Comparing different accelerometer cut-points for sedentary time in children

Actigraph accelerometers are hypothesized to be valid measurements for assessing children's sedentary time. However, there is considerable variation in accelerometer cut-points used. Therefore, we compared the most common accelerometer sedentary cut-points of children performing sedentary behaviors. Actigraph Actitrainer uniaxial accelerometers were used to measure children's activity intensity (29 children, 5-11 years old) during different activities, namely playing computer games, nonelectronic sedentary games, watching television and playing outdoors. A structured protocol was the criterion for assessing the validity of four common cut-points (100, 300, 800, 1100 counts/minute). The median counts during all sedentary behaviors were below the lowest comparison cut-point of 100 cpm. The 75th percentile values for the sedentary behaviors were always below the cut-point of 300 cpm. Our results suggest that the cut-point of <100 cpm is the most appropriate.

Youth physical activity and sedentary time and associations with cardiometabolic health

In recent years, there has been increasing interest in the effects of sedentary behaviour on children’s health, defined as sitting behaviours that require low levels of energy expenditure (≤1.5 METs).¹ There is some evidence that sedentary behaviours may be detrimental to children’s health, though the majority of associations observed are derived from cross-sectional studies examining television viewing and adiposity.² This study adds to the literature by examining cross-sectional and prospective associations between objectively measured moderate- to vigorous physical activity (MVPA) and sedentary time, and cardiometabolic risk factors in youth aged 4–18 years.

Promoting physical activity and reducing sedentary behavior in disadvantaged neighborhoods : a qualitative study of what women want

Since women living in socioeconomically disadvantaged neighborhoods are more likely to be physically inactive and engage in higher levels of sedentary behavior than women living in more advantaged neighborhoods, it is important to develop and test the feasibility of strategies aimed to promote physical activity and reduce sedentary behavior amongst this high-risk target group. Thirty-seven women (aged 19–85) living in a disadvantaged neighborhood, and five key stakeholders, received a suite of potential intervention materials and completed a qualitative questionnaire assessing the perceived feasibility of strategies aimed to increase physical activity and reduce sedentary behavior. Thematic analyses were performed. Women perceived the use of a locally-relevant information booklet as a feasible strategy to increase physical activity and reduce sedentary behavior. Including weight-loss information was suggested to motivate women to be active. Half the women felt the best delivery method was mailed leaflets. Other suggestions included reference books and websites. Many women mentioned that an online activity calendar was motivational but too time-consuming to commit to. Most women preferred the information booklet as a strategy to increase physical activity/reduce sedentary behavior, yet several suggested that using the booklet together with the online calendar may be more effective. These findings make an important contribution to research informing the development of intervention strategies to increase physical activity and reduce sedentary behavior amongst women living in disadvantaged neighborhoods.

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.

Associations between usual school lunch attendance and eating habits and sedentary behaviour in French children and adolescents

Background/Objective: Our objective was to investigate whether school lunch attendance was associated with overall eating habits and sedentary behaviour in a French sample of children and adolescents.

Subjects/Methods: Data for the study were taken from the second French cross-sectional dietary survey (INCA2-2006-07). In total, 1413 school children aged 3–17 years old were classified according to their school type and their usual school lunch attendance. Eating habits included meal regularity, dietary diversity, purchase in vending machine, snacking habits and frequency of eating in fast-foods. Two composite indices of eating habits were derived from multiple correspondence analyses. Sedentary behaviour was assessed by the average daily screen times for TV and computer. The association between school lunch attendance and each variable was tested. Multivariate association between school lunch attendance and the composite indices of eating habits and sedentary behaviours was studied.

Results: In all, 69.0% (CI95%: 64.2–73.9) of secondary school children and 63.0% (CI95%: 58.5–67.5) of pre- and elementary school children usually attended school lunch at least once a week. Pre- and elementary school children attending school lunches showed a higher dietary diversity score (P=0.02) and ate morning snacks more frequently (P=0.02). In secondary school children, attending school canteen was related to a lower rate of skipping breakfast (P=0.04) and main meals (P=0.01). In all school children, school lunch attendance was simultaneously associated with healthier overall eating habits and less sedentary behaviour.

Conclusion: In France, children attending school canteens seem to have healthier eating habits and display less sedentary behaviour, independently of their socio-economic and demographic background.

What factors are associated with adolescents' school break time physical activity and sedentary time?

Purpose Adolescents' physical activity levels during school break time are low and understanding correlates of physical activity and sedentary time in this context is important. This study investigated cross-sectional and longitudinal associations between a range of individual, behavioural, social and policy/organisational correlates and objectively measured school break time physical activity and sedentary time.

Methods In 2006, 146 adolescents (50% males; mean age = 14.1±0.6 years) completed a questionnaire and wore an accelerometer for ≥3 school days. Time spent engaged in sedentary, light (LPA) and moderate-to-vigorous physical activity (MVPA) during school break times (recess and lunchtime) were calculated using existing cut-points. Measures were repeated in 2008 among 111 adolescents. Multilevel models examined cross-sectional and longitudinal associations.

Results Bringing in equipment was cross-sectionally associated with 3.2% more MVPA during break times. Females engaged in 5.1% more sedentary time than males, whilst older adolescents engaged in less MVPA than younger adolescents. Few longitudinal associations were observed. Adolescents who brought sports equipment to school engaged in 7.2% less LPA during break times two years later compared to those who did not bring equipment to school.

Conclusion These data suggest that providing equipment and reducing restrictions on bringing in sports equipment to school may promote physical activity during school recess. Strategies targeting females' and older adolescents', in particular, are warranted.

What helps children to be more active and less sedentary? Perceptions of mothers living in disadvantaged neighbourhoods

Background Increasing children's participation in physical activity and decreasing time spent in sedentary behaviours is of great importance to public health. Despite living in disadvantaged neighbourhoods, some children manage to engage in health-promoting physical activity and avoid high levels of screen-based activities (i.e. watching TV, computer use and playing electronic games). Understanding how these children manage to do well and whether there are unique features of their home or neighbourhood that explain their success is important for informing strategies targeting less active and more sedentary children. The aim of this qualitative study was to gain in-depth insights from mothers regarding their child's resilience to low physical activity and high screen-time.

Methods Semi-structured face-to-face interviews were conducted with 38 mothers of children who lived in disadvantaged neighbourhoods in urban and rural areas of Victoria, Australia. The interviews were designed to gain in-depth insights about perceived individual, social and physical environmental factors influencing resilience to low physical activity and high screen-time.

Results Themes relating to physical activity that emerged from the interviews included: parental encouragement, support and modelling; sports culture in a rural town; the physical home and neighbourhood environment; child's individual personality; and dog ownership. Themes relating to screen-time behaviours encompassed: parental control; and child's individual preferences.

Conclusions The results offer important insights into potential avenues for developing ‘resilience’ and increasing physical activity and reducing screen-time among children living in disadvantaged neighbourhoods. In light of the negative effects of low physical activity and high levels of screen-time on children's health, this evidence is urgently needed.