Background: Physical activity has many health benefits for young people. In 2018, WHO launched More Active People for a Healthier World, a new global action on physical activity, including new targets of a 15% relative reduction of global prevalence of insufficient physical activity by 2030 among adolescents and adults. We describe current prevalence and trends of insufficient physical activity among school-going adolescents aged 11-17 years by country, region, and globally.

Methods: We did a pooled analysis of cross-sectional survey data that were collected through random sampling with a sample size of at least 100 individuals, were representative of a national or defined subnational population, and reported prevalence of of insufficient physical activity by sex in adolescents. Prevalence had to be reported for at least three of the years of age within the 10-19-year age range. We estimated the prevalence of insufficient physical activity in school-going adolescents aged 11-17 years (combined and by sex) for individual countries, for four World Bank income groups, nine regions, and globally for the years 2001-16. To derive a standard definition of insufficient physical activity and to adjust for urban-only survey coverage, we used regression models. We estimated time trends using multilevel mixed-effects modelling.

Findings: We used data from 298 school-based surveys from 146 countries, territories, and areas including 1·6 million students aged 11-17 years. Globally, in 2016, 81·0% (95% uncertainty interval 77·8-87·7) of students aged 11-17 years were insufficiently physically active (77·6% [76·1-80·4] of boys and 84·7% [83·0-88·2] of girls). Although prevalence of insufficient physical activity significantly decreased between 2001 and 2016 for boys (from 80·1% [78·3-81·6] in 2001), there was no significant change for girls (from 85·1% [83·1-88·0] in 2001). There was no clear pattern according to country income group: insufficient activity prevalence in 2016 was 84·9% (82·6-88·2) in low-income countries, 79·3% (77·2-87·5) in lower-middle-income countries, 83·9% (79·5-89·2) in upper-middle-income countries, and 79·4% (74·0-86·2) in high-income countries. The region with the highest prevalence of insufficient activity in 2016 was high-income Asia Pacific for both boys (89·0%, 62·8-92·2) and girls (95·6%, 73·7-97·9). The regions with the lowest prevalence were high-income western countries for boys (72·1%, 71·1-73·6), and south Asia for girls (77·5%, 72·8-89·3). In 2016, 27 countries had a prevalence of insufficient activity of 90% or more for girls, whereas this was the case for two countries for boys.

Interpretation: The majority of adolescents do not meet current physical activity guidelines. Urgent scaling up of implementation of known effective policies and programmes is needed to increase activity in adolescents. Investment and leadership at all levels to intervene on the multiple causes and inequities that might perpetuate the low participation in physical activity and sex differences, as well as engagement of youth themselves, will be vital to strengthen the opportunities for physical activity in all communities. Such action will improve the health of this and future young generations and support achieving the 2030 Sustainable Development Goals.

Funding: WHO.