Search Results

You are looking at 1 - 10 of 35 items for

  • Author: Gregory J. Welk x
  • Refine by Access: All Content x
Clear All Modify Search
Restricted access

Harmonizing Monitor- and Report-Based Estimates of Physical Activity Through Calibration

Gregory J. Welk

A major challenge in public health research on physical activity is in reconciling the commonly observed differences between estimates provided by monitor-based methods and report-based methods. Calibration methods are widely used in measurement research to rescale or convert an estimate so that it matches a more robust criterion value. Accelerometry-based activity monitors are routinely calibrated against more robust estimates of indirect calorimetry, but surprisingly little research is done to calibrate report-based estimates. The purpose of the paper was to document the utility of calibration methods for harmonizing estimates from report-based measures to correspond with data from monitor-based methods. While there are also limitations associated with monitor-based methods, this procedure provides a systematic way to promote harmonization of estimates obtained from these different methods. This enables the more feasible report-based measures to provide more accurate group-level estimates of physical activity for different research applications.

Restricted access

Strengthening the Scientific Basis of the FITNESSGRAM ® Program

Gregory J. Welk

Restricted access

The Intersection of Physical Activity and Public Health: Opportunities for Kinesiology

Gregory J. Welk and Duane Knudson

Restricted access

Parental Influences on Physical Activity in Children: An Exploration of Potential Mechanisms

Gregory J. Welk, Kherrin Wood, and Gina Morss

This study examined the utility of a model to explain parental influence on children’s physical activity. Children (n = 994) from 3 elementary schools completed a survey with scales assessing physical activity, attraction to activity, perceived competence, and perceived parental influence. Self-report data on the physical activity levels of parents (n = 536) were also obtained to test the hypothesis that active parents may provide more encouragement and support for their children. The parental influence scales accounted for 20%, 26%, and 28% of the variance in physical activity, attraction to physical activity, and perceptions of competence, respectively. Correlations between parent and child levels of activity were low, but children of active parents had higher scores on the parental influence measures and psychosocial correlates than inactive parents. This study provides further confirmation of the important influence that parents exert on their child’s physical activity behavior.

Restricted access

Comparison of Two Versions of the PACER Aerobic Fitness Test

James J. McClain, Gregory J. Welk, Michelle Ihmels, and Jodee Schaben

Background:

The PACER test is a valid and reliable assessment of aerobic capacity in children. However, many schools lack adequate space to administer the test. This study compared the utility of the standard 20m PACER test with an alternative 15m PACER protocol in 5th and 8th grade students.

Methods:

A total of 171 students completed both PACER protocols in a counterbalanced design. Agreement between the two protocols was assessed with correlations, repeated-measures ANOVA, and classification agreement into the FITNESSGRAM ® healthy fitness zones.

Results:

The difference in estimated VO2max between the two tests was slightly larger for boys (5th grade, 1.32 ml/kg/min; 8th grade, 1.72 ml/kg/min) than girls (5th grade, 0.14 ml/kg/min; 8th grade, 1.11 ml/kg/min), but these differences are probably not of practical significance. Classification agreement was 88% for boys and 91% for girls.

Conclusions:

Collectively, the results suggest that the 15m and 20m PACER provide similar information about aerobic fitness in youth. The 20m test is recommended when possible, but the 15m provides a useful alternative for schools with smaller gymnasiums.

Restricted access

The Reliability and Convergent Validity of Field Tests of Body Composition in Young Adolescents

Michelle Ihmels, Gregory J. Welk, James J. McClain, and Jodee Schaben

Background:

Advances in BIA offer practical alternative approaches to assessing body composition in young adolescents and have not been studied for comparability.

Methods:

This study compared reliability and convergent validity of three field tests (2-site skinfold, Omron and Tanita BIA devices) on young adolescents. Reliability was determined using intraclass correlation coefficients, convergent validity was examined by computing correlations among the three estimates, differences in estimated body fat values were evaluated using repeated-measures ANOVA, and classification agreement was computed for achieving FITNESSGRAM ® Healthy Fitness Zone.

Results:

ICC values of all three measures exceeded .97. Correlations ranged from .74 to .81 for males and .79 to .91 for females. Classification agreement values ranged from 82.8% to 92.6%.

Conclusions:

Results suggest general agreement among the selected methods of body composition assessments in both boys and girls with the exception that percent body fat in boys by Tanita BIA is significantly lower than skinfold estimation.

Restricted access

Large-Scale Youth Physical Fitness Testing in the United States: A 25-Year Retrospective Review

Russell R. Pate, Gregory J. Welk, and Kerry L. McIver

Restricted access

Physical Activity and Physical Fitness in Children Schooled at Home and in Public Schools

Gregory J. Welk, Jodee A. Schaben, and Mack Shelley

Homeschooling is increasingly popular, but little is known about how homeschooling affects physical activity patterns or fitness levels. This study compares patterns of physical fitness, physical activity, and psychosocial correlates of physical activity in homeschooled youth and youth attending public school. Fitness levels were obtained using the PACER aerobic fitness test, physical activity levels were assessed with 3 days of accelerometry, and psychosocial correlates were assessed with the Children’s Physical Activity Correlates scale. There were no significant main effects for fitness comparisons, but significant age and gender interactions indicate that variability exists within these samples for fitness. No school type effects were evident for the physical activity measures or the psychosocial correlate measures, but trends in the data suggest the possibility of age-related interactions for the psychosocial measures. Additional research on possible differences between homeschooled youth and youth attending public school is needed to better understand these trends.

Restricted access

The Predictive Utility of the Children’s Physical Activity Correlates (CPAC) Scale Across Multiple Grade Levels

Jodee A. Schaben, Gregory J. Welk, Roxane Joens-Matre, and Larry Hensley

Understanding physical activity (PA) correlates in youth is challenging due to the inherent changes in activity patterns, activity preferences, and social norms that occur during the normal developmental transition from childhood into adolescence. This study examines possible age-related differences in physical activity correlates using the Children’s Physical Activity Correlates Scale (CPAC). The Children’s Physical Activity Questionnaire (PAQ) was used to measure typical levels of PA. Results indicate high school youth had lower levels of PA and lower levels on the psychosocial correlates than middle school youth. Parental influence accounted for ~ 15% of the variance in PA while the predisposing factors (perceived competence, attraction to PA) accounted for 20% and 17% of the variance for middle and high school students, respectively. CPAC has similar predictive validity across the age range. The CPAC scale offers potential to help understand factors that influence physical activity behavior during the transition from childhood into adolescence.

Restricted access

Correlates of Children’s Moderate and Vigorous Physical Activity During Weekdays and Weekends

Stuart J. Fairclough, Nicola D. Ridgers, and Gregory Welk

Background:

Vigorous-intensity physical activity (VPA) may confer superior health benefits for children compared to moderate-intensity physical activity (MPA), but the correlates of MPA and VPA may differ. The study purpose was to investigate associations between selected enabling, predisposing, and demographic physical activity correlates, and MPA and VPA during weekdays and at weekends.

Methods:

Data were gathered from 175 children (aged 10 to 11 years). MPA and VPA were assessed using accelerometers. Correlates were measured at child and school levels. Multilevel analyses identified correlates that significantly predicted MPA and VPA.

Results:

Gender significantly predicted weekday MPA (P < .001), and weekend MPA (P = .022) and VPA (P = .035). Weekday VPA was predicted by gender (P < .001), indices of multiple deprivation score (P < .003), BMI (P = .018), and school playground area (P = .046).

Conclusions:

Gender was the most significant correlate of MPA and VPA. Children most likely to engage in weekday VPA were boys with lower deprivation scores and BMI values, with access to larger playground areas.