EAL

Pediatrics and Physical Activity

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To describe the physical activity, body fat, and blood pressure patterns of 6th grade African American girls.

Inclusion Criteria:

6th grade girls from a Houston middle school.
Parental and child consent.

Exclusion Criteria:

Incomplete records

Description of Study Protocol:

Recruitment

A cross sectional analysis of a 5-year longitudinal study of physical activity patterns of African American girls.

Students were recruited from a middle school in Houston, Texas.

Data is gathered from the girls in the cohort twice a year.

Design

Theoretical framework for assessing antecedents and consequences of physical activity was taken from Sallis and Howells mtultidimensional model of physical activity based on operant and cognitive learning theories. 54 item predictor of physical activity questionnaire was administered in an interview.

Overweight determined as >85th percentile of National Health and Nutrition Evaluation Survey.

Blinding used: none

Intervention: none

Statistical Analysis

Pearson and Spearman correlations. Linear regression analysis.

Data Collection Summary:

Timing of Measurements

Twice yearly.

Dependent Variables

Blood pressure (Dinamap 8100 automatic monitor after 5 minute rest period: two measurements)
Physical activity patterns (from physical activity interview, including list of 41 activities, MET values assigned based on intensity of activity)
Physical Fitness

Independent Variables

Weight: (balance beam scale)
Body fat: (calipers: five skinfolds)
Body fat distribution (inclastic tape and calipers: five skinfolds, waist to hip and waist to thigh ratio)
Height (Harpenden stadiometer)
Cognitive and social factors (Predictors of Physical Activity Questionnaire)
Menarch (self report)
Physical activity patterns (self report)
Tanner stages (self report)
Predictors of physical activity
Smoking (modified Youth Risk Behavior Survey Questionnaire)
Drinking (modified Youth Risk Behavior Survey Questionnaire)
Dieting (modified Youth Risk Behavior Survey Questionnaire)
Drug use (modified Youth Risk Behavior Survey Questionnaire)
Fitness (treadmill VO₂max measured)
O₂ and CO₂ consumption (metabolic cart)

Confounding Variables

Dietary intake (FFQ)
Nutrient intake (estimated)

Description of Actual Data Sample:

Initial N: 120 girls

Attrition (final N): 82 girls

Age: 6th grade (11-13 years; mean age 12.3 years)

Ethnicity: Predominantly (93%) African American, also Hispanic and European American

Other relevant demographics: 54% of subjects were eligible for reduced or free school lunches (low SES).

Anthropometrics

62% reached menarche
mean subscapular skinfolds: 16.9mm
mean triceps skinfolds: 18.8mm
mean height: 156.4cm
mean weight: 57kg
mean BMI: 23.2
mean blood pressure: 115.8 mm Hg (systolic), 58.5 mm Hg (diastolic)
mean energy intake: 1525 kcal (SD: 454)
mean percent energy from fat: 37% (SD: 5)
mean VO₂max: 30 ml/kg (SD: 5)

Location: Houston, Texas

Summary of Results:

BMI >85th percentile

Of the sample:

11 year-olds: 21.6%
12 year-olds: 22.7%
13 year-olds: 23.2%

BMI had no significant relationship to diet, physical activity, or predictors of physical activity in the multivariate model. BMI was significantly associated with breast development in the multivariate model.

Blood Pressure: no significant relationship to any predictor variables

Physical Activity

Significantly related (adjusting for physical fitness, cognitive factors, BMI, and social factors in multivariate analyses) to:

percent kcal from fat (negative association, p=.021)
breast stage (negative association, p=.013)
waist/thigh ratio (positive association, p=.013)

Author Conclusion:

The sample of girls consumed a greater % kcal from saturated fat than another national sample.

"In analyzing variables related to blood pressure, physical activity and body fat, we found that systolic and diastolic blood pressure were not significantly associated with BMI, maturity, physical activity, percent calories from fat, or a combination of BMI and physical activity....Physical activity was negatively related to both percent calories from fat and breast stages and positively related to waist/thigh ratio."

Funding Source:

Government:

NHLBI

Reviewer Comments:

Strengths

Carefully designed study (well described methodology)
Focused on specific population (middle school African American girls)

Limitations

Small sample size
Cross sectional design
Self report measures for some variables
Specific time of measurements and specific characteristics of the population limit generalizability

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?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	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?		N/A
	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.)	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?	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%.)	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?		No
	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.)	No
	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?	Yes
	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?	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?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	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)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
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?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes