Charles F. Morgan

Pedometer-Measured Physical Activity Patterns of Youth: A 13-Country Review

CONTEXT Insufficient physical activity among young people aged 5-18 years is a global public health issue, with considerable disparities among countries. A systematic review was conducted to identify studies reporting pedometer daily steps (steps x day(-1)) in order to compile comparative, global cross-sectional data on youth physical activity patterns. EVIDENCE ACQUISITION Articles were included if they were in English, published by April 2009, and reported steps x day(-1) for boys and girls, separately, and reported steps x day(-1) for age groupings of no more than 4 years (e.g., 5-8 years) or combined no more than three grade levels (e.g., third- to fifth-graders). Studies could have been intervention-based but had to have reported baseline steps x day(-1), which would reflect unadulterated physical activity steps x day(-1) estimates. Inverse variance weighted estimates (steps x day(-1w)) were calculated for each country, and random effects models were estimated. Analyses were conducted in May and June 2009. EVIDENCE SYNTHESIS Forty-three studies, representing young people in 13 countries (N=14,200), were included. The majority of studies were from the U.S. (17/43). Overall, there was considerable variation within and among countries in steps x day(-1w). Boys and girls from European and Western Pacific regions had significantly more steps x day(-1w) than young people from the U.S. and Canada. Significantly lower steps x day(-1w) estimates for girls were observed for studies that combined measured steps x day(-1) for weekdays and weekend days, in comparison to weekdays only. CONCLUSIONS Limited sample sizes and non-population-based data preclude definitive statements regarding projected steps x day(-1) within countries. Nevertheless, these findings provide preliminary information for policymakers and researchers on the extent of the disparities among countries in the physical activity patterns of young people.

Effect of a Low-Cost, Teacher-Directed Classroom Intervention on Elementary Students' Physical Activity.

BACKGROUND Effective physical activity (PA) interventions are warranted for youth, and schools have been identified as logical locations for such involvement. Experts and professionals in the field promote comprehensive school PA programs, including classroom PA. The purpose of this study was to determine the effect of a low-cost, teacher-directed classroom-based intervention on the school PA of elementary children. METHODS Nine classroom teachers were provided inexpensive curricula and trained to implement and instruct PA breaks (2 × 30 minute training sessions). The teachers were encouraged to lead 1 activity break per day after the training. One hundred and six elementary students wore pedometers up to 12 days over 3 monitoring periods during the school year (baseline, follow-up, post follow-up) to assess the effectiveness and the sustainability of the intervention. The teachers self-reported the frequency of activity breaks instructed. RESULTS The teachers (n = 5) who complied with the recommended 1 activity break per day had students who accrued ∼33% more mean school steps/day at follow-up (∼1100) and post follow-up (∼1350) compared to controls. Teachers (n = 4) in the intervention who did not comply with the 1 activity break per day recommendation had students accrue similar mean school steps/day as controls. CONCLUSION Inexpensive, teacher-directed classroom-based PA interventions can be effective in improving childrens PA levels if teachers implement 1 activity break per school day. We recommend promoting the notion of 1 activity break per day in the classroom as part of a comprehensive school PA program that includes quality physical education, recess, and before/after school programs.

Seasonality in Children's Pedometer-Measured Physical Activity Levels.

(2008). Seasonality in Childrens Pedometer-Measured Physical Activity Levels. Research Quarterly for Exercise and Sport: Vol. 79, No. 2, pp. 256-260.

Convergent Validity of Pedometer and Accelerometer Estimates of Moderate-to-Vigorous Physical Activity of Youth

BACKGROUND Pedometer step-frequency thresholds (120 steps·min-1, SPM) corresponding to moderate-to-vigorous intensity physical activity (MVPA) have been proposed for youth. Pedometers now have internal mechanisms to record time spent at or above a user-specified SPM. If pedometers provide comparable MVPA (P-MVPA) estimates to those from accelerometry, this would have broad application for research and the general public. The purpose of this study was to examine the convergent validity of P-MVPA to accelerometer-MVPA for youth. METHODS Youth (N = 149, average 8.6 years, range 5 to 14 years, 60 girls) wore an accelerometer (5-sec epochs) and a pedometer for an average of 5.7 ± 0.8 hours·day-1. The following accelerometer cutpoints were used to compare P-MVPA: Treuth (TR), Mattocks (MT), Evenson (EV), Puyau (PU), and Freedson (FR) child equation. Comparisons between MVPA estimates were performed using Bland-Altman plots and paired t tests. RESULTS Overall, P-MVPA was 24.6 min ± 16.7 vs. TR 25.2 min ± 16.2, MT 18.8 min ± 13.3, EV 36.9 min ± 21.0, PU 22.7 min ± 15.1, and FR 50.4 min ± 25.5. Age-specific comparisons indicated for 10 to 14 year-olds MT, PU, and TR were not significantly different from P-MVPA; for the younger children (5-8 year- olds) P-MVPA consistently underestimated MVPA. CONCLUSIONS Pedometer-determined MVPA provided comparable estimates of MVPA for older children (10-14 year-olds). Additional work is required to establish age appropriate SPM thresholds for younger children.

Children's In-School and Out-of-School Physical Activity During Two Seasons

Physical activity (PA) promotion for youth has long been thought of as a public health issue (Sallis & McKenzie, 1991). However, with increases in diseases associated with a sedentary lifestyle and the known benefits of PA, increasing the PA levels of children and adolescents has become a major public health concern (Strong et al., 2005). To this end, numerous organizations are calling on schools to take a leadership role in youth PA promotion (National Assocation for Sport and Physical Education, 2008; Pate et al., 2006). The Institutes of Medicine ( Koplan, Liverman, & Kraak, 2005) suggested that decreased opportunity for PA during school is one of five environmental factors preventing children from meeting PA recommendations of 60+ min/day. In addition, nearly all children attend school and spend as much as 30% of their waking hours in that setting (Hofferth & Sandberg, 2001; Snyder, Dillow, & Hoffman, 2009). For these reasons, schools are a logical setting to influence youth PA. Prior to developing and evaluating interventions, it is important to understand the amount of PA children accumulate during the school day and across the school year. Although increasing students’ activity levels during school hours is important, examining the impact of school-day interventions on students’ activity levels outside of school is also crucial. A comprehensive approach that promotes PA both in school and out of school activities is necessary to maximize daily PA (Pate et al., 2006). Previous studies examining PA levels during specific times of the school day suggest that children can accumulate meaningful amounts of activity (Beighle, Morgan, Le Masurier, & Pangrazi, 2006; Morgan, Beighle, & Pangrazi, 2007; Ridgers, Stratton, & Fairclough, 2006; Tudor-Locke, Lee, Morgan, Beighle, & Pangrazi, 2006). Others have reported children’s activity levels during school and outside of school. Gidlow and colleagues (2008) used accelerometry and found that for British children ages 3–16 years, school activity represented 30% of their daily activity. These interventions also found that children do not compensate for low school activity by being more active outside of school. In New Zealand, the number of steps taken during school accounted for approximately 47% of total daily steps for elementary-age students (Cox, Schofield, Greasley, & Kolt, 2006). Similarly, in a sample of U.S. students, steps taken during school represented 40% of daily steps (Morgan, Pangrazi, & Beighle, 2003). It is also important to understand the role of season on children’s PA, including school-day PA (Beighle, Alderman, Morgan, & Le Masurier, 2008). Several factors, such as temperature, weather conditions, and daylight may have an impact on children’s PA. While some argued that seasonality has a limited role in children’s PA levels (Fisher et al., 2005) others found children are more active when the weather is more conducive to outdoor activity (Goran et al., 1998; Rowlands & Hughes, 2006; Tremblay, Barnes, Esliger, & Copelane, 2005). These studies examined PA levels throughout the day. However, little is known about the impact of seasonality on children’s school PA. A better understanding of how children’s PA levels vary, including school-day PA, during different times of the year may help prioritize or reallocate resources to increase PA during particularly low activity seasons. The purpose of this study was to examine the steps taken by children both during school and out-of-school Children’s In-School and Out-of-School Physical Activity During Two Seasons

Step-rate recommendations for moderate-intensity walking in overweight/obese and healthy weight children.

BACKGROUND Physical activity guidelines for youth and adults include recommendations for moderate intensity activity to attain health benefits. Indirect calorimetry studies have consistently reported a 100 step·min(-1) threshold for moderate intensity walking in adults. No indirect calorimetry studies have investigated step-rate thresholds in children and therefore the primary purpose of the study was to determine preliminary step-rate thresholds for moderate physical activity walking in children. METHODS Oxygen consumption was measured at rest and used to determine 3 and 4 age-adjusted metabolic equivalents (A-AMETs) for 4 treadmill trials (self-selected, 2.5, 3.0, and 3.5 MPH). Two trained observers simultaneously counted childrens steps during each walking trial. Step-rate thresholds associated with moderate-intensity activity, defined as 3 and 4 A-AMETs, were determined using hierarchical linear modeling. RESULTS Regression analysis determined an overall step rate of 112 and 134 steps·min(-1) for 3 and 4 A-AMETs respectively. Body mass index (BMI) weight status and age were positively related to A-AMETs. CONCLUSIONS We suggest age and BMI weight status specific recommendations that range from a low of 100 step·min(-1) threshold (3 A-AMETs) for overweight/obese 11- to 12-year-olds to a high of 140 step·min(-1) threshold (4 A-AMETs) for healthy weight 9- to 10-year-old children.

Allometric Grip Strength Norms for Children of Hawaiian Lineage

Abstract Kocher, MH, Romine, RK, Stickley, CD, Morgan, CF, Resnick, PB, and Hetzler, RK. Allometric grip strength norms for children of Hawaiian lineage. J Strength Cond Res 31(10): 2794–2807, 2017—The purpose of the study was to determine allometric exponents for scaling grip strength in children that effectively control for body mass (BM) and stature (Ht) and to develop normative grip strength data for Hawaiian children. One thousand, four hundred thirty-seven students (754 boys) from a rural community in Hawaii participated in this 5-year study, resulting in 2,567 data points. Handgrip strength, BM, and Ht were collected every year. Multiple log-linear regression was used to determine allometric exponents for BM and Ht. Appropriateness of the allometric model was assessed through regression diagnostics, including normality of residuals and homoscedasticity. Allometrically scaled, ratio-scaled, and unscaled grip strength were then correlated with BM and Ht to examine the effectiveness of the procedure in controlling for body size. Allometric exponents for BM and Ht were calculated separately for each age group of boys and girls to satisfy the common exponent and group difference principles described by Vanderburgh. Unscaled grip strength had moderate to strong positive correlations with BM and Ht (p ⩽ 0.05 for all) for all age groups. Ratio-scaled handgrip strength had significant moderate to strong negative correlations with BM (p ⩽ 0.05 for all) and, to a lesser extent, Ht (p ⩽ 0.05 for 8- to 12-year-old boys; p ⩽ 0.05 for 8- to 12- and 14-year-old girls). Correlations between allometrically scaled handgrip strength and BM and Ht were not significant and approached zero. This study was the first to allometrically scale handgrip strength for BM and Ht in Hawaiian children. Allometric scaling applied to grip strength provides a useful expression of grip strength free of the confounding influence of body size.