Validity of the ActivPAL™ and the ActiGraph monitors in preschoolers.

PURPOSE: This study aimed to compare three objective measures (GT1M ActiGraph, ActivPAL™, and direct observation) of sedentary behavior in preschoolers. METHODS: Fifty-two 4- to 6-yr-old preschoolers wore an ActivPAL™ and a GT1M ActiGraph for five consecutive days and were videotaped for 1 h during classroom activities at preschool. The area under the receiver operating characteristic curve was calculated to assess the criterion validity of the ActivPAL™ (sitting/lying, with and without standing still) and the GT1M ActiGraph (<100 counts per minute) to estimate sedentary behavior (directly observed sitting behaviors). A two-way repeated-measures ANOVA was used to define the convergent validity of the ActivPAL™ and the GT1M ActiGraph sedentary behavior estimates across the measurement days. The practical utility of the ActivPAL™ was tested in the same sample by asking the parents how their child perceived wearing the ActivPAL™. RESULTS: Results indicated a poor classification accuracy for both devices (area under the receiver operating characteristic curve, 0.6) to measure sedentary behavior based on the direct observation, with and without the inclusion of standing. Time defined as sedentary behavior (sitting/lying) was lower for the ActivPAL™ compared with the GT1M ActiGraph (mean bias, 7.7%; limits of agreement, -29.01% to 13.6%). According to the parental reports, 38% of the preschoolers had skin irritation due to wearing the ActivPAL™ for consecutive days. CONCLUSIONS: Low classification accuracy was found for the ActivPAL™ and the GT1M ActiGraph to measure sedentary behavior in preschoolers. No correction factor can be suggested to make the sedentary estimates of the GT1M ActiGraph and the ActivPAL™ convergent as no systematic bias and wide limits of agreement were found. Furthermore, the practical utility of the ActivPAL™ was perceived to be lower compared with the ActiGraph accelerometer in preschoolers.

The impact of a teacher-led structured physical activity session on preschoolers' sedentary and physical activity levels.

OBJECTIVES: The purpose of this observational study was to examine differences in preschoolers' sedentary time and physical activity (PA) participation between preschool-attending weekdays with and without a teacher-led structured PA session. DESIGN: A sample of 200 preschoolers (5.3±0.4y; 113 boys) from 26 preschools in Flanders, Belgium were included in data analysis. METHODS: Participants wore a GT1M ActiGraph accelerometer on one preschool-attending weekday with and on one preschool-attending weekday without the provision of a teacher-led structured PA session. Preschoolers' sedentary time, light PA, and moderate-to-vigorous physical activity (MVPA) during the time in preschool (08:00-16:00h) and after preschool (16:00-20:00h) were estimated. To assess differences in the outcome measures between both days, multi-level linear regression models were conducted. RESULTS: During the time at preschool, lower sedentary levels (ß=13.0min; SE=1.6; p<0.001) and higher light PA (ß=2.9min; SE=0.7 p<0.001) and MVPA levels (ß=10.1min; SE=1.1; p<0.001) were prevalent on days with a structured PA session compared to days without a structured PA session in both boys and girls. After preschool, no differences were found between both days in sedentary time (ß=0.7; SE=1.4; p>0.05), light PA (ß=0.3; SE=0.5; p>0.05), and MVPA (ß=0.3; SE=0.9; p>0.05). CONCLUSIONS: The results demonstrate that no compensatory changes were found after preschool for the structured PA session during the preschool hours. Therefore, a teacher-led structured PA session integrated in the preschool curriculum is a promising mean to decrease sedentary time and to increase PA in preschool-aged boys and girls.

Objectively measured sedentary time and physical activity time across the lifespan: a cross-sectional study in four age groups.

BACKGROUND: From a health perspective it is suggested to promote a positive balance between time spent in light intensity physical activity (LIPA) and sedentary behaviour (SB) (i.e. spending more time in LIPA than time spent in SB). However, no studies have reported prevalence rates of the LIPA-SB balance yet. The aim of this study was to objectively investigate the time spent in SB, in LIPA and moderate-to-vigorous intensity physical activity (MVPA) in four Belgian age groups and to explore which proportion of the population had a favorable balance between LIPA and SB and combined this with recommended amount of MVPA. METHODS: Accelerometer data from 7 cross-sectional studies (N=2083) in four age groups (preschoolers, primary schoolchildren, secondary schoolchildren and adults) were aggregated. Differences in SB and PA between age groups and between men and women were determined by two-way MANCOVA. LIPA-SB balance was calculated and participants were categorized into one of four groups: (1) positive LIPA-SB balance (LIPA> SB) & sufficient MVPA (2) negative LIPA-SB balance & sufficient MVPA (3) positive LIPA-SB balance & insufficient MVPA (4) negative LIPA-SB balance & insufficient MVPA. RESULTS: For the total sample, 55% of the waking time was spent in SB, 39% in LIPA and 6% in MVPA. Differences in SB between age groups was dependent from gender (p<0.001). Further, a positive LIPA-SB balance was assessed in 18% of the total sample and only 10% combined this positive balance with recommended amount of MVPA. Secondary schoolgirls were most at risk, with only 1% of the sample combining a positive LIPA-SB balance with sufficient MVPA. Another risk group was the large proportion (43%) of adult men who combined sufficient MVPA with a negative LIPA-SB balance. CONCLUSION: A high proportion of the Belgian population is at risk if taking into account both SB and PA levels. Secondary schoolgirls have the unhealthiest SB and PA profile and are therefore an important target group for interventions both increasing MVPA and decreasing SB. In men more attention should be given in promoting a positive LIPA-SB balance independently from their compliance with the MVPA guidelines.

Patterns of physical activity and sedentary behaviour in preschool children.

BACKGROUND: Little is known about patterns of sedentary behavior (SB) and physical activity among preschoolers. Therefore, in this observational study patterns of SB and moderate-to-vigorous physical activity (MVPA) were examined in detail throughout the week in preschool-aged boys and girls. METHODS: A sample of 703 Melbourne preschool children (387 boys; 4.6 ± 0.7 y) were included in data analysis. SB and MVPA data were collected using accelerometry over an eight-day period. Percentage of time per hour in SB and in MVPA between 08:00 h and 20:00 h was calculated. Multi-level logistic regression models were created to examine the hour-by-hour variability in SB and MVPA for boys and girls across weekdays and weekend days. Odds ratios (OR) were calculated to interpret differences in hour-by-hour SB and MVPA levels between boys and girls, and between weekdays and weekend days. RESULTS: The highest SB levels co-occurred with the lowest MVPA levels from the morning till the early afternoon on weekdays, and during the morning and around midday on weekends. Besides, participation in SB was the lowest and participation in MVPA was the highest from the mid afternoon till the evening on weekdays and weekend days. The variability across the hours in SB and, especially, in MVPA was rather small throughout weekdays and weekends. These patterns were found in both boys and girls. During some hours, girls were found to be more likely than boys to demonstrate higher SB levels (OR from 1.08 to 1.16; all p < 0.05) and lower MVPA levels (OR from 0.75 to 0.88; all p < 0.05), but differences were small. During weekends, hour-by-hour SB levels were more likely to be lower (OR from 0.74 to 0.98; all p < 0.05) and hour-by-hour MVPA levels were more likely to be higher (OR from 1.15 to 1.50; all p < 0.05), than during weekdays, in boys and girls. CONCLUSION: Entire weekdays, especially from the morning till the early afternoon, and entire weekend days are opportunities to reduce SB and to promote MVPA in preschool-aged boys and girls. Particularly weekdays hold the greatest promise for improving SB and MVPA. No particular time of the week was found where one sex should be targeted.

Efficacy and feasibility of lowering playground density to promote physical activity and to discourage sedentary time during recess at preschool: a pilot study.

OBJECTIVE: This pilot study examined if lowering playground density is feasible and effective in improving preschoolers' activity and sedentary levels during recess. METHOD: Between November and December 2011, a within-subject design was used to study preschoolers' activity via accelerometry during recesses in the usual conditions (baseline) and with lower playground density (intervention). During the intervention, preschools scheduled extra recesses so that the number of classes usually sharing the playground was halved. Effects were investigated, using two-level linear regression models, in 128 4- to 6-year-old children (69 boys) from 4 preschools in Ghent, Belgium. The four preschool principals filled in a questionnaire after the intervention. RESULTS: At baseline, available play space was on average 7.4 (SD=1.7) m(2)/child; during the intervention this increased to 16.7 (SD=5.1) m(2)/child. The intervention was effective in decreasing sedentary time (-1 min; -5.1%) and increasing light-to-vigorous (+1 min; +5.1%) and moderate-to-vigorous physical activity (+0.8 min; +4.8%) during recess. None found it difficult to implement the intervention. All agreed it was possible to use this strategy in the future. CONCLUSIONS: Although it was feasible to implement this intervention, improvements in preschoolers' activity levels were small. This intervention could especially be important for preschools with higher playground density.

Comparison of Actical and activPAL measures of sedentary behaviour in preschool children.

OBJECTIVES: The purpose of this study was to examine the convergent validity of the Actical and activPAL to measure sedentary behaviour (SB) and non-SB in preschoolers in a free-living environment. DESIGN: A convenience sample of 49 preschoolers (22 boys; 4.0 ± 0.5 years) from six early childhood centres in Auckland, New Zealand were included in data analysis. METHODS: Participants wore a hip-mounted Actical and a thigh-mounted activPAL accelerometer simultaneously during centre attendance for one day and data were collected in 15s epochs. Bland-Altman tests were used to assess differences in group mean minutes and percentage of time in (non-)SB between both monitors. Agreement between binary coded (SB vs. non-SB) 15s-by-15s Actical and activPAL data was evaluated by calculating percentage agreement and κ statistic. RESULTS: The monitors were worn on average for 294.8 ± 46.3 min resulting in a total of 57,780 15s epochs. Bland-Altman tests suggested a small group mean difference in (non-)SB (1.3 min; 0.1%) and a wide prediction interval (121.3 min; 39.2%). No obvious systematic bias was observed in the Bland-Altman plot. Percentage agreement between the 15s-by-15s Actical and activPAL data of all participants was 73.0% (inter-child range: 36.8-93.8%). The κ statistic showed moderate agreement with a value of 0.46 (95% CI: 0.45-0.47). CONCLUSIONS: Although the group mean estimate of (non-)SB was similar between the Actical and activPAL, the output of both monitors cannot be considered convergent as meaningful random disagreement was found between both monitors.

Effectiveness of workplace interventions in Europe promoting healthy eating: a systematic review.

BACKGROUND: The worksite is a promising setting for health promotion. This review summarizes the evidence of effect of intervention studies in European countries promoting a healthy diet solely and in combination with increasing physical activity at the workplace. METHODS: A systematic review of published literature was carried out. Inclusion criteria were: studies conducted in European countries; papers published from 1 January 1990 to 1 October 2010; worksite-based interventions promoting a healthy diet solely or in combination with physical activity; primary prevention; measurement of anthropometrical or behavioural change and adults (≥18 years old). Levels of evidence for intervention effectiveness on behavioural determinants, nutrition and physical activity behaviours and body composition and the quality of the included interventions were assessed. RESULTS: Seventeen studies solely focusing on promotion of a healthy diet were identified. Eight were educational, one used worksite environmental change strategies, and eight used a combination of both (multi-component). None of the interventions were rated as 'strong'; seven met the criteria for 'moderate' quality. The reviewed studies show moderately evidence for effects on diet. Thirteen studies focusing both on nutrition and physical activity (nine educational and four multi-component studies) were identified. Ten were rated as having 'weak' and three as having 'moderate' methodological quality, providing inconclusive evidence for effects. CONCLUSION: Limited to moderate evidence was found for positive effects of nutrition interventions implemented at the workplace. Effects of workplace health promotion interventions may be improved if stronger adherence to established quality criteria for such interventions is realized.

Within- and between-day variability of objectively measured physical activity in preschoolers.

In this study, physical activity (PA) was objectively measured in 213 Belgian preschoolers (M(age) = 4.98, SD = .88 years) over 4 consecutive days including two weekend days. Within-day variability in PA showed a typical activity pattern during weekdays and weekend days. Weekdays clearly reflected a preschool attending day with more peaks and troughs than weekend days and after-school hours were characterized by a decrease in activity. Between-day variability in PA was identified in preschool girls above the age of four, suggesting that the lack of a structured preschool environment is already related with a decrease in PA in this sex-specific age group. The results of this study are informative for the development of future PA interventions and indicate that both the preschool and the home environment should be targeted in the promotion of preschoolers' PA.

Feasibility and validity of accelerometer measurements to assess physical activity in toddlers.

BACKGROUND: Accelerometers are considered to be the most promising tool for measuring physical activity (PA) in free-living young children. So far, no studies have examined the feasibility and validity of accelerometer measurements in children under 3 years of age. Therefore, the purpose of the present study was to examine the feasibility and validity of accelerometer measurements in toddlers (1- to 3-year olds). METHODS: Forty-seven toddlers (25 boys; 20 ± 4 months) wore a GT1M ActiGraph accelerometer for 6 consecutive days and parental perceptions of the acceptability of wearing the monitor were assessed to examine feasibility. To investigate the validity of the ActiGraph and the predictive validity of three ActiGraph cut points, accelerometer measurements of 31 toddlers (17 boys; 20 ± 4 months) during free play at child care were compared to directly observed PA, using the Observational System for Recording Physical Activity in Children-Preschool (OSRAC-P). Validity was assessed using Pearson and Spearman correlations and predictive validity using area under the Receiver Operating Characteristic curve (ROC-AUC). RESULTS: The feasibility examination indicated that accelerometer measurements of 30 toddlers (63.8%) could be included with a mean registration time of 564 ± 62 min during weekdays and 595 ± 83 min during weekend days. According to the parental reports, 83% perceived wearing the accelerometer as 'not unpleasant and not pleasant' and none as 'unpleasant'. The validity evaluation showed that mean ActiGraph activity counts were significantly and positively associated with mean OSRAC-P activity intensity (r = 0.66; p < 0.001; n = 31). Further, the correlation among the ActiGraph activity counts and the OSRAC-P activity intensity level during each observation interval was significantly positive (ρ = 0.52; p < 0.001; n = 4218). Finally, the three sedentary cut points exhibited poor to fair classification accuracy (ROC-AUC: 0.56 to 0.71) while the three light PA (ROC-AUC: 0.51 to 0.62) and the three moderate-to-vigorous PA cut points (ROC-AUC: 0.53 to 0.57) demonstrated poor classification accuracy with respect to detecting sedentary behavior, light PA and moderate-to-vigorous PA, respectively. CONCLUSIONS: The present findings suggest that ActiGraph accelerometer measurements are feasible and valid for quantifying PA in toddlers. However, further research is needed to accurately identify PA intensities in toddlers using accelerometry.

Calibration and comparison of accelerometer cut points in preschool children.

OBJECTIVE: The present study aimed to develop accelerometer cut points to classify physical activities (PA) by intensity in preschoolers and to investigate discrepancies in PA levels when applying various accelerometer cut points. METHODS: To calibrate the accelerometer, 18 preschoolers (5.8 ± 0.4 years) performed eleven structured activities and one free play session while wearing a GT1M ActiGraph accelerometer using 15 s epochs. The structured activities were chosen based on the direct observation system Children's Activity Rating Scale (CARS) while the criterion measure of PA intensity during free play was provided using a second-by-second observation protocol (modified CARS). Receiver Operating Characteristic (ROC) curve analyses were used to determine the accelerometer cut points. To examine the classification differences, accelerometer data of four consecutive days from 114 preschoolers (5.5 ± 0.3 years) were classified by intensity according to previously published and the newly developed accelerometer cut points. Differences in predicted PA levels were evaluated using repeated measures ANOVA and Chi Square test. RESULTS: Cut points were identified at 373 counts/15 s for light (sensitivity: 86%; specificity: 91%; Area under ROC curve: 0.95), 585 counts/15 s for moderate (87%; 82%; 0.91) and 881 counts/15 s for vigorous PA (88%; 91%; 0.94). Further, applying various accelerometer cut points to the same data resulted in statistically and biologically significant differences in PA. CONCLUSIONS: Accelerometer cut points were developed with good discriminatory power for differentiating between PA levels in preschoolers and the choice of accelerometer cut points can result in large discrepancies.

Worksite physical activity interventions and obesity: a review of European studies (the HOPE project).

OBJECTIVE: Our aim was to review the effectiveness of physical activity promotion interventions in the worksite setting in Europe in order to identify those studies that had measured obesity-related outcomes and to evaluate how external validity of the findings had been assessed. METHODS: We conducted a review of studies conducted in Europe, published up to December 2009. We assessed levels of evidence regarding effectiveness and analysed external validity using the RE-AIM framework. RESULTS: Studies included (n = 33) were divided in 6 intervention categories. Moderate evidence of effectiveness was found for physical fitness outcomes with exercise training interventions and for physical activity outcomes with active commuting interventions. There was no or inconclusive evidence for obesity-related outcomes for all intervention categories. For external validity, elements receiving the least attention (<20%) were representativeness of participants, setting-level inclusion/exclusion criteria and representativeness, characteristics regarding intervention staff, implementation of intervention, costs, long-term effects and programme sustainability. CONCLUSIONS: Active commuting and exercise training appear as promising approaches to promote physical activity or fitness in the workplace. The effect of interventions on obesity-related outcomes remains to be further investigated. There is a need to better report elements of generalizability and dissemination for translation into practice of worksite physical activity interventions.

Effectiveness of school-based interventions in Europe to promote healthy nutrition in children and adolescents: systematic review of published and 'grey' literature.

The objective of the present review was to summarise the existing European published and 'grey' literature on the effectiveness of school-based interventions to promote a healthy diet in children (6-12 years old) and adolescents (13-18 years old). Eight electronic databases, websites and contents of key journals were systematically searched, reference lists were screened, and authors and experts in the field were contacted for studies evaluating school-based interventions promoting a healthy diet and aiming at primary prevention of obesity. The studies were included if they were published between 1 January 1990 and 31 December 2007 and reported effects on dietary behaviour or on anthropometrics. Finally, forty-two studies met the inclusion criteria: twenty-nine in children and thirteen in adolescents. In children, strong evidence of effect was found for multicomponent interventions on fruit and vegetable intakes. Limited evidence of effect was found for educational interventions on behaviour, and for environmental interventions on fruit and vegetable intakes. Interventions that specifically targeted children from lower socio-economic status groups showed limited evidence of effect on behaviour. In adolescents, moderate evidence of effect was found for educational interventions on behaviour and limited evidence of effect for multicomponent programmes on behaviour. In children and adolescents, effects on anthropometrics were often not measured, and therefore evidence was lacking or delivered inconclusive evidence. To conclude, evidence was found for the effectiveness of especially multicomponent interventions promoting a healthy diet in school-aged children in European Union countries on self-reported dietary behaviour. Evidence for effectiveness on anthropometrical obesity-related measures is lacking.

The contribution of preschool playground factors in explaining children's physical activity during recess.

BACKGROUND: Low levels of physical activity are characteristic in preschoolers. To effectively promote physical activity, it is necessary to understand factors that influence young children's physical activity. The present study aimed to investigate how physical activity levels are influenced by environmental factors during recess in preschool. METHODS: Preschool playground observations and pedometry during recess were carried out in 39 randomly selected preschools (415 boys and 368 girls; 5.3 +/- 0.4 years old). In order to examine the contribution of playground variables to physical activity levels, taking adjustment for clustering of subjects within preschools into account, multilevel analyses were conducted. RESULTS: During recess boys took significantly more steps per minute than girls (65 +/- 36 versus 54 +/- 28 steps/min). In both genders higher step counts per minute were significantly associated with less children per m2 and with shorter recess times. Only in boys a hard playground surface was a borderline significant predictor for higher physical activity levels. In girls higher step counts were associated with the presence of less supervising teachers. Playground markings, access to toys, the number of playing or aiming equipment pieces and the presence of vegetation or height differences were not significant physical activity predictors in both genders. CONCLUSION: In preschool children physical activity during outdoor play is associated with modifiable playground factors. Further study is recommended to evaluate if the provision of more play space, the promotion of continued activity by supervisors and the modification of playground characteristics can increase physical activity levels in preschoolers.