Rachel A. Jones

Tracking Physical Activity and Sedentary Behavior in Childhood: A Systematic Review

CONTEXT To date, no reviews have investigated the evidence of tracking of physical activity and sedentary behavior specifically during early childhood (aged 0-5.9 years) or from early childhood to middle childhood (aged 6-12 years). It is important to review the evidence of tracking of these behaviors to determine their stability during the foundational early years of life. EVIDENCE ACQUISITION A literature search of studies was conducted in seven electronic databases (January 1980 to April 2012). Studies were compared on methodologic quality and evidence of tracking of physical activity or sedentary behavior. Tracking was defined as the stability (or relative ranking within a cohort) of behaviors, such as physical activity and sedentary behavior, over time. EVIDENCE SYNTHESIS Eleven studies met the inclusion criteria. All studies reporting physical activity outcomes had high methodologic quality; 71% of studies reporting sedentary behavior outcomes had high methodologic quality. Of the tracking coefficients for physical activity, 4% were large, 60% were moderate, and 36% were small. Of the tracking coefficients for sedentary behavior, 33% were large, 50% were moderate, and 17% were small. Overall, there was evidence of moderate tracking of physical activity during early childhood, and from early childhood to middle childhood, and of moderate-to-large tracking of sedentary behavior during early childhood and from early childhood to middle childhood. CONCLUSIONS This review highlights the importance of establishing recommended levels of physical activity and sedentary behavior during the early years of life. Based on this review, the following recommendations are made: (1) early childhood should be targeted as a critical time to promote healthy lifestyle behaviors through methodologically sound prevention studies; and (2) future tracking studies should assess a broad range of sedentary behaviors using objective measures.

Poly(2-alkylacrylic acid) polymers deliver molecules to the cytosol by pH-sensitive disruption of endosomal vesicles

The permeability barrier posed by cell membranes represents a challenge for the delivery of hydrophilic molecules into cells. We previously proposed that poly(2-alkylacrylic acid)s are endocytosed by cells into acidified vesicles and are there triggered by low pH to disrupt membranes and release the contents of endosomes/lysosomes to the cytosol. If this hypothesis is correct, these polymers could be valuable in drug-delivery applications. The present paper reports functional comparisons of a family of three poly(2-alkylacrylic acid)s. Poly(2-propylacrylic acid) (PPAA), poly(2-ethylacrylic acid) (PEAA) and poly(2-methylacrylic acid) (PMAA) were compared in red-blood-cell haemolysis assays and in a lipoplex (liposome-DNA complex) assay. We also directly examined the ability of these polymers to disrupt endosomes and lysosomes in cultured human cells. Our results show that: (i) unlike membrane-disruptive peptides, the endosomal-disruptive ability of poly(2-alkylacrylic acid)s cannot necessarily be predicted from their haemolytic activity at low pH, (ii) PPAA (but not PEAA or PMAA) potently facilitates gene transfection by cationic lipoplexes and (iii) endocytosed poly(2-alkylacrylic acid)s are triggered by luminal acidification to selectively disrupt endosomes (not lysosomes) and release their contents to the cytosol. These results will facilitate the rational design of future endosomal-disrupting polymers for drug delivery.

Efficacy of Interventions to Improve Motor Development in Young Children: A Systematic Review

OBJECTIVE: The objective of this study was to systematically review evidence from controlled trials on the efficacy of motor development interventions in young children. METHODS: A literature search of interventions was conducted of 14 electronic databases. Three reviewers independently evaluated studies to determine whether they met the inclusion criteria. Studies were compared on 5 components: design, methodologic quality, intervention components, efficacy, and alignment with the Consolidated Standard of Reporting Trials (CONSORT) and Transparent Reporting of Evaluation with Nonrandomized Designs (TREND) statements. RESULTS: Seventeen studies met the inclusion criteria. More than half (65%) were controlled trials and delivered at child care settings or schools (65%). Three studies had high methodologic quality. Studies were ∼12 weeks in duration and delivered by teachers, researchers, and students. Parents were involved in only 3 studies. Nearly 60% of the studies reported statistically significant improvements at follow-up. Three studies aligned with the CONSORT and TREND statements. CONCLUSIONS: This review highlights the limited quantity and quality of interventions to improve motor development in young children. The following recommendations are made: (1) both teachers and researchers should be involved in the implementation of an intervention; (2) parental involvement is critical to ensuring transfer of knowledge from the intervention setting to the home environment; and (3) interventions should be methodologically sound and follow guidelines detailed in the CONSORT or TREND statement.

Multi-site randomized controlled trial of a child-centered physical activity program, a parent-centered dietary-modification program, or both in overweight children: the HIKCUPS study

OBJECTIVE To evaluate whether a child-centered physical activity program, combined with a parent-centered dietary program, was more efficacious than each treatment alone, in preventing unhealthy weight-gain in overweight children. STUDY DESIGN An assessor-blinded randomized controlled trial involving 165 overweight/obese 5.5- to 9.9- year-old children. Participants were randomly assigned to 1 of 3 interventions: a parent-centered dietary program (Diet); a child-centered physical activity program (Activity); or a combination of both (Diet+Activity). All groups received 10 weekly face-to-face sessions followed by 3 monthly relapse-prevention phone calls. Analysis was by intention-to-treat. The primary outcome was change in body mass index z-score at 6 and 12 months (n=114 and 106, respectively). RESULTS Body mass index z-scores were reduced at 12-months in all groups, with the Diet (mean [95% confidence interval]) (-0.39 [-0.51 to 0.27]) and Diet + Activity (-0.32, [-0.36, -0.23]) groups showing a greater reduction than the Activity group (-0.17 [-0.28, -0.06]) (P=.02). Changes in other outcomes (waist circumference and metabolic profile) were not statistically significant among groups. CONCLUSION Relative body weight decreased at 6 months and was sustained at 12 months through treatment with a child-centered physical activity program, a parent-centered dietary program, or both. The greatest effect was achieved when a parent-centered dietary component was included.

Correlates of objectively measured physical activity in obese children.

The aim of this study was to identify potential correlates of objectively measured physical activity in a sample of obese children. A cross‐sectional design was used to assess 137 5–9‐year‐old obese children (mean ± s.d. age = 8.3 ± 1.1 years; mean BMI z‐score = 2.76 ± 0.70; 58% girls) from two regional cities in New South Wales, Australia, before commencement in a treatment trial. Correlates examined included age, BMI z, parental BMI, perceived competence, health‐related quality of life, daily minutes spent in small screen recreation (SSR), and fundamental motor skill (FMS) proficiency. Physical activity was assessed using accelerometers and values were calculated for % of monitored time spent in moderate‐ (MPA) and vigorous (VPA)‐intensity physical activity and mean counts per minute (CPM). Analyses were conducted separately for boys and girls. Motor skill proficiency was significantly correlated with a number of physical activity variables for boys and girls. For boys, regression analysis revealed object‐control proficiency predicted CPM (R2 = 0.25) and age was a predictor of %MPA (R2 = 0.56). Age and object‐control skill proficiency were salient predictors of %VPA (R2 = 0.34). For girls, age and daily minutes of SSR were the only significant predictors for CPM (R2 = 0.13). Age was the sole predictor of %MPA (R2 = 0.38) and %VPA (R2 = 0.15). The targeting of FMSs at an early age should be tested in experimental studies as potential strategies to increase physical activity among obese children, particularly for boys. Interventions aimed at reducing sedentary behaviors among obese girls should also be considered.

Promoting healthy lifestyles among adolescent boys: The Fitness Improvement and Lifestyle Awareness Program RCT

OBJECTIVE To assess the feasibility, acceptability, and potential efficacy of a school-based obesity prevention program among adolescent boys with sub-optimal cardiorespiratory fitness. METHODS In 2007, a 6-month, 2-arm parallel group, randomized controlled pilot trial was conducted in a single school setting (Sydney, Australia). Thirty-three 7th Grade boys (mean age=12.5+/-0.4 years) were randomly assigned to intervention (n=16) or active comparison group (n=17). The intervention consisted of one 60-minute curriculum session and two 20-minute lunchtime physical activity sessions per week. The active comparison group continued with their usual physical activity curriculum sessions (Friday afternoons 2-3 pm). The pilot trials curriculum sessions were additional to Physical Education (PE) lessons. The primary outcome was BMI, and secondary outcomes included waist circumference, percentage body fat, cardiorespiratory fitness, objectively measured physical activity and small screen recreation time. RESULTS Screening, recruitment and retention goals were exceeded. The majority of data were collected as planned. Implementation and attendance rates were acceptable. At follow-up, compared with boys in the active comparison group, boys in the intervention group displayed a smaller increase in BMI (adjust diff.=-0.2, 95% confidence interval [CI] -0.78, 0.39; Cohens d=0.05); greater reductions in waist circumference (-1.65 cm [-4.67, 1.36]; d=0.15); percentage body fat (-1.69% [-4.98, 1.60]; d=0.22) and time spent in small screen recreation on weekends (-1.13 h [-5.06, 2.80]; d=0.19); and a greater increase in cardiorespiratory fitness (2.13 laps [6.22, 10.48]; d=0.16); and participation in total weekday physical activity (140.74 counts/min [-159.44, 440.92]; d=0.36). CONCLUSIONS This study verified the feasibility, acceptability and potential efficacy of a multifaceted school-based intervention to prevent unhealthy weight gain among adolescent boys.

Predictive validity and classification accuracy of actigraph energy expenditure equations and cut-points in young children

Objectives Evaluate the predictive validity of ActiGraph energy expenditure equations and the classification accuracy of physical activity intensity cut-points in preschoolers. Methods Forty children aged 4–6 years (5.3±1.0 years) completed a ∼150-min room calorimeter protocol involving age-appropriate sedentary, light and moderate-to vigorous-intensity physical activities. Children wore an ActiGraph GT3X on the right mid-axillary line of the hip. Energy expenditure measured by room calorimetry and physical activity intensity classified using direct observation were the criterion methods. Energy expenditure was predicted using Pate and Puyau equations. Physical activity intensity was classified using Evenson, Sirard, Van Cauwenberghe, Pate, Puyau, and Reilly, ActiGraph cut-points. Results The Pate equation significantly overestimated VO2 during sedentary behaviors, light physical activities and total VO2 (P<0.001). No difference was found between measured and predicted VO2 during moderate-to vigorous-intensity physical activities (P = 0.072). The Puyau equation significantly underestimated activity energy expenditure during moderate-to vigorous-intensity physical activities, light-intensity physical activities and total activity energy expenditure (P<0.0125). However, no overestimation of activity energy expenditure during sedentary behavior was found. The Evenson cut-point demonstrated significantly higher accuracy for classifying sedentary behaviors and light-intensity physical activities than others. Classification accuracy for moderate-to vigorous-intensity physical activities was significantly higher for Pate than others. Conclusion Available ActiGraph equations do not provide accurate estimates of energy expenditure across physical activity intensities in preschoolers. Cut-points of ≤25counts⋅15 s−1 and ≥420 counts⋅15 s−1 for classifying sedentary behaviors and moderate-to vigorous-intensity physical activities, respectively, are recommended.

Movement skills and physical activity in obese children: randomized controlled trial

PURPOSE The purpose of this study was to evaluate the Hunter Illawarra Kids Challenge Using Parent Support physical activity program in overweight children. METHODS A multisite randomized controlled trial was conducted with three intervention arms: 1) child-centered physical activity skill development program (Activity), 2) parent-centered dietary modification program (DIET), or 3) both programs combined (PA+DIET). Movement skill proficiency, perceived athletic competence, accelerometer-assessed physical activity, and parent-reported time spent in screen behaviors were assessed at baseline, 6 months, and 12 months in 165 prepubertal children aged 5.5-9 yr (59% girls, 78% obese). Differences in changes in outcomes between groups were assessed using linear mixed models. RESULTS Compared with the diet group, the activity group (mean (95% confidence interval): +7.7 units (3.8-11.6 units)) and the activity + diet group (+6.7 units (2.9-10.5 units)) displayed 11%-13% greater improvement in overall movement skill proficiency (gross motor quotient) at 6 months. Perceived athletic competence increased across groups at follow-up (across groups: 6 months = +0.21 units (0.11-0.31 units), 12 months = +0.21 units (0.07-0.35 units)). Groups did not differ statistically for change in physical activity outcomes. Total screen time (min·wk(-1)) decreased in all groups at 6 months (across groups: -385.4 (-501.0 to -269.8)) and in the activity group (-261.8 (-470.5 to -53.1)) and activity + diet group (-340.5 (-534.6 to -146.4)) at 12 months. The diet group reported greater reductions in TV or DVD viewing time at 6 months compared with the activity group (248.6 (24.0-473.3)). CONCLUSIONS The activity and the activity + diet programs were efficacious in improving overweight childrens movement skill proficiency. All programs were efficacious in reducing time spent in screen behaviors. Other correlates may need to be targeted in addition to movement skills to increase physical activity among overweight children.

Randomised controlled trials in overweight children: Practicalities and realities

AIM To highlight and discuss the practical aspects of conducting high quality, randomised controlled trials (RCTs) with overweight and obese children and their families. CONTENT Realistic considerations and suggestions for researchers arising from the experiences of three Australian interventions in overweight/obese children are highlighted. The practical implications of key issues arising during this type of RCT include study design, obtaining ethical approval, choice of outcome measures, recruitment, working with families, impact and process evaluation, retention strategies, managing multi-site trials and data management. CONCLUSION Interventions for overweight children and their families are challenging. Although there were some differences in the design and outcome measures among the three studies, there were many similarities. Multi-site trials, although more expensive than single-site trials, are advantageous in increasing sample size and external validity. Collectively we have developed strategies to address key problems in conducting RCTs, including the common challenges of recruitment, retention and working with families.

Proficiency deficiency: mastery of fundamental movement skills and skill components in overweight and obese children

The purpose of this observational study was to compare the mastery of 12 fundamental movement skills (FMS) and skill components between a treatment‐seeking sample of overweight/obese children and a reference sample from the United States. Mastery of six locomotor and six object‐control skills (24 components in each subdomain) were video‐assessed by one assessor using the test of gross motor development‐2 (TGMD‐2). The 153 overweight/obese children (mean ± s.d. age = 8.3 ± 1.1 years, BMI z‐score = 2.78 ± 0.69, 58% girls, 77% obese) were categorized into age groups (for the underhand roll and strike: 7–8 years and 9–10 years; all other FMS: 6–7 years and 8–10 years) and mastery prevalence rates were compared with representative US data (N = 876) using χ2 analysis. For all 12 skills in all age groups, the prevalence of mastery was lower among overweight/obese children compared with the reference sample (all P < 0.05). This was consistent for 18 locomotor and upto 21 object‐control skill components (all P < 0.05). Differences were largest for the run, slide, hop, dribble, and kick. Specific movement patterns that could be targeted for improvement include positioning of the body and feet, the control or release of an object at an optimal position, and better use of the arms to maintain effective force production during the performance of FMS. Physical activity programs designed for overweight and obese children may need to address deficiencies in FMS proficiency to foster the movement capabilities required for participation in health‐enhancing physical activity.