observed physical activity level and body composition among 3 or 4 year old children.

Inclusion Criteria:

Not specified

Exclusion Criteria:
  • Families whose immediate members had a history of a chronic illness that could affect diet or exercise habit
  • Families in which English was not spoken,
  • Families without at least one parent residing in the household
  • Children with a disability which could affect participation were excluded.
  • Children born outside the US and Hispanics other than Mexican Americans, were excluded due to cultural differences.
Description of Study Protocol:

During 4 annual summer clinics, physiological and self report measures were collected. Between annual clinics, children were observed in the field for 6-12 hours (approximately every 3 months).

Statistical Analyses:

Between day intraclass correlation reliability was computed using ANOVA to determine within child and between child variation.

Mixed modeling ANOVA which provided for the fixed 3x2 demographic variables (ethnicity and gender) and random effect of children nested in demographic groups, and months (fixed) within children.

Correlations (pearson product moment) between television behavior and mean activity and body composition were computed on children who had at least 3 days of observation.

Data Collection Summary:

Dependent Variables

  • Body composition – BMI, 7 site skinfolds, circumference (hip/waist ratio).  Used average values for year 1 and 2.

Independent Variables

  • Physical activity – CARS observation system, minute by minute recording as well as the location of the activity (max of 5 per minute)
  • Television Watching -  (attending to the program) observation

Confounding –

  • Age (3 & 4)
  • Ethnicity (Anglo-american, Mexican – American, African – American)
Description of Actual Data Sample:

N: 191 children,

Age: 3 or 4, 

Race/Ethnicity: 41.4% African American, 23% Mexican American, and 35.6% Anglo-American.

Summary of Results:

Physical activity during television watching was lowest during the longest bout of television viewing compared to outside minutes, inside non-television minutes, and inside television minutes.

The level of physical activity during television watching time was highest during the months of October, November (2.08) and lowest during March, April, June, and July (1.57 to 1.59).

Longest bout of television watching and percent of minutes watching television to total observed minutes was inversely related to mean PA (-.24, -.20), percent of minutes in PA levels 3,4,5 (-.27, -.19) and percent of PA levels 4, 5 (-.26, -.27).

Television viewing time was not significantly correlated with sum of 7 skin folds, waist to hip ratio, or BMI.  No patterns were observed between TV and obesity either. 

Author Conclusion:

Television watching was weakly negatively correlated with PA levels, and PA was lower during television-watching than non-television-watching time in this sample of children. Television viewing was not associated with body composition.

Overall, inactivity does not relate to obesity or overweight based on this study. 

Funding Source:
University/Hospital: Children's Hospital Harvard Medical school, Emory University's School of Public Health, Medical College of Georgia
Reviewer Comments:

The reliability analysis revealed that at least 6.3 days of observation were needed to obtain reliability estimates of .80 for TV viewing as a percent of minutes spent inside. They only collected an average of 2.5 days. 

They went into the child’s environment.  It is possible that the child changed their behavior in the presence of the observer.

Additionally, children were observed a different number of days, ideally they should be observed the same number of days.

This was a regional data collection so the extent to which they generalize remains to be determined.

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? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
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? Yes
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? No
  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? No
  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? Yes
  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? No
  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? No
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  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? No
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? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  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? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
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