Pediatric Weight Management

Pediatrics and Physical Activity


McMurray RG, Harrell JS, Deng S, Bradley CB, Cox LM, Bangdiwala SI. The influence of physical activity, socioeconomic status, and ethnicity on the weight status of adolescents. Obesity Research 2000;8(2):130-39.


PubMed ID: 10757199
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The purpose of this study was to examine the effects of PA, physical inactivity, television viewing, and video game play on weight status, taking into account consideration SES, ethnicity and gender.

Inclusion Criteria:

None specified

Exclusion Criteria:

None specified

Description of Study Protocol:

Subjects completed the questionnaires at school in small groups under the direction of a research associate. Physiological data was also obtained in the schools.

Statistical Analyses:

ANOVA’s were computed examining the effect of hours of television viewing or video game play on BMI. These analyses were computed by gender, ethnicity, and SES.

Simple regression analyses were performed within each gender to determine the relationship between being over weight and hours of viewing TV or playing video games. Follow up gender specific regression analyses were adjusted for ethnicity and SES.

The entire sample was categorized into least, average and highly active. Chi-square analyses were computed to determine significant differences in the proportion of obese children in each of the three groups.

Logistic regression was used to determine the relative risk of being overweight comparing subjects in the lease active with those in the average and most active.

Gender specific logistic regression was used to determine which factors had the most effect on the relative risk for being overweight; TV>2 hrs, video play > 2 hrs, highly active PA classification.

Data Collection Summary:

Dependent Variables

  • BMI (measured heights and weights)
  • SKinfolds (Triceps and subscapular sites)

Independent Variables

  • Physical activity (questionnaires – 32 common activities listed, # of times per week they participated in each of the activities) - categorical
  • Physical Inactivity (questionnaire – no details given)
  • Television viewing (questionnaire – hours spent watching TV
  • Video game playing (questionnaire - # of hours spent playing video games)


  • SES (Based on parental education as suggested by Abramson 1982)
  • Ethnicity (self –report)
  • Gender (self-report)
Description of Actual Data Sample:

2563 middle school adolescents (10-16); 1123 newly recruited rural subjects were added.


Representation of minority subject other than African American was low therefore they were eliminated from the analyses.

Total sample consisted of 2389 youth 52% female, 48% male, 77% white, 23% African American, 77% rural, 23% urban.

Summary of Results:

Prevalence of obesity was higher among low SES than moderate or high SES. Prevalence was also higher for black s than whites.

For males TV viewing was positively associated with BMI (P = .002) but no association was seen for school days. When adjusted for SES and ethnicity no significant effects were found.

With respect to video games, BMI was found to be higher, for males that played videos 2 to 3 hours/day compared with those who played less than 1 hour/day. The effect remained after adjustments

For Females, television viewing on school days was positively associated with BMI (p = .003). The relationship between non-school day TV viewing and BMI was significant (p = .003) but after adjusting for ethnicity and SES, no significant effect was found.

Author Conclusion:

Little relation was found between overweight and TV viewing or video game play when the analyses were adjusted for ethnicity and SES.

For males, lack of participation in high intensity exercise was associated with being overweight.

The results show that for males that watched 2-3 hours of TV/ day but spent 15 minutes 3-5 times per week in high intensity PA, had a reduced risk of being overweight.

Overall conclusion:

Weight status for males appears to be more related to exercise habits than to TV or video games. Therefore participation in high intensity exercise thus appears to be important.

For females, neither exercise nor video habit appear to be related to risk of being overweight.  However, ethnicity and SES may be important factors that influence body weight status while TV may be of some importance.

Funding Source:
Government: National Institute of Nursing Research
University/Hospital: University of North Carolina
Reviewer Comments:


  • Much of the data was collected by questionnaire, which is necessary for a sample of this size but also allows for bias.
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? Yes
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) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? Yes
  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? Yes
  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%.) Yes
  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? 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? Yes
  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? 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? N/A
  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? No
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
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