The Effect of Swimming During Childhood and Adolescence on Bone Mineral Density: A Systematic Review and Meta-Analysis.

Background: The effects of swimming on bone mineral density (BMD) have been studied by several researchers, with inconsistent results. Aim: This meta-analysis aims to determine whether systematic swimming training may influence BMD during childhood and adolescence. Methods: A systematic search was performed in PubMed, SPORTDiscus and ClinicalTrials.gov from the earliest possible year to March 2015, with data extraction and quality assessment performed independently by two researchers following the PRISMA methodology. Swimmers were compared to sedentary controls and to athletes performing highly osteogenic sports. Therefore, a total of two meta-analyses were developed. Results: Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to sedentary controls and lower than other high-impact athletes. Femoral neck and lumbar spine BMD differences between swimmers and sedentary controls and between swimmers and athletes practicing osteogenic sports appeared to increase with age and favored the non-swimming groups. There were no differences by sex. Conclusion: While swimming is associated with several health benefits, it does not appear to be an effective sport for improving BMD. Swimmers might be in need of additional osteogenic exercises for increasing BMD values. [ABSTRACT FROM AUTHOR]