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This study examines the association between objectively-measured physical activity (PA) intensities and sedentary behavior (SED) in a cohort of 532 children aged 8-10 y. PA and SED were assessed by accelerometer over 7-days. Television and computer/video-game use were self-reported. Associations between PA intensities and SED variables were assessed by Spearman correlations and adjusted multiple linear regression. Higher mean daily moderate-to-vigorous and vigorous PA (MVPA, VPA) were negatively associated with mean daily SED (r = -0.47 and -0.37; p< .001), and positively associated with mean daily total PA (r = .58 and 0.46; p< .001). MVPA was also positively associated with light PA (LPA; r = .26, p < .001 ). MVPA and VPA were not significantly associated with TV, computer/video or total screen time; accelerometer SED was only weakly associated with specific SED behaviors. On average, for each additional 10 min daily MVPA, children accumulated >14 min less SED, and for each additional 5 min VPA, 11 min less SED. Thus, over the course of a week, higher mean daily MVPA may displace SED time and is associated with higher total PA over and above the additional MVPA, due to concomitant higher levels of LPA. Public health strategies should target both MVPA and SED to improve overall PA and health in children. [ABSTRACT FROM AUTHOR]

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Background: Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children. Purpose: To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8–11 years with a family history of obesity. Methods: Data from 286 boys and 236 girls living in Quebec, Canada, with at least one biological parent with obesity (QUALITY cohort) were collected from 2005–2008, and analyzed in 2013. Sedentary behavior, light and moderate-to-vigorous physical activity were measured over 7 days using accelerometry. Leisure time computer/video game use and TV viewing over the past 7 days were self-reported. Outcomes included waist circumference, body mass index Z-score, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol, C-reactive protein and a continuous cardiometabolic risk score. Results: After adjustment for confounders, breaks in sedentary time and the number of sedentary bouts lasting 1–4 minutes were associated with reduced cardiometabolic risk score and lower BMI Z-score in both sexes (all p<0.05). The number of sedentary bouts lasting 5–9 minutes was negatively associated with waist circumference in girls only, while the number of bouts lasting 10–14 minutes was positively associated with fasting glucose in girls, and with BMI Z-score in boys (all p<0.05). Leisure time computer/video game use was associated with increased cardiometabolic risk score and waist circumference in boys, while TV viewing was associated with increased cardiometabolic risk, waist circumference, and BMI Z-score in girls (all p<0.05). Conclusions: These results suggest that frequent interruptions in sedentary time are associated with a favourable cardiometabolic risk profile and highlight the deleterious relationship between screen time and cardiometabolic risk among children with a family history of obesity. [ABSTRACT FROM AUTHOR]

The article discusses research investigating interest of an individualized score among children using a maximal cycling test, called the OMNI cycle scale. Researchers studied the differences between perceived exertion and actual effort, measured by peak oxygen consumption, at various stages of the test to determine whether perceived exertion and actual effort differed according to body mass status or physical activity level. The study's experimental design and methodology, a discussion of the results, and researchers' conclusions regarding the relationship between the effort performed, the OMNI cycle scale score, body mass status, and physical activity level are presented.

Copyright of Applied Physiology, Nutrition & Metabolism is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The authors examined the potential association between changes in the number of moderate-to-vigorous physical activity (MVPA) sessions per week, adiposity, and systolic blood pressure (SBP) during adolescence. SBP and anthropometric factors were assessed biannually (1999/2000, 2002, and 2004) in a cohort of 1,293 Canadian adolescents aged 12–13 years in 1999. Self-reported 7-day recall data on MVPA sessions ≥5 minutes in duration were collected every 3 months over the 5-year period. Estimates of initial level and rate of decline in number of MVPA sessions per week from individual growth models were used as predictors of SBP in linear regression models. A decline of 1 MVPA session per week with each year of age was associated with 0.29-mm Hg and 0.19-mm Hg higher SBPs in girls and boys, respectively, in early adolescence (ages 12.8–15.1 years) and 0.40-mm Hg and 0.18-mm Hg higher SBPs, respectively, in late adolescence (ages 15.2–17.0 years). The associations were not attenuated by changes in body mass index, waist circumference, or skinfold thickness in girls during late adolescence. Although weaker, associations were evident in boys during late adolescence, as well as in both girls and boys during early adolescence. These results support prevention of declines in MVPA during adolescence to prevent higher blood pressure in youth. [ABSTRACT FROM PUBLISHER]

Objectives: To describe the prevalence and co-occurrence of lifestyle risk factors for chronic disease by family origin.Design: Cross-sectional analysis.Setting: Multiethnic, low-income, urban neighborhoods in Montreal, Canada.Participants: 2033 adults (42.2% male), mean age 39.7 (standard deviation 6.4) yearsOutcome Measures: Smoking, level of physical activity, dietary habits, body mass index.Methods: Subjects completed self-report questionnaires on sociodemographic characteristics, height, weight, and lifestyle behaviors. We tested family origin (based on language first learned in childhood and country of birth) as an independent correlate of co-occurrence (having at least two lifestyle risk factors) in multivariate logistic regression analyses.Results: The prevalence of smoking and poor diet was highest among participants of French Canadian family origin. Although physical inactivity was uniformly high across family origins, it was highest among participants of Portuguese, Italian, and Haitian family origin. Obesity was highest among Europeans. The prevalence of smoking was lowest among Haitians; poor diet was lowest among South Asians; and physical inactivity was lowest among Eastern Europeans. Obesity was lowest among Asians, with the exception that 55.9% of South Asians were overweight or obese. Relative to French Canadians, adults in all other family-origin groups had a lower risk of co-occurrence of lifestyle risk factors. Adults of Asian family origin had the lowest prevalence of co-occurrence of lifestyle risk factors.Conclusion: Variation in the distribution of lifestyle risk factors may explain in part differences in chronic disease morbidity and mortality across ethnic groups. Prevention programs should take differential distribution of lifestyle risk factors by ethnicity into account. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Findings from prospective studies on associations between physical activity and adiposity among youth are inconsistent. Our aim was to describe physical activity trajectories during secondary school and examine the association with change in adiposity in youth. Methods: Physical activity was measured in 20 survey cycles from 1999 to 2005; anthropometrics were measured in survey cycles 1, 12, and 19. Individual growth curves modeling moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) were estimated. Estimates of initial level and rate of decline in MVPA and VPA bouts per week were included as potential predictors of body fat% and body mass index using age- and sex-specific linear regression. Results: Complete data were available for 840 and 760 adolescents aged 12–13 years at baseline, followed from survey cycles 1–12 and 12–19, respectively. Among girls, yearly declines of one MVPA and one VPA bout per week during earlier adolescence were associated with increases of 0.19 (95% confidence interval [CI], 0.02–0.36) and 0.47 (95% CI, 0.015–0.92) units of body fat%, respectively. In boys, a yearly decline of one MVPA bout per week was associated with an increase of 0.38 (95% CI, 0.05–0.70) units of body fat% during later adolescence. Conclusions: Obesity prevention programs should include strategies to prevent declines in physical activity. [Copyright &y& Elsevier]