Pediatric Weight Management

Pediatrics and Physical Activity


Maffeis C, Zaffanello M, Schutz Y Relationship between physical inactivity and adiposity in prepubertal boys. Journal of Pediatrics 1997;131:288-92

PubMed ID: 9290618
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

The purpose of the present study was to explore the relationship between body fatness, the energy expenditure for physical activity and the relative and absolute levels of physical activity assessed in free-living conditions in a group of 9 year old boys.

Inclusion Criteria:
Not specified
Exclusion Criteria:
Not specified
Description of Study Protocol:

Pre-pubertal children came to the pediatric department for diagnosis and treatment of obesity. They also brought a non-obese friend who agreed to participate. In a fasting condition the boys arrived.

Then after resting for 30 minutes indirect calorimetry initiated the respiratory exchange.  They boys watched cartoons during this time and were observed to make sure they were resting quietly.  After this period (the PMR) a light meal was served and then 2 hours later a treadmill test was done.

Data Collection Summary:

Independent Variables: 

  • Fat mass (%)
  • Fat mass (kg)
  • Fat free mass
  • BMI

Dependent Variables:

  • Activity energy expenditure (EEact) – TEE – (REE + .01 TEE)
  • Resting Energy expenditure (REE) - Indirect calorimetry ( a mean for the 3 resting activities)
  • Total Energy Expenditure (TEE) – adding sleeping, sedentary, and active energy expenditures.


  • Gender (only looked at boys)
  • Age (only examined 9 year olds)
  • Sedentary EE was calculated by multiplying the non-sleepig time under flex HR during the day by REE.

Statistical Analyses:

A stepwise  multiple regression was used to evaluate the joint effect of EE(act), TEE./(REE + 10% TEE) ratio, sedentary time and non-sedentary time on obesity status.

Description of Actual Data Sample:

N: 28 overweight pre-pubertal children and a non-overweight friend.

Age: average was 9.3,

Race/Ethnicity: Not reported


  • weight 37.8,
  • height 138,
  • BMI of 19.8,
  • Fat mass of 23%,
  • Fat mass in KG of 9.5
  • Fat-Free mass of 28.3

Location: Italy

Summary of Results:
  • TEE, REE, and EEact were 9388 + 1859, 5154 + 642, 3295 + 1356 kJ/day, respectively.
  • Daily time devoted to sedentary and non-sedentary activities averaged 290 + 155 minutes and 534 + 150 minutes respectively. 
  • Time spent on sedentary activities was directly proportional to fat mass percentage (r = .46, P<.05).  It was the only variable, among the free-living physical activity ratio, times spent in non-sedentary and sedentary activities variables, which remained significant in the multiple step-down regression analysis final equation (r = .46, p <.05).
Author Conclusion:
  • The positive relationship between adiposity and time spent on sedentary activities in 9 year old boys suggests the importance of the role played by muscular activity, at least in the maintenance of obesity in childhood. Pre-pubertal children should be encouraged to spend less time on sedentary activities to treat and prevent their obesity.
  • Overall, physical inactivity (time spent in sedentary activities) was related to adiposity.
  • The positive relationship between adiposity and time spent on sedentary activities in 9 year old boys suggests the importance of the role played by muscular activity, at least in the maintenance of obesity in childhood. Pre-pubertal children should be encouraged to spend less time on sedentary activities to treat and prevent their obesity.
  • Overall, physical inactivity (time spent in sedentary activities) was related to adiposity.
Funding Source:
University/Hospital: University of Verona (Italy), University of Lausanne (Switzerland)
Reviewer Comments:
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? No
  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? No
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) No
  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? 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? 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? No
  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? No
  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? 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? N/A
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
10. Is bias due to study's funding or sponsorship unlikely? No
  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