Relationships between Objectively Measured Physical Activity and Health Indicators in School-Aged Children and Youth

PURPOSE: Moderate-to-vigorous physical activity (MVPA) is an accepted strategy for disease prevention and health promotion. Emerging evidence suggests that other intensities of physical activity (PA), including light-intensity (LPA), may also be important in this regard, but there has been no rigorous evaluation of the evidence. Therefore, the purpose of this review was to examine the relationships between objectively measured PA (total and all intensities) and health indicators in children and youth. METHODS: Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, aged 5-17 years), intervention/exposure and comparator (volumes, durations, frequencies, and intensities of objectively measured PA), and outcome (adiposity, cardiometabolic biomarkers, fitness, behavioural conduct/pro-social behaviour, cognition/academic achievement, quality of life/well-being, harms, bone health, motor development, psychological distress, self-esteem). Quality of evidence was assessed using the GRADE framework. Heterogeneity precluded meta-analyses; narrative synthesis of included studies was conducted. RESULTS: 162 publications were included (85,532 participants from 31 countries). Overall, there was strong, consistent evidence that total PA (greater durations and intensities) was favourably associated with adiposity, fitness, cognition/academic achievement and bone health; weaker evidence of favourable relationships with cardiometabolic biomarkers and motor development; and little evidence regarding other outcomes. LPA was favourably associated with several cardiometabolic biomarkers; there was a paucity of data in relation to other outcomes. Evidence quality was very low to moderate. CONCLUSION: These findings continue to support the importance of MVPA for health promotion and disease prevention in children and youth, but also highlight the potential benefits of LPA and total PA. All intensities of PA should be considered in future work aimed at better elucidating the health benefits of PA in children and youth. Funded by: Canadian Society for Exercise Physiology, Conference Board of Canada, Healthy Active Living and Obesity Research Group at the CHEO Research Institute, Public Health Agency of Canada.