Pediatric Weight Management

Pediatrics and Physical Activity


Ekelund U, Aman J, Yngve A, Renman C, Westerterp K, Sjostrom M. Physical activity but not energy expenditure is reduced in obese adolescents: a case-control study. American Journal of Clinical Nutrition 2002; 76:935-941

PubMed ID: 12399263
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 test the hypothesis that the intensity and duration of PA differ between obese and normal weight adolescents, with no difference in estimated energy.

Inclusion Criteria:
Not specified
Exclusion Criteria:
Subjects with chronic diseases and those taking medication regularly, except for oral contraceptives in girls were excluded.
Description of Study Protocol:

Subjects were admitted to the lab at 10:00pm on the night before their measurements.

Day 1 subjects arrive in a fasted state.  RMR, body weight, height and body composition are measured.  The subjects then complete an exercise test after having a light breakfast.  Then subjects are instructed on how to wear the accelerometer. 

On day 15 the activity diary and accelerometers were returned.

Data Collection Summary:

Independent Variable 

  • Obese Vs. Non-Obese (matched on gender and age) – BMI and DEXA

Dependent Variables 

  • RMR (Resting Metabolic Rate)
  • TEE (Total energy expenditure) (DLW method)
  • AEE (Activity energy expenditure)
  • Physical activity (CSA) – counts/min/day


  • Age
  • Gender

Statistical Analyses:

The effects of sex and group, which were considered as fixed factors, on physical characteristic variables were analyzed by ANOVA. When ANCOVA was used RMR, TEE, and AEE were examined as DV with FFM as the covariate.

Description of Actual Data Sample:

N: 18 obese adolescents

Age: 14-19

Race/Ethnicity: Not reported

Anthropometrics: BMI >30 and a matched group of adolescents on age and gender. All subjects were at a tanner stage 4 or 5.

Location: Not reported

Summary of Results:
  • Physical Activity level (PAL) was significantly lower in the obese group (P<.05)
  • The lengths of time (min/d) spent while sedentary and at a physical activity of light intensity did not different significantly between the 2 groups.
  • Compared with the control group, the obese adolescents showed significantly (P<.05) less accumulated time at a PA of moderate intensity.
  • The obese group spent significantly less time in continuous physical activity (P<.01) and their daily average of number of continuous 10-min periods spent at a PA of this intensity level was significantly smaller (P<.01)
  • The total amount of PA expressed as total counts over the registered time was significantly lower (P<.001) in the obese group.
  • ANOVA results showed a significant group (P<.001) and time (P<.001) effect for averaged per hour activity over the 14-d period.
  • Percentage body fat was significantly and negatively associated with PAL in the 2 groups (r = -.53, P = .001).
Author Conclusion:

Physical activity measured with the accelerometer was lower in obese adolescents than in age, gender, and education matched control subjects activity levels from measures of RMR, TEE and AEE did not differ significantly between these groups.

These results indicate a difference in the overall PA between the obese subjects and their normal weight peers through the entire day and it is the moderate intensity activity that was significantly lower influencing their total physical activity and the PAL value.

Overall conclusion: 

The obese adolescents in the present study were less physically active, on the basis of both total physical activity and the time spent at physical activity of moderate or higher intensity than were a matched control group.
Funding Source:
Government: Stockholm County Council, Orebro Councty Council
University/Hospital: Swedish National Center for Research in Sports
Reviewer Comments:




Use of 2 methods of assessing PA
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) 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? N/A
  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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  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? Yes
7. Were outcomes clearly defined and the measurements valid and reliable? No
  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? No
  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