Physical activity and sedentary behavior (performed primarily while sitting) play a key role in the current and future health of young people. Most health evidence and intervention strategies targeting reductions in children’s sedentary behavior have focused on television viewing, with mixed evidence as to the effectiveness of these strategies and of the importance of television viewing for children’s health. Evidence from studies with adults using objective measures of sedentary behavior suggests that accumulated sedentary time is independently associated with metabolic health; importantly, emerging evidence suggests that the manner in which the sedentary behavior is accrued (ie, frequency of interruptions to time spent sedentary) may also have independent effects on health. Potential novel intervention approaches to reduce children’s sedentary time include activity breaks during class time at school, delivery of active lessons and homework, and changes to the classroom environment. Further evidence of the importance of sedentary time (both total accumulation and frequency of interruptions) on children’s health is required. Future studies should assess the effectiveness of interventions targeting organizational and pedagogical changes in schools as well as using homework to engage with families in more active ways.
Verity Cleland, Michael Schmidt, Jo Salmon, Terry Dywer and Alison Venn
We investigated associations of total sedentary behavior (SB) and objectively-measured and self-reported physical activity (PA) with obesity.
Data from 1662 adults (26–36 years) included daily steps, self-reported PA, sitting, and waist circumference. SB and PA were dichotomized at the median, then 2 variables created (SB/self-reported PA; SB/objectively-measured PA) each with 4 categories: low SB/high PA (reference group), high SB/high PA, low SB/low PA, high SB/low PA.
Overall, high SB/low PA was associated with 95 –168% increased obesity odds. Associations were stronger and more consistent for steps than self-reported PA for men (OR 2.68, 95% CI 1.36–5.32 and OR 1.95, 95% CI 1.01–3.79, respectively) and women (OR 2.66, 95% CI 1.58–4.49 and OR 2.00, 95% CI 1.21–3.31, respectively). Among men, obesity was higher when daily steps were low, irrespective of sitting (low SB/low steps OR 2.07, 95% CI 1.03–4.17; high SB/low steps OR 2.68, 95% CI 1.36–5.32).
High sitting and low activity increased obesity odds among adults. Irrespective of sitting, men with low step counts had increased odds of obesity. The findings highlight the importance of engaging in physical activity and limiting sitting.
Y.J. Huang, Stephen H.S. Wong and Jo Salmon
This study aimed to examine the reliability and validity of the modified Children’s Leisure Activities Study Survey (CLASS) Chinese-version questionnaire in assessing physical activity among Hong Kong Chinese Children. Test-retest reliability was examined in 84 boys and 136 girls aged 9–12 years by comparing data from two administrations of the survey conducted one week apart. Validity was determined by comparing data from the second administration with accelerometer estimates. The results suggested that the questionnaire provided reliable and valid estimates in overall physical activity patterns in Hong Kong Chinese children. However, substantial overestimation was observed in vigorous activity.
Trina Hinkley, Anna Timperio, Jo Salmon and Kylie Hesketh
Little is known about the associations of preschoolers’ health behaviors with their later psychosocial wellbeing. This study investigates the association of 3- to 5-year-old children’s physical activity and electronic media use with their later social-emotional skills (6-8 years).
Data were collected in 2008–2009 and 2011–2012 for the Healthy Active Preschool and Primary Years (HAPPY) Study in metropolitan Melbourne. Participants were a random subsample (n = 108) of the 567 children at follow-up. Physical activity was objectively measured using ActiGraph GT1M accelerometers; electronic media use (television viewing, sedentary electronic games and active electronic games) was parent proxy-reported. Social and emotional skills were child-reported using the Bar-On Emotional Quotient Inventory—Youth Version. Regression analyses controlled for sex, clustering by center of recruitment, and accelerometer wear time (for physical activity analyses).
Sedentary electronic games were positively associated with intrapersonal and stress management skills and total emotional quotient. Computer/internet use was inversely associated with interpersonal, and positively associated with stress management, skills.
Findings suggest that physical activity is not associated with children’s psychosocial health while some types of electronic media use are. Future research should investigate the contexts in which preschoolers participate in these behaviors and potential causal mechanisms of associations.
Denise Azar, Kylie Ball, Jo Salmon and Verity Cleland
A number of factors have been identified as important correlates of physical activity (PA) among young women. Young women at risk of depression have a greater likelihood of being physically inactive and it is unknown whether correlates differ for women at risk and not at risk of depression.
A sample of 451 women aged 18 to 35 years self-reported leisure-time PA, enjoyment of and self-efficacy for walking and vigorous PA, barriers, social support, access to sporting/leisure facilities, and access to sporting equipment in the home. Depression risk was assessed using the General Health Questionnaire (cut point ≥5). Logistic regression analyses examined differences in PA correlates among women at risk and not at risk of depression.
Self-efficacy for vigorous PA was statistically different between groups in predicting odds for meeting PA recommendations but odds ratios were similar across groups. No other significant interactions between correlates and depressive symptoms were identified.
The findings suggest few differences in the individual, social, and physical environmental correlates of PA among young women who are and are not at risk of depression. Further research is needed to confirm the existence of any PA correlates specific to this high-risk target group.
Claudia Fischer, Mine Yılıdrım, Jo Salmon and Mai J.M. Chinapaw
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.
Amanda Telford, Jo Salmon, Damien Jolley and David Crawford
This study aimed to develop a reliable, valid, and feasible method for assessing physical activity among children ages 5–6 and 10–12 years. Test–retest reliability of a parental proxy questionnaire and a children’s self-report questionnaire was assessed in 280 children and parents. The criterion validity of the questionnaires was assessed using accelerometry. The proxy questionnaire provided a reliable measure of the type, frequency, and duration of children’s physical activity. Neither version of the questionnaire provided an accurate estimate of individual children’s physical activity. To assess the type, frequency, intensity, and duration of children’s activity, a combination of questionnaire and objective measures should be employed.
Amanda Telford, Jo Salmon, Anna Timperio and David Crawford
The aim of this study was to describe the type, frequency, duration, and intensity of children’s physical activity and to examine differences by sex, age, and SES. Participants consisted of 5- to 6-year-old (n = 291) and 10- to 12-year-old (n = 919) children and their parents taking part in the Children’s Leisure Activities Study (CLASS). Parents completed proxy questionnaires about their child’s activity, and all children wore an accelerometer for 8 days. Accelerometry data showed that younger children accumulated approximately 4 hrs of moderate- to vigorous-intensity physical activity (MVPA) per day, and older children accumulated approximately 2 hrs per day. Fewer than three- quarters of 10- to 12-year-old boys and less than half of 10- to 12-year-old girls recorded 120 min of MVPA per day. Significant differences in the number of activities, as well as the type and frequency of activities performed, were observed by age and sex. The findings indicate that physical activities that appeal to older girls, such as lifestyle, noncompetitive activities, should be considered in the development of physical activity promotion strategies.
Kylie Ball, Verity J. Cleland, Anna F. Timperio, Jo Salmon and David A. Crawford
This study aimed to examine cross-sectional and longitudinal associations between socioeconomic position (SEP) and physical activity and sedentary behaviors among children and adolescents.
Maternal education was reported by parents of 184 children 5 to 6 years old and 358 children 10 to 12 years old in 2001. In 2001 and 2004, physical activity was assessed by accelerometry. Older children self-reported and parents of younger children proxy-reported physical activity and TV-viewing behaviors. Linear regression was used to predict physical activity and sedentary behaviors, and changes in these behaviors, from maternal education.
Among all children, accelerometer-determined and self- or parent-reported moderate and vigorous physical activity declined over 3 years. Girls of higher SEP demonstrated greater decreases in TV-viewing behaviors than those of low SEP. In general, no prospective associations were evident between SEP and objectively assessed physical activity. A small number of prospective associations were noted between SEP and self-reported physical activity, but these were generally weak and inconsistent in direction.
This study did not find strong evidence that maternal education was cross-sectionally or longitudinally predictive of children’s physical activity or sedentary behaviors. Given the well-documented inverse relationship of SEP with physical activity levels in adult samples, the findings suggest that such disparities might emerge after adolescence.
Nicola D. Ridgers, Karen E. Lamb, Anna Timperio, Helen Brown and Jo Salmon
Background: Little is known about whether physical activity compensation occurs. This study experimentally explored the activitystat hypothesis by investigating children’s short-term responses to imposed or restricted physical activity. Methods: A total of 156 children (46 boys; mean age = 11.3 y) from 9 schools wore an ActiGraph accelerometer for 5 days (Monday–Friday) across 2 consecutive weeks. In addition, 145 children (49% boys) simultaneously wore a SenseWear Armband. Schools were randomized to participate in 1 of the 3 experimental conditions that took place on 1 occasion: additional moderate- to vigorous-intensity physical activity (3 schools), additional light-intensity physical activity (3 schools), or restriction of light-intensity physical activity and moderate- to vigorous-intensity physical activity (3 schools). Multilevel linear regression models were conducted to examine associations between the day the condition took place and the following day and week (baseline and experiment) for each condition. Results: There was no evidence of a difference between children’s activity levels on the day after the experiment condition compared with their usual activity for that day. Conclusion: The findings suggest that children do not compensate their sedentary time and/or physical activity levels following imposed or restricted physical activity in the short term.