Screen time viewing behaviors and isometric trunk muscle strength in youth

A Cross-Sectional Investigation of Preadolescent Cardiometabolic Health: Associations with Fitness, Physical Activity, Sedentary Behavior, Nutrition, and Sleep

BACKGROUND

Cardiometabolic disease (CMD) risk often begins early in life. Healthy lifestyle behaviors can mitigate risk, but the optimal combination of behaviors has not been determined. This cross-sectional study simultaneously examined the associations between lifestyle factors (fitness, activity behaviors, and dietary patterns) and CMD risk in preadolescent children.

METHODS

1480 New Zealand children aged 8-10 years were recruited. Participants included 316 preadolescents (50% female, age: 9.5 ± 1.1 years, BMI: 17.9 ± 3.3 kg/m²). Fitness (cardiorespiratory fitness [CRF], muscular fitness), activity behaviors (physical activity, sedentary, sleep), and dietary patterns were measured. Factor analysis was used to derive a CMD risk score from 13 variables (adiposity, peripheral and central hemodynamics, glycemic control, and blood lipids).

RESULTS

Only CRF (β = -0.45, p < 0.001) and sedentary time (β = 0.12, p = 0.019) were associated with the CMD risk score in the adjusted multivariable analysis. CRF was found to be nonlinear (VO₂ max ≤ ≈42 mL/kg/min associated with higher CMD risk score), and thus a CRF polynomial term was added, which was also associated (β = 0.19, p < 0.001) with the CMD risk score. Significant associations were not found with sleep or dietary variables.

CONCLUSION

The findings indicate that increasing CRF and decreasing sedentary behavior may be important public health targets in preadolescent children.

Do school physical activity policies and programs have a role in decreasing multiple screen time behaviours among youth?

Screen time in youth has been associated with a wide range of poor health outcomes. Evidence indicates the need to develop physical activity (PA) school policies and programs that are aimed at decreasing youth screen time behaviours. This study aims to understand the association between PA policies and programs embedded into the functioning of 89 schools across two provinces in Canada and multiple screen time behaviours. As part of the COMPASS Study, a total of 44,861 youth aged between 13 and 18years and belonging to 89 schools in two Canadian provinces completed a validated questionnaire for health behaviours and outcomes data. PA policies and programs were measured using the School Policies and Practices Questionnaire, completed by the relevant school administrator. Participation in before-school, noon hour, or after-school intramural programs, participation in varsity sports, and access to indoor areas of PA during non-instructional time, was associated with significantly lower multiple screen time behaviours across both provinces. With exposure to multiple electronic and digital devices only predicted to increase among youth in the future, there is a need to conceptualize and integrate school-based screen time reducing PA policies and programs into the regular functioning of the schools.

Systematic review of sedentary behaviour and health indicators in school-aged children and youth: an update

This systematic review is an update examining the relationships between objectively and subjectively measured sedentary behaviour and health indicators in children and youth aged 5–17 years. EMBASE, PsycINFO, and Medline were searched in December 2014, and date limits were imposed (≥February 2010). Included studies were peer-reviewed and met the a priori-determined population (apparently healthy children and youth, mean age: 5–17 years), intervention (durations, patterns, and types of sedentary behaviours), comparator (various durations, patterns, and types of sedentary behaviours), and outcome (critical: body composition, metabolic syndrome/cardiovascular disease risk factors, behavioural conduct/pro-social behaviour, academic achievement; important: fitness, self-esteem) study criteria. Quality of evidence by outcome was assessed using the Grading of Recommendations Assessment, Development, and Evaluation framework. Due to heterogeneity, a narrative analysis was conducted. A total of 235 studies (194 unique samples) were included representing 1 657 064 unique participants from 71 different countries. Higher durations/frequencies of screen time and television (TV) viewing were associated with unfavourable body composition. Higher duration/frequency of TV viewing was also associated with higher clustered cardiometabolic risk scores. Higher durations of TV viewing and video game use were associated with unfavourable behavioural conduct/pro-social behaviour. Higher durations of reading and doing homework were associated with higher academic achievement. Higher duration of screen time was associated with lower fitness. Higher durations of screen time and computer use were associated with lower self-esteem. Evidence ranged from “very low” to “moderate” quality. Higher quality studies using reliable and valid sedentary behaviour measures should confirm this largely observational evidence.