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Wendy C. Stephen and Ian Janssen

Background:

Little is known about the effects of physical activity on weight loss in older adults.

Methods:

Participants included 4512 community-dwelling older (≥65 yr) men and women from the Cardiovascular Health Study. Physical activity (PA) was determined from a questionnaire at baseline and subjects were divided into sex-specific PA quartiles. Weight was measured at baseline and annually over the 8 years of follow-up. The influence of PA on longitudinal changes in body weight was examined using mixed models while adjusting for lifestyle variables, sociodemographic characteristics, and disease status.

Results:

Body weight declined in a curvilinear manner over time with accelerated weight loss occurring in the final years. Over the 8 yr follow-up period, the least active PA quartile lost 2.72 kg. Weight loss was attenuated by 0.55 kg (20%, P = .057), 0.80 kg (29%, P = .05), and 0.69 kg (25%, P = .016) within the second through fourth PA quartiles. The effects of PA did not differ by gender, but increased with advancing age.

Conclusion:

Participation in modest amounts of PA attenuated age-related weight loss by approximately 25% with little additional benefit observed at higher PA levels. This finding adds to the growing number of health outcomes that are positively affected by PA.

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Amy E. Mark and Ian Janssen

Background:

Despite the plethora of research examining the physical activity-adiposity relation in youth, questions remain regarding the ideal intensity. Therefore, the purpose of this study was to explore the independent effects of physical activity intensity and incidental movement on total and trunk adiposity.

Methods:

The sample consisted of 1165 youth aged 8 to 17 years from the 2003−04 U.S. National Health and Nutrition Examination Survey. Physical activity (low, moderate, vigorous intensity) and incidental movement (activity level when not physically active) were measured using Actigraph accelerometers over 7 days. Total body and trunk fat were measured using dual-energy X-ray absorptiometry; age- and sex-specific percentile scores were calculated.

Results:

Bivariate analyses revealed an inverse relation between total, low, moderate and vigorous intensity physical activity with total body and trunk fat. After consideration of the total volume of physical activity in the multivariate analyses, moderate-to-vigorous intensity physical activity remained significantly related to total and trunk fat. Participants with the highest (top 12.5%) moderate-to-vigorous intensity activity values had total fat percentile scores that were 34 points lower than participants with the lowest (bottom 25%) values.

Conclusion:

These results are consistent with public health guidelines which recommend that children and youth participate in moderate-to-vigorous intensity physical activity.

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Marianne Nichol, Ian Janssen and William Pickett

Background:

The safety of neighborhoods and availability of parks and facilities may influence adolescent physical activity independently or interactively.

Methods:

9114 Canadians in grades 6 to 10 completed the 2006 Health Behavior in School-Aged Children Survey. The outcome of interest was students’ self-reported participation in moderate-to-vigorous physical activity outside of school. A composite scale based on questions measuring student perceptions of safety was used to capture individual perceptions of safety. In addition, schools were grouped into quintiles based on the mean of the perceived safety scale, used as a proxy for peer perceptions. The number of parks and recreational facilities within 5 km of schools was abstracted from a geographical information system.

Results:

Moderate gradients in physical activity were observed according to individual and group perceptions of safety. Boys and girls with the highest perceptions of safety were 1.31 (95% CI: 1.17−1.45) and 1.45 (1.26−1.65) times more likely to be physically active, respectively, than those with the lowest perceptions. Compared with those who perceived the neighborhood as least safe, elementary students in higher quintiles were 1.31, 1.39, 1.37, and 1.56 times more likely to be physically active (P trend = 0.012). Increased numbers of recreational features were not related to physical activity irrespective of neighborhood safety.

Conclusions:

Individual and group perceptions of neighborhood safety were modestly associated with adolescents’ physical activity.

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Allana G.W. LeBlanc and Ian Janssen

We examined differences between objective (accelerometer) and subjective (self-report) measures of moderate-to-vigorous physical activity (MVPA) in youth. Participants included 2761 youth aged 12–19 years. Within each sex and race group, objective and self-reported measures of MVPA were poorly correlated (R 2 = .01–.10). Self-reported MVPA values were higher than objective values (median: 42.4 vs. 15.0 min/d). 65.4% of participants over-reported their MVPA by 35 min/d. The difference between self-reported and objective measures was not influenced by sex, age, or race. There was, however, a systematic difference such that inactive participants over-reported their MVPA to the greatest extent.

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Valerie Carson, Jodie Stearns and Ian Janssen

The main purpose of this study was to examine the relationships between parental and children’s physical activity and screen time behaviors in a large sample of children in the early years. The results are based on 738 children aged 0–5 years and their parents from the Kingston, Canada area. Parents completed a questionnaire from May to September 2011 that assessed sociodemographic characteristics, their physical activity and screen time, and their child’s physical activity and screen time. Logistic regression models, adjusted for potential confounders, were conducted. Parents in the lowest quartile of physical activity were 2.77 (95% confidence interval (CI): 1.68–4.57) times more likely to have a child in the lowest quartile of physical activity compared with parents in the highest quartile of physical activity. Relationships were stronger in two parent homes compared with single-parent homes. Parents in the second (odds ratio = 2.27, 95% CI: 1.36–3.78), third (2.30, 1.32–3.99), and fourth (7.47, 4.53–12.33) screen time quartiles were significantly more likely to have a child in the highest quartile of screen time compared with parents in quartile one. To optimize healthy growth and development in the early years, future family-centered interventions targeting both physical activity and screen time appear important.

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Ian Janssen, Peter T. Katzmarzyk, William F. Boyce and William Pickett

Background:

The purpose of this study was to examine the independent influence of physical inactivity and obesity on health complaints in school-aged youth.

Methods:

The findings are based on Canadian records from the 2001-2002 Health Behaviour in School-Aged Children Survey. The study cohort consisted of 5673 youth in grades 6 to 10. Body weight and height (used to calculate body mass index and adiposity level), physical activity, and somatic (physical) and psychological health complaints were measured by questionnaire. General linear models were used to characterize the associations between physical activity and adiposity with somatic and psychological health complaints.

Results:

In boys and girls, adiposity level alone was independently associated with somatic health complaints, whereas both physical activity level and adiposity level were independently associated with psychological health complaints.

Conclusion:

The findings suggest that the prevention and treatment of both physical inactivity and obesity are important in school-aged youth.

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Emily Borgundvaag, Michael McIsaac, Michael M. Borghese and Ian Janssen

Background: A limitation of accelerometer measures of moderate to vigorous physical activity (MVPA) is nonwear time. Nonwear-time data is typically deleted prior to estimating MVPA. In this study, we used an approach that used sociodemographic, health, and time data to guide the imputation of nonwear-time data. We determined whether imputing nonwear-time data influences estimates of MVPA and the association between MVPA, body mass index, and blood pressure. Methods: Seven days of accelerometer data were collected on 332 children aged 10–13 years. MVPA was estimated in a “nonimputed dataset,” wherein nonwear-time data were deleted prior to estimating MVPA, and in an “imputed dataset,” wherein nonwear-time data were imputed using sociodemographic and health characteristics of participants and time characteristics of the nonwear period prior to estimating MVPA. Results: Nonwear time represented 7% of waking hours. Average MVPA estimates did not differ in the nonimputed and imputed datasets (56.8 vs 58.4 min/d). The strength of the relationship between MVPA and the 2 health outcomes did not differ in the nonimputed and imputed datasets. Conclusions: Studies achieving high accelerometer wear-time compliance can obtain MVPA estimates without substantial bias if they use the traditional approach of deleting nonwear-time data.

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Casey E. Gray, Joel D. Barnes, Jennifer Cowie Bonne, Christine Cameron, Jean-Philippe Chaput, Guy Faulkner, Ian Janssen, Peter T. Katzmarzyk, Angela M. Kolen, Stephen R. Manske, Art Salmon, John C. Spence, Brian W. Timmons and Mark S. Tremblay

Background:

The Active Healthy Kids Canada (AHKC) Report Card consolidates and translates research and assesses how Canada is being responsible in providing physical activity opportunities for children (3- to 11-years-old) and youth (12- to 17-years-old). The primary aim of this article is to summarize the results of the 2014 AHKC 10th Anniversary Report Card.

Methods:

Ten physical activity indicators were graded using the AHKC Report Card development process, which includes a synthesis of the best available research, surveillance, policy and practice findings, and expert consensus.

Results:

Grades assigned were for: ‘Behaviors that Contribute to Overall Physical Activity Levels’ (Overall Physical Activity Levels, D-; Organized Sport Participation, C+; Active Play, INCOMPLETE; Active Transportation, D; Sedentary Behaviors, F), ‘Settings and Sources of Influence’ (Family and Peers, C; School, C+; and Community and the Built Environment, B+), and ‘Strategies and Investments’ (Government Strategies and Investments, C; and Non-Government Strategies and Investments, A-).

Conclusions:

Despite good availability of policies, programs, and infrastructure, the overall physical activity levels of Canadian children and youth remain low while sedentary behavior levels remain high. As with many nations, there is room for improvement in most physical activity behaviors and some sources of influence.

Open access

Joel D. Barnes, Christine Cameron, Valerie Carson, Jean-Philippe Chaput, Rachel C. Colley, Guy E.J. Faulkner, Ian Janssen, Roger Kramers, Travis J. Saunders, John C. Spence, Patricia Tucker, Leigh M. Vanderloo and Mark S. Tremblay

Open access

Joel D. Barnes, Christine Cameron, Valerie Carson, Jean-Philippe Chaput, Guy E.J. Faulkner, Katherine Janson, Ian Janssen, Roger Kramers, Allana G. LeBlanc, John C. Spence and Mark S. Tremblay

Background:

The ParticipACTION Report Card on Physical Activity for Children and Youth is the most comprehensive assessment of child and youth physical activity in Canada and provides an update or “state of the nation” that assesses how Canada is doing at promoting and facilitating physical activity opportunities for children and youth. The purpose of this paper is to summarize the results of the 2016 ParticipACTION Report Card.

Methods:

Twelve physical activity indicators were graded by a committee of experts using a process that was informed by the best available evidence. Sources included national surveys, peer-reviewed literature, and gray literature such as government and nongovernment reports and online content.

Results:

Grades were assigned to Daily Behaviors (Overall Physical Activity: D-; Organized Sport and Physical Activity Participation: B; Active Play: D+; Active Transportation: D; Physical Literacy: D+; Sleep: B; Sedentary Behaviors: F), Settings and Sources of Influence (Family and Peers: C+; School: B; Community and Environment: A-), and Strategies and Investments (Government: B-; Nongovernment: A-).

Conclusions:

Similar to previous years of the Report Card, Canada generally received good grades for indicators relating to investment, infrastructure, strategies, policies, and programming, and poor grades for behavioral indicators (eg, Overall Physical Activity, Sedentary Behaviors).