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Pedro F. Saint-Maurice, Gregory J. Welk, Pedro Silva, Mohammad Siahpush and Jennifer Huberty

To better understand and promote youth physical activity (PA) it is important to determine settings and characteristics that promote or influence behavior. This study evaluated the utility of a multi-method approach (accelerometers plus direct observation) to better understand youth PA at recess. A total of 100 third through fifth grade children (52 males and 48 females) wore an Actigraph accelerometer during school recess for five consecutive days in both Fall and Spring. Trained observers coded PA behaviors at the same recess periods using the System for Observing Play and Leisure Activities (SOPLAY). Overall, gender comparisons based on both instruments indicated that boys were more active than girls. MVPA levels were higher during climbing/sliding activities (40–50%) and when the activity setting was supervised and equipped (30%). Both assessments indicated that boys were more active but the contextual data from the SOPLAY indicate that differences may vary according to the environmental context.

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Yang Bai, Kelly Allums-Featherston, Pedro F. Saint-Maurice, Gregory J. Welk and Norma Candelaria

Purpose: The consensus is that physical activity (PA) and sedentary behavior (SB) are independent behaviors, but past findings suggest that they may be influenced by common underlying factors. To clarify this issue, we examined associations between enjoyment of PA and participation in both PA and SB in a large sample of 4th- to 12th-grade US youth. Methods: A total of 18,930 students from 187 schools completed the youth activity profile, a self-report 15-item survey that assesses time spent in PA and SB in school and home settings. Two additional items captured enjoyment of PA and physical education. Two-way (gender × enjoyment and grade × enjoyment) mixed analysis of variances were conducted. Results: Pearson correlation results revealed a positive relationship between enjoyment and PA (r = .38, P < .05) and an inverse correlation between enjoyment and SB (r = −.23, P < .05). Statistically significant main effects of enjoyment were found in the 2-way analysis of variance for both PA and SB. The simple main effect from analysis of variance indicated students with high enjoyment of PA reported higher levels of PA and lower levels of SB compared with students reporting moderate or low levels of enjoyment. Conclusion: The results provide new insights related to the relevance of enjoyment as a common underlying variable influencing both PA and SB across gender and grade levels.

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Kate A. Heelan, Bryce M. Abbey, Joseph E. Donnelly, Matthew S. Mayo and Gregory J. Welk

Background:

Walking to and from school has potential to increase daily physical activity among children.

Methods:

A Walking School Bus (WSB) intervention was implemented for 2 years in 2 schools with a third school as a control. The primary aim evaluated school-wide prevalence of walking to school by self-report 6 times (fall, winter, spring). The secondary aims compared objective physical activity levels among a subsample of research participants (intervention [INT] = 201, control [CON] =123) and between frequency of walking to school groups. INT and CON participants wore an accelerometer during 4 time periods to assess daily physical activity and were measured for body mass index (BMI) and body fat each fall and spring.

Results:

School-wide prevalence of walking to school frequently (>50% of the time each week) was 27% higher in the WSB schools than in the control school. INT obtained significantly more daily physical activity than CON (78.0 [38.9] vs 60.6 [27.7] min/d, P < .05). In addition, across all schools, frequent walkers obtained 25% more physical activity (P < .05), gained 58% less body fat (P < .05), and attenuated BMI by 50% (P < .05) compared with passive commuters.

Conclusion:

This study suggests a WSB intervention may increase frequency of walking to school and establishes a link with increased daily physical activity.

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Jack L. Groppel, In-Sik Shin, Jo Ann Thomas and Gregory J. Welk

This study explored the effects of string type and tension on various factors involved with tennis ball–racquet impact in midsized and oversized racquets. String and racquet material, racquet flexibility, and grip firmness were held constant for each test condition. The dependent variables included postimpact and preimpact ball velocity ratio, racquet head displacement, maximum ball compression, and ball contact duration. It was found that racquet size and string material have varying effects on impact. Although changes in string tension do affect the impact, it is not in a linear fashion. Various string tensions change a racquet's flexibility, thus affecting ball velocity and other factors associated with impact. The results of this study demonstrate the complexity of string and frame interaction.

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Richard P. Troiano, Kelley K. Pettee Gabriel, Gregory J. Welk, Neville Owen and Barbara Sternfeld

Context:

Advances in device-based measures have led researchers to question the value of reported measures of physical activity or sedentary behavior. The premise of the Workshop on Measurement of Active and Sedentary Behaviors: Closing the Gaps in Self-Report Methods, held in July 2010, was that assessment of behavior by self-report is a valuable approach.

Objective:

To provide suggestions to optimize the value of reported physical activity and sedentary behavior, we 1) discuss the constructs that devices and reports of behavior can measure, 2) develop a framework to help guide decision-making about the best approach to physical activity and sedentary behavior assessment in a given situation, and 3) address the potential for combining reported behavior methods with device-based monitoring to enhance both approaches.

Process:

After participation in a workshop breakout session, coauthors summarized the ideas presented and reached consensus on the material presented here.

Conclusions:

To select appropriate physical activity assessment methods and correctly interpret the measures obtained, researchers should carefully consider the purpose for assessment, physical activity constructs of interest, characteristics of the population and measurement tool, and the theoretical link between the exposure and outcome of interest.

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Mark A. Sarzynski, Joey C. Eisenmann, Gregory J. Welk, Jared Tucker, Kim Glenn, Max Rothschild and Kate Heelan

The present study examined the association between the angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism, physical activity, and resting blood pressure (BP) in a sample of 132 children (48.4% female). Children attaining 60 min/day of moderate-to-vigorous physical activity (MVPA) possessed lower % body fat (29% vs 24%, p < .05). Resting BP did not significantly differ between genotypes. Furthermore, partial correlations between MVPA and BP were low and did not vary by ACE genotype. Thus, the ACE I/D genotype is not associated with BP and does not modify the relationship between physical activity and BP in this sample of children.

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Miguel A. Calabro, Gregory J. Welk, Alicia L. Carriquiry, Sarah M. Nusser, Nicholas K. Beyler and Charles E. Matthews

Purpose:

The purpose of this study was to examine the validity of a computerized 24-hour physical activity recall instrument (24PAR).

Methods:

Participants (n = 20) wore 2 pattern-recognition activity monitors (an IDEEA and a SenseWear Pro Armband) for a 24-hour period and then completed the 24PAR the following morning. Participants completed 2 trials, 1 while maintaining a prospective diary of their activities and 1 without a diary. The trials were counterbalanced and completed within a week from each other. Estimates of energy expenditure (EE) and minutes of moderate-to-vigorous physical activity (MVPA) were compared with the criterion measures using 3-way (method by gender by trial) mixed-model ANOVA analyses.

Results:

For EE, pairwise correlations were high (r > .88), and there were no differences in estimates across methods. Estimates of MVPA were more variable, but correlations were still in the moderate to high range (r > .57). Average activity levels were significantly higher on the logging trial, but there was no significant difference in the accuracy of self-report on days with and without logging.

Conclusions:

The results of this study support the overall utility of the 24PAR for group-level estimates of daily EE and MVPA.

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Sarah M. Nusser, Nicholas K. Beyler, Gregory J. Welk, Alicia L. Carriquiry, Wayne A. Fuller and Benjamin M.N. King

Background:

Physical activity recall instruments provide an inexpensive method of collecting physical activity patterns on a sample of individuals, but they are subject to systematic and random measurement error. Statistical models can be used to estimate measurement error in activity recalls and provide more accurate estimates of usual activity parameters for a population.

Methods:

We develop a measurement error model for a short-term activity recall that describes the relationship between the recall and an individual’s usual activity over a long period of time. The model includes terms for systematic and random measurement errors. To estimate model parameters, the design should include replicate observations of a concurrent activity recall and an objective monitor measurement on a subsample of respondents.

Results:

We illustrate the approach with preliminary data from the Iowa Physical Activity Measurement Study. In this dataset, recalls tend to overestimate actual activity, and measurement errors greatly increase the variance of recalls relative to the person-to-person variation in usual activity. Statistical adjustments are used to remove bias and extraneous variation in estimating the usual activity distribution.

Conclusions:

Modeling measurement error in recall data can be used to provide more accurate estimates of long-term activity behavior.

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Sharon A. Plowman, Charles L. Sterling, Charles B. Corbin, Marilu D. Meredith, Gregory J. Welk and James R. Morrow Jr.

Initially designed by Charles L. Sterling as a physical fitness “report card” FITNESSGRAM ® / ACTIVITYGRAM ® is now an educational assessment and reporting software program. Based on physiological/epidemiological, behavioral, and pedagogical research, FITNESSGRAM is committed to health-related physical fitness, criterion-referenced standards, an emphasis on physical activity including behavioral based recognitions, and the latest in technology. The evolution of these major concepts is described in this history of FITNESSGRAM.

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Robin P. Shook, Nicole C. Gribben, Gregory A. Hand, Amanda E. Paluch, Gregory J. Welk, John M. Jakicic, Brent Hutto, Stephanie Burgess and Steven N. Blair

Background:

Subjective measures of moderate and vigorous physical activity (MVPA) rely on relative intensity whereas objective measures capture absolute intensity; thus, fit individuals and unfit individuals may perceive the same activity differently.

Methods:

Adults (N = 211) wore the SenseWear Armband (SWA) for 10 consecutive days to objectively assess sedentary time and MVPA. On day 8, participants completed the International Physical Activity Questionnaire (IPAQ) to subjectively assess sitting time and MVPA. Fitness was assessed via a maximal treadmill test, and participants were classified as unfit if the result was in the bottom tertile of the study population by sex or fit if in the upper 2 tertiles.

Results:

Overall, estimates of MVPA between the IPAQ and SWA were not significantly different (IPAQ minus SWA, 67.4 ± 919.1 MVPA min/wk, P = .29). However, unfit participants overestimated MVPA using the IPAQ by 37.3% (P = .02), but fit participants did not (P = .99). This between-group difference was due to overestimation, using the IPAQ, of moderate activity by 93.8 min/wk among the unfit individuals, but underestimation of moderate activity among the fit participants by 149.4 min/wk.

Conclusion:

Subjective measures of MVPA using the IPAQ varied by fitness category; unfit participants overestimated their MVPA and fit participants accurately estimated their MVPA.