Accelerometry-measured activity or sedentary time and overweight in rural boys and girls

Quantification of the Number of Steps in a School Recess by Means of Smart Bands: Proposal of Referential Values for Children and Adolescents

(1) Background: Regular physical activity has multiple benefits. Therefore, school recess is a key tool to provide opportunities for schoolchildren to engage in extracurricular physical activity, have fun, play and interact with their peers. The aim is to provide reference data to quantify the number of steps that children and adolescents perform in a school recess using smart bands according to age range and sex. (2) Method: A descriptive cross-sectional study was carried out in 494 schoolchildren aged 6 to 17 years (292 males and 202 females). Weight, standing height and waist circumference (WC) were evaluated. The body mass index (BMI) was calculated. The quantification of the number of steps during school recess was performed using a smart band. (3) Results: Percentiles were constructed for the number of steps (number of steps/recess). The cut-off points considered were <p25 (below average), p25 to p75 (average) and >p75 (above average). The median values in both sexes decreased as the age range increased. Youth who walked fewer steps during recess (<p25: below average) had elevated BMI and WC values relative to those who walked within average and above average. (4) Conclusion: The number of steps taken by schoolchildren during school recess decreases drastically with advancing age. The proposed reference values can be used to categorize schoolchildren according to the number of steps taken and to compare them among their peers. The results suggest their use and application in schools as a way of achieving the minimum physical activity recommendations.

Fit24, a digital health intervention to reduce type 2 diabetes risk among Hispanic youth: Protocol for a feasibility pilot study

BACKGROUND

Poor physical activity (PA) and sleep behaviors in Hispanic adolescents contributes to increased risk for type 2 diabetes. Commonly owned digital devices and services like smartphones and text-messaging are highly used among adolescents and are promising intervention tools for reaching this age group. Personal activity trackers assess activity and sleep, making them ideal tools for addressing these behaviors. We propose to examine the feasibility of a 12-week intervention that uses theoretically grounded text messages and a Fitbit device to improve PA and sleep among Hispanic adolescents with obesity, as compared to a wait-list control group with a Fitbit device only.

METHODS

Participants (N = 48; 14-16 years) will be randomized (1:1) to the intervention or wait-list control group. Youth in the intervention will receive a Fitbit Charge 5 and daily text messages. Youth in the wait-list control group will receive a Fitbit Charge 5 and information on PA and sleep guidelines.

RESULTS

Feasibility will be examined by collecting process evaluation data on the following criteria: (1) recruit 48 Hispanic adolescents 14-16 years; (2) retain 85% of participants for post-assessments; (3) Fitbit wear ≥4 days/week and respond to 80% of text messages when prompted; (4) ≤10% technical issues; and (5) obtain 80% satisfaction from participants.

DISCUSSION

This study will advance our knowledge on the feasibility of digital prevention strategies to promote PA and sleep behaviors to reduce T2D risk among Hispanic youth. If feasible, this approach has the potential to be a scalable, cost-effective diabetes prevention strategy among high-risk youth.

TRIAL REGISTRATION

NCT04953442, registered on July 8, 2021.

Movement Behaviour and Health Outcomes in Rural Children: A Systematic Review

BACKGROUND

Studies with rural children are limited, and results are divergent regarding the information on movement behaviours.

PURPOSE

to (i) describe the physical activity and sedentary behaviour in children; (ii) synthetize the year and place of publication, methodological quality, and instruments used to measure physical activity and sedentary behaviour; and (iii) to analyse the relationship between physical activity, sedentary behaviour, and health outcomes in these children.

METHODS

We use the databases PubMed, Web of Science, SPORTDiscus, Scopus, Virtual Health Library, and SciELO, considering papers published until October 2021. A total of 12,196 studies were identified, and after the exclusion of duplicate, title and abstract screening, and the full-text assessment, a total of 68 were included in the study.

RESULTS

A cross-sectional design was dominant among the studies, with sample sizes ranging from 23 to 44,631 children of both sexes. One-third of the studies were conducted in North America and Europe, and most of them used device-based measurements. Inequalities were observed regarding sex, age, economic level, race, and physical activity domains within and between the places of residence. Sociodemographic characteristics were also related to health outcomes for children living in rural and urban areas.

CONCLUSION

It is necessary to increase the evidence on movement behaviours among children living in the countries of South America and Oceania, as well as to increase the level of evidence on the role of school for physical activity in children in rural areas, given the inconsistent findings.

Relationship of Physical Activity and Sedentary Time with Metabolic Health in Children and Adolescents Measured by Accelerometer: A Narrative Review

The purpose of this study was to summarize the associations of physical activity (PA) and sedentary time (SED) with metabolic health and examine the effects of time reallocation on metabolic health in adolescents using accelerometer data. A literature search was conducted using PubMed, ScienceDirect, Web of Science, Cochran Library, and Google Scholar, and 27 articles were reviewed. Recent research generally confirms the associations of PA and SED with metabolic health. High PA levels and low SED levels had a positive relationship with metabolic health. Moreover, reallocating 10 min of daily SED to PA was associated with better metabolic health indicators. These results were stronger for moderate-to-vigorous physical activity than for light intensity PA. Thus, efforts to convert SED into PA of at least moderate intensity appear to be an effective strategy to prevent metabolic disease development in children and adolescents. However, some of the associations between PA and metabolic health indicators were inconsistent, depending on age, obesity degree, and PA intensity. Additionally, various accelerometer data collection and processing criteria impact the interpretation of the results. Therefore, consistent accelerometer data collection and analysis methods are needed in future studies. Further, intervention studies are required to verify the causality and effectiveness of the isotemporal substitution model.

Longitudinal analysis of physical activity, sedentary behaviour and anthropometric measures from ages 6 to 11 years

BACKGROUND/OBJECTIVES

The aim of this study was to examine the effect of physical activity (PA) and sedentary behaviour (SB) on body mass index (BMI) and fat mass index (FMI) in children over the course of five years and identify potential bi-directional associations.

SUBJECTS/METHODS

Data were drawn from the EU Childhood Obesity Project (CHOP). PA and SB were measured with the SenseWear Armband 2 at the ages of 6 (T1), 8 (T2) and 11 (T3) years. Height and weight were measured and BMI was calculated at each time point, resulting in 1254 complete observations from 600 children. Bio impedance analysis was used to measure body fat mass and eventually calculate FMI. To examine the longitudinal association between PA/SB and BMI/FMI as well as to account for repeated measure on these children, mixed model analysis was employed.

RESULTS

Higher levels of total PA and moderate-to-vigorous PA (MVPA) were associated with lower BMI and FMI and higher SB with higher BMI and FMI over the five year period. When looking at the age dependent effects, negative associations of MVPA (β_{MVPA x age}: - 0.05, 95% confidence interval (CI): - 0.09 - -0.01, p = 0.007) and positive associations of SB (β_{SB x age}: 0.04, 95% CI: 0.02-0.06, p < 0.001) increased with each year of age. In a model combining these two effects, only SB x age interaction remained significant (β_{SB x age}: 0.04, 95% CI: 0.03-0.06, p = 0.01). No significant interaction between MVPA and SB could be discerned. Light Physical activity showed no significant associations with BMI or FMI. When reversing outcome and predictor; higher BMI or FMI showed a negative association with MVPA and a positive association with SB, but no age dependency.

CONCLUSIONS

More time per day in SB was associated with a higher BMI over the course of five years, whereas higher MVPA had an inverse effect. In a combined model, only effects of higher SB remained significant, emphasizing the importance of SB in obesity prevention. Present bidirectional associations, where lower body size was associated with higher PA and lower SB, indicated the need for an integrated approach of activity and weight control for obesity prevention.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00338689 . Registered: June 19, 2006 (retrospectively registered).

BMI and recommended levels of physical activity in school children

Background

Physical activity (PA) and its health benefits are a continuous point of discussion. Recommendations for children’s daily PA vary between guidelines. To better define the amount of PA necessary to prevent overweight and obesity in children, further research is needed. The present study investigates children’s compliance to physical activity guidelines (PAGs) and the association between objectively measured PA and body mass index (BMI).

Methods

Participating children were 11 years old (n = 419) and part of the European CHOP trial, which was conducted in Germany, Belgium, Poland, Spain, Italy. At least 2 days of PA measurements were collected from each child using a SenseWear™ armband. BMI was calculated from children’s height and weight. Thresholds of min·day⁻¹ in PA needed to differentiate between normal and excess weight (overweight/obesity) were determined with Receiver Operator Characteristics (ROC) analysis. Additionally, adjusted linear and logistic regressions models were calculated for group differences and effects of a 5, 15 and 60 min·day⁻¹ increases in PA on BMI.

Results

Median time spent in total PA was 462 min·day⁻¹ (25th percentile; 75th percentile: 389; 534) and 75 min·day⁻¹ (41; 115) in moderate to vigorous PA (MVPA). Girls spent 36 min·day⁻¹ less in MVPA than boys and overweight/obese children 24 min·day⁻¹ less than normal weight children (linear regression, p < 0.001). 63.2% of the children met PAGs of 60 min·day⁻¹ in MVPA. The optimal threshold for min·day⁻¹ in MVPA determined with ROC analysis was 46 min·day⁻¹. Comparing 5, 15 and 60 min·day⁻¹ increases in PA revealed that an additional 15 min·day⁻¹ of vigorous PA had the same effect as 60 min·day⁻¹ of MVPA. Sedentary time and light PA showed contrary associations to one another, with light PA being negatively and sedentary time being positively associated with excessive weight.

Conclusions

Current PAGs are met by 2/3 of children and seem appropriate to prevent excess weight in children. An official recommendation of daily 15–20 min of vigorous PA and further reduction of sedentary time could help to fight youth overweight and thus be of potential public health importance.

Trial registration

ClinicalTrials.gov Identifier: NCT00338689. Registered: June 19, 2006 (retrospectively registered).

Associations between accelerometer-measured physical activity and body fatness in school-aged children

Background

The main aim of the study was to examine the cross-sectional associations between objectively measured physical activity (PA) and body fatness in 7–12-year-old children.

Methods

We performed an analysis of 365 children (209 girls). Participant recruitment was performed in eight randomly selected elementary schools in cities and towns with various numbers of inhabitants. The body composition analysis was performed according to a multi-frequency bioelectrical impedance analysis; PA was monitored using an accelerometer.

Results

In terms of the overall PA, boys were more active than girls. No significant associations (unadjusted and adjusted models) were found between light PA and all body fatness indicators in either sex. Moderate-to-vigorous PA was significantly negatively associated with all body fatness indicators only in girls. These associations strengthened after adjustment for age, height and sedentary time (β ranging from –0.49 to –0.36, P ≤ 0.01). In contrast, vigorous PA was strongly negatively associated with body fatness indicators only in boys. In the fully adjusted model the significant negative associations were found for fat mass percentage (β = –0.15, P = 0.048) and fat mass index (β = –0.15, P = 0.040).

Conclusions

The present study suggests that increasing sex-specific PA of different intensities may be an appropriate approach for decreasing body fatness in children. Longitudinal studies are needed to verify these associations.

Cross-Sectional Associations of Objectively-Measured Physical Activity and Sedentary Time with Body Composition and Cardiorespiratory Fitness in Mid-Childhood: The PANIC Study

BACKGROUND

The minimum intensity of physical activity (PA) that is associated with favourable body composition and cardiorespiratory fitness (CRF) remains unknown.

OBJECTIVE

To investigate cross-sectional associations of PA and sedentary time (ST) with body composition and CRF in mid-childhood.

METHODS

PA, ST, body composition and CRF were measured in a population-based sample of 410 children (aged 7.6 ± 0.4 years). Combined heart-rate and movement sensing provided estimates of PA energy expenditure (PAEE, kJ/kg/day) and time (min/day) at multiple fine-grained metabolic equivalent (MET) levels, which were also collapsed to ST and light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Fat mass index (FMI, kg/m2), trunk fat mass index (TFMI, kg/m2) and fat-free mass index (FFMI, kg/m2.5) were derived from dual-energy X-ray absorptiometry. Maximal workload from a cycle ergometer test provided a measure of CRF (W/kg FFM). Linear regression and isotemporal substitution models were used to investigate associations.

RESULTS

The cumulative time above 2 METs (221 J/min/kg) was inversely associated with FMI and TFMI in both sexes (p < 0.001) whereas time spent above 3 METs was positively associated with CRF (p ≤ 0.002); CRF increased and adiposity decreased dose-dependently with increasing MET levels. ST was positively associated with FMI and TFMI (p < 0.001) but there were inverse associations between all PA categories (including LPA) and adiposity (p ≤ 0.002); the magnitude of these associations depended on the activity being displaced in isotemporal substitution models but were consistently stronger for VPA. PAEE, MPA and to a greater extent VPA, were all positively related to CRF (p ≤ 0.001).

CONCLUSIONS

PA exceeding 2 METs is associated with lower adiposity in mid-childhood, whereas PA of 3 METs is required to benefit CRF. VPA was most beneficial for fitness and fatness, from a time-for-time perspective, but displacing any lower-for-higher intensity may be an important first-order public health strategy. Clinical trial registry number (website): NCT01803776 ( https://clinicaltrials.gov/ct2/show/NCT01803776 ).

Differences in erect sitting and natural sitting spinal alignment-insights into a new paradigm and implications in deformity correction

BACKGROUND CONTEXT

Sitting spinal alignment is increasingly recognized as a factor influencing strategy for deformity correction. Considering that most individuals sit for longer hours in a "slumped" rather than in an erect posture, greater understanding of the natural sitting posture is warranted.

PURPOSE

This study aimed to investigate the differences in sagittal spinal alignment between two common sitting postures: a natural, patient-preferred posture; and an erect, investigator-controlled posture that is commonly used in alignment studies.

DESIGN/SETTING

This is a randomized, prospective study of 28 young, healthy patients seen in a tertiary hospital over a 6-month period.

PATIENT SAMPLE

Twenty-eight patients (24 men, 4 women), with a mean age of 24 years (range 19-38), were recruited for this study. All patients with first episode of lower back pain of less than 3 months' duration were included. The exclusion criteria consisted of previous spinal surgery, radicular symptoms, red flag symptoms, previous spinal trauma, obvious spinal deformity on forward bending test, significant personal or family history of malignancy, and current pregnancy.

OUTCOME MEASURES

Radiographic measurements included sagittal vertical axis (SVA), lumbar lordosis (LL), thoracolumbar angle (TL), thoracic kyphosis (TK), and cervical lordosis (CL). Standard spinopelvic parameters (pelvic incidence, pelvic tilt [PT], and sacral slope) and sagittal apex and end vertebrae were also measured.

METHODS

Basic patient demographics (age, gender, ethnicity) were recorded. Lateral sitting whole spine radiographs were obtained using a slot scanner in the imposed erect and the natural sitting posture. Statistical analyses of the radiographical parameters were performed comparing the two sitting postures using chi-squared tests for categorical variables and paired t tests for continuous variables.

RESULTS

There was forward SVA shift between the two sitting postures by a mean of 2.9 cm (p<.001). There was a significant increase in CL by a mean of 11.62° (p<.001), and TL kyphosis by a mean of 11.48° (p<.001), as well as a loss of LL by a mean of 21.26° (p<.001). The mean PT increased by 17.68° (p<.001). The entire thoracic and lumbar spine has the tendency to form a single C-shaped curve with the apex moving to L1 (p=.002) vertebra in the majority of patients.

CONCLUSIONS

In a natural sitting posture, the lumbar spine becomes kyphotic and contributes to a single C-shaped sagittal profile comprising the thoracic and the lumbar spine. This is associated with an increase in CL and PT, as well as a constant SVA. These findings lend insight into the body's natural way of energy conservation using the posterior ligamentous tension band while achieving sitting spinal sagittal balance. It also provides information on one of the possible causes of proximal junctional kyphosis or proximal junctional failure.

Associations Between Sedentary Time, Physical Activity, and Dual-Energy X-ray Absorptiometry Measures of Total Body, Android, and Gynoid Fat Mass in Children

Negative health outcomes are associated with excess body fat, low levels of physical activity (PA), and high sedentary time (ST). Relationships between PA, ST, and body fat distribution, including android and gynoid fat, assessed using dual-energy X-ray absorptiometry (DXA) have not been measured in children. The purpose of this study was to test associations between levels of activity and body composition in children and to evaluate if levels of activity predict body composition by DXA and by body mass index percentile in a similar manner. PA, ST, and body composition from 87 children (8.8-11.8 yr, grades 3-5, 44 boys) were used to test the association among study variables. Accelerometers measured PA and ST. Body composition measured by DXA included bone mineral content (BMC) and fat and lean mass of the total body (TB, less head), android, and gynoid regions. ST (range: 409-685 min/wk) was positively associated with TB percent fat (0.03, 95% confidence interval [CI]: 0.00-0.05) and android fat mass (1.5 g, 95% CI: 0.4-3.0), and inversely associated with the lean mass of the TB (-10.7 g, 95% CI: -20.8 to -0.63) and gynoid regions (-2.2 g, 95% CI: -4.3 to -0.2), and with BMC (-0.43 g, 95% CI: 0.77-0.09). Moderate-to-vigorous PA was associated with lower TB (-53 g, 95% CI: -87 to -18), android (-5 g, 95% CI: -8 to -2]), and gynoid fat (-6 g, 95% CI: -11 to -0.5). Vigorous activity results were similar. Light PA was associated with increased TB (17.1 g, 95% CI: 3.0-31.3) and gynoid lean mass (3.9 g, 95% CI: 1.0-6.8) and BMC (0.59 g, 95% CI: 0.10-1.07). In boys, there were significant associations between activity and DXA percent body fat measures that were not found with the body mass index percentile. Objective measures of PA were inversely associated with TB, android, and gynoid fat, whereas ST was directly associated with TB percent fat and, in particular, android fat. Activity levels predict body composition measures by DXA and, in particular, android fat distribution.

Trajectories of objectively measured sedentary time among secondary students in Manitoba, Canada in the context of a province-wide physical education policy: A longitudinal analysis

OBJECTIVES

Canadian adolescents' sedentary behaviour (SB) is poorly understood and greatly understudied compared to physical activity (PA). Accumulating evidence suggests that SB poses long-term health risks regardless of PA levels. To design effective interventions that target SB, it is critical to first understand adolescents' sedentary time (ST) trajectories in a Canadian context. Therefore, we examined longitudinal trajectories of Manitoba students' ST from 2008 to 2011 and identified associated factors in the context of a province-wide physical education (PE) policy.

METHODS

Secondary schools offering grades 9 through 12 were randomly selected in blocks to represent the urban and rural geography of Manitoba. In each selected school (n = 31), a convenience sample of grade 9 or 10 PE classes was recruited, leading to a final sample of 447 students. To assess ST, participants wore accelerometers on 7 consecutive days at baseline (2008) and during at least one follow-up period (2009, 2010 and 2011).

RESULTS

At baseline, students accumulated an average of 540 minutes/day of ST. Over the course of secondary school, students' ST trajectories remained stable. Females compared to males had a slightly higher rate of decline in ST (p = 0.035), adjusting for socio-demographic variables. ST trajectories were not associated with baseline PA, body mass index and school neighbourhood socio-economic status.

CONCLUSION

Adolescent ST remained high throughout secondary school. SB may be well established by early adolescence and track through late adolescence. Our findings suggest the potential need for additional interventions to reduce SB before and over the course of secondary school.

Objectively measured sedentary behaviour and health and development in children and adolescents: systematic review and meta-analysis

Sedentary behaviour has emerged as a unique determinant of health in adults. Studies in children and adolescents have been less consistent. We reviewed the evidence to determine if the total volume and patterns (i.e. breaks and bouts) of objectively measured sedentary behaviour were associated with adverse health outcomes in young people, independent of moderate-intensity to vigorous-intensity physical activity. Four electronic databases (EMBASE MEDLINE, Ovid EMBASE, PubMed and Scopus) were searched (up to 12 November 2015) to retrieve studies among 2- to 18-year-olds, which used cross-sectional, longitudinal or experimental designs, and examined associations with health outcomes (adiposity, cardio-metabolic, fitness, respiratory, bone/musculoskeletal, psychosocial, cognition/academic achievement, gross motor development and other outcomes). Based on 88 eligible observational studies, level of evidence grading and quantitative meta-analyses indicated that there is limited available evidence that the total volume or patterns of sedentary behaviour are associated with health in children and adolescents when accounting for moderate-intensity to vigorous-intensity physical activity or focusing on studies with low risk of bias. Quality evidence from studies with robust designs and methods, objective measures of sitting, examining associations for various health outcomes, is needed to better understand if the overall volume or patterns of sedentary behaviour are independent determinants of health in children and adolescents.

Associations of Objectively Measured Vigorous Physical Activity With Body Composition, Cardiorespiratory Fitness, and Cardiometabolic Health in Youth: A Review

Background. Increasing evidence suggests that vigorous physical activity (VPA) in youth may yield greater health benefits than moderate (MPA) or moderate-to-vigorous physical activity (MVPA). The purpose of this review was to assess the relationship between PA intensity and body composition, cardiorespiratory fitness (CRF), and cardiometabolic (CM) biomarkers in youth. Methods. We conducted a systematic review of observational studies examining PA intensity and selected health outcomes in youth aged 6 to 18 years. Forty-five articles were selected for final review. Results. VPA was more strongly associated with reduced body fat and central adiposity compared with MPA and/or MVPA. Additionally, VPA was more strongly associated with increased CRF when compared with lower intensities. Findings were inconclusive between all PA intensity levels and CM biomarkers, and several significant relationships observed for VPA were attenuated when controlling for CRF. Conclusions. A potential VPA dose is identified as yielding favorable health benefits in adiposity and fitness. While CM biomarkers were not consistently associated with PA intensity level, the literature suggests VPA may yield health benefits above those received from MPA for reduced adiposity and improved CRF. This review highlights the need for longitudinal observational and experimental studies to determine optimal VPA dose for CM health in youth.

Effects of Behavioral Contingencies on Adolescent Active Videogame Play and Overall Activity: A Randomized Trial

OBJECTIVE

This study evaluated the effect of four active videogames (AVGs) varying in behavioral contingencies (behavior-consequence relations) on adolescent AVG play and overall activity levels over 4 weeks.

MATERIALS AND METHODS

Each AVG, manufactured by SSD/Xavix(®) (Shiseido Co. of Japan, Tokyo, Japan), was coded and scored for the number of positive and aversive behavioral contingencies within the games. "Bowling" and "Tennis" were classified as having "higher contingency scores," and "Boxing" and aerobic fitness training were classified as having "lower contingency scores." Adolescents (n=63; 11-15 years old; 62% male; 38% Hispanic; 44% overweight or obese) were randomized to play one of the four AVGs at home and recorded game play sessions in a paper log. Baseline and week 4 assessments were completed at home; week 1, 2, and 3 assessments were completed by telephone. Accelerometers were worn during baseline and weeks 1 and 4.

RESULTS

Accelerometer-measured sedentary and light activity hours/day were stable over time, whereas moderate-vigorous physical activity minutes/day increased in the higher contingency group and decreased in the lower contingency group (interaction effect, 6.43, P=0.024). Reported game play minutes decreased in both groups from week 1 to week 4 (-29.42 minutes, P=0.001).

DISCUSSION

There was some support for the hypothesis that AVGs with more behavioral contingencies, compared with AVGs with fewer behavioral contingencies, result in more physical activity. However, overall AVG play decreased substantially after the first week. Further study is needed to better understand how behavioral contingencies can be used in AVGs to enhance their potential to provide health benefits to game players.

Magnitude and determinants of change in objectively-measured physical activity, sedentary time and sleep duration from ages 15 to 17.5y in UK adolescents: the ROOTS study

Background

Self-reported physical activity (PA) and sleep duration (SLP) change markedly throughout adolescence. We sought to quantify changes in objectively-measured PA, sedentary time (ST) and SLP through adolescence, and to investigate baseline body composition and baseline activity levels as determinants of change.

Methods

Individually calibrated combined heart rate and movement sensing was used to estimate PA energy expenditure (PAEE), SLP, daily ST and time in light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous physical activity (MVPA) in 144 adolescents (50 % boys) of mean age 15.1(±0.3)y at baseline and 17.5(±0.3)y at follow-up. Changes in PA (ΔPA), ST (ΔST) and SLP (ΔSLP) were calculated as follow-up minus baseline values. Waist circumference (WC) was measured at baseline and follow-up, as was fat mass index (FMI) and fat-free mass index (FFMI) by a pooled estimation method including bio-impedance. Comparison of baseline and follow-up activity was made by mixed-model ANOVA. Linear regression adjusted for baseline demographics, total and weekend hours of monitor wear time and the seasons of activity measurements, was used to investigate baseline body composition as determinants of ΔPA, ΔST and ΔSLP. A further model adjusted for baseline of the outcome assessed baseline activity as a predictor of behaviour change, and investigated associations for baseline body composition independent of the baseline level of the outcome.

Results

From baseline to follow-up levels of MPA and VPA declined (p ≤ 0.039). The annual decline in MVPA was equivalent to -4.5 and -3.0 min/d in boys and girls, respectively. Baseline FMI, FFMI and WC were positively associated with ΔLPA and negatively associated with ΔST in boys when adjusted for baseline of the outcome (p ≤ 0.037 for all). SLP increased from baseline to follow-up (p = 0.004) but ΔSLP was not associated with baseline body composition (p ≥ 0.13). For all variables, higher baseline levels were associated with greater declines over time (p ≤ 0.003).

Conclusions

Levels of higher-intensity PA decline from mid-to-late adolescence, whereas the duration of sleep increases. Changes in LPA and ST may be associated with baseline body composition, but the baseline level of the outcome is consistently the strongest predictor of changes in adolescent activity.

School day and weekend patterns of physical activity in urban 11-year-olds: a cross-cultural comparison

OBJECTIVES

This multi-center study was conducted to objectively evaluate energy expenditure and physical activity (PA) patterns on school days and weekends in urban 11-year-olds.

METHODS

The sample consisted of 241 children from three cities: Zagreb, Ljubljana (both in Central Europe) and Ann Arbor (United States). Energy expenditure and PA were assessed during two school days and two weekend days using a multiple-sensor body monitor.

RESULTS

Differences between the cities were observed for all PA variables. The highest level of moderate to vigorous PA (MVPA) was noted in Ljubljana boys [284 (98) min/day] and the lowest in Zagreb girls [179 (95) min/day]. In Zagreb and Ljubljana, boys were more physically active than girls, while in Ann Arbor the opposite was observed. In contrast, no gender difference in sedentary behavior was observed in any of the cities. A decline in PA from school days to weekends was noted in all city groups in both genders. However, the magnitude of the reduction in daily energy expenditure differed between the cities, with the largest differences being observed in Ljubljana and the smallest in Ann Arbor. In all three city groups, the great majority of boys and girls achieved current recommendations of 60 min of MVPA either during school days or weekends.

CONCLUSIONS

Weekends seem to be an appropriate target when promoting PA in 11-year-olds in all the cities included in the study. Increasing vigorous activity on weekends seems to be of particular importance in Zagreb and Ljubljana.

Objectively measured sedentary behaviour and cardio-metabolic risk in youth: a review of evidence

The aim of this paper was to review studies that examine the association between volume and pattern of objectively measured sedentary behaviour and markers of cardio-metabolic risk in youth. A search for relevant articles was conducted in PubMed and SportDiscus, and the following inclusion criteria were applied: (i) youth participants (age range 6-19); (ii) accelerometer-measured volume and/or pattern of sedentary behaviour and its association with ≥1 cardio-metabolic outcome; and (iii) published, in press or accepted in an English language peer-reviewed journal between January 2000 and October 2013. A total of 45 articles met the a priori criteria and, thus, were considered eligible for inclusion. Although youth accumulate approximately 6 to 8 h of daily sedentary behaviour, little evidence supports an association with individual and clustered cardio-metabolic risk when adjusted for moderate-to-vigorous physical activity (MVPA).

CONCLUSION

We suggest that youth should be encouraged to engage in recommended levels of MVPA and reduce excessive time spent in screen-based sedentary behaviour. Future studies should examine the association between volume and pattern of objectively measured sedentary behaviour and cardio-metabolic risk independent of time spent in MVPA.

Long-term effects of 4-year longitudinal school-based physical activity intervention on the physical fitness of children and youth during 7-year followup assessment

Many school-based physical activity (PA) interventions have been developed, but only a few have assessed their long-term effects. A PA intervention taking place in the first four years of some Slovenian primary schools entails an enhanced physical education (PE) curriculum, including two extra lessons of PE per week, a wider selection of PE content, and additional outdoor education delivered by both a specialist PE teacher and a general teacher. The effects of the intervention on children's physical fitness (motor tasks and anthropometry) were evaluated within a quasi-experimental study. In total, 324 children from nine Slovenian primary schools either received the enhanced curriculum (intervention (n=160)) or standard PE (control (n=164)), and were followed for a four-year intervention period and seven years post intervention. Data from the SLOFIT database were used to compare differences in the physical fitness of children each year. Linear Mixed Models were used to test the influence of the PA intervention. Over an 11-year period, the PA intervention group significantly differed in all motor tasks, but not in anthropometric measures or body mass index, after controlling for year of measurement and sex. Differences between the control and intervention groups decreased with time. This study highlights the importance of tracking the long term effects of PA interventions. PA intervention in the first four years of Slovenian primary school offers the possibility of improving physical performance in children; initiatives aiming to increase their performance (physical fitness, physical activity) and health outcomes are warranted.

Levels and patterns of objectively-measured physical activity volume and intensity distribution in UK adolescents: the ROOTS study

BACKGROUND

Few studies have quantified levels of habitual physical activity across the entire intensity range. We aimed to describe variability in total and intensity-specific physical activity levels in UK adolescents across gender, socio-demographic, temporal and body composition strata.

METHODS

Physical activity energy expenditure and minutes per day (min/d) spent sedentary and in light, moderate, and vigorous intensity physical activity were assessed in 825 adolescents from the ROOTS study (43.5% boys; mean age 15.0 ± 0.30 years), by 4 days of individually calibrated combined heart rate and movement sensing. Measurement days were classified as weekday or weekend and according to the three school terms: summer (April-July), autumn (September-December), and spring (January-March). Gender and age were self-reported and area-level SES determined by postcode data. Body composition was measured by anthropometry and bio-electrical impedance. Variability in physical activity and sedentary time was analysed by linear multilevel modelling, and logistic multilevel regression was used to determine factors associated with physical inactivity (<60 min moderate-to-vigorous intensity physical activity/d).

RESULTS

During awake hours (15.8 ± 0.9 hrs/d), adolescents primarily engaged in light intensity physical activity (517 min/d) and sedentary time (364 min/d). Boys were consistently more physically active and less sedentary than girls, but gender differences were smaller at weekends, as activity levels in boys dropped more markedly when transitioning from weekday to weekend. Boys were more sedentary on both weekend days compared to during the week, whereas girls were more sedentary on Sunday but less sedentary on Saturday. In both genders light intensity physical activity was lower in spring, while moderate physical activity was lower in autumn and spring terms, compared to the summer term; sedentary time was also higher in spring than summer term. Adolescents with higher fatness engaged in less vigorous intensity physical activity. Factors associated with increased odds of physical inactivity were female gender, both weekend days in boys, and specifically Sunday in girls.

CONCLUSIONS

Physical activity components vary by gender, temporal factors and body composition in UK adolescents. The available data indicate that in adolescence, girls should be the primary targets of interventions designed to increase physical activity levels.

Does participation in physical education reduce sedentary behaviour in school and throughout the day among normal-weight and overweight-to-obese Czech children aged 9-11 years?

Participation of 9 to 11-year-old children in physical education lessons (PEL) contributes to a significantly higher duration of moderate-to-vigorous physical activity (MVPA) during the school day and, in overweight/obese girls and normal-weight boys, to an increase in overall daily MVPA as shown by previous research. However, it is not known whether this increase in MVPA is at the expense of light physical activity (LPA) or sedentary behaviour (SED). SED, LPA, and MVPA were assessed in 338 schoolchildren aged 9–11 years (50.3% girls; 29.6% overweight/obese) over two school days (with and without a PEL) using a triaxial accelerometer during various segments of the school day. SED, LPA, and MVPA were quantified based on the duration of the activity (minutes). Participation in PEL led to significantly higher school MVPA in the overweight/obese and normal-weight girls and boys (p < 0.005) compared to MVPA of those children on the school day without PEL. Participation in PEL led to a significantly higher overall daily MVPA duration compared to that during the day without PEL for the overweight/obese girls (p < 0.05), normal-weight girls (p < 0.05) and boys (p < 0.005). Participation in PEL contributed not only to significantly higher LPA in the normal-weight girls and boys (p < 0.01) during the school day but also reduced school-time SED in the overweight/obese children (p < 0.01) and normal-weight girls (p < 0.005). Moreover, participation in PEL significantly reduced the overall daily SED in the normal-weight children and overweight/obese boys (p < 0.05). Adding one PEL to the daily school routine appears to be a promising strategy for effectively reducing SED in children.

Promoting healthy weight in primary school children through physical activity and nutrition education: a pragmatic evaluation of the CHANGE! randomised intervention study

BACKGROUND

This pragmatic evaluation investigated the effectiveness of the Children's Health, Activity and Nutrition: Get Educated! (CHANGE!) Project, a cluster randomised intervention to promote healthy weight using an educational focus on physical activity and healthy eating.

METHODS

Participants (n = 318, aged 10-11 years) from 6 Intervention and 6 Comparison schools took part in the 20 weeks intervention between November 2010 and March/April 2011. This consisted of a teacher-led curriculum, learning resources, and homework tasks. Primary outcome measures were waist circumference, body mass index (BMI), and BMI z-scores. Secondary outcomes were objectively-assessed physical activity and sedentary time, and food intake. Outcomes were assessed at baseline, at post-intervention (20 weeks), and at follow-up (30 weeks). Data were analysed using 2-level multi-level modelling (levels: school, student) and adjusted for baseline values of the outcomes and potential confounders. Differences in intervention effect by subgroup (sex, weight status, socio-economic status) were explored using statistical interaction.

RESULTS

Significant between-group effects were observed for waist circumference at post-intervention (β for intervention effect =-1.63 (95% CI = -2.20, -1.07) cm, p<0.001) and for BMI z-score at follow-up (β=-0.24 (95% CI = -0.48, -0.003), p=0.04). At follow-up there was also a significant intervention effect for light intensity physical activity (β=25.97 (95% CI = 8.04, 43.89) min, p=0.01). Interaction analyses revealed that the intervention was most effective for overweight/obese participants (waist circumference: β=-2.82 (95% CI = -4.06, -1.58) cm, p<0.001), girls (BMI: β=-0.39 (95% CI = -0.81, 0.03) kg/m2, p=0.07), and participants with higher family socioeconomic status (breakfast consumption: β=8.82 (95% CI = 6.47, 11.16), p=0.07).

CONCLUSIONS

The CHANGE! intervention positively influenced body size outcomes and light physical activity, and most effectively influenced body size outcomes among overweight and obese children and girls. The findings add support for the effectiveness of combined school-based physical activity and nutrition interventions. Additional work is required to test intervention fidelity and the sustained effectiveness of this intervention in the medium and long term.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN03863885.

Examination of mid-intervention mediating effects on objectively assessed sedentary time among children in the Transform-Us! cluster-randomized controlled trial

Background

The optimal targets and strategies for effectively reducing sedentary behavior among young people are unknown. Intervention research that explores changes in mediated effects as well as in outcome behaviors is needed to help inform more effective interventions. Therefore, the purpose of this study was to examine the mid-intervention mediating effects on children’s objectively assessed classroom and total weekday sedentary time in the Transform-Us! intervention.

Methods

The results are based on 293 children, aged 7- to 9-years-old at baseline, from 20 schools in Melbourne, Australia. Each school was randomly allocated to one of four groups, which targeted reducing sedentary time in the school and family settings (SB; n = 74), increasing or maintaining moderate- to vigorous-intensity physical activity in the school and family settings (PA; n = 75), combined SB and PA (SB + PA; n = 80), or the current practice control (C; n = 64). Baseline and mid-intervention data (5–9 months) were collected in 2010 and analyzed in 2012. Classroom and total weekday sedentary time was objectively assessed using ActiGraph accelerometers. The hypothesized mediators including, child enjoyment, parent and teacher outcome expectancies, and child perceived access to standing opportunities in the classroom environment, were assessed by questionnaire.

Results

The SB + PA group spent 13.3 min/day less in weekday sedentary time at mid-intervention compared to the control group. At mid-intervention, children in the SB group had higher enjoyment of standing in class (0.9 units; 5-unit scale) and all intervention groups had more positive perceptions of access to standing opportunities in the classroom environment (0.3-0.4 units; 3-unit scale), compared to the control group. However, none of the hypothesized mediator variables had an effect on sedentary time; thus, no mediating effects were observed.

Conclusions

While beneficial intervention effects were observed on some hypothesized mediating variables and total weekday sedentary time at mid-intervention, no significant mediating effects were found. Given the dearth of existing information, future intervention research is needed that explores mediated effects. More work is also needed on the development of reliable mediator measures that are sensitive to change overtime.

Trial registration

ACTRN12609000715279

ISRCTN83725066

Comparison of BMI and physical activity between old order Amish children and non-Amish children

OBJECTIVE

The Old Order Amish (OOA) is a conservative Christian sect of European origin living in Pennsylvania. Diabetes is rare in adult OOA despite a mean BMI rivaling that in the general U.S. non-Hispanic white population. The current study examines childhood factors that may contribute to the low prevalence of diabetes in the OOA by comparing OOA children aged 8-19 years with National Health and Nutrition Examination Survey (NHANES) data and children from Maryland's Eastern Shore (ES), a nearby, non-Amish, rural community. We hypothesized that pediatric overweight is less common in OOA children, that physical activity (PA) and BMI are inversely correlated, and that OOA children are more physically active than ES children.

RESEARCH DESIGN AND METHODS

We obtained anthropometric data in 270 OOA children and 229 ES children (166 non-Hispanic white, 60 non-Hispanic black, 3 Hispanic). PA was measured by hip-worn accelerometers in all ES children and in 198 OOA children. Instrumentation in 43 OOA children was identical to ES children.

RESULTS

OOA children were approximately 3.3 times less likely than non-Hispanic white ES children and NHANES estimates to be overweight (BMI ≥85th percentile, Centers for Disease Control and Prevention). Time spent in moderate/vigorous PA (MVPA) was inversely correlated to BMI z-score (r = -0.24, P = 0.0006). PA levels did not differ by ethnicity within the ES group, but OOA children spent an additional 34 min/day in light activity (442 ± 56 vs. 408 ± 75, P = 0.005) and, impressively, an additional 53 min/day in MVPA (106 ± 54 vs. 53 ± 32, P < 0.0001) compared with ES children. In both groups, boys were more active than girls but OOA girls were easily more active than ES boys.

CONCLUSIONS

We confirmed all three hypotheses. Together with our previous data, the study implies that the OOA tend to gain their excess weight relatively late in life and that OOA children are very physically active, both of which may provide some long-term protection against diabetes.

Relationships between health behaviors and weight status in American Indian and white rural children

PURPOSE

Preventing obesity in childhood is an increasingly important public health goal. Prevention efforts can be improved by better understanding relationships between health behaviors and overweight and obesity. This study examined such relationships in young American Indian and white children living in the rural United States.

METHODS

Self-report measures of diet, screen time (passive and active), and physical activity were combined with cardiovascular fitness in cross-sectional analyses to predict weight categories based on body mass index percentiles in 306 American Indian and white children (aged 8-9 years) from a rural area in the upper Midwestern United States.

FINDINGS

Multinomial logistic regression models were statistically significant for girls (χ2 [20] = 42.73, P < .01), boys (χ2 [20] = 50.44, P < .001), American Indian (χ2 [20] = 36.67, P < .05), and white children (χ2 [20] = 55.99, P < .001). Obesity was associated with poorer cardiovascular fitness in girls (OR = 0.82), boys (OR = 0.83), American Indian (OR = 0.79), and white children (OR = 0.85), and with passive screen time in girls (OR = 1.69), boys (OR = 2.1), and white children (OR = 1.81). Overweight was associated with passive screen time (OR = 2.24) and inversely with active screen time (OR = 0.54), but only in boys.

CONCLUSIONS

Logistic regression models were more successful at predicting obesity than overweight in all groups of participants. Poorer cardiovascular fitness showed the strongest and most consistent association with obesity, but passive screen time was also a significant and important contributor to the prediction of obesity in most prediction models. Prediction models were similar in girls, boys, American Indian, and white children.

Correlates of weight status among Norwegian 11-year-olds: The HEIA study

Background

The underlying mechanisms of overweight and obesity in adolescents are still not fully understood. The aim of this study was to investigate modifiable and non-modifiable correlates of weight status among 1103 Norwegian 11-year-old adolescents in the HEalth in Adolescents (HEIA) study, including demographic factors such as gender and parental education, and behavioral factors such as intake of sugar-sweetened beverages, snacks and breakfast consumption, watching TV and playing computer games, physical activity and sedentary time.

Methods

Weight and height were measured objectively, body mass index (BMI) was calculated and International Obesity Task Force cut-offs were used to define weight status. Physical activity and sedentary time were measured by accelerometers. Other behavioral correlates and pubertal status were self-reported by questionnaires. Parental education was reported by the parents on the consent form for their child. Associations were investigated using logistic regressions.

Results

There were gender differences in behavioral correlates of weight status but not for weight status itself. Adolescents with parents in the highest education category had a 46% reduced odds of being overweight compared to adolescents with parents in the lowest education category. Adolescents with parents with medium education had 42% lower odds of being overweight than adolescents with parents with the lowest education category. Level of parental education, breakfast consumption and moderate to vigorous physical activity were positively associated with being normal weight, and time watching TV was positively associated with being overweight for the total sample. Gender differences were detected; boys had a doubled risk of being overweight for every additional hour of watching TV per week, while for girls there was no association.

Conclusions

The present study showed a social gradient in weight status in 11-year-olds. Both breakfast consumption and moderate to vigorous physical activity were inversely associated with weight status. No associations were found between intake of sugar-sweetened beverages and snacks, playing computer games and weight status. Watching TV was positively associated with weight status for boys but not for girls. Interventions are needed to gain more insight into the correlates of change in weight status.

Trends in general and abdominal obesity among Chinese children and adolescents 1993-2009

OBJECTIVE

This study aimed to examine the secular trends in body mass index (BMI) and waist circumference (WC), and the prevalence of general and abdominal obesity among Chinese children and adolescents from 1993 to 2009.

METHODS

Data were obtained from the China health and nutrition survey conducted from 1993 to 2009. 9693 children and adolescents aged 6-17 years were included in this study, with their height, weight and WC measured. General obesity was defined using the BMI cut-offs for overweight recommended by the International Obesity Task Force, and abdominal obesity was assessed when a WC is above the 90th percentile for gender and age.

RESULTS

Among the total participants, mean BMI and WC increased significantly over the period 1993-2009: BMI increased from 17.6 to 17.8 kg m(-2) , and WC increased from 61.4 to 63.1 cm (both increases P < 0.001). The prevalence of general obesity and abdominal obesity increased significantly over the period: general obesity (including overweight) rose from 6.1% to 13.1% and abdominal obesity from 4.9% to 11.7% (both increases P < 0.001). WC and abdominal obesity increased at a relatively higher rate than BMI and general obesity. Upward trends in the prevalence of general and abdominal obesity were observed in all subgroups of gender, age and region (all increases P < 0.05), except for abdominal obesity in girls aged 13-17 years (P = 0.102).

CONCLUSION

General and abdominal obesity increased significantly over the past 17 years in Chinese children.

Physical Activity Patterns and Quality of Life of Overweight Boys: A Preliminary Study

Objective

We compared the physical activity (PA) patterns and the quality of life (QoL) between overweight and normal-weight boys, and examined the relationship between PA and QoL of overweight boys.

Methods

Eighteen overweight boys (age range: 8–10 years, mean ± standard deviation: 9.36 ± 0.82 years) and 18 age-matched, normal-weight counterparts (age range: 8–10 years, mean ± standard deviation: 9.01 ± 0.65 years) participated in this study. All participants were in the 3rd or 4th grade. Each boy completed a QoL questionnaire and wore an accelerometer on his waist for a week to measure his PA during that period. Independent t tests were used to examine the differences in QoL and PA between the overweight and normal-weight boys. Paired t tests were used to test the differences in PA between weekdays and weekend days for each group. Finally, Pearson correlations were used to analyze the relationships between PA and QoL in overweight boys.

Results

Overweight boys reported a significantly lower QoL, and participated in significantly less PA on weekends than did normal-weight boys. A moderate and marginally significant correlation was found between PA on weekends and QoL in overweight boys.

Conclusion

Our findings suggest the importance of increasing weekend PA for overweight boys. Occupational therapists should encourage overweight boys to engage in PA that the boys are interested in on weekends, and conduct a PA program for overweight boys.

Levels of physical activity and sedentary time among 10- to 12-year-old boys and girls across 5 European countries using accelerometers: an observational study within the ENERGY-project

Background

The study aim was to objectively assess levels of sedentary time, light, moderate and vigorous physical activity (PA) among 10-12 year olds across five European countries and to examine differences in sedentary time and PA according to gender and country.

Methods

686 children (mean age = 11.6 ± 0.8 years, 53% girls, mean BMI = 19.0 ± 3.4 kg/m²) from Belgium, Greece, Hungary, the Netherlands and Switzerland wore Actigraph accelerometers and had at least 2 weekdays with minimum 10 h-wearing time and 1 weekend day with minimum 8 h-wearing time. Data were analyzed using multivariate analyses of covariance.

Results

Girls spent significantly more time sedentary (500 minutes/day) than boys (474 minutes/day) and significantly less time in light (267 minutes/day) and moderate-to-vigorous PA (32 minutes/day) than boys (284 minutes/day; 43 minutes/day respectively; p < 0.001). 4.6% of the girls and 16.8% of the boys met moderate-to-vigorous PA recommendations of at least 60 minutes/day. Greek boys were more sedentary (510 minutes/day; all at p < 0.05) than other boys. Dutch girls were less sedentary (457 minutes/day; all at p < 0.05) than other girls. Swiss girls displayed more moderate-to-vigorous PA (43 minutes/day; at p < 0.05) than other girls.

Conclusions

Large proportions of children across different European countries did not meet PA recommendations and spent a lot of time sedentary. Mean time spent in moderate-to-vigorous PA was significantly lower than the recommended 60 minutes. Obesity prevention programmes focusing on both decreasing sedentary time and increasing light, moderate and vigorous PA are needed for European children, particularly girls.

Evaluation of low-cost, objective instruments for assessing physical activity in 10-11-year-old children

This study compared step counts detected by four, low-cost, objective, physical-activity-assessment instruments and evaluated their ability to detect moderate-to-vigorous physical activity (MVPA) compared to the ActiGraph accelerometer (AG). Thirty-six 10-11-year-old children wore the NL-1000, Yamax Digiwalker SW 200, Omron HJ-151, and Walk4Life MVP concurrently with the AG during school hours on a single day. AG MVPA was derived from activity count data using previously validated cut points. Two of the evaluated instruments provided similar group mean MVPA and step counts compared to AG (dependent on cut point). Low-cost instruments may be useful for measurement of both MVPA and steps in children's physical activity interventions and program evaluation.

Cross-sectional analysis of levels and patterns of objectively measured sedentary time in adolescent females

Background

Adolescent females have been highlighted as a particularly sedentary population and the possible negative effects of a sedentary lifestyle are being uncovered. However, much of the past sedentary research is based on self-report or uses indirect methods to quantity sedentary time. Total time spent sedentary and the possible intricate sedentary patterns of adolescent females have not been described using objective and direct measure of body inclination. The objectives of this article are to examine the sedentary levels and patterns of a group of adolescent females using the ActivPAL™ and to highlight possible differences in sedentary levels and patterns across the week and within the school day. A full methodological description of how the data was analyzed is also presented.

Methods

One hundred and eleven adolescent females, age 15-18 yrs, were recruited from urban and rural areas in the Republic of Ireland. Participants wore an ActivPAL physical activity monitor for a 7.5 day period. The ActivPAL directly reports total time spent sitting/lying every 15 seconds and accumulation (frequency and duration) of sedentary activity was examined using a customized MATLAB^® computer software programme.

Results

While no significant difference was found in the total time spent sitting/lying over the full 24 hour day between weekday and weekend day (18.8 vs. 18.9 hours; p = .911), significantly more sedentary bouts of 1 to 5 minutes and 21 to 40 minutes in duration were accumulated on weekdays compared to weekend days (p < .001). The mean length of each sedentary bout was also longer (9.8 vs. 8.8 minutes; p < .001). When school hours (9 am-3 pm) and after school hours (4 pm-10 pm) were compared, there was no difference in total time spent sedentary (3.9 hours; p = .796) but the pattern of accumulation of the sedentary time differed. There were a greater number of bouts of > 20 minutes duration during school hours than after school hours (4.7 vs. 3.5 bouts; p < .001) while after school time consisted of shorter bouts < 20 minutes.

Conclusions

School is highlighted as a particularly sedentary setting for adolescent females. Interventions to decrease sedentary time at school and the use of wearable devices which distinguish posture should be encouraged when examining sedentary patterns and behaviors in this population.

Influence of intensity of physical activity on adiposity and cardiorespiratory fitness in 5-18 year olds

Physical activity (PA) is being increasingly promoted in children in an attempt to curb the rising epidemic of childhood obesity and its future consequences of obesity and cardiovascular diseases in adulthood. Although many reviews and guidelines have been published regarding PA in children and adolescents, none have specifically focused on the influence of intensity of activity on the crucial health aspects of fatness and cardiorespiratory fitness. Therefore, we conducted an online search for pertinent literature and reviewed 25 studies for this purpose. We found that there were limited studies that assessed the influence of 'intensity' of PA on health parameters, and there was considerable inconsistency in defining the thresholds for moderate (MPA) and vigorous (VPA) levels of PA. Collectively, we concluded that VPA is a significant predictor of fatness and significantly correlated to fitness. The association between the intensity of PA and cardiorespiratory fitness is more obscure compared with fatness because of limited studies and the varying conclusions made by them. However, decreased adiposity and increased aerobic capacity have been observed with participants who spent more time performing VPA. Further research needs to be undertaken to arrive at uniform thresholds for defining MPA and VPA and to obtain the exact dose of VPA and MPA, individually, to increase aerobic fitness and decrease adiposity.

Influences of social support, perceived barriers, and negative meanings of physical activity on physical activity in middle school students

BACKGROUND

A profound decline in physical activity occurs in puberty. This phenomenon is not well understood. Therefore, the purpose of this study is to examine associations between family/friend social support for physical activity, negative meanings of physical activity (NMPA), and internal /external barriers to physical activity with moderate to vigorous physical activity (MVPA), and sedentary and light behavior (SLB) in youth.

METHODS

A total of 350 participants from 7 Los Angeles County middle schools participated in the study (62% Latina, 79% females). Hypothesized pathways were examined using structural equation modeling. Psychosocial variables and participation in MVPA and SLB were assessed by self-reported questionnaires.

RESULTS

NMPA were related to lower levels of family/friend social support and greater internal/external barriers. Family social support was the only significant indicator of MVPA (β=0.79). Low family social support was related to higher SLB (β=-0.25).

CONCLUSIONS

Family social support seems crucial to promote MVPA and reduce SLB in adolescents and might be influenced by child's feelings about physical activity. Future research should consider the interrelationship between psychosocial correlates of physical activity.

Accelerometry measured ethnic differences in activity in rural adolescents

BACKGROUND

To determine if there are differences in time spent in physical activity and sedentary behavior between rural African American and Caucasian children.

METHODS

Children wore accelerometers for 3 weekdays. The students were randomly selected from a larger sample of children participating in a weight gain prevention intervention. Usable data were obtained from 272 of the 310 students who agreed to participate. The outcome data included counts per minute (CPM), time spent in moderate to vigorous (MVPA), light (LPA), and sedentary (SED) activity. The equation and cutoff used to analyze national accelerometry data were used for the current study.

RESULTS

The sample had an average age of 10.4 (1.1) years and 76% were African American. Lower SES African Americans had more CPM (P=.012) and spent more time in MVPA (P=.008) compared with middle SES African American and lower SES Caucasian children. Lower SES African American children also spent fewer minutes in SED activity (P=.044) compared with middle SES African American children.

CONCLUSIONS

These findings support recent results that also used objective activity measures. Children appeared less active and more sedentary than a national sample, warranting interventions in minority and rural populations.

Fatness, fitness, and cardiometabolic risk factors among sixth-grade youth

PURPOSE

Examine whether cardiometabolic risk factors are predicted by fitness or fatness among adolescents.

METHODS

Participants are 4955 (2614 female) sixth-grade students with complete data from 42 US middle schools. Fasting blood samples were analyzed for total cholesterol, HDL- and LDL-cholesterol, triglyceride, glucose, and insulin concentrations. Waist circumference and blood pressure were assessed. Body mass index (BMI) was categorized as normal weight, overweight, or obese as a measure of fatness. Fitness was assessed using the multistage shuttle test and was converted into gender-specific quintiles. Gender-specific regression models, adjusted for race, pubertal status, and household education, were run to identify whether BMI group predicted risk factors. Models were repeated with fitness group and both fitness and fatness groups as predictors.

RESULTS

Means for each risk factor (except HDL, which was the reverse) were significantly higher (P < 0.0001) with increased fatness and differed across all BMI groups (P < 0.001). Waist circumference, LDL-cholesterol, triglycerides, diastolic blood pressure, and insulin were inversely associated with fitness (P < 0.001). When both fatness and fitness were included in the model, BMI was associated (P < 0.001) with almost all cardiometabolic risk factors; fitness was only associated with waist circumference (both genders), LDL-cholesterol (males), and insulin (both genders). Other associations between fitness and cardiometabolic risk factors were attenuated after adjustment for BMI group.

CONCLUSIONS

Both fatness and fitness are associated with cardiometabolic risk factors among sixth-grade youth, but stronger associations were observed for fatness. Although maintaining high levels of fitness and preventing obesity may positively affect cardiometabolic risk factors, greater benefit may be obtained from obesity prevention.

Physical activity levels and estimated energy expenditure in overweight and normal-weight 11-year-old children

AIM

To objectively evaluate physical activity and energy expenditure in overweight and normal-weight 11-year-old children.

METHODS

The final sample consisted of 91 children (32 overweight and 59 normal-weight children), mean age (SD) = 11.3 (0.2) years. Energy expenditure and physical activity were assessed during two weekdays and two weekend days using a multiple-sensor body monitor (SenseWear Armband; BodyMedia Inc., Pittsburgh, PA, USA).

RESULTS

Time spent in physical activity was higher in normal-weight compared with overweight children (p = 0.002). The highest level of physical activity was noted in normal-weight boys [mean (SD) = 258 (114) min/day] and the lowest in overweight girls [mean (SD) = 136 (59) min/day] (p = 0.002). In contrast, energy expended during physical activity did not differ between normal-weight and overweight children (2.6 and 2.7 MJ/day, respectively, p = 0.89). The average decrease in physical activity at weekends was 39 min in overweight children (from 166 to 127 min/day) and 27 min in their normal-weight counterparts (from 230 to 203 min/day).

CONCLUSION

Overweight children engaged in less physical activity of both moderate and vigorous intensity compared with their normal-weight peers. Both overweight and normal-weight children were less active at weekends than on weekdays. Initiatives aiming to increase physical activity of overweight children at weekends are warranted.

Objectively measured physical activity, physical activity related personality and body mass index in 6- to 10-yr-old children: a cross-sectional study

Background

The prevalence and level of overweight in childhood is rapidly increasing. One potential contributor to the rise in overweight is a decline in physical activity (PA). The purpose of this study was to compare levels and patterns of PA and PA related personality in normal-weight (NW) and overweight (OW) 6- to 10-yr-old children.

Methods

Subjects were grouped into OW (N = 59, BMI = 24.2 ± 4.8 kg/m²) or NW (N = 61, BMI = 15.7 ± 1.5 kg/m²) according to International Obesity Task Force cut-offs. PA was assessed by accelerometry. Parents filled in a questionnaire on PA and sedentary behaviour and PA related personality of their child (born tired, moves slowly, is often tired, lacks energy, avoids physical efforts, prefers watching playing children instead of joining them, is always active, needs to let himself/herself go, has a lot of energy).

Results

NW children spent on average 77 min/day in MVPA, whereas OW children only 57 min/day (p = .001). OW children had fewer 5, 10 and 20 min bouts of MVPA (p = .01). OW and NW children showed identical PA patterns on both week days and weekends, although at different levels. According to parents' report, a greater percentage of OW children was not engaged in any sport (46% versus 23%, chi² = 6.3, p = .01). OW children had a less active personality (p < .001), watched more TV during weekend (p < .01), but no differences were found in outside play or non-active play. BMI of mother and father explained 29% of the variance in children's BMI z-score (p < .001). PA related personality, screen behaviour during weekend and MVPA explained an additional 12% (p < 0.01).

Conclusion

The results of this study demonstrate that NW children spent on average 20 min per day more in MVPA. PA patterns were similar in NW versus OW children, although at different levels. Greatest differences in PA according to weight status were found in the afternoon during after school hours. This is the first study to show distinct PA related personality traits in OW children compared to NW peers.

Translating research on healthy lifestyles for children: meeting the needs of diverse populations

This article provides two examples of approaches nursing can take to reach diverse populations of children and their families to enhance health lifestyles. First, a descriptive summary of a brief after-school intervention program aimed at influencing 8- and 9-year-old children's media habits and the prevention of negative health behaviors is presented. Design consideration for translating health lifestyles research findings into a nurse-managed inner city primary care practice is reviewed in the second example.

Amount of time spent in sedentary behaviors in the United States, 2003-2004

Sedentary behaviors are linked to adverse health outcomes, but the total amount of time spent in these behaviors in the United States has not been objectively quantified. The authors evaluated participants from the 2003-2004 National Health and Nutrition Examination Survey aged >/=6 years who wore an activity monitor for up to 7 days. Among 6,329 participants with at least one 10-hour day of monitor wear, the average monitor-wearing time was 13.9 hours/day (standard deviation, 1.9). Overall, participants spent 54.9% of their monitored time, or 7.7 hours/day, in sedentary behaviors. The most sedentary groups in the United States were older adolescents and adults aged >/=60 years, and they spent about 60% of their waking time in sedentary pursuits. Females were more sedentary than males before age 30 years, but this pattern was reversed after age 60 years. Mexican-American adults were significantly less sedentary than other US adults, and White and Black females were similarly sedentary after age 12 years. These data provide the first objective measure of the amount of time spent in sedentary behavior in the US population and indicate that Americans spend the majority of their time in behaviors that expend very little energy.

Sedentary behaviour and obesity development in children and adolescents

Sedentary lifestyle patterns in children and adolescents, i.e. playing digital games, using computers and especially watching television, have been associated with obesity. However, not all sedentary behaviour has shown the same relevance to, and relationship with, obesity. Therefore, we conducted a review including published studies found in PubMed and other medical journals, dated between January 1990 and April 2007. The ages of the children and adolescents who were the object of the study ranged between 2 and 18 years. For the purpose of this paper, we selected cross-sectional, longitudinal and intervention studies. Sufficient evidence exists to recommend setting a limit to the time spent watching TV, especially for younger children. However, video games and computers do not represent such a high risk compared to watching TV, when they do not replace physical activity too much. In fact, there is no evidence to suggest that sedentary behaviour displaces physical activity levels. Mechanisms that explain the link between sedentariness and obesity are also discussed. Finally, future studies should take into account important mediators such as socioeconomic status and family structure.

Habitual physical activity and body composition of black township adolescents residing in the North West Province, South Africa

Objective

It is known that stunting and obesity affect a large proportion of children in the world, and these can be affected by the physical activity levels of the children. In the present study, we evaluated the association between physical activity, physical development and body composition in black adolescent children.

Design

Cross-sectional study.

Setting

Black township schools in the North West Province, South Africa.

Methods

Three-hundred and thirteen grade 8 children were included in the Physical Activity in Youth study. Anthropometric measurements, body composition measures and maturity level as assessed by Tanner stages were determined in these children. In addition, Previous Day Physical Activity Recall questionnaires were administered on the children to record the various activities they undertake daily.

Results

The demographic characteristics of the children showed a high level of homogeneity. A high prevalence of stunting (16.3%) was observed in the children, which was higher in boys than in girls (21.6 vs. 12.3%). Also prevalent was overweight/obesity (8.6%), but this was higher in girls than in boys (13.4 vs. 1.6%). The children also showed a reduction in levels of physical activity with advancement in maturity; furthermore, boys showed a more central form of fat deposition whilst girls showed more gynoid deposition.

Conclusions

The study revealed that physical activity plays a role in determining body composition, and further indicated that physical activity is associated with favourable body composition measures. Children who were more active were likely to have less fat deposits.

Trends and sociocultural factors for childhood overweight in La Reunion Island

OBJECTIVE

To examine time trends (study 1) and sociocultural factors associated with childhood overweight (study 2) in La Reunion Island.

DESIGN

Study 1: a longitudinal analysis of anthropometric data available from health services in the town of Saint-Pierre. Study 2: a case - control study.

SUBJECTS

Study 1: 1753 children born between 1977 and 1996. Study 2: 101 six-year old overweight children sex-matched with 101 non-overweight children.

MEASUREMENTS

Study 1: overweight at birth (birth weight>4 kg) and at age 4 and 6 using French references and references from the International Obesity Task Force. Study 2: parental and perinatal data, child's lifestyle and representation of food, all collected from the mother.

RESULTS

Study 1: a dramatic increase in the prevalence rate of overweight at 4 and at 6 is observed, more severe in girls. Study 2: multivariate logistic regressions showed that mother's overweight was the only variable significantly associated with overweight in both the sexes. The other associated factors were related to sociocultural and family features and sedentarity. Logistic probability functions derived from these data are proposed as a tool for detection of at risk families.

CONCLUSION

Our results show the need for a targeted prevention of overweight. We offer a proposal based on education and behaviour modification in La Reunion Island.

Weekend and weekday patterns of physical activity in overweight and normal-weight adolescent girls

OBJECTIVE

To describe the patterns (specifically comparing weekdays and weekends classified by intensities) of physical activity (PA) measured by accelerometry in adolescent girls.

RESEARCH METHODS AND PROCEDURES

Healthy sixth grade girls (n=1603), 11 to 12 years old, were randomly recruited from 36 schools participating in the Trial of Activity in Adolescent Girls. Age, ethnicity, socioeconomic status, weight, and height were taken. PA patterns were measured for 6 days using accelerometry.

RESULTS

Adolescent girls spend most of their time in sedentary (52% to 57% of the day) and light activity (40% to 45% of the day) on weekdays and weekends. In all girls, total PA comprised 44.5% of the day (41.7% light, 2.2% moderate, and 0.7% vigorous) with sedentary activity comprising 55.4%. Moderate-to-vigorous PA (MVPA) was higher (p<0.001) on weekdays than weekends in all girls, but MVPA was lower in at-risk of overweight+overweight girls (p<0.001) on both weekdays and weekends compared with normal-weight girls.

DISCUSSION

Adolescent girls are more active at moderate and vigorous intensities on weekdays than on weekends, and at-risk of overweight and those overweight spend less time engaging in MVPA than normal-weight girls.

The reliability of the Adolescent Sedentary Activity Questionnaire (ASAQ)

OBJECTIVE

To determine the test-retest reliability of a self-report questionnaire (the Adolescent Sedentary Activities Questionnaire; ASAQ) which assesses the time spent in a comprehensive range of sedentary activities, among school-aged young people.

METHOD

Two-hundred and fifty school students aged 11-15 years from four primary and four high schools in metropolitan Sydney (New South Wales, Australia) completed the questionnaire under the same conditions on two occasions, 2 weeks apart during Autumn, 2002.

RESULTS

Test-retest correlations for time total spent in sedentary behavior were >or=0.70, except for Grade 6 boys (Intraclass correlation coefficient (ICC)=0.57, 95%CI: 0.25, 0.76). Repeatability was generally higher on week days compared with week end days. ICC values for travel and social activities tended to be lower than for the other categories of sedentary behavior. There was little difference in the reliability across age groups.

CONCLUSIONS

ASAQ has good to excellent reliability in the measurement of a broad range of sedentary behaviors among young people. ASAQ has good face validity, but further validity testing is required to provide a complete assessment of the instrument.

Promotion of physical activity in primary care for obesity treatment/prevention in children

PURPOSE OF REVIEW

Physical activity has been highlighted internationally as a beneficial intervention for weight control and the improvement of physical and mental health. This review highlights findings from recent literature to guide office-based promotion of physical activity for obesity treatment and prevention.

RECENT FINDINGS

Children worldwide participate in far less than the current physical activity recommendations. Family-based activity provides children with positive role modeling as well as motivational support for maintaining an active lifestyle. The integration of physical activity into daily life can be an effective alternative to sports and structured exercise programs. Decreasing sedentary behaviors is also a positive contribution, although its link to physical activity levels is still unclear. Some families may see neighborhood safety and access to recreational facilities as barriers to keeping their children physically active.

SUMMARY

Research in the field of pediatric obesity and overweight treatment and prevention continues to find challenges and solutions. Promotion of physical activity by the pediatric provider is demonstrated by current evidence to be a positive intervention against this global problem.

Visceral abdominal fat is correlated with whole-body fat and physical activity among 8-y-old children at risk of obesity

BACKGROUND

Abdominal fat is more related to health risk than is whole-body fat. Determining the factors related to children's visceral fat could result in interventions to improve child health.

OBJECTIVE

Given the effects of physical activity on adults' visceral fat, it was hypothesized that, after accounting for whole-body fat, physical activity would be inversely related to children's visceral (VAT), but not to subcutaneous (SAT), abdominal adipose tissue.

DESIGN

In this cross-sectional observational study conducted in forty-two 8-y-old children (21 boys, 21 girls) at risk of obesity [>75th body mass index (BMI) percentile, with at least one overweight parent], familial factors (eg, maternal BMI), historic weight-related factors (eg, birth weight), and the children's current physical activity (self-reported and measured with accelerometry) and diet were examined as potential correlates of the children's whole-body composition (measured with BMI and dual-energy X-ray absorptiometry) and abdominal fat distribution (measured by magnetic resonance imaging).

RESULTS

Accelerometer-measured physical activity was related to whole-body fat (r = -0.32, P < 0.10), SAT (r = -0.29, P < 0.10), and VAT (r = -0.43, P < 0.05). In regression models, whole-body fat was positively associated with and the only significant correlate of SAT. Whole-body fat was positively related and accelerometer-measured physical activity was negatively and independently related to the children's VAT.

CONCLUSIONS

Both SAT and VAT in 8-y-old children at risk of obesity are most closely associated with whole-body fat. However, after control for whole-body fat, greater physical activity is only associated with lower VAT, not SAT, in these children.