Years of running, chronic diseases, and allergies are associated with gradual onset Achilles tendon injuries in 61,252 running race entrants: SAFER XXXIX study

Background Gradual‐onset Achilles tendon injuries (GoATIs) in runners are common. Data show that chronic diseases are associated with GoATI. Objective To determine risk factors associated with a history of GoATIs among long‐distance runners (21.1 and 56 km) entering a mass community‐based running event. Methods Online pre‐race medical screening questionnaire data from 76,654 consenting Two Ocean Marathon race entrants (71.8% entrants) were collected prospectively over 4 years (2012–2015); this cross‐sectional study is a retrospective analysis of these data. A total of 617 entrants (0.8%) reported a GoATI in the last 12 months; 60,635 entrants reported no history of any running injury (controls). Categories of factors associated with GoATI were explored (univariate and multiple regression analyses): demographics (age group, sex, race, distance), training/racing history, and history of allergy, history of chronic disease, and Composite Chronic Disease Score. Prevalence and prevalence ratios (PRs; 95% CI) are reported. Results Factors associated with a higher prevalence of a history of GoATI (univariate analysis vs. controls) were older age (>31 years) ( p < .001), male sex (PR = 1.76; p < .001), and longer race distance (56 km vs. 21.1 km) (PR = 2.06; p < .001). Independent factors associated with a history of GoATI (multiple regression) were increased years of recreational running (PR = 1.17 for every 5‐year increase, p < .001), higher Composite Chronic Disease Score (PR = 2.07 for every 2‐unit increase, p < .001), and allergy history (PR = 1.98 p < .001). Conclusion Novel independent factors associated with a history of GoATI in distance runners were increased years of recreational running, chronic disease history, and allergy history. Runners at risk for GoATI could be targeted for injury prevention interventions. Future studies should focus on establishing a causal relationship.