Physical Activity Level During Adolescence—Possible Ways to Apply the Knowledge Gathered

Elhakeem et al¹ observed that a higher level of physical activity during adolescence was associated with higher hip bone mineral density (BMD) at age 25 years. More specifically, adolescents who spent more time in moderate to vigorous–intensity physical activity had higher BMD at age 25 years, whereas the associations between light-intensity physical activity and BMD were less consistently observed. Using data from the Avon Longitudinal Study of Parents and Children, the authors monitored a considerable number of participants throughout adolescence (ages 12, 14, and 16 years) to young adulthood (age 25 years), identifying 3 patterns of light-intensity and moderate to vigorous–intensity physical activity. In our interpretation, there is 1 key message in this study: a higher intensity of physical activity during adolescence, especially early adolescence, plays an important role in later BMD.

The study by Elhakeem et al¹ adds another piece of knowledge to the body of evidence in favor of a physically active lifestyle during adolescence. It is generally accepted that a higher level of physical activity is associated with better metabolic and mental health during adolescence and later in life. Nevertheless, the rates of insufficient physical activity (<60 minutes per day of moderate to vigorous–intensity activity) continue to be high among adolescents (77.6% in boys and 84.7% in girls).² Although some interventions have been associated with increases in the level of adolescent physical activity, scaling up interventions is not an easy and straightforward task.

One of the possible barriers to scaling up successful interventions is the cooperation, or lack of it, between researchers and policy makers.³ On the one hand, researchers are not trained to cooperate and communicate with politicians; scientific reports are rarely accessible or comprehensible to nonresearchers, and economic evaluations, in which public sector involvement is important, are not always conducted. Online platforms, such as Twitter and Facebook, have shortened the distance between scientists and society, but technical reports designed for governmental departments could strengthen the cooperation between researchers and the public sector. On the other hand, policy makers do not always seek support from scientists to evaluate new and ongoing programs that are focused on increasing the physical activity level of the population.³ A thorough evaluation of existing programs would possibly enhance their effectiveness and outreach and provide a rationale for public costs and investment.

The involvement of adolescents, parents, family, and school faculty and staff in the research design and dissemination of programs might increase the chance of success in scaling up physical activity interventions for adolescents.⁴ Patient and public involvement is becoming more common, and scientific journals are encouraging researchers to consider including the community in different phases of research. Patient and public involvement might improve the quality and relevance of research. Empowering the target group and the society might enhance the implementation and sustainability of the intervention, assisting in the process of scaling up.

Initiatives often do not succeed in scaling up physical activity interventions because of problems with implementation.^3,4 Therefore, it is important to conduct implementation evaluations during all phases of the process, which already occurs in pilot studies, to guarantee that the protocol will be properly implemented and identify the aspects of the protocol that need improvement. In addition, a certain flexibility in the intervention protocol is desirable in large-scale implementation. It is necessary to tailor the intervention protocol to account for the specific characteristics of the community because adaptation to the local setting may improve the success of the implementation.⁴ In this sense, the consideration of socioeconomic characteristics, such as family income, is essential.

Evaluation of the mechanisms underlying the association of interventions with increases in the physical activity level of adolescents is often not conducted.⁵ Mediation analyses have been increasingly used and may help to propose theoretical models and investigate associations. Nevertheless, studies should be adequately powered and designed to estimate the association of mediation with changes that occur owing to the intervention. A deeper understanding of the factors that mediate the changes associated with the intervention may identify weaker areas, enhancing the intervention’s results and outreach and increasing the chances of success in scaling up.⁴

Although we listed several barriers, the fact that most adolescents, even those in lower-income countries, are enrolled in the school system⁶ is a major strength in the scaling-up of interventions aiming at increasing the physical activity level of adolescents. Moreover, interventions could be tailored to address other health issues, boosting the investment involved. It is important to highlight that adolescents may spend less time at school in lower-income countries and may have specific needs that should be taken into account when implementing successful protocols in lower-income settings.

Adolescence is a critical period during which behaviors are incorporated and reproduced over a lifetime. Physically active adolescents are more likely to become physically active adults who are less susceptible to all-cause mortality.⁷ Thus, it is important to increase the physical activity level of the adolescent population.

It is time to join forces and test protocols to increase the levels of adolescent physical activity in different communities and regions. Interventions will only be embedded in society by becoming public policy, and the school setting is the ideal location to implement and scale up interventions targeting physical activity and health in adolescents. The involvement of society and the public sector is another important element, especially regarding program adherence. It is hard to imagine that researchers alone will be able to scale up interventions without the support of the public sector and the involvement of the community.

Published: August 17, 2020. doi:10.1001/jamanetworkopen.2020.13900

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Lima RA et al. JAMA Network Open.

Corresponding Author: Rodrigo Antunes Lima, PhD, Institute of Sport Science, University of Graz, Mozartgasse 14, Graz 8010, Austria (rodrigoantlima@gmail.com).

Conflict of Interest Disclosures: None reported.