Combined effects of physical activity and calcium on bone health in children and adolescents: a systematic review of randomized controlled trials

Background: A better understanding of the role of exercise and nutrition in bone health is significant for preventing osteoporosis. The aim of this review was to assess the combined effects of physical activity and calcium intake on improving bone mineral density in children and adolescents. Methods: A search of electronic databases (MedLine, ISI Web of Science, Science Direct) and the literature references were performed. Randomized controlled trials published between 1997 and 2017, evaluating the effect of both physical activity and calcium intake intervention on bone mineral density or bone mineral content among children aged 3–18 years were selected. The Improved Jadad Rating Scale was used to assess the methodological quality of the included studies. Study characteristics were summarized in accordance with the review’s PICO criteria. Changes in bone mineral content were detected at several different bone sites. Results: A total of nine studies involving 908 participants were included in this review. The combined intervention of physical activity and calcium increased bone mineral in children and adolescents, especially when baseline calcium intake level was low and among participants on the stage of early puberty. Conclusions: Regular physical activity combined with high level of calcium intake is beneficial for bone health in young population. Further research is needed to evaluate the dose–response associations and long-term effects of the interaction between physical activity and calcium intake.