No abstract

Author contributorship: Carel T. Viljoen -Conception and design of the study, literature search, review of literature for final inclusion of relevant studies, data extraction, level of evidence rating of included studies, quality assessment of included studies, data interpretation, manuscript write-up, manuscript editing Dina C. Janse van Rensburg -Conception and design of the study, review of literature for final inclusion of relevant studies, data extraction, manuscript editing Evert Verhagen -Conception and design of the study, review of literature for final inclusion of relevant studies, data extraction, manuscript editing Willem van Mechelen -Manuscript editing Rita Tomas -Data extraction, manuscript editing Marlene Schoeman -Data extraction, manuscript editing, level of evidence rating of included studies Susan Scheepers -Literature search, manuscript editing Elzette Korkie -Quality assessment of included studies, manuscript editing Data sharing statement: No additional data are available Funding: None Conflict of interests:The authors declare that there are no conflict of interests.

Introduction-Trail running is characterized by elevation changes, with uneven and varying running surfaces. Risk factors that may predict gradual-onset running-related injuries (GORRIs) in short-distance trail running have not been explored. The objective was to determine risk factors that predict GORRIs in trail running race entrants who entered mass community-based trail running events.Methods-In this descriptive cross-sectional study, data were collected prospectively from a prerace medical screening questionnaire over 4 trail run events held annually. Using a Poisson regression model, runner demographics, race distance, running training/racing variables, history of chronic diseases (number of chronic diseases reported as a cumulative "chronic disease composite score"), and allergies were investigated to determine factors predicting self-reported GORRI history in the previous 12 mo.Results-This study included 2824 race entrants (80% of entrants). The retrospective annual incidence for GORRIs was 13%. Independent risk factors predicting GORRIs were longer race distance (P<0.0001), increasing chronic disease composite score (P=0.0012), and a history of allergies (P=0.0056). The lower limb (94%) was the main anatomic region of GORRIs, and soft tissue injuries accounted for most (83%) GORRIs. Common specific GORRIs were iliotibial band syndrome (22%), Achilles tendon injury (10%), and hamstring injury (9%).Conclusions-Independent risk factors predicting GORRIs among trail running entrants included longer race distance, a higher chronic disease composite score, and a history of allergies. This study has highlighted trail running race entrants at risk for sustaining GORRIs who could be targeted for future injury prevention interventions.