What are the main risk factors for running-related injuries?

BACKGROUND Despite several studies that have been conducted on running injuries, the risk factors for running-related injuries are still not clear in the literature. OBJECTIVE The aim of this study was to systematically review prospective cohort studies that investigated the risk factors for running injuries in general. DATA SOURCES We conducted electronic searches without restriction of language on EMBASE (1980 to Dec 2012), PUBMED (1946 to Dec 2012), CINAHL (1988 to Dec 2012) SPORTDiscus (1977 to Dec 2012), Latin American and Caribbean Centre on Health Sciences Information (1985 to Dec 2012) and Scientific Electronic Library Online (1998 to Dec 2012) databases, using subject headings, synonyms, relevant terms and variant spellings for each database. STUDY SELECTION Only prospective cohort studies investigating the risk factors for running-related musculoskeletal injuries were included in this review. Two independent reviewers screened each article and, if they did not reach a consensus, a third reviewer decided whether or not the article should be included. STUDY APPRAISAL AND SYNTHESIS METHODS Year of publication, type of runners, sample size, definition of running-related musculoskeletal injury, baseline characteristics, reported risk factors and the statistical measurement of risk or protection association were extracted from the articles. A scale adapted by the authors evaluated the risk of bias of the articles. RESULTS A total of 11 articles were considered eligible in this systematic review. A total of 4,671 pooled participants were analysed and 60 different predictive factors were investigated. The main risk factor reported was previous injury (last 12 months), reported in 5 of the 8 studies that investigated previous injuries as a risk factor. Only one article met the criteria for random selection of the sample and only six articles included a follow-up of 6 months or more. There was no association between gender and running injuries in most of the studies. LIMITATIONS It is possible that eligible articles for this review were published in journals that were not indexed in any of the searched databases. We found a great heterogeneity of statistical methods between studies, which prevented us from performing a meta-analysis. CONCLUSIONS The main risk factor identified in this review was previous injury in the last 12 months, although many risk factors had been investigated in the literature. Relatively few prospective studies were identified in this review, reducing the overall ability to detect risk factors. This highlights the need for more, well designed prospective studies in order to fully appreciate the risk factors associated with running.