Comparison of ActiGraph GT3X+ and Actical accelerometer data in 9-11-year-old Canadian children.

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Associations between sleep patterns and lifestyle behaviors in children: an international comparison.

OBJECTIVES: Although evidence is accumulating on the importance of a good night's sleep for healthy eating and activity behaviors, existing research has mainly been conducted in high-income, developed countries with limited sociocultural variability. This study is the first to examine the associations between sleep patterns and lifestyle behaviors in children from 12 countries in five major geographic regions of the world. METHODS: This observational, multinational cross-sectional study included 5777 children aged 9-11 years from sites in Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom and the United States. Nocturnal sleep duration (hours per night), sleep efficiency (%) and bedtime (h:min) were monitored over 7 consecutive days using an accelerometer. Lifestyle behaviors included moderate-to-vigorous physical activity (MVPA), total sedentary time (SED), self-reported screen time (ST) and healthy/unhealthy diet patterns (HDP/UDP). Multilevel modeling analyses were used to account for the hierarchical nature of the data. RESULTS: Overall, participants averaged 8.8 (s.d. 0.9) hours of sleep with 96.2% (s.d. 1.4) sleep efficiency and a mean bedtime of 2218 hours. After adjustment for age, sex, highest parental education and BMI z-score, results showed that (i) sleep duration was negatively associated with MVPA, SED and UDP score; (ii) sleep efficiency was negatively associated with MVPA and UDP score, and positively associated with SED; and (iii) later bedtime was positively associated with SED, ST and UDP score, and negatively associated with MVPA and HDP score. Results using categories of sleep patterns were consistent with the linear associations. Results also revealed that associations between sleep patterns and MVPA, SED and ST were significantly different between study sites, with stronger associations in high-income countries compared with low/middle-income countries. CONCLUSIONS: Sleep characteristics are important correlates of lifestyle behaviors in children. Differences between countries suggest that interventions aimed at improving sleep and lifestyle behaviors should be culturally adapted.

Are participant characteristics from ISCOLE study sites comparable to the rest of their country?

OBJECTIVES: The International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) provides robust, multi-national information on physical activity, diet and weight status in 9-11-year-old children around the world. The purpose of this analysis was to examine the similarities and differences between participant characteristics from ISCOLE sites and data from nationally representative surveys from ISCOLE countries (Australia, Brazil, Canada, China, Colombia, Finland, Kenya, India, Portugal, South Africa, the United Kingdom and the United States). METHODS: Distributions of characteristics were assessed within each ISCOLE country-level database, and compared with published data from national or regional surveys, where available. Variables of comparison were identified a priori and included body mass index (BMI), physical activity (accelerometer-determined steps per day) and screen time (child-report). RESULTS: Of 12 countries, data on weight status (BMI) were available in 8 countries, data on measured physical activity (steps per day) were available in 5 countries and data on self-reported screen time were available in 9 countries. The five ISCOLE countries that were part of the Health Behaviour in School-aged Children Survey (that is, Canada, Finland, Portugal, the United Kingdom (England) and the United States) also provided comparable data on self-reported physical activity. Available country-specific data often used different measurement tools or cut-points, making direct comparisons difficult. Where possible, ISCOLE data were re-analyzed to match country-level data, but this step limited between-country comparisons. CONCLUSIONS: From the analyses performed, the ISCOLE data do not seem to be systematically biased; however, owing to limitations in data availability, data from ISCOLE should be used with appropriate caution when planning country-level population health interventions. This work highlights the need for harmonized measurement tools around the world while accounting for culturally specific characteristics, and the need for collaboration across study centers and research groups.

Objectively measured physical activity, sedentary time and sleep duration: independent and combined associations with adiposity in canadian children.

OBJECTIVE: To examine independent and combined associations among objectively measured movement/non-movement behaviors (moderate-to-vigorous-intensity physical activity (MVPA), total sedentary time and sleep duration) and adiposity indicators in a sample of Canadian children. METHODS: A cross-sectional study was conducted on 507 children aged 9-11 years from Ottawa, Canada. Movement/non-movement behaviors were assessed using an Actigraph GT3X+ accelerometer over 7 days (24-h protocol). Outcomes included percentage body fat (bioelectrical impedance) and waist-to-height ratio. RESULTS: After adjustment for age, sex, ethnicity, maturity offset, fast food consumption, annual household income and highest level of parental education, MVPA was inversely and sedentary time positively associated with adiposity indicators, whereas sleep duration was not. However, only MVPA remained significantly associated with adiposity indicators after additional adjustment for the other movement/non-movement behaviors. Combined associations using tertiles of the three movement/non-movement behaviors showed that higher levels of MVPA were associated with lower adiposity indicators, irrespective of total sedentary time and sleep duration. CONCLUSIONS: Higher levels of MVPA were associated with lower adiposity in this sample of children regardless of sedentary time and sleep duration. Although correlational in nature, these findings suggest that future efforts of obesity reduction should focus more on increasing MVPA than on reducing sedentary time or increasing sleep duration to maximize the effectiveness of interventions.