Comparison of children’s free-living physical activity derived from wrist and hip raw accelerations during the segmented week

Raw Acceleration from Wrist- and Hip-Worn Accelerometers Corresponds with Mechanical Loading in Children and Adolescents

The purpose of this study was to investigate associations between peak magnitudes of raw acceleration (g) from wrist- and hip-worn accelerometers and ground reaction force (GRF) variables in a large sample of children and adolescents. A total of 269 participants (127 boys, 142 girls; age: 12.3 ± 2.0 yr) performed walking, running, jumping (<5 cm; >5 cm) and single-leg hopping on a force plate. A GENEActiv accelerometer was worn on the left wrist, and an Actigraph GT3X+ was worn on the right wrist and hip throughout. Mixed-effects linear regression was used to assess the relationships between peak magnitudes of raw acceleration and loading. Raw acceleration from both wrist and hip-worn accelerometers was strongly and significantly associated with loading (all p's < 0.05). Body mass and maturity status (pre/post-PHV) were also significantly associated with loading, whereas age, sex and height were not identified as significant predictors. The final models for the GENEActiv wrist, Actigraph wrist and Actigraph hip explained 81.1%, 81.9% and 79.9% of the variation in loading, respectively. This study demonstrates that wrist- and hip-worn accelerometers that output raw acceleration are appropriate for use to monitor the loading exerted on the skeleton and are able to detect short bursts of high-intensity activity that are pertinent to bone health.

Reference values for wrist-worn accelerometer physical activity metrics in England children and adolescents

BACKGROUND

Over the last decade use of raw acceleration metrics to assess physical activity has increased. Metrics such as Euclidean Norm Minus One (ENMO), and Mean Amplitude Deviation (MAD) can be used to generate metrics which describe physical activity volume (average acceleration), intensity distribution (intensity gradient), and intensity of the most active periods (MX metrics) of the day. Presently, relatively little comparative data for these metrics exists in youth. To address this need, this study presents age- and sex-specific reference percentile values in England youth and compares physical activity volume and intensity profiles by age and sex.

METHODS

Wrist-worn accelerometer data from 10 studies involving youth aged 5 to 15 y were pooled. Weekday and weekend waking hours were first calculated for youth in school Years (Y) 1&2, Y4&5, Y6&7, and Y8&9 to determine waking hours durations by age-groups and day types. A valid waking hours day was defined as accelerometer wear for ≥ 600 min·d^-1 and participants with ≥ 3 valid weekdays and ≥ 1 valid weekend day were included. Mean ENMO- and MAD-generated average acceleration, intensity gradient, and MX metrics were calculated and summarised as weighted week averages. Sex-specific smoothed percentile curves were generated for each metric using Generalized Additive Models for Location Scale and Shape. Linear mixed models examined age and sex differences.

RESULTS

The analytical sample included 1250 participants. Physical activity peaked between ages 6.5-10.5 y, depending on metric. For all metrics the highest activity levels occurred in less active participants (3^rd-50^th percentile) and girls, 0.5 to 1.5 y earlier than more active peers, and boys, respectively. Irrespective of metric, boys were more active than girls (p < .001) and physical activity was lowest in the Y8&9 group, particularly when compared to the Y1&2 group (p < .001).

CONCLUSIONS

Percentile reference values for average acceleration, intensity gradient, and MX metrics have utility in describing age- and sex-specific values for physical activity volume and intensity in youth. There is a need to generate nationally-representative wrist-acceleration population-referenced norms for these metrics to further facilitate health-related physical activity research and promotion.

The Physical Behaviour Intensity Spectrum and Body Mass Index in School-Aged Youth: A Compositional Analysis of Pooled Individual Participant Data

We examined the compositional associations between the intensity spectrum derived from incremental acceleration intensity bands and the body mass index (BMI) z-score in youth, and investigated the estimated differences in BMI z-score following time reallocations between intensity bands. School-aged youth from 63 schools wore wrist accelerometers, and data of 1453 participants (57.5% girls) were analysed. Nine acceleration intensity bands (range: 0−50 mg to ≥700 mg) were used to generate time-use compositions. Multivariate regression assessed the associations between intensity band compositions and BMI z-scores. Compositional isotemporal substitution estimated the differences in BMI z-score following time reallocations between intensity bands. The ≥700 mg intensity bandwas strongly and inversely associated with BMI z-score (p < 0.001). The estimated differences in BMI z-score when 5 min were reallocated to and from the ≥700 mg band and reallocated equally among the remaining bands were −0.28 and 0.44, respectively (boys), and −0.39 and 1.06, respectively (girls). The time in the ≥700 mg intensity band was significantly associated with BMI z-score, irrespective of sex. When even modest durations of time in this band were reallocated, the asymmetrical estimated differences in BMI z-score were clinically meaningful. The findings highlight the utility of the full physical activity intensity spectrum over a priori-determined absolute intensity cut-point approaches.

Relationship Between Parent and Child Physical Activity Using Novel Acceleration Metrics

Background: Raw acceleration data lend themselves to innovative metrics in which comparisons can be made across populations. This study examined whether the intensity gradient (IG) or average acceleration (AvAcc) was associated with body mass index (BMI) in children and adults and explored parent-child associations between time spent in physical activity intensities and BMI. Methods: Parent-child dyads (n = 90) wore a wrist-mounted ActiGraph GT3X+ monitor for ≥ 3 valid days (i.e., ≥ 16 hrs each day). Participants' BMI was calculated. Results: Girls' BMI-z scores were positively associated with parent BMI and inactive time. Parent BMI was negatively associated with boys' inactive time. Parental inactive time predicted girls' BMI-z scores. The metrics were not associated with parent BMI, and no independent effects were observed between the metrics. Associations between boys' IG and BMI z-score were observed. No independent effects were observed between the metrics and no significant associations were observed between boys' BMI z-score and AvAcc. Girls' AvAcc and IG were not associated with BMI z-score and no independent effects were observed between the metrics. Conclusion: Findings support previous research which suggests that parent's activity does not influence their child's activity.

Segmented physical activity and sedentary behavior patterns among children in Maasai village and Nairobi city

OBJECTIVES

Urban-rural comparisons between those who maintain traditional lifestyles such as pastoralist Maasai children, and those who live in cities such as Nairobi, provide implications on how urbanization is associated with children's physical activity (PA) and sedentary behavior (SB) patterns. This study compares PA and SB volumes and patterns across different segments of the week among children in Maasai village and Nairobi city in Kenya.

METHOD

A total of 261 children (11.4 ± 1.3 years) from Maasai (n = 118) and Nairobi (n = 143) participated in this cross-sectional study. Moderate- to vigorous-intensity PA (MVPA) and SB on weekdays (before, during, and after school) and weekends (morning, afternoon, and evening) were calculated using accelerometers (ActiGraph). Screen time and sleep duration were assessed using questionnaires.

RESULTS

Maasai children were more physically active than Nairobi children with MVPA (min/day) of 166.6 and 81.4 for Maasai and Nairobi boys and 116.4 and 77.4 for Maasai and Nairobi girls, respectively. Our week segments analyses suggested that Maasai children were more active both in and out of school than Nairobi children. Additionally, Nairobi children spent more time watching television and playing computer games than Maasai children. There was no significant difference in sleep duration between Maasai and Nairobi children.

CONCLUSION

Our findings suggest that urbanization is negatively associated with activity patterns both in and out of school in Kenyan children. This is concerning given that Kenya is currently undergoing rapid urbanization, which may lead to further reductions in PA among Kenyan children.

Physical activity in children and adolescents with CHD: review from a measurement methodological perspective

AIM

To compile a literature overview of physical activity in children with CHD and to critically evaluate the methodology used for physical activity assessment.

METHODS

A review of the literature was performed using PubMed to identify studies examining accelerometer and subjectively assessed physical activity in children and adolescents with CHD.

RESULT

A total of 15 studies were included (6 studies using subjective measures and 9 articles using accelerometers for the assessment of physical activity). The patients generally failed to meet the recommendations of physical activity. When compared to healthy controls, the results were widely divergent in the subjectively assessed measures and the accelerometer-based studies showed a tendency of no difference in physical activity. Neither subjective methods nor accelerometer-based studies reported any difference in physical activity in general, in relation to the severity of the heart disease.

CONCLUSION

Methodological variation and limitations in the assessment of physical activity largely explain the divergent results and the inability to establish differences in physical activity between children with CHD of different severity and compared to healthy controls. Methodological knowledge and guidelines are provided for improved assessment of physical activity using accelerometers in clinical research.

Measurement of Physical Activity by Shoe-Based Accelerometers-Calibration and Free-Living Validation

There is conflicting evidence regarding the health implications of high occupational physical activity (PA). Shoe-based accelerometers could provide a feasible solution for PA measurement in workplace settings. This study aimed to develop calibration models for estimation of energy expenditure (EE) from shoe-based accelerometers, validate the performance in a workplace setting and compare it to the most commonly used accelerometer positions. Models for EE estimation were calibrated in a laboratory setting for the shoe, hip, thigh and wrist worn accelerometers. These models were validated in a free-living workplace setting. Furthermore, additional models were developed from free-living data. All sensor positions performed well in the laboratory setting. When the calibration models derived from laboratory data were validated in free living, the shoe, hip and thigh sensors displayed higher correlation, but lower agreement, with measured EE compared to the wrist sensor. Using free-living data for calibration improved the agreement of the shoe, hip and thigh sensors. This study suggests that the performance of a shoe-based accelerometer is similar to the most commonly used sensor positions with regard to PA measurement. Furthermore, it highlights limitations in using the relationship between accelerometer output and EE from a laboratory setting to estimate EE in a free-living setting.

Comparison between self-reported and accelerometer-derived measurements for classifying children and adolescents as physically active in Chile

The aim of this study was to compare self-reported with two accelerometer-derived methods to classify Chilean children and adolescents as physically active. In total, 247 students wore an accelerometer on their hips during 7 consecutive days to classify them as physically active based on (1) daily accumulation of ≥ 60 minutes of moderate-to-vigorous physical activity (MVPA) on each of the seven days, and (2) average MVPA ≥ 60 minutes/day. Also, participants were classified as physically active if they reported being active for at least 60 minutes in all seven days. When using the accelerometer data, 0.8% were active in all seven days, while 10.5% recorded ≥ 60 minutes MVPA per day on average. Based on self-report, 7.2% were physically active. The agreement between self-reported and accelerometer estimations were poor. Important differences were observed between the self-reported and device-derived methods for classifying children and adolescents as physically active. When comparing them, some considerations should be taken. The findings suggest that these methods are not interchangeable. Therefore, if possible, they should be used as complementary measurements.

Children's moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis

Purpose

The Structured Days Hypothesis (SDH) posits that children’s behaviors associated with obesity – such as physical activity – are more favorable on days that contain more ‘structure’ (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children’s moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset.

Methods

Data were received from the International Children’s Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status.

Results/findings

Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively.

Conclusions

Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

Physical activity and sedentary time of youth in structured settings: a systematic review and meta-analysis

BACKGROUND

Structured settings, such as school, childcare, afterschool programs, summer camps, and physical activity/sport programs are crucial to promoting physical activity (PA) opportunities and reducing sedentary (ST) for children and adolescents. However, little is known about how much PA and ST children and adolescents accumulate in structured settings. The aim of this study is to conduct a systematic review and meta-analysis of the absolute amount of time youth spend physically active and sedentary in different structured settings (Prospero number: 42018111804).

METHODS

Observational and experimental/quasi-experimental studies (baseline data only) with full-text available, written in English and published in a peer-reviewed journal, reporting the total amount of objectively measured PA (light, moderate, vigorous, and/or total physical activity) and/or time spent ST during structured settings among youth (3 to 18 years) were eligible. Adjusted meta-analysis was conducted to estimate the pooled mean of time spent in PA and ST, by settings and sex.

RESULTS

A total of 187 studies (childcare n=60; school n=91; afterschool programs n=14; summer camp n=4; and Physical activity/ sport programs n=18) from 30 countries (47.9% United States), representing 74,870 youth (mean age 8.6 years old) were included. Overall, there was a high variation between studies in outcomes and settings. The meta-analyses revealed, on average, youth spend 221.8 minutes (36.7 min/hour) in ST and 32.1 minutes (5.1 min/hour) in MVPA during childcare hours, and 223.9 minutes (36.7min/hour) in ST and 27.8 min (4.4 min/hour) in MVPA at school. Relatively, youth are engaged in more MVPA in afterschool programs (11.7 min/hour), PA/ sport programs (20.9 min/hour), and summer camps (6.4 min/hour), when compared to childcare and school.

CONCLUSION

Total PA accumulated during childcare and MVPA accumulated during schools hours were close to recommendations, despite high proportion of ST. Afterschool programs, summer camp and PA/ sport programs are important settings that can contribute to daily PA and reduced ST. Ensuring all youth have access to these structured settings may be an important step forward for public health.

Cultural adaptation of an existing children's weight management programme: the CHANGE intervention and feasibility RCT

BACKGROUND

Excess weight in children is a continuing health issue. Community-based children's weight management programmes have had some effect in promoting weight loss. Families from minority ethnic communities are less likely to complete these programmes but, to date, no programmes have been culturally adapted to address this.

OBJECTIVES

We aimed to (1) culturally adapt an existing weight management programme for children aged 4-11 years and their families to make it more suited to Pakistani and Bangladeshi communities but inclusive of all families and (2) evaluate the adapted programme to assess its feasibility and acceptability, as well as the feasibility of methods, for a future full-scale trial.

DESIGN

In phase I, a cultural adaptation of a programme that was informed by formative research and guided by two theoretical frameworks was undertaken and in phase II this adapted programme was delivered in a cluster-randomised feasibility study (for which the clusters were the standard and adapted children's weight management programmes).

SETTING

Birmingham: a large, ethnically diverse UK city.

PARTICIPANTS

In phase I, Pakistani and Bangladeshi parents of children with excess weight, and, in phase II, children aged 4-11 years who have excess weight and their families.

INTERVENTIONS

A culturally adapted children's weight management programme, comprising six sessions, which was delivered to children and parents, targeting diet and physical activity and incorporating behaviour change techniques, was developed in phase I and delivered in the intervention arm to 16 groups in phase II. The eight groups in the comparator arm received the standard (unadapted) children's weight management programme.

MAIN OUTCOME MEASURES

The primary outcome was the proportion of Pakistani and Bangladeshi families completing (attending ≥ 60% of) the adapted programme. Secondary outcomes included the proportion of all families completing the adapted programme, the feasibility of delivery of the programme, the programme's acceptability to participants, the feasibility of trial processes and the feasibility of collection of outcome and cost data.

RESULTS

The proportion of Pakistani and Bangladeshi families and all families completing the adapted programme was 78.8% [95% confidence interval (CI) 64.8% to 88.2%] and 76.3% (95% CI 67.0% to 83.6%), respectively. The programme was feasible to deliver with some refinements and was well received. Ninety-two families participated in outcome data collection. Data collection was mostly feasible, but participant burden was high. Data collection on the cost of programme delivery was feasible, but costs to families were more challenging to capture. There was high attrition over the 6-month follow-up period (35%) and differential attrition in the two study arms (29% and 52% in the intervention and comparator arms, respectively).

LIMITATIONS

The study was not designed to address the issue of low participant uptake of children's weight management programmes. The design of a future trial may include individual randomisation and a 'minimal intervention' arm, the acceptability of which has not been evaluated in this study.

CONCLUSIONS

The theoretically informed, culturally adapted children's weight management programme was highly acceptable to children and families of all ethnicities. Consideration should be given to a future trial to evaluate clinical effectiveness and cost-effectiveness of the adapted programme, but the design of a future trial would need to address the logistics of data collection, participant burden and study attrition.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN81798055.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 33. See the NIHR Journals Library website for further project information. Kate Jolly is part-funded by the Collaboration for Leadership in Applied Health Research and Care West Midlands.

Segmented sedentary time and physical activity patterns throughout the week from wrist-worn ActiGraph GT3X+ accelerometers among children 7-12 years old

BACKGROUND

This study examined the volume and patterns of physical activity (PA) and sedentary time (ST) across different segments of the week among boys and girls.

METHODS

A total of 188 children aged 7-12 years wore a wrist-mounted ActiGraph GT3X+ accelerometer for 7 days. Time spent in PA and ST was calculated using ActiLife software. The mean number of minutes of light PA, moderate PA, vigorous PA, moderate-to-vigorous PA (MVPA), and ST were calculated per weekday (before school, during school, and after school) and per weekend day (morning and afternoon-evening).

RESULTS

After school represented the greatest accumulation of ST compared with before school and during school segments. Boys engaged in 225.4 min/day of ST (95% confidence interval (CI): 216-235), and girls engaged in 222.2 min/day of ST (95%CI: 213-231). During school, boys engaged in significantly more MVPA than girls (46.1 min/day (95%CI: 44-48) vs. 40.7 min/day (95%CI: 39-43)). Across the whole weekday, boys participated in significantly more MVPA than girls (103.9 min/day (95%CI: 99-109) vs. 95.7 min/day (95%CI: 90-101)). The weekend afternoon-evening segment represented the larger accumulation of ST, where boys were significantly more sedentary than girls (367.5 min/day (95%CI: 353-382) vs. 339.8 min/day (95%CI: 325-355), respectively).

CONCLUSION

Our findings suggest that children are highly sedentary and spend little of their time in school in MVPA, especially girls. Routine breaks in school elicit increases in light PA and MVPA. Future work should consider the use of more active breaks within school time to encourage PA and reduce ST.

Calibration and Validation of the Youth Activity Profile as a Physical Activity and Sedentary Behaviour Surveillance Tool for English Youth

Self-reported youth physical activity (PA) is typically overestimated. We aimed to calibrate and validate a self-report tool among English youth. Four-hundred-and-two participants (aged 9-16 years; 212 boys) wore SenseWear Armband Mini devices (SWA) for eight days and completed the self-report Youth Activity Profile (YAP) on the eighth day. Calibration algorithms for temporally matched segments were generated from the YAP data using quantile regression. The algorithms were applied in an independent cross-validation sample, and student- and school-level agreement were assessed. The utility of the YAP algorithms to assess compliance to PA guidelines was also examined. The school-level bias for the YAP estimates of in-school, out-of-school, and weekend moderate-to-vigorous PA (MVPA) were 17.2 (34.4), 31.6 (14.0), and -4.9 (3.6) min·week^-1, respectively. Out-of-school sedentary behaviour (SB) was over-predicted by 109.2 (11.8) min·week^-1. Predicted YAP values were within 15%-20% equivalence of the SWA estimates. The classification accuracy of the YAP MVPA estimates for compliance to 60 min·day^-1 and 30 min·school-day^-1 MVPA recommendations were 91%/37% and 89%/57% sensitivity/specificity, respectively. The YAP generated robust school-level estimates of MVPA and SB and has potential for surveillance to monitor compliance with PA guidelines. The accuracy of the YAP may be further improved through research with more representative UK samples to enhance the calibration process and to refine the resultant algorithms.

Measurement of physical activity in clinical practice using accelerometers

Accelerometers are commonly used in clinical and epidemiological research for more detailed measures of physical activity and to target the limitations of self-report methods. Sensors are attached at the hip, wrist and thigh, and the acceleration data are processed and calibrated in different ways to determine activity intensity, body position and/or activity type. Simple linear modelling can be used to assess activity intensity from hip and thigh data, whilst more advanced machine-learning modelling is to prefer for the wrist. The thigh position is most optimal to assess body position and activity type using machine-learning modelling. Frequency filtering and measurement resolution needs to be considered for correct assessment of activity intensity. Simple physical activity measures and statistical methods are mostly used to investigate relationship with health, but do not take advantage of all information provided by accelerometers and do not consider all components of the physical activity behaviour and their interrelationships. More advanced statistical methods are suggested that analyse patterns of multiple measures of physical activity to demonstrate stronger and more specific relationships with health. However, evaluations of accelerometer methods show considerable measurement errors, especially at individual level, which interferes with their use in clinical research and practice. Therefore, better objective methods are needed with improved data processing and calibration techniques, exploring both simple linear and machine-learning alternatives. Development and implementation of accelerometer methods into clinical research and practice requires interdisciplinary collaboration to cover all aspects contributing to useful and accurate measures of physical activity behaviours related to health.

The backwards comparability of wrist worn GENEActiv and waist worn ActiGraph accelerometer estimates of sedentary time in children

OBJECTIVES

To examine the backward comparability of a range of wrist-worn accelerometer estimates of sedentary time (ST) with ActiGraph 100countmin^-1 waist ST estimates.

DESIGN

Cross-sectional, secondary data analysis METHODS: One hundred and eight 10-11-year-old children (65 girls) wore an ActiGraph GT3X+ accelerometer (AG) on their waist and a GENEActiv accelerometer (GA) on their non-dominant wrist for seven days. GA ST data were classified using a range of thresholds from 23 to 56mg ST estimates were compared to AG ST 100countmin^-1 data. Agreement between the AG and GA thresholds was examined using Cronbach's alpha, intraclass correlation coefficients (ICC), limits of agreement (LOA), Kappa values, percent agreement, mean absolute percent error (MAPE) and equivalency analysis.

RESULTS

Mean AG total ST was 492.4min over the measurement period. Kappa values ranged from 0.31 to 0.39. Percent agreement ranged from 68 to 69.9%. Cronbach's alpha values ranged from 0.88 to 0.93. ICCs ranged from 0.59 to 0.86. LOA were wide for all comparisons. Only the 34mg threshold produced estimates that were equivalent at the group level to the AG ST 100countmin^-1 data though sensitivity and specificity values of ∼64% and ∼74% respectively were observed.

CONCLUSIONS

Wrist-based estimates of ST generated using the 34mg threshold are comparable with those derived from the AG waist mounted 100countmin^-1 threshold at the group level. The 34mg threshold could be applied to allow group-level comparisons of ST with evidence generated using the ActiGraph 100countmin^-1 method though it is important to consider the observed sensitivity and specificity results when interpreting findings.

Establishing Raw Acceleration Thresholds to Classify Sedentary and Stationary Behaviour in Children

This study aimed to: (1) compare acceleration output between ActiGraph (AG) hip and wrist monitors and GENEActiv (GA) wrist monitors; (2) identify raw acceleration sedentary and stationary thresholds for the two brands and placements; and (3) validate the thresholds during a free-living period. Twenty-seven from 9- to 10-year-old children wore AG accelerometers on the right hip, dominant- and non-dominant wrists, GA accelerometers on both wrists, and an activPAL on the thigh, while completing seven sedentary and light-intensity physical activities, followed by 10 minutes of school recess. In a subsequent study, 21 children wore AG and GA wrist monitors and activPAL for two days of free-living. The main effects of activity and brand and a significant activity × brand × placement interaction were observed (all p < 0.0001). Output from the AG hip was lower than the AG wrist monitors (both p < 0.0001). Receiver operating characteristic (ROC) curves established AG sedentary thresholds of 32.6 mg for the hip, 55.6 mg and 48.1 mg for dominant and non-dominant wrists respectively. GA wrist thresholds were 56.5 mg (dominant) and 51.6 mg (non-dominant). Similar thresholds were observed for stationary behaviours. The AG non-dominant threshold came closest to achieving equivalency with activPAL during free-living.

A cluster-randomised feasibility trial of a children's weight management programme: the Child weigHt mANaGement for Ethnically diverse communities (CHANGE) study

BACKGROUND

Community-based programmes for children with excess weight are widely available, but few have been developed to meet the needs of culturally diverse populations. We adapted an existing children's weight management programme, focusing on Pakistani and Bangladeshi communities. We report the evaluation of this programme to assess feasibility of programme delivery, acceptability of the programme to participants from diverse communities, and feasibility of methods to inform a future trial.

METHODS

A cluster-randomised feasibility trial was undertaken in a large UK city. Children's weight management programmes (n = 24) were randomised to be delivered as the adapted or the standard programme (2:1 ratio). Routine data on participant attendance (n = 243) at the sessions were used to estimate the proportion of families completing the adapted and standard programmes (to indicate programme acceptability). Families planning to attend the programmes were recruited to participate in the feasibility study (n = 92). Outcome data were collected from children and parents at baseline, end of programme, and 6 months post-programme. A subsample (n = 24) of those attending the adapted programme participated in interviews to gain their views of the content and delivery and assess programme acceptability. Feasibility of programme delivery was assessed through observation and consultation with facilitators, and data on costs were collected.

RESULTS

The proportion of Pakistani and Bangladeshi families and families of all ethnicities completing the adapted programme was similar: 78.8% (95% CI 64.8-88.2%) and 76.3% (95% CI 67.0-83.6%) respectively. OR for completion of adapted vs. standard programme was 2.40 (95% CI 1.32-4.34, p = 0.004). The programme was feasible to deliver with some refinements, and participant interview data showed that the programme was well received. Study participant recruitment was successful, but attrition was high (35% at 6 months). Data collection was mostly feasible, but participant burden was high. Data collection on cost of programme delivery was feasible, but costs to families were more challenging to capture.

CONCLUSIONS

This culturally adapted programme was feasible to deliver and highly acceptable to participants, with increased completion rates compared with the standard programme. Consideration should be given to a future trial to evaluate its clinical and cost-effectiveness.

TRIAL REGISTRATION

ISRCTN81798055, registered: 13/05/2014.

A comparison of physical activity from Actigraph GT3X+ accelerometers worn on the dominant and non-dominant wrist

The purpose of this study was to evaluate the agreement between several activity measures using raw acceleration data from accelerometers worn concurrently on the dominant and non-dominant wrist. Fifty-five adults (31·9 ± 9·7 years, 26 males) wore two ActiGraph GT3X+ monitors continuously for 1 day, one on their non-dominant wrist and the other on their dominant wrist. Paired t-tests were undertaken with sequential Holm-Bonferroni corrections to compare wear time, moderate-vigorous physical activity (MVPA), time spent in 10-min bouts of MVPA (MVPA_10 min ) and the average magnitude of dynamic wrist acceleration (ENMO). Level of agreement between outcome variables from the wrists was examined using intraclass correlation coefficients (ICC, single measures, absolute agreement) with 95% confidence intervals and limits of agreement (LoA). Time spent across acceleration levels in 40 mg resolution were also examined. There were no significant differences between the non-dominant and dominant wrist for ENMO, wear time, MVPA or MVPA_10 min . Agreement between wrists was strong for most outcomes (ICC ≥0·92) including wear time, ENMO, MVPA, MVPA_10 min and the distribution of time across acceleration levels. Agreement was strong in the low acceleration bands (ICC = 0·970 and 0·922) with a mean bias of 3·08 min (LoA -55·18 to 61·34) and -5·43 (LoA -43·47 to 32·62). In summary, ENMO, MVPA, MVPA_10 min , wear time and the distribution of time across acceleration levels compared well at the group level. The LOA from the two lowest acceleration levels suggest further work over a longer monitoring period is needed to determine whether outputs from each wrist are comparable.

The Feasibility of a Novel School Peer-Led Mentoring Model to Improve the Physical Activity Levels and Sedentary Time of Adolescent Girls: The Girls Peer Activity (G-PACT) Project

Regular physical activity (PA) is associated with numerous physical and psychological health benefits. Adolescents, specifically girls, are at risk of physical inactivity. To date, there is limited research on PA interventions involving peers, which could encourage more adolescent girls to engage in PA. The investigation aimed to evaluate the feasibility of a novel school three-tier peer-led mentoring model designed to improve PA levels and reduce sedentary time (ST) of adolescent girls. Two-hundred and forty-nine Year 9 adolescent girls (13⁻15 years old) from three UK secondary schools were invited to participate in a peer-led mentoring intervention (Girls Peer Activity (G-PACT) project). The peer-led mentoring model was delivered in all three schools. Two of the schools received an additional after-school PA component. PA and ST were assessed through wrist-worn accelerometry. Girls who received an exercise class after-school component significantly increased their whole day moderate-to-vigorous PA (MVPA) (3.2 min, p = 0.009, d = 0.33). Girls who received no after-school component significantly decreased their MVPA (3.5 min, p = 0.016, d = 0.36) and increased their ST (17.2 min, p = 0.006, d = 0.43). The G-PACT intervention demonstrated feasibility of recruitment and data collection procedures for adolescent girls. The peer-led mentoring model shows promise for impacting girls' MVPA levels when combined with an after-school club PA opportunity.

Evaluation of a Pilot School-Based Physical Activity Clustered Randomised Controlled Trial-Active Schools: Skelmersdale

Schools are key environments in which physical activity (PA) can be promoted. Various strategies and opportunities should be used to engage children in PA within schools. The aim of this study was to evaluate the effectiveness of the multi-component Active Schools: Skelmersdale (AS:Sk) pilot intervention on children's PA and sedentary time (ST). The AS:Sk intervention was implemented for eight weeks in four schools with three control schools continuing normal practice. It consisted of eight components: active breaks, bounce at the bell, 'Born To Move' videos, Daily Mile or 100 Mile Club, playground activity challenge cards, physical education teacher training, newsletters, and activity homework. Child-level measures were collected at baseline and follow-up, including objectively measured PA. After accounting for confounding variables, the intervention had a significant effect on school day ST which was significantly less for the intervention children by 9 min per day compared to the control group. The AS:Sk pilot intervention was effective in reducing school day ST but significant changes in PA were negligible. To increase the efficacy of the current and future school-based interventions, authors should focus on implementation and process evaluations to better understand how schools are implementing intervention components.

Comparability of children's sedentary time estimates derived from wrist worn GENEActiv and hip worn ActiGraph accelerometer thresholds

OBJECTIVES

To examine the comparability of children's free-living sedentary time (ST) derived from raw acceleration thresholds for wrist mounted GENEActiv accelerometer data, with ST estimated using the waist mounted ActiGraph 100count·min^-1 threshold.

DESIGN

Secondary data analysis.

METHOD

108 10-11-year-old children (n=43 boys) from Liverpool, UK wore one ActiGraph GT3X+ and one GENEActiv accelerometer on their right hip and left wrist, respectively for seven days. Signal vector magnitude (SVM; mg) was calculated using the ENMO approach for GENEActiv data. ST was estimated from hip-worn ActiGraph data, applying the widely used 100count·min^-1 threshold. ROC analysis using 10-fold hold-out cross-validation was conducted to establish a wrist-worn GENEActiv threshold comparable to the hip ActiGraph 100count·min^-1 threshold. GENEActiv data were also classified using three empirical wrist thresholds and equivalence testing was completed.

RESULTS

Analysis indicated that a GENEActiv SVM value of 51mg demonstrated fair to moderate agreement (Kappa: 0.32-0.41) with the 100count·min^-1 threshold. However, the generated and empirical thresholds for GENEActiv devices were not significantly equivalent to ActiGraph 100count·min^-1. GENEActiv data classified using the 35.6mg threshold intended for ActiGraph devices generated significantly equivalent ST estimates as the ActiGraph 100count·min^-1.

CONCLUSIONS

The newly generated and empirical GENEActiv wrist thresholds do not provide equivalent estimates of ST to the ActiGraph 100count·min^-1 approach. More investigation is required to assess the validity of applying ActiGraph cutpoints to GENEActiv data. Future studies are needed to examine the backward compatibility of ST data and to produce a robust method of classifying SVM-derived ST.

Wear compliance, sedentary behaviour and activity in free-living children from hip-and wrist-mounted ActiGraph GT3X+ accelerometers

The GT3X+ worn at the wrist promotes greater compliance than at the hip. Minutes in SB and PA calculated from raw accelerations at the hip and wrist provide contrasting estimates and cannot be directly compared. Wear-time for the wrist (15.6 to 17.4 h.d^-1) was greater than the hip (15.2 to 16.8 h.d^-1) across several wear-time criteria (all P < 0.05). Moderate-strong associations were found between time spent in SB (r = 0.39), LPA (r = 0.33), MPA (r = 0.99), VPA (r = 0.82) and MVPA (r = 0.81) between the two device placements (All P < 0.001). The wrist device detected more minutes in LPA, MPA, VPA and MVPA whereas the hip detected more SB (all P = 0.001). Estimates of time in SB and all activity outcomes from the wrist and hip lacked equivalence. One hundred and eighty-eight 9-12-year-old children wore a wrist- and hip-mounted accelerometer for 7 days. Data were available for 160 (hip) and 161 (wrist) participants. Time spent in SB and PA was calculated using GGIR. This study examined the compliance of children wearing wrist- and hip-mounted ActiGraph GT3X+ accelerometers and compared estimates of sedentary behaviour (SB) and physical activity (PA) between devices.

Replacement of Sedentary Time with Physical Activity: Effect on Lipoproteins

PURPOSE

Limited data on the relationship between physical activity and lipoprotein particle profiles exist. Our objective was to investigate associations between objectively measured physical activity and lipoprotein particle size and number, and specifically whether substituting daily sedentary behavior with light activity or moderate-to-vigorous physical activity (MVPA) is associated with beneficial alterations to the lipoprotein profile among adults and those at increased cardiometabolic risk (obese and insulin-resistant subjects).

METHODS

Sedentary behavior and physical activity intensity and duration were measured for 7 consecutive days using the GENEActiv accelerometer in a cross-sectional adult cohort (n = 396; mean age, 59.6 ± 5.5 yr). Lipoprotein particle size and subclass concentrations were determined using nuclear magnetic resonance spectroscopy. Isotemporal substitution regression modeling quantified the associations between replacing 30 min·d of sedentary behavior with equal amounts of light activity and MVPA on lipoprotein profiles.

RESULTS

Daily duration of MVPA was inversely associated with large VLDL particles and lipoprotein insulin resistance scores (P < 0.05, after adjustment for sedentary time and other confounding factors). Reallocating 30 min of sedentary time with MVPA, but not light activity, was associated with less large VLDL particles resulting in more favorable average VLDL particle size and improved lipoprotein insulin resistance score (P < 0.05). Analysis of high-cardiometabolic-risk groups revealed similar beneficial alterations to VLDL profiles (P < 0.05) with substitution of sedentary time for MVPA among the insulin-resistant (homeostasis model assessment for insulin resistance ≥75th percentile) but not the obese (body mass index ≥30 kg·m) individuals.

CONCLUSIONS

Daily MVPA duration and theoretical replacement of sedentary time with MVPA, but not light activity, were associated with less atherogenic VLDL profiles, particularly among the insulin-resistant individuals. These findings, which require further investigation, highlight the need to develop physical activity interventions aimed at improving atherogenic dyslipidemia and lowering cardiometabolic risk.

Cluster-randomised controlled trial to assess the effectiveness and cost-effectiveness of an obesity prevention programme for Chinese primary school-aged children: the CHIRPY DRAGON study protocol

INTRODUCTION

Childhood obesity in China has increased more rapidly and over a shorter time period than in other countries. However, there is a paucity of rigorously developed and evaluated prevention interventions. We aim to evaluate the clinical and cost-effectiveness as well as the implementation process of a complex multicomponent intervention developed using the UK Medical Research Council (MRC) framework. This study provides one of the first examples of rigorous development and evaluation of a childhood obesity prevention programme in a non-western population using the MRC methods.

METHODS AND ANALYSIS

A cluster-randomised controlled trial in 40 primary schools in Guangzhou, China, including children aged 6-7 years at baseline. Schools will be randomly allocated to either the usual practice (n=20) or intervention arm (n=20). The 12-month intervention consists of four components targeting diet and physical activity behaviours in and outside school, with family involvement. The primary objective is to compare the difference in mean body mass index (BMI) z-score between the intervention and control arms at the end of the intervention (starting March/April 2017). A sample size of 1640 pupils recruited from 40 schools is sufficient to detect a difference of 0.17 units in the mean BMI z-score with a power of 80% (ICC=0.01. ICC, intraclass correlation coefficient) and a significance level of 5%. Treatment effects will be tested using a mixed linear model in STATA adjusting for the child baseline BMI z-score and clustering by school. All analyses will be by intention to treat. Secondary analyses will additionally adjust for prespecified school-level and child-level covariates. The incremental cost-effectiveness ratio for the intervention versus usual practice will be 'cost per quality-adjusted life year (QALY)'. Cost per change in BMI z-score will also be assessed. A range of methods will be used to evaluate intervention implementation, mechanisms of impact and contextual factors.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Life and Health Sciences Ethical Review Committee at the University of Birmingham and the Ethical Committee of Guangzhou Centre for Disease Control and Prevention. The primary, secondary, process evaluation and economic evaluation results of the trial will be disseminated through relevant international peer-reviewed journals and conferences.

TRIAL REGISTRATION NUMBER

ISRCTN11867516; Pre-results.

Predictors of Segmented School Day Physical Activity and Sedentary Time in Children from a Northwest England Low-Income Community

Background: Schools have been identified as important settings for health promotion through physical activity participation, particularly as children are insufficiently active for health. The aim of this study was to investigate the child and school-level influences on children′s physical activity levels and sedentary time during school hours in a sample of children from a low-income community; Methods: One hundred and eighty-six children (110 boys) aged 9–10 years wore accelerometers for 7 days, with 169 meeting the inclusion criteria of 16 h∙day⁻¹ for a minimum of three week days. Multilevel prediction models were constructed to identify significant predictors of sedentary time, light, and moderate to vigorous physical activity during school hour segments. Child-level predictors (sex, weight status, maturity offset, cardiorespiratory fitness, physical activity self-efficacy, physical activity enjoyment) and school-level predictors (number on roll, playground area, provision score) were entered into the models; Results: Maturity offset, fitness, weight status, waist circumference-to-height ratio, sedentary time, moderate to vigorous physical activity, number of children on roll and playground area significantly predicted physical activity and sedentary time; Conclusions: Research should move towards considering context-specific physical activity and its correlates to better inform intervention strategies.

Fitness, fatness and the reallocation of time between children's daily movement behaviours: an analysis of compositional data

BACKGROUND

Movement behaviours performed over a finite period such as a 24 h day are compositional data. Compositional data exist in a constrained simplex geometry that is incongruent with traditional multivariate analytical techniques. However, the expression of compositional data as log-ratio co-ordinate systems transfers them to the unconstrained real space, where standard multivariate statistics can be used. This study aimed to use a compositional data analysis approach to examine the adiposity and cardiorespiratory fitness predictions of time reallocations between children's daily movement behaviours.

METHODS

This study used cross-sectional data from the Active Schools: Skelmersdale study, which involved Year 5 children from a low-income community in northwest England (n = 169). Measures included accelerometer-derived 24 h activity (sedentary time [ST], light physical activity [LPA], moderate-to-vigorous physical activity [MVPA], and sleep), cardiorespiratory fitness determined by the 20 m shuttle run test, objectively measured height, weight and waist circumference (from which zBMI and percent waist circumference-to-height ratio (%WHtR) were derived) and sociodemographic covariates. Log-ratio multiple linear regression models were used to predict adiposity and fitness for the mean movement behaviour composition, and for new compositions where fixed durations of time had been reallocated from one behaviour to another, while the remaining behaviours were unchanged. Predictions were also made for reallocations of fixed durations of time using the mean composition of three different weight status categories (underweight, normal-weight, and overweight/obese) as the starting point.

RESULTS

Replacing MVPA with any other movement behaviour around the mean movement composition predicted higher adiposity and lower CRF. The log-ratio model predictions were asymmetrical: when time was reallocated to MVPA from sleep, ST, or LPA, the estimated detriments to fitness and adiposity were larger in magnitude than the estimated benefits of time reallocation from MVPA to sleep, ST or LPA. The greatest differences in fitness and fatness for reallocation of fixed duration of MVPA were predicted at the mean composition of overweight/obese children.

CONCLUSIONS

Findings reinforce the key role of MVPA for children's health. Reallocating time from ST and LPA to MVPA in children is advocated in school, home, and community settings.

Context matters! sources of variability in weekend physical activity among families: a repeated measures study

Background

Family involvement is an essential component of effective physical activity (PA) interventions in children. However, little is known about the PA levels and characteristics of PA among families. This study used a repeated measures design and multiple data sources to explore the variability and characteristics of weekend PA among families.

Methods

Families (including a ‘target’ child aged 9–11 years, their primary caregiver(s) and siblings aged 6–8 years) were recruited through primary schools in Liverpool, UK. Participants completed a paper-based PA diary and wore an ActiGraph GT9X accelerometer on their left wrist for up to 16 weekend days. ActiGraph.csv files were analysed using the R-package GGIR version 1.1–4. Mean minutes of moderate-to-vigorous PA (MVPA) for each weekend of measurement were calculated using linear mixed models, and variance components were estimated for participant (inter-individual), weekend of measurement, and residual error (intra-individual). Intraclass correlation coefficients (ICC) were calculated from the proportion of total variance accounted for by inter-individual sources, and used as a measure of reliability. Diary responses were summed to produce frequency counts. To offer contextual insight into weekend PA among family units, demographic, accelerometer, and diary data were combined to form two case studies representative of low and high active families.

Results

Twenty-five participants from 7 families participated, including 7 ‘target’ children (mean age 9.3 ± 1.1 years, 4 boys), 6 siblings (mean age 7.2 ± 0.7 years; 4 boys) and 12 adults (7 mothers and 5 fathers). There was a high degree of variability in target children’s (ICC = 0.55), siblings (ICC = 0.38), and mothers’ MVPA (ICC = 0.58), but not in fathers’ MVPA (ICC = 0.83). Children’s weekend PA was mostly unstructured in nature and undertaken with friends, whereas a greater proportion of parents’ weekend PA was undertaken alone in structured settings. The family case studies demonstrated that in the selected cases MVPA levels and variability across weekends were contingent on mode of PA participation.

Conclusions

These novel findings enhance understanding of the variability and characteristics of weekend PA among family units. The study demonstrates the utility of PA diaries in conjunction with accelerometers to provide understanding of the mode and contexts of out-of-school and family-based PA.