Habitual Physical Activity and Bone Growth and Development in Children and Adolescents: A Public Health Perspective

Abstract

During the growing years, habitual physical activity contributes to bone strength by increasing bone material mass and improving structure. In fact, the effect of physical activity to bone mass is similar (after puberty) or higher (before the end of puberty) to the effect of the antireabsortive therapy observed in the adult population with osteoporosis. An advantage of physical activity to antireabsortive therapy is that the bone mass increases associated with physical activity usually occur in bone regions that are strategic to bone strength, where the mechanical demands are the greatest, taking into account the structural diversity of the bone. However, in primary school, more than 50% of the children are not sufficiently active to fully achieve this and other health benefits, and the percentage of not sufficiently active youth is even higher in elementary and secondary schools. Throughout the critical growing years, girls have lower levels of physical activity than boys. Efforts should be made to evaluate, educate, and motivate children and adolescents to increase their physical activity, particularly within school settings where they spend so much of their time. All school-based physical activity interventions should be focused not only on obesity prevention (energy expenditure) but also on bone strength (mechanical loading). Activities with a high-intensity mechanical load (activities including jumping), with the duration of 10–15 min per day, 2–3 times a week, or with lower mechanical intensity (activities including jogging and running), 30–40 min per day, everyday, seem to be effective for optimizing bone health. When taking into account other ways in which physical activity impacts health, particularly obesity prevention, children and adolescents should accumulate 60 min per day of physical activity of at least moderate intensity as specified by the World Health Organization.