Is competitive swimming training a risk factor for osteoporosis? A systematic review of the literature and quality of evidence

Introduction Due to the controversy regarding bone health in swimmers compared to weight-bearing athletes, the aim of this work was to comprehensively analyze the effect of swimming on bone mass, cortical geometry, and trabecular microarchitecture as well as to assess the methodological quality of the available evidence. Methods A systematic literature search was conducted on PubMed and Scopus following the PICOS (Participants, Interventions, Comparators, Outcome and Study) strategy and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Forty-one studies were included and screened with Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies for determining their quality of evidence. Results Swimmers’ bone mass tended to be lower compared to athletes engaged in high-impact sports, but similar compared to moderate- and non-impact sports as well as non-athletes, independently of gender and anatomical region assessed. Swimmers’ cortical geometry and trabecular microarchitecture tended to be similar to that of both athletes, independently of their impact loading profile, and non-athletes. Results were, nevertheless, based on studies with only a poor to fair quality of evidence, with most of them displaying a serious risk of bias. Conclusions No high-quality evidence was found suggesting that swimmers could be a population at risk of developing osteopenia or osteoporosis later in life. There is no evidence that swimming negatively compromises bone mass accrual, cortical bone geometry, or trabecular microarchitecture.